Electronics General - /ohm/

[Anonymous No.708779]

Old thread:
>>698995

>I'm new to electronics, where do I get started?

There are several good books that are commonly recommended for beginners and those wanting to learn more. There are also plenty of good Youtube channels that teach about the basics as well as advanced concepts. The best way to get involved in electronics is just to make stuff. Don't be afraid to get your hands dirty. Take something apart or build something you find cool on one of the many electronics websites.

>What books are there?

Beginner:

Getting Started in Electronics by Forrest Mims III
Make: Electronics by Charles Platt
How to Diagnose and Fix Everything Electronic by Michael Jay Greier

Intermediate:

All New Electronics Self-Teaching Guide by Harry Kybett, Earl Boysen
Practical Electronics for Inventors by Paul Scherz and Simon Monk

Advanced:

The Art of Electronics by Paul Horowitz

>What Youtube channels are there?

https://www.youtube.com/user/EEVblog
https://www.youtube.com/channel/UChturLXwYxwTOf_5krs0qvA
https://www.youtube.com/channel/UCosnWgi3eorc1klEQ8pIgJQ
https://www.youtube.com/channel/UChtY6O8Ahw2cz05PS2GhUbg
https://www.youtube.com/channel/UC1rxMIOt82ieNE19w15U5YQ

>What websites feature electronics projects? Where can I get ideas for projects?

https://www.adafruit.com/
http://www.instructables.com/tag/type-id/category-technology/
http://makezine.com/category/electronics/

>Where do I get components and lab equipment from?

http://www.jameco.com/
https://www.sparkfun.com/
http://www.ramseyelectronics.com/
http://www.allelectronics.com/
http://futurlec.com/
http://www.ladyada.net/library/procure/hobbyist.html
http://www.mouser.com
http://www.alliedelec.com
http://www.newark.com
And sometimes even just ebay.

>What circuit sim software do you use?

This mostly comes down to personal preference. These are the most common ones though:

NI Multisim
LTSpice
CircuitLab
iCircuit for Macs

>What software should I use to print circuits

Circuit Wizard
ExpressPCB
EAGLE

[Anonymous No.708810]

This should be added to the sticky

[Anonymous No.708812]

>>708779
How could you forget Jeri Ellsworth? The queen of electronics

[Anonymous No.708823]

>>708812

>ermagerd a girl who can do electronics and isn't awful looking

She's not bad, average in talent like almost all people on YouTube. But she's a she so she'll be popular

[Anonymous No.708834]

>>708823
>>708823
>ermagerd a girl who can do electronics and isn't awful looking

How could you possibly infer that from a simple sentence like "How could you forget Jeri Ellsworth? The queen of electronics"? Projecting your own biases much?

[Anonymous No.708836]

>>708834

>Queen of electronics

That's what I got it from. She's not bad, bettrr at electronics than me, I'll happily admit that. But queen is silly.

[Anonymous No.708838]

>>708836

>bettrr

She'd be better at spelling too I imagine.

And all you folks are forgetting Photonicinduction for inspiration.

[Anonymous No.708839]

If I had 10 capacitors rated at 10 volts each ( arbitary number ) wired in series to allow 100 volts overall then how would I prevent blowing a cap over the entire capacitor bank?

[Anonymous No.708841]

>>708839

Balancing resistors bro. Work out how fast the capacitors need to charge, then how long they need to stay charged for and select a value based on that.

[Anonymous No.708844]

I need a 555 to be able to maintain it's duty cycle while changing the frequency with a pot resistor.

How do I do this? Bonus points if someone tells me how to easily adjust the duty cycle on the go too.

Ideally I want an ultrasonic frequency between 20 and 30 kHz and the duty cycle should be anything between 50 and 70%.

[Anonymous No.708845]

>>708839

you're better off just getting one cap rated at 100 volts

[Anonymous No.708851]

>>708844

Is this good enough?, or the duty cycle will vary with the resistance in the pot?

[Anonymous No.708866]

>>708844
My god, i love that picture

[Anonymous No.708880]

What's the difference between a Zener Diode and an avalanche diode?
The seem to have practically the same use.

[Anonymous No.708888]

>>708880
Zener and avalanche diode are terms often used interchangeably.

This is a reference from: http://people.seas.harvard.edu/~jones/es154/lectures/lecture_2/breakdown/breakdown.html

"Avalanche breakdown occurs in lightly-doped pn-junctions where the depletion region is comparatively long.ÝThe doping density controls the breakdown voltage.ÝThe temperature coefficient of the avalanche mechanism is positive.ÝThat is, as the temperature increases, so does the reverse breakdown voltage.ÝThe magnitude of the temperature coefficient also increases with increasing breakdown voltage. For example, the temperature coefficient of a 8.2 V diode is in the range 3 - 6 mV/K while the temperature coefficient of an 18 V diode is in the range ofÝ 12 - 18 mV/K.

"Zener breakdown occurs in heavily doped pn-junctions.ÝThe heavy doping makes the depletion layer extremely thin. So thin, in fact,Ýcarriers canít accelerate enough to cause impact ionization.ÝWith the depletion layer so thin, however, quantum mechanical tunnelingÝ through the layer occurs causing current to flow.ÝThe temperature coefficient of the Zener mechanism is negativeóthe breakdown voltage for a particular diode decreases with increasing temperature.ÝHowever, the temperature coefficient is essentially independent of the rated breakdown voltage, and on the order ofÝ -3 mV/K.

[Anonymous No.708889]

>>708888
To summarize:
The difference is in the doping levels. Zener is heavy doping so the depletion gap is very thin and too close to conduct by ionisation. Avalanche is lightly doped so the gap is bigger and conduction also includes ionisation and they work at higher range of voltages.

[Anonymous No.709047]

>>708779
I'm trying to hook up multiple i2c devices on 1 i2c bus.
The issue is that these devices can only have 2 addresses.
I need high speed so addressing them one at a time is not an option.
What should I do?
I thought about just buying an uC chip for every 2 devices but how would I get the data from the uC to the main controller?
i2c would be taken
spi?
I have the tools for AVR chips, not PIC.

[Anonymous No.709055]

>>708851

Bump for this.

[Anonymous No.709057]

>>708889
In more practical terms: if you buy zener diodes, you get zener diodes, avalanche diodes, mixed mode diodes or even series-connected junction diodes, depending on the voltage rating.
If you buy a component which is specifically marketed as an avalanche diode, it's usually a rectifier diode and avalanche isn't really a part of the intended operation. Their avalanche voltages have usually very loose tolerances as well. The idea is that such diodes are capable of handling random overvoltage spikes in a controlled manner, as long as the spike energy stays within specified limits.

>>709047
You say you don't have time for addressing them one at a time, but you would still prefer having them all on the same bus?
I guess I don't understand your problem, but if you want speed, you could bit-bang multiple 100kHz or 400kHz I2C buses at the same time.
Or if you want to manage with one (hardware?) I2C port, you could use a multiplexer.
Or maybe you could try to find a similar chip with more flexible addressing or more user friendly interface.

[Anonymous No.709059]

>>709057
The i2c slaves are IMU sensors called MPU 6050.
They're fairly cheap and pretty much one of a kind in that price range.
The fuckers don't support SPI so that's out of the question.
Is there any chip out there that does 5 i2c busses on hardware level?

[Anonymous No.709061]

>>709059
5 busses because I need to interface with 10 of them and they support changing the address to another arbitrary one, allowing 2 on the same bus.

[Anonymous No.709095]

>>709055

Turd shaped multiplier related.

[Anonymous No.709109]

>>708810
Seconding this. It should also be added to the wiki, which is quite empty.

[Anonymous No.709162]

Shouldn't we add allaboutcircuits.com?

And what about resources for AVR? There is newbiehack and that sticky post in the AVRFreaks forums with a shitton of links

[Anonymous No.709193]

Needs digikey on the list of places to buy.

[Swifts !WiNDUPyWhk No.709228]

Guys, I need to you to make a choice for me.

a) Play with IR barrier and re-solder my shitty connections
b) Start drawing circuit for LC meter
c) Masturbate and go to bed early

[Anonymous No.709232]

>>709228
All at the same time.

[Anonymous No.709279]

>>709228

I always wanted to build and LC meter but I don't want to spend $30 in an arduino nano + LCD.

Post pics if completed.

[Anonymous No.709303]

Hola people, just a little question, i need to power a 5v coil with a 9v battery, i had the idea of doing it with a 5.1v zener diode (also could use a lm7805, but thats a bit overkill rite?)
Pic related is my idea, my question is, what resistance value should i use?
will the zener diode get fugd when i turn off? (working as a flyback diode? or is that just for HV?) What would be the current drag of all this stuff? Just want you guys to tell me if i'm fucking up.

[Anonymous No.709305]

OP you should add oddwires to the list of places to buy, they always have great prices

[Anonymous No.709309]

>>709303
Also, would a 12v coil work decently with 9v?

[Anonymous No.709325]

>>709303

I've calculated 80 ohms for a 3 volt drop and 50mA of current.

Don't use a zener, use a 4007 like everybody else, I don't even understand why you put it that way. When the coil discharges generates a voltage peak. By placing a diode facing the positive side you redirect that voltage.
Anyway, there's not to much to be damaged in that circuit by a voltage spike.

12v relays usually work fine with 9v, but the circuit will be less efficient.

[Anonymous No.709327]

>>709303
9V batteries are pretty crappy for driving any amount of current.
I suggest driving your 5V coil with three 1.5V batteries instead.
Most 5V relays I have played with work fine with 3V. No need to split the atom here.

[Anonymous No.709328]

>>709325

Forgot to say once you got the right current the relay coil resistance will do the rest to control the current.

[Anonymous No.709334]

>>709303
>>709309

Relay coils are sized for two conflicting goals:

They need to be low enough in resistance that the applied voltage can actuate the contacts quickly.

They need to be high enough in resistance that they don't draw a lot of power.

Too low a resistance and it will actuate fast, but dissipate (waste) a lot of power, if not outright overheat. Too high a resistance and the response of the contacts will be sluggish, which causes accelerated wear, assuming it actuates at all.

As a purely electromechanical device, however, you have much more leeway than you would with a semiconductor. The coils are not sensitive to voltage, only current. Lowering the voltage is not necessary as long as your resistor can adequately limit current (and handle the associated power dissipation), you can drop the zener entirely. However, if your coil's switch is a silicon device of some sort, you should have a flyback diode or RC snubber on it to prevent the back EMF from doing any damage.


Current limiting resistor should be (in your case) 4/5 of the resistance of the coil.

A 9V coil would probably work alright on 12V, although you're going to be generating 1.69x the normal amount of heat.

[Anonymous No.709335]

>>709325
I was thinking about using a zener just to keep the voltage constant (under a specific current)
>>709327
I have a 9v power supply too, so it wouldn't be a problem,
Hmm i think i'm just gonna get both the 12v and the 5v and see how good they work. Thanks guise.
>>709328
I didn't understand this very well, could you rephrase?

[Anonymous No.709345]

>>709334
Thanks! my switch is mechanical, so there would be no need to diode at all then? (be it zener for V regulation or a common for flyback)
This relay wouldn't be in continuos service, and i don't need it to be extremely fast, so I wouldn't mind it getting a bit slow if that makes it less power heavy.

[Anonymous No.709519]

>>709059
Probably, but I've never seen such thing.
If I wanted more hardware I2C ports, I'd check NXP's offers first and consider CPLD or FPGA next.
But like I said, I'd consider bit-banging the ports first, if multiplexing is too slow.

[Anonymous No.709523]

>>709335

Answer to the answer: The zener breaks at 5,1, the battery is at 9, the battery will break through the zenner to ground, overheat and making the circuit to be as useful as a potato.
If you want to achieve a constant voltage use a resistor or a regulator.
Use 4007 diodes for spike voltages, if you don't understand why you should, google it.
>Could you rephrase?

If you apply the right voltage to the zener the coils inner reaistance will do the rest to control the current. This is because the relays are desigbed to use that current when the correct voltage is applied.

A 80 ohms resistor will drop the 9 volts till 5, relay works with 5 so the current will be the specified by the manufacturer for that type of relay.

[Anonymous No.709524]

>>709523
If you apply the right voltage to the *relay*

[Anonymous No.709544]

>>709061
I don't understand why you can't put all ten on one bus.

>>709519
Multiplexing asynchronous hardware is always a lot faster than bit banging, and with an I2C bus you only need to multiplex the clock to get separate buses. Put a cd4051 on the I2C clock line. Now in one tick you can select between eight separate I2C busses.

[Anonymous No.709549]

>>709544
>I don't understand why you can't put all ten on one bus.
If you'd read the thread, it was already explained that the devices don't offer enough address options.

[Anonymous No.709561]

I decided to get a AVR per 2 sensors and wire those up with SPI with a central unit.
It seems the easy way.

[Anonymous No.709566]

I have to make a circuit in the next few weeks for a simple alarm that can be reset using a 555 timer.
Any basic information I can find out for this?

[Anonymous No.709568]

>>709566
Needs more information.

[Anonymous No.709577]

>>709345
>Thanks! my switch is mechanical, so there would be no need to diode at all then?

No, although having a flyback diode would reduce the wear on the contacts of your control switch. However, at currents as low as you're talking about, it's probably not going to make much of a difference.

>>709345
>This relay wouldn't be in continuos service, and i don't need it to be extremely fast, so I wouldn't mind it getting a bit slow if that makes it less power heavy.

You can oversize the resistor to reduce current to just over the amount required by the relay to actuate (check the datasheet for this; it should be there). If you want to save power even further (and keep rapid actuation, too) wire up a switch with a resistor sized to keep current down to the relay's holding current and a pushbutton in parallel that gives the relay its normal power. That way, the coil is supplied only with what it needs to stay closed, but can still actually BE closed by the button. I'm assuming this thing isn't going to be in something that moves around; you risk the relay opening on its own when jarred if you do this in that case.

[Swifts !WiNDUPyWhk No.709593]

Yay, got a working probe for my oscilloscope

[Anonymous No.709705]

>all those component links and no Tayda Electronics

You can even get monthly 10% off codes from their Facebook page for fucks sake.

>linking kikelec, the "i dont ship partial orders or update the quantities on my website so if your order is missing a single component it wont ship for 3-4 months and you wont find out until you email us."

[Anonymous No.709730]

Can anyone recommend a decent variable power supply for under $200? I've been looking, and it seems that most cheaper power supplies are unreliable Chinese clones.

[Anonymous No.709744]

>>709730
To do what ?
The only *decent* ones under that price are the second hand ones.
As for what kind of quality and resolution you're expecting, I don't know.

If you specifically want a NEW "buy once never look back" powersupply, the rigol DP832 has good press. But it's a bit above your budget.

[Anonymous No.709764]

>>708851

I need to know this please. I can't find any 555 configuration like that one.

[Anonymous No.709767]

>>709730
Why don't you make yourself one with a LM317?
It can get a decent amount of current with a good heat sink and it's very easy to configure.
They are like 20W max i think, but you might wire them in parallel.

[Anonymous No.709832]

>>709764

I found what might be the answer after a long time in google:

>"The circuit shown in the next diagram is not an accurate method of producing a 50 percent duty cycle using 555 timers, either bipolar or CMOS types. The circuit can produce a duty cycle that is close to 50 percent but when a load is added to the output of the timer, the voltage drops across its output transistors will increase and the duty cycle will shift."

Happy with it if that's true.

Another thing, can someone recommend me a popular array of Darlington transistors in a chip (4 of them per chip)?, it's for stepper motor driving, so they should be rated 1 amp at least.

I also need a hall effect sensor, so If you know a popular one I'll buy it.

Thanks.

[Anonymous No.710292]

Anyone knows a good free book or internet page to learn about tubes and their applications? i found some old public domain books online but it's not entry level so i don't understand shit.

[Anonymous No.710294]

>>710292
the NJ7P website usually has a description of what the tube was usually used for.
http://www.nj7p.org/Tube.php

[Anonymous No.710298]

I'd like to buy and repair a pinball or arcade machine but have very little experience in such things.

Would this be too overwhelming or just time consuming?

[Anonymous No.710307]

>>710298
just enjoy every minute of it. also learn to use multimeter

[Anonymous No.710316]

>>709832
>Another thing, can someone recommend me a popular array of Darlington transistors in a chip (4 of them per chip)?, it's for stepper motor driving, so they should be rated 1 amp at least.
what you want is called a 'half-H driver'
L293DNE is one that is 36v and 1amp. Jameco has them for $3 each.

if you want bomb-proof, you would probably get better results using individual power transistors: there's ones for fifty cents that are rated for 100 volts and 5 amps. they need to be heat-sinked tho

also consider using a full-H driver. search Google for "L298 driver" for various solutions.

[Anonymous No.710334]

>>710292
How much do you want to know? If it's circuit design, it may actually be easier to learn transistor circuits first, then come back to tubes.

[Anonymous No.710386]

>>710316
Thanks!

[Anonymous No.710410]

>>709832
>>710316
>>710386
You use H-bridges and half-bridge circuit to drive bipolar steppers because you need to run current through the coils in both directions.

Unipolar steppers only run current through the coils in one direction, so you use darligntons. ULN2803 is what I always go with for unipolar steppers. Eight darlingtons on one chip, half an amp on each one.

[Anonymous No.710450]

>>710410
>You use H-bridges and half-bridge circuit to drive bipolar steppers because you need to run current through the coils in both directions.
>Unipolar steppers only run current through the coils in one direction, so you use darligntons.
yea but,,,,,,, a lot of motors are bipolar (they only have four wires) and you can always hook up a unipolar motor in bipolar mode
so a bipolar drive can run either motor type. a unipolar drive cant, so unless you KNOW you need a unipolar driver it is better to avoid it.

if you were running an RC brushless motor with "Y" wiring then a unipolar drive would work.
But then, most RC motors I've looked at seem to be deltas. Outrunner motors can be rewired pretty easily tho. I plan on doing this eventually because RC motors are the only small, high-quality motors I could find at retail prices.

[Anonymous No.710523]

http://www.bitsbox.co.uk/ is a great place to buy components in the UK.

[Anonymous No.710556]

>>709705
There are thousands of suppliers. I just listed the ones off the top of my head, I'll try to include that in the next general.

[Anonymous No.710628]

>>710386

The L293 is giving me problems, I havent bought the L298.

I followed a tutorial in adafruit and my stepper seems to act randomly. It vibrated, made some steps, strange sounds... I managed to run if for 10 seconds several times, all of them the chip was makimg sounds that were getting pitchier and pitchier until the motor stops and is resetted.

Can any fellow arduinofags poimt me the error? Thanks

[Anonymous No.710631]

>>710628

I used this simple code:


#include <Stepper.h>

int in1Pin = 12;
int in2Pin = 11;
int in3Pin = 10;
int in4Pin = 9;
int in5Pin = A0;
int val = 0;

Stepper motor(200, in1Pin, in2Pin, in3Pin, in4Pin);

void setup()
{
pinMode(in1Pin, OUTPUT);
pinMode(in2Pin, OUTPUT);
pinMode(in3Pin, OUTPUT);
pinMode(in4Pin, OUTPUT);
pinMode(in5Pin, INPUT);

motor.setSpeed(5); // I tried different speeds with different results, all of them quite random
}

void loop()
{
val = digitalRead(in5Pin);

if(val==HIGH){

int steps = 20000;
motor.step(steps);

}

}

Also here's the tutorial: https://learn.adafruit.com/adafruit-arduino-lesson-16-stepper-motors/breadboard-layout

[Anonymous No.710636]

>>710631

I'm not totally sure about if I broke the chip or not, tomorrow I'll buy another to check it.

Hopefully the L298 will work and I'll forget about the L293

[Anonymous No.710650]

>>710636

Ok, L293 is fine, I made it work with a smaller motor, I guess the arduino couldn't output 0.7 amps from the +5 pin. This is less powerful than the first one.

https://www.youtube.com/watch?v=ZrKBBFvWp_A

I've discovered this motors are a pain to get right, they seem very sensitive to the voltage applied, and jumping steps is quite common.

How can I fix this? The big motor says 1.9V 0.7 A.

[Anonymous No.710654]

>>710650
The 5v pin on the arduino is connected straight to the power supply, so that's what's not giving you enough current if that's the issue. Another possibility is that you're trying to spin the motor too fast, one of the coils is backwards or disconnected, it's not a 5v stepper, its unipolar, or its a bipolar motor but that library is meant for unipolar .

>>710450
This is correct, but the sequence you need to cycle through for a unipolar stepper isn't the same as bipolar. Some H-bridge chips have a little logic on top of the darlingtons so they aren't capable of it.

[Anonymous No.710855]

>>710654

The motor of the tutorial is bipolar, you can check the specs at their website. I think mine is bipolar too since it only has four wires, two per coil.
I tried all the possible combinations, but all I can get is a small vibration and the shaft gets stuck. I also tried with different speeds, I only managed to make work the smaller stepper.

I think it has to do with excessive voltages or currents, since changing the input of the chip from 5v to 3.3 has drastic effects in the performance, I get better results with 3.3, with 5 the small motor gets stuck, misses steps...

[Anonymous No.710862]

>>710855

Indeed, I tested supplying different voltages to the driver circuit instead of just plugging 5 or 3.3 volts to it. I ended mapping a voltage zone in which the big motor works. There must be a relationship between speed and voltage/current supplied.

[Anonymous No.710878]

You guys probably get this a lot, but what do I do to get into robotics? Is being an expert in EE a prerequisite? What books would I read? What and where would I buy tools to make stuff?

[Anonymous No.710902]

>>710878


>Is being an expert in EE a prerequisite?

Nowadays no, everyone can make robots as long as they have a basic knowledge about electronics and programming, although having an advanced knowledge about electronics does help when overcoming electronic problems or simplifying circuits. (I'm an EE student)

You can start by buying an arduino, their environment is simple but very powerful, and you can easily acquire a advanced programming skills in less than 5-6 months if you practice regularly. Forums, tutorials and related are very useful, I wouldn't recommend you to buy a book about arduino since there are many pdfs and documentation online.

>What and where would I buy tools to make stuff?

That depends, if you live near electronic stores you can buy your components there, many people prefer to buy them on the internet, but I'm too impatient to wait for them. I also use lots of scrap components. >>710628 this beautiful motor comes from a printer.

Once you have mastered your arduino you can get into more complex microcontrollers that allow you to use more advanced programs, or reduce the size of your circuits by using small microcontrollers like AVRs or PICs.

[Anonymous No.710908]

hey I have a simple amplifier running after an arduino with a 2n2222 hooked directly up to a speaker.
if I'd like better performance, do I look for a transistor with a better hfe? what determines its gain in this sort of application?
pic related, disregard the numbers

[Anonymous No.710911]

>>710654
>>710855

You don't run steppers at their rated voltage. You usually run them anywhere from 5-20x that value. Running them at the voltage on their nameplate will get you borderline-inoperable performance.

Additionally, when doing this, they need to be current-limited (via PWM or something else) to keep them from immediately frying themselves.

[Anonymous No.710922]

>>710908

The 3904 is faster than the 2n2222 and it's intended for audio applications, you might get better results with it, but the current limit is set at 200mA I think while the 2222 has 1A max.

>what determines its gain in this sort of application?

The gain is provided by the ratio between currents or voltages that enter the base and currents or voltages that go out the emitter.

>>710911

>Additionally, when doing this, they need to be current-limited (via PWM or something else) to keep them from immediately frying themselves.

That's what I'm doing wrong, I'll try to hook up a LM317 in a current limiting way.

[Swifts !WiNDUPyWhk No.710934]

>>710902
Senpai, I want to learn arduino, AVR and PIC programming, wat do?

I can work with PLC's but that's about where my knowledge ends.

[Anonymous No.710946]

>>710934

You can do what I did, get an arduino, start with the basic functions, combine examples, mix code... until you can make entire programs. Many times I use fragments of other programs adapting them to my needs to avoid having to write lots of lines.

The AVR chips are quite user friendly from what I know, you can program them with the arduino language (using special arduino couplers and libraries) or you can get programmers an program them with specific programs and code, PICs scape from my knowledge, there are a wide range of them for many applications, they are programmed with programmers too (pickit), I think some use C and some use assembly, I don't really know.

[Anonymous No.710963]

>>710908
With only a 10 ohm resistor at the base you're already putting the transistor into saturation. You don't need a transistor with better hfe.

You get higher power through your speaker by increasing the voltage. Current will go up according to ohms law using the speaker resistance. An 8 ohm resistor at 12v is 1.5Amps. Don't go over the max speaker power (amps * voltage). You need to pick a transistor that can handle the current and voltage. 2n222 can only handle 1A 60V, so choose a different one if either of these parameters is too small.

You can also drive your speaker with an H-bridge or Half-Bridge instead of a single transistor. This will double the volume (linearly). Adding decoupling capacitors helps if your battery has a lot of internal resistance.


>>710922
Faster switching will allow for higher frequencies, not improve decibel level. 2N2222 can amplify audio signals with less distortion, but all the guy is doing is running arduino PWM into it, so that doesn't matter.

[Anonymous No.710991]

>>710934
There's a ton of tutorials and links on the AVR Freaks forum. However I'd also suggest picking up a copy of "The C Programming Lanugage" and learning how to program in C on your desktop first.

[Anonymous No.711028]

Good news /ohm/! I finally got my own lab at my university to work on my modular flexible LED monitor concept. It may be slow since we're only a team of 4 at the moment, but it seems promising. I don't want to reveal too many details but I may upload pictures as development progresses.

[Anonymous No.711235]

>>711028

Congratulations.

[Anonymous No.711253]

Anyone got experience with a Teensy?
I want to directly program it, without using the Arduino bootloader. Mostly because I want to learn a bit about ARM.
I can't find any non-Arduino tutorials as to where to start.
I know avrdude can upload HEX files.
But what compiler am I supposed to use?

I have decent experience with the arduino ecosystem but it's feels so detached from the electronics.
Also the Teensy has a DAC

[Anonymous No.711263]

>>711253
>ARM
You mean AVR? You need avr-gcc. Do you have a programmer? For a first step, try writing straight C and use the Arduino bootloader (just paste it into a sketch).

[Anonymous No.711304]

>>711263
No, I mean ARM.
>MK20DX256 32 bit ARM Cortex-M4 72 MHz
To be exact.
I know what avr-gcc is. I don't think that works with ARM.
Basically I need the equivalent to avr-gcc and avrdude for an ARM chip. And a compatible programmer. I don't think I can use an AVR programmer.

[Anonymous No.711442]

>>711304
For the toolchain, see eg. https://launchpad.net/gcc-arm-embedded
Get a decent, cheap and supported JTAG/SWD interface like the ST-Link V2. Use OpenOCD to sit between gdb and the JTAG dongle.

[Anonymous No.711477]

>>710654

I finally made the stepper motor work with a great range of speeds by adjusting the current to 0.7 Amps with an LM317. But it heats quite a lot.

>TL:DR I need a way to adjust a the current to 0.7 amps, LM317 heats too much.

[Anonymous No.711481]

>>711477
Reduce supply voltage and/or bolt it on a heatsink. Or use some other method of current limiting.

[Anonymous No.711496]

Quick question
Why are resistors rated with watts and not amps?
Isn't the amp responsible for heating up the thing?
Am I missing something here?

[Anonymous No.711497]

>>711496
You're missing the convenience. Well, one kind of convenience. The maximum allowable power dissipation is dependent on resistor size, materials and shape. Thus, resistors of certain size, made in certain way, have all (roughly) the same maximum power dissipation.

[Anonymous No.711502]

>>711481

I can't reduce the input voltage because that is what I want, more voltage means more speed and torque control. I already have a heat sink. I need a more efficient way to regulate the current, the LM317 leaks about 0.7 Watts of power.

[Anonymous No.711504]

>>711502
Doesn't the LM317 limit the current by cutting of voltage?

[Anonymous No.711512]

>>711504

Indeed, just checked with my multimeter, sorry for being a retard, the voltage is constant at 4.2 with low speeds. I can't get it to work at higher speeds because the current starts to drop and the voltage rises even though the LM317 is conected, I don't know exactly why this happens.

[Anonymous No.711515]

>>711504

Indeed, just checked with my multimeter, sorry for being a retard, the voltage is constant at 4.2 with low speeds. I can't get it to work at higher speeds because the current starts to drop even though the LM317 is connected, I don't know exactly why this happens, maybe I overpass the capabilities of the LM317.

[Anonymous No.711517]

>>711515
Heat increases resistance in motors.

[Anonymous No.711520]

>>711517

>Heat increases resistance in motors.

The motor is cool all the time, it has 2 ohms per coil, so it can't rise too high, unless I see smoke coming out of it.

I'll just keep trying.

[Anonymous No.711521]

>>711502
Which is the input voltage?

[Anonymous No.711528]

>>711521

See.

>>711504
>>711515

Now the input is about 7 volts, doesn't overheats. I guess with that speed is enough, I haven't tried to make the L298 driver yet, so I have another option just in case.

[Anonymous No.711531]

>>711528
Can you now use the motor with high speeds or it just works with low speeds?

[Anonymous No.711539]

>>711531

This is normal speed and normal torque, if I go a bit faster it starts to lose a lot of torque and eventually gets stuck. The stepper is from a printer with no gears, just a belt, so it should reach a reasonable speed.

https://www.youtube.com/watch?v=5AycGjwckMc

Also it makes a small sound every rotation, like tappings, you can feel like bumps or taps when you're holding it with the hand, with smaller speeds doesn't happens. I don't know if this is normal.

[Anonymous No.711540]

>>711539

Well, it's actually like 2 or 3 bumps per rotation.

[Anonymous No.711712]

I'm thinking about sticking two of those batteries (https://www.adafruit.com/products/2011)) in the UMD compartment and one of this (https://www.sparkfun.com/products/339)) in the battery compartment, all connected in parallel.
Will it be alright? I will probably make a new hole or rewire the current power port to charge the batteries safely from a correct charger rather than the normal PSP charger.

Also, I'm doing this so I can have a PSP with 5000mAh rather than 1200mAh.

[Anonymous No.711730]

>>711502
> I can't reduce the input voltage
Yes you can. The LM317 is lowering the voltage. Stepper is drawing less current because you've lowered the voltage. Instead of using the LM317 start with a lower voltage supply or use a more efficient switching regulator instead of a dropout circuit.

[Anonymous No.711745]

>>711712
You would have to treat the batteries as cells.
But the different sizes might be a problem. Also you must never connect the PSP on the standard port. You would be stuck with the custom charger and you would have to disconnect the batteries if you wanted to use power from the wall.
All in all, not worth it. Just get a big battery.

[Anonymous No.711760]

>>711745
I can't really find a big battery with the proper size, it's 7mm deep.

[Anonymous No.711765]

>>711730

The motor can run at 4 volts, if I use more it gets stuck, loses steps..., it is more consistent with a constant current of 0,7 amps regulated by the LM317.

[Anonymous No.711798]

>>709767
No, you just use pass transistors. It's much cheaper and you can get basically unlimited current out of a single 317.

[Anonymous No.711976]

>>711712
>>711730
>>711745
Yeah, now I understand that using batteries in parallel might drastically shorten the batteries' lives.
I'm currently looking for a large lipo battery that takes most of the space or I'll just stick with the two 2000mAh in the UMD compartment.

[Anonymous No.712315]

need some help, new to this

I need an npn transistor. I have a tip31 that I'm using a variable relay to control some leds. only problem is it only fully closes around 1.4 volts and up. i need it to close around 0.1 volts and up.

through my research of things i don't really understand i believe a 2n3904 may do this, but I'm not sure. I'm trying to use one from the limited selection at radio shack because I'm trying to get this project done today, but if i can't get one that's suitable today then I will order from the internet.

set up is
40 leds in parallel, series of 4 at 12 volts
tip31 acts as switch
an audio feed from an amp that varies between 0 and 2.5 volts
trying to keep the amp in 0 to .5 range

any suggestion of a transistor that could work for that? the lights work exactly as i want when the amp is cranked, work less well as volume is decreased until half power where they cease to work

[Anonymous No.712345]

Hopefully this is the right thread, Didn't want to bump a thread off the board for a stupid question.

My Turntable has a terrible ground hum when using it. It's currently hooked up to my soundcard via RCA -> 3.5mm TRS. Then the PC outputs using SPDIF to my A/V Receiver on the other side of the room (no ground hum with this usually). Both the turntable & PC are powered from the same socket and are on their own.

I don't think it's possible to ground it connecting it this way to my PC. Will using a phono pre-amp that can be grounded potentially solve this or would it be a waste of time and money? Would a ground loop isolator also help?

Thanks /diy/ for any help.

[Anonymous No.712357]

>>712315

- the TIP31 and the 2N3904 are both NPNs so they both need about +0.6V on the base to turn on.
- the 2N3904 is more sensitive, so you dont have to pump as much current into it to turn it on
- however, it can only handle around 200mA of output current, so it'll probably get too hot. the tip31 can handle much more.
- maybe there's a FET that can turn on at 0.1V, but I dont understand FETs so I dont use 'em.
- an alternative idea is to use a second amplifier for the TIP31, so you can crank up the volume on that without making a lot of noise.
- you can try computer speakers, a mini-stereo, battery-operated external speakers for MP3 players, or make your own LM386 amplifier.

[Anonymous No.712361]

>>712345

if you plugged the box into the MIC input on your sound card, you will definitely get hum. you should only use the AUX input or an external USB sound card like the one in the pic.

(if using the MIC is unavoidable, then at least make sure you havent checked ''20dB gain" in the recording settings.)

[Anonymous No.712369]

>>712361
My soundcard doesn't have an AUX port and only has an AUX input header. It also has a MIC/Line shared input (the one I'm using).

Mic boost/gain is switched off but there's still the ground hum which is noticeable. Other devices when plugged in (including when using the same cable) are fine it's only the turntable which is why I was thinking about going down the pre-amp route (which would also allow me to connect directly to my receiver).

I'm just wondering if this would help to solve the issue.

[Anonymous No.712375]

ah, when I saw the pic of the pre-amp, I thought you already had one. yeah, using one will definitely work to get rid of the hum.

connecting a phono input directly to a computer is definitely a bad idea, given the tiny signals invloved, and the amount of noise a computer generates. I've seen people use PHONO-to-USB interface boxes to digitize their records, and those work ok, tho.

[Anonymous No.712444]

>>712357
I think I'm good as far as current goes, I'm only using a 500mah power supply and was using twice as many lights in a dual set up off it. i might try it.

the dual amp idea is good, but i have this thing wired so it'll take the soundboard line out on the amp(sounds terrible, will never use it for it's intended purpose). i have an identical back up amp head that i could use, but I'd need a 16ohm load for it that could handle and dissipate the heat of 300volts. they make products like that i was actually thinking about getting for other reasons so that might be the route i go in the future. for the interim I realized I had an old mixing board that might boost the level enough to switch the transistor, it worked but not as good as full volume. passable though.

thanks for your input

[Anonymous No.712795]

How do i into transformer design and calculations??
I mean, i know and understand transformers, how they work, their electrical model their efficiency and all that.
But that's just theory, and i'd like to make some transformers for Power and maybe for Audio later.
Could you reccomend me a book or something?

[Anonymous No.712869]

>>712795
Any of the books at the intermediate level and higher on the OP go into that. Also, most of the channels listed in the OP cover that as well.

[Anonymous No.713101]

Hey /diy/nosaurs, I was planning on buying these 2 components for a project of mine.
>>http://www.sainsmart.com/arduino/arduino-shields/lcd-shields/sainsmart-1602-lcd-keypad-shield-for-arduino-duemilanove-uno-mega2560-mega1280.html
>>http://www.sainsmart.com/sainsmart-hall-effect-sensor-switch-magnetic-detector-module-for-arduino-motor.html
and my main problem is not on quality since I know that I get what I pay for, the problem is: should I trust this site at all? Have you ever had any bad experiences from this seller?

[Anonymous No.713148]

>>713101
http://lmgtfy.com/?q=sainsmart+experience

[Anonymous No.713157]

>>712795
This is mostly about the mains transformers.
Actually making them: http://ludens.cl/Electron/trafos/trafos.html
Design: http://ludens.cl/Electron/Magnet.html

[Anonymous No.713180]

I thinkt this might be the best thread to ask.

I want to customize my room's illumination and want to program, when the light fades and when it starts to shine brighter according to the outside light shining in. Furthermore I want to program it so that the light is on highest brightness in the morning so I can wake up without any alarms.
I am pretty sure it will save a lot of money.
what do I need to know?

[Swifts !WiNDUPyWhk No.713183]

>>713180
Get a photoresistor and learn how to deal with analog input on your controller of choice

[Anonymous No.713195]

>>708838
>person makes typo
YOU SUCK AT SPELLING HURR DURR

>>>/gtfo/.

[Anonymous No.713210]

Does anybody have any pointers towards schematics for an RF receiver that is tuned to one frequency with a crystal oscillator?

[Anonymous No.713237]

Beginner here.
One of my first projects. Wiring took about 5h because I was doing it without any schematic, also I stripped the cables myself with sandpaper.
Code was the tricky part and took me more time, also because the Arduino IDE is shit.
Basically I used two 74HC595 shift registers to make an 8-segment 4-digit display work with my Arduino UNO.
It's a hexadecimal counter, adding 1 every second.
I used 5 nested fors in the code to make it work, one for the thousands, one for the hundreds, one for the tenths and one for the units.
The innermost for handles the multiplexing, basically inside each digit is written one after another with a 1ms delay() between each (which means 4ms total to write the whole 4 digit number once)
for 250 times, which makes one second. After that the number is increased by one and it starts over.
I'm gonna post the code here, though I don't know whether /diy/ supports the tag:
(continued in next post)

[Anonymous No.713242]

(continuing from last post)

//Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
//Pin connected to DS of 74HC595
int dataPin = 11;

/*byte numbers[32] = {
0x01,0x80, //0 0,1
0x07,0xB0, //1 2,3
0x05,0x40, //2 4,5
0x05,0x10, //3 6,7
0x03,0x30, //4 8,9
0x09,0x10, //5 10,11
0x09,0x00, //6 12,13
0x05,0xB0, //7 14,15
0x01,0x00, //8 16,17
0x01,0x10, //9 18,19
0x01,0x20, //A 20,21
0x0B,0x00, //b 22,23
0x09,0xC0, //C 24,25
0x07,0x00, //d 26,27
0x09,0x40, //E 28,29
0x09,0x60 //F 30,31
};*/

byte numbers[16][2] = {
{0x01,0x80}, //0 0,1
{0x07,0xB0}, //1 2,3
{0x05,0x40}, //2 4,5
{0x05,0x10}, //3 6,7
{0x03,0x30}, //4 8,9
{0x09,0x10}, //5 10,11
{0x09,0x00}, //6 12,13
{0x05,0xB0}, //7 14,15
{0x01,0x00}, //8 16,17
{0x01,0x10}, //9 18,19
{0x01,0x20}, //A 20,21
{0x0B,0x00}, //b 22,23
{0x09,0xC0}, //C 24,25
{0x07,0x00}, //d 26,27
{0x09,0x40}, //E 28,29
{0x09,0x60} //F 30,31
};

void setup() {
//Start Serial for debuging purposes
Serial.begin(9600);
//set pins to output because they are addressed in the main loop
pinMode(latchPin, OUTPUT);

}

void loop() {
//count up routine
for (int mil = 0; mil<16; mil++){
for (int cent = 0; cent < 16; cent++){
for (int dec = 0; dec < 16; dec++){
for (int unit = 0; j < 16; j++) {
for (int ms = 0; ms < 250; ms++){//refreshes for about 1 sec
write_n(unit,8);
write_n(dec,4);
write_n(cent,2);
write_n(mil,1);
}
}
}
}
}
}

write_n() in next post.
As for shiftOut(), I used the example for dual '595s from arduino.cc, you can get it from there.

[Anonymous No.713247]

>>713237
(continuing from last post)
//Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
//Pin connected to DS of 74HC595
int dataPin = 11;
byte numbers[16][2] = {
{0x01,0x80}, //0
{0x07,0xB0}, //1
{0x05,0x40}, //2
{0x05,0x10}, //3
{0x03,0x30}, //4
{0x09,0x10}, //5
{0x09,0x00}, //6
{0x05,0xB0}, //7
{0x01,0x00}, //8
{0x01,0x10}, //9
{0x01,0x20}, //A
{0x0B,0x00}, //B
{0x09,0xC0}, //C
{0x07,0x00}, //d
{0x09,0x40}, //E
{0x09,0x60} //F
};

void setup() {
//Start Serial for debugging purposes
Serial.begin(9600);
//set pins to output because they are addressed in the main loop
pinMode(latchPin, OUTPUT);

}

void loop() {
//count up routine
for (int mil = 0; mil<16; mil++){
for (int cent = 0; cent < 16; cent++){
for (int dec = 0; dec < 16; dec++){
for (int unit = 0; unit < 16; unit++) {
for (int ms = 0; ms < 250; ms++){//refreshes for about 1 sec
write_n(unit,8);
write_n(dec,4);
write_n(cent,2);
write_n(mil,1);
}
}
}
}
}
}
write_n() in next post.
As for shiftOut(), I used the example for dual '595s from arduino.cc, you can get it from there.

[Anonymous No.713253]

>>713247
(continuing from last post)

void write_n(int numb, int pos){ //writes numb on pos, 8 is 1000 so first position (units), 4 is 2nd
digitalWrite(latchPin, 0);
//count up on GREEN LEDs
shiftOut(dataPin, clockPin, numbers[numb][0]);
//count down on RED LEDs
shiftOut(dataPin, clockPin, numbers[numb][1]+pos);
//return the latch pin high to signal chip that it
//no longer needs to listen for information
digitalWrite(latchPin, 1);
delay(1);
}


What do you think about it, /diy/?

I'm gonna rip it apart now, since I want to make my first 555 circuit (and I don't have other solderless breadboards), which is also gonna be the first one without the Arduino and the first one which I'm gonna solder.

[Anonymous No.713285]

>>713253

That's pretty creative, but why not use an LED driver?

[Anonymous No.713295]

Any Ideas on building a simple compass, maybe with magnetoresistive components? I have a microcontroller to go with it and it won't have to deal with being at an angle, and it should be buildable on a breadboard

[Anonymous No.713297]

>>713285
I don't have one, also I just bought lots of 595s and wanted to use them for stuff like this.
The idea was that HIGH pins could be connected to the positive leads of the LEDs and LOW pins to the negative ones, so I wouldn't need a driver.
Besides, isn't this board called Do It Yourself?
>wheredoyouthinkweare.jpg

[Anonymous No.713333]

Any high frequency mosfets that can work up to ~50kHz and deliver anything below 8 Amps?

[Anonymous No.713336]

>>713297
>The idea was that HIGH pins could be connected to the positive leads of the LEDs and LOW pins to the negative ones
Wait, what? You either connect the cathode to an output pin and the anode to ground, or the cathode to power and the anode to an output (with the necessary series resistors, of course). Having the IC act as both source and sink is just nonsense. Or did I completely misunderstand what you're saying?

[Anonymous No.713338]

>>713336
We're talking about a 4 digit-seven segment display. I have to control both which anodes and which cathodes "work" at any given time.

[Anonymous No.713398]

>>713157
Wow, very extensive and a nice brush up on my electromagnetism knowledge, thanks!
Also it surprised me that it's a chilean page, guy seems to be German diaspora, cool.

[Anonymous No.713419]

>>713333
All of them will work just fine at 50kHz. Blame your gate drivers, if you are having problems.

[Anonymous No.713642]

>>713210
> schematics for an RF receiver that is tuned to one frequency with a crystal oscillator?

http://thepiratebay.se/torrent/10044754/Ham_Radio_ARRL_Handbook_2014

[Anonymous No.713695]

>>713333

I was just searching for a general purpose mosfet that can handle around 10A. I'm making a high voltage driver.

[Anonymous No.713749]

>>708779
I'd like to build or buy a wireless audio transmitter (with the receiver).
I have a microphone with a transmitter, that hooks up to a receiver but thw wireless transmitter eats a 9v battery every 3hours. This is crazy

[Anonymous No.713963]

So /diy/nosaurs. I would like your help with an electronics project.

I want to build some 5 or 10 minute timers that will set off a buzzer or light up an LED when the timer is done.

I have looked and looked and looked for this, but everything I have found uses an Arduino. I don't want to use an Arduino because I want to make several.

It's for a "defuse the bomb" game of paintball I'm working on and I want working props that will be lit or buzz.

Every time I try to find something, I get the 555 timer, which, from what I've read, isn't good for this sort of thing.

Thanks so much in advance for any help you can give, guys.

>The lower the parts count, the better.

[Anonymous No.713965]

>>713963
555 timer is good for this sort of thing. Build the standard monostable circuit. You won't be able to get five minutes down to the second with normal 5% capacitor and resistor accuracy but that doesn't seam to be an issue for this project.

[Anonymous No.713970]

>>713333

50kHz is really slow, and decidedly nowhere near what you'd label as "high frequency". As long as your gate drivers can switch them fast enough, just about anything with a suitable current/voltage ratings should work.

>>713963

I don't know why a 555 wouldn't be suitable, though that's admittedly a fairly long time period and you'd have some accuracy issues there due to tolerances on parts. Not sure that's a huge issue since what you're doing isn't terribly time critical anyway.

You could use one of the cheap AVRs or PICs (~$1 for the smallest chips). That way you could easily tweak the time period or even use it for things more complex than a simple timer. The code for a basic countdown could be done in about a half-dozen lines. You'd need a programmer (like $5 for a usbasp) but a single chip and whatever peripheral indicator/noisemaker/whatever is probably the lowest parts count you could realistically get, although the tolerance on the factory-calibrated internal oscillator might be relevant, depending.

The absolute fewest parts count I think you could do would be the battery, microcontroller, a resistor, and an LED. A piezo buzzer would be marginally more complex than that.

[Anonymous No.713972]

>>713965
>>713970

Do you think either of you could link to me a circuit or schematic using the 555 timer or PIC? My Google-Fu is apparently lacking in this subject. Thanks so much for the reply.

[Anonymous No.713975]

>>713963
I dunno about lowest part count, but this would probably be the cheapest. The timing won't be accurate at all and the light might come on slowly instead of all a sudden, but it will come on after some amount of time.

[Anonymous No.713977]

>>713963
I dunno about lowest part count, but this would probably be the cheapest. The timing won't be accurate at all and the light might come on slowly instead of all a sudden, but it will come on after some amount of time.
fuck off moot

[Anonymous No.713983]

>>713963
>I have looked and looked and looked for this, but everything I have found uses an Arduino. I don't want to use an Arduino because I want to make several.
aint that much... a Sainsmart Uno is $8 + shipping right now.
arduino pro minis are $10 at sparkfun

a kit with the Sainsmart Uno and the {LCD+buttons} shield is $20. all you'd need is a power switch + transistor + speaker + batteries, and the LCD could show a countdown timer.

[Anonymous No.713984]

>>713983
nigga for that price he could get a wristwatch complete with display and buzzer with accuracy down to the millisecond

[Anonymous No.713986]

>>713972

Google "555 monostable". That'd be what you're looking for. Should also be able to find the formula for calculating the delay on the timer.

For a programmable microcontroller, you could use any of the GPIO pins to hook up to whatever indicator you're using.

>>713977

You're flat-out not going to be able to get a lower part count than by using a microcontroller (pic related; throw in a crystal and two capacitors if you want accurate timing), although, yes, you should be able to do cheaper.

[Anonymous No.713987]

>>713972
http://www.csgnetwork.com/ne555timer1calc.html

[Anonymous No.713988]

>>713986

Note that I forgot a decoupling capacitor on this. Just...imagine it's there, I guess.

[Anonymous No.713990]

>>713988
You also forgot a pullup on the reset pin, and without an Xtal this won't work unless the MCU has an internal osc.

[Anonymous No.713991]

>>713990

Guess I should have specified that would be an ATtiny as opposed to a generic MCU. AVRs have an optional internal pull-up on all pins, along with internal RC oscillators. Granted you'll still need a crystal if you want more than the ~1% accuracy you can get with a calibrated oscillator.

[Anonymous No.713992]

>>713990
>>713991

And, now that I think about it, is there any 8-bit MCU that _doesn't_ have an internal clock source?

[Anonymous No.713996]

>>713992
There are thousands. Off the top of my head I can list: PIC16F54, PIC16F57, and P89V51RD2. MCUs with internal oscillators weren't ubiquitous ten years ago.

[Anonymous No.713998]

>>713996

Huh. Only passingly familiar with anything that isn't an AVR or a PSoC at this point. Figured the internal oscillator thing would be the norm now, at least for smaller chips.

[Anonymous No.714007]

>>713986
>>713987

Bless you, kind anons. I will get right on these. Thanks a ton.

[Anonymous No.714043]

>>713984
>nigga for that price he could get a wristwatch complete with display and buzzer with accuracy down to the millisecond
yea but ........ lame.
the tarduino could blink LEDs. ;)
,,,,
or, blink a few LEDs different colors and patterns, increasing based on the time countdown. And there is 5 buttons already there to use for setting different options. You could leave a jumper exposed and then "disconnecting the red wire" could be used to stop the countdown. Plus the arduinos could be lit AND buzz....

[Anonymous No.714184]

>>713195

Actually I made both of those posts, the second one was mocking my spelling so no one else would.

I stand by calling her the "queen" of electronics is stupid, you don't see someone calling themselves the king.

[Anonymous No.714188]

>>714184
> you don't see someone calling themselves the king.
And we're not seeing Jeri Ellsworth call herself the queen either, unless of course >>708812 is in face Jeri Ellsworth, in which case I welcome her wholeheartedly, because unlike a decent chunk of this board, she knows her shit, and will be able to provide solid advice.

[Anonymous No.714204]

So how to you guise attach microswitches?

I was stocking up on some smaller hardware (threaded rod, nuts, washers, locking washers and nylon-insert locknuts) and I saw that mcmaster-carr has nylon insert locknuts all the way down to 2-56. But I didn't order any because I was getting some #4-40 and figured that would be small enough....

...And it aint. When I measured the holes in the switches, it turns out that a 2-56 threaded rod is the largest size that will fit.

You can hot glue them but then adjusting the position is difficult... or hot-glue them to a piece of metal or plastic that has larger bolt holes in it. I just hate trying to use small bolts with plain nuts because it seems like they always come loose rather quickly.

[Anonymous No.714208]

>>714204
I just use M2's.

[Anonymous No.714343]

So I put 8 full adders together in a logic simulation program (pic related), but it doesn't seem to work well.
I don't get what I did wrong.
Actually everything works fine unless I set the first bit of any of the two operands to one.
If I let it at 0 and use the others, addition works just fine.

[Anonymous No.714345]

>>714343
Your topmost adder has one input floating. Maybe that's the reason your simulator rather sucks dicks than works.

[Anonymous No.714349]

>>714345
Yeah, just figured that out by myself.
Basically this shitty program doesn't count inputs of gates that aren't connected to anything and just thinks "all of this AND's inputs are true, therefore lets just say it's true despite only one input being HIGH BECAUSE I LIKE SUCKING COCK AND I HATE YOU ANON MWAHAHAH"

Fuck this is not how gates work irl

[Anonymous No.714389]

>>714349
It's a logic simulator, not a circuit simulator. Go download LTspice, Qucs or some similar package if that's what you want.

[Anonymous No.714400]

>>714389
>It's a logic simulator
I don't want a circuit simulator, I only care about logic.
Doesn't mean this program isn't bad or that its behaviour was ok.
An input nothing is connected to should be considered 0 not 1.

[Anonymous No.714404]

>>714400
>An input nothing is connected to should be considered 0 not 1.
Why?

[Anonymous No.714408]

>>714400
>An input nothing is connected to should be considered 0 not 1.
oh dear.
be thankful it defaults to a single value rather than inject random noise.

[Anonymous No.714411]

Would this work as a circuit that filters and amplifies an audio signal from a headphone out port ? The ic is supposed to be an op amp. All I want to power at the end is an led

[Anonymous No.714425]

Hey guys,

I asked this a few threads ago and didnt get any response so here goes. Building a lamp for my gf's birthday, a nuka cola "reactor" style lamp using this instructable;

http://www.instructables.com/id/Nuka-Cola-Quantum-and-Nuclear-Reactor-Display-Stan/

Im switching the pvc pipe for an actual steel pipe, and I think i fucked myself. As the switch comes in through the pipe, theres very little gap between the three prongs and the body itself, and so Im worried it will short out.

I picked up some liquid electrical tape and I thought id brush it over where the switch will be, but will this be enough?

tl;dr i dont want to kill my girl friend. Thanks!

[Anonymous No.714434]

>>714411
what is this a pair of passive filters and then an op amp? what is the rectifier for? a little unecessary as long as the output from the opamp isn't larger than the reverse breakdown of the LED it won't mind being put in reverse. opamp gain will have more effect than losing half of the waveform.
check out active filters, where the r-c network is built around the opamp.

>>714425
if you are using a 9v adapter nobody is going to get a shock from it. i would suggest some heatshrink tube, slip it over the wire before you solder it to the switch, then slip it down over the connection and hold the shaft of the iron near it (or rub it a little) and it shrinks tight. that's how the pro's do it.

[Anonymous No.714441]

>>714434
I want to make a visual equaliser type thing, Seems I can just ignore the rectifier then and I'll have a look at active filters. Thanks

[Anonymous No.714449]

>>714441
be very VERY careful around audio people.
this isn't an equaliser its really a spectrum analyser.
an ordinary human wouldn't bat an eyelid because they know what you mean.

anyhow the reason i brought it up was to say perhaps you may have hit a dead end looking for equaliser circuits and perhaps have a go looking for SA circuit examples

[Anonymous No.714454]

>>714204
two nuts, spring washer, loctite
take your pick

[Anonymous No.714499]

>>714400
It makes things easier anon, you just need to know that beforehand, it saves you the pain in the ass of adding 1's to all AND gates with more inputs than you need

[Anonymous No.714558]

>>714408
If you look at >>714349's pic, you'll see that AND's floating input was simulated as one, while XOR's floating input was simulated as zero.
Even basic logic simulator should understand the concept of undefined.

[Anonymous No.714619]

So someone gave me an old CRT TV.
>pic related
It works.
I opened it, though I tried not to break or desolder anything.
I wanted to use it for some kind of electronic project, but now I feel like breaking it would be a waste. It's a working screen after all.

Could I actually make something out of it that would be worth it?

By the way, I put my fingers under that plastic suction cap, expecting it to shock me, and let's just say it did meet my expectations. But what is it? can I remove it from the tube? It seems to be attached with two wires.

[Anonymous No.714621]

>>714619
>>714619
>By the way, I put my fingers under that plastic suction cap, expecting it to shock me, and let's just say it did meet my expectations.

Wow, you are a fucking dumbass.

[Anonymous No.714623]

>>714619
Lol flybacked

[Anonymous No.714625]

>>714619
If it has a video input, you can use it as an output device for microcontroller projects.
You just need to make a video signal with an DAC made out of resistors.
Just an idea for inspiration of what you can do with that tv.

[Anonymous No.714626]

>>714621
I was wearing plastic gloves, so nothing really happened.
I "felt" the shock, but it didn't really hurt me like the electrostatic shocks you sometimes get by touching other people would.
In fact, it didn't hurt at all.
I was "shocked" in a psychological sense thoughm despite expecting it.

[Anonymous No.714629]

>>714619
The CR tube is a giant capacitor; it's the potential difference across it that accelerates the electrons at the screen. One side of the capacitor is the outside, this is connected to ground.

The other side is the inside of the front of the screen. It's held at over nine thousand volts, and the connection to it is the hole under the suction cup. There's two wires because the two wires make a clip that clips onto the hole.

[Anonymous No.714630]

>>714625
>If it has a video input, you can use it as an output device for microcontroller projects.
>You just need to make a video signal with an DAC made out of resistors.
http://en.wikipedia.org/wiki/Resistor_ladder
I didn't know you could make a dac out of just RESISTORS.
I thought you needed complex ICS for that.
Well pic related is the in/out. There's a SCART in on the main board but this seems practical since it's got its own little PCB and an audio jack, which, surprisingly, is connected directly to the speakers.

[Anonymous No.714631]

>>714434
really? even if one of the prongs made contact with the steel chassis, 9v isnt enough to do any harm? If i did brush on a coat of the liquid tape that would prevent that from ever happening though, right.

[Anonymous No.714640]

>>714630
Just wire up to a SCART plug, then it'll work with any SCART device.

[Anonymous No.714724]

I'm trying to figure out an efficient way to drive three 0.5W LEDs.

I thought about using a joule thief with a Darlington transistor and placing the three LED's in series. The thing would work with 4 AA batteries, to achieve a power of around 7000-9000 mAh (- .7 efiiciency of Ni-Mh batteries).

But I'm sure there must be more efficient ways to power this, the LED's need 450mA in series for maximum brightness.

What about driver chips with inductors? Is there any popular one?

[Anonymous No.714736]

>>714724

I already designed the PCB traces to connect them in series.

[Anonymous No.714818]

The efficiency of the joule thief is quite lame, with different transistors the current going in is about twice as high as the current that passes through the LED.

I'm going to try with a smaller coil.

[Anonymous No.714833]

>>714818

It seems the 1 kOhm resistor makes the whole switching process to be slower, I need a faster joule thief design in order to achieve more current.

[Anonymous No.714857]

>>714724
Tell us the voltage of the LEDs

[Anonymous No.714876]

>>714857

Around 3.5, they are warm white-yellow.

[Anonymous No.714883]

>>714876
Your math doesn't add up then.
If they're 0.5W 3.5v each then a single LED draws 140mA. Putting LEDs in series adds up the voltage, not the current. Three in series will be 140mA 10.5v.

>a power of around 7000-9000 mAh
mAh is a unit of energy not power.

[Anonymous No.715074]

>>714883

That voltage is for a single LED, in series they add up to 10 volts, I know that.
The current doesn't adds up, you're right, I didn't realize it, same branch same current for all, sorry I'm stupid.

>mAh is a unit of energy not power
Sorry again, I don't know what I was thinking about when I wrote that.

I found an LED driver, I'll be datasheets of LED drivers to see if I can get more efficiency out of them.

[Anonymous No.715104]

I had an idea yeasterday while eating at nandos. They gave me a loyalty card but not the type you stamp every time you eat its the credit-card type when every order you have brought gets scaned on the card and when you have been there enough times you get say a free chicken or som shit.

How hard would it be to put the information on that card that would say youve spent a lot of money at nandoes and you get the free food. what equipment would you need to put that information on the card, and what if any software would you use or have to write yourself, is it even possible?

[Anonymous No.715105]

I need some simple practical help.

I want to get this light working using the digital balast. But where do I connect wires and are there any fixtures I could buy? I cant find any because I probably am not using the correct search terms.

[Anonymous No.715107]

>>715105
The wire up details are literally written on the ballast. Number the pins on the tube 1-4 from top to bottom, then,

> tube pin 1 to 16
> tube pin 2 to 15
> tube pin 3 to 14
> tube pin 4 to 13

[Anonymous No.715110]

>>715104
pls halp with this im a total novice

[Anonymous No.715113]

>>715110
No. Pay for shit like the rest of us you cheap little faggot.

[Anonymous No.715114]

>>715104
I wouldn't expext that information to be on the card itself. Usually there is just an identification number on there that tells the system which card it is. The keeping track of how much you bought is likely on some database just tagged with your number.

[Anonymous No.715117]

>>715074
why would the forward voltage change with two in series? doesn't make sense to me.

[Anonymous No.715120]

>>715107
Why does the lamp need 4 connections though?

[Anonymous No.715127]

>>715120

For the hot cathode or anode, to increase efficiency.

[Anonymous No.715128]

>>715117
Because LEDs are semiconductors, not simple resistant loads. If the potential difference across them is greater than their forward voltage, they conduct; if it isn't, they don't. Non-ideal LEDs, as found in the real world, also go on fire, which is why you need a current-limiting resistor.

Because their forward voltage is always the same no matter what you do to them, three LEDs in series will have a forward voltage three times that of one LED.

[Anonymous No.715158]

How can I make an LC meter for lesss than a real one? Any good tutorials?

[Anonymous No.715164]

>>715158
I just put a suitable resistor in series with it and use a scope and a signal generator. Shitty and imprecise, but usually sufficient. You can do the same with PC audio ports.
I'd assume even the Chinese can't make a real instrument cheaper.

[Anonymous No.715279]

>>715164

I don't have an oscilloscope nor a function generator. I was thinking about making one with an arduino, I have found some good tutorials about how to do it.

[Anonymous No.715282]

How do you guise mount stuff you've built?
I am building a couple machines that use arduinos. I I wanted a few different features and put them on separate small circuit boards so the whole thing would be modular, but I can't think of any really good way to mount the mess now.

The best I can imagine is below: a post will extend upward from the machine, and that will hold a piece of wood at an angle. Each circuit board will have threaded rod held into the top two corners, and then there will be holes drilled into the wood for the threaded rods. So each circuit board will just sort-of "hang" like that.

It doesn't need to be child-proof or look nice really, and I'd prefer cheap and quick. But I still want something that allows easy access to check wiring, and I can't find a lot that can do all that.

[Anonymous No.715286]

>>715282

When I have to work with modular circuits (different circuits and components for DC supply, microcontroller, drivers, sensors,...) I usually buy pin headers and connectors and after some time figuring out the best alignment for the connections I can stack up everything, it looks nice and tight. You can drill holes at the corners and secure everything with plastic rods and nuts or with spacer screws.

[Anonymous No.715288]

>>715282
You can use pcb stand-off, usually come free with pc casing or motherboard.
Or, if you have nylon screw, you can screw it straight to wood or plastic support board without afraid of bending the pcb.

[Anonymous No.715303]

>>715128
Still, if the curent on a LED is, say 150mA, It will show the same voltage drop even i theres 23 more LEDs ther, a potato or whatever you want.
Unless you fuck with the current the voltage drop should not change.

[Anonymous No.715307]

>>715282
Dupont connectors

[Anonymous No.715366]

>>715307
>Dupont connectors
I already have the separate boards all connected electrically. The issue was how to mount them so that they could be easily used.

One of the boards has 16 buttons on it.... I wanted to have buttons with keycaps that had clear covers so that I could easily label each button, but they would have ended up costing like $6 each and I didn't want them that much.
,,,,
Next time I'll just get a touch-screen instead. It seemed frivolous at first, but overall it would have been a lot simpler and nicer to use.

[Anonymous No.715375]

>>715303
LEDs do not behave like resistors, incandescent bulbs, or potatoes. Show here is the I vs V curve of a resistor and LED. Resistor is just a diagonal line because it follows ohm`s law. LED is a semiconductor, it does not follow ohm`s law.

There is a very narrow range of voltage between not lighting up at all and burning out from drawing way too much current. A 3.5v LED needs very close to that voltage to operate properly, and will drop 3.5v. In a series circuit the sum of the voltage drop equals the source voltage. so three 3.5v LEDs in series means you need 10.5 v.

With a voltage source like batteries or simple DC power supply the voltage remains constant and current increases with power. With a current source the current remains constant and voltage varies depending on power. If an LEDs voltage is a few millivolts off from the ideal level the current changes dramatically. If an LEDs current is a few milliamps off from the ideal level the voltage drop doesn`t change too much. There is a much wider range of currents you can give an LED that will cause the desired voltage drop. This is why LEDs are ideally powered with current sources. The max voltage of the current source still needs to be at or above the LED voltage drop.

[Anonymous No.715383]

>>714188

Having not paid much attention to her channel for the same reason as EEV blog, I believed her channel was called "What's her name, the queen of electronics".

My bad

[Swifts !WiNDUPyWhk No.715522]

Hey /ohm/, what are you doing on this fine Friday night?

I might start building a PLC kit I got as a school project.

[Anonymous No.715553]

>>715522

I don't know what to do, and electronic store closes in 1 hour. I can go out like the normal people, halp!

What do I build? (intermediate electronics)

[Anonymous No.715556]

>>715553

*can't

[Anonymous No.715565]

What's with these "SIP" sockets?
Aren't they just breakaway female pin headers? Can I just use them as that?
Why is their socket round?

[Anonymous No.715566]

>>714818

Any step up (boost) DC-DC converters that work with >2.6 input and can deliver 150 mA?

I've been checking for a long time and I only find them in strange packages.

>>715565

They work great to hold chips and similar stuff, the socket is round because they have a round clippy piece inside to keep the pins tight. If you want to use it as a female pin header I don't know if you will be able to get these kind of pins(see picture) inside, because I have the same strips and I can't.

[Anonymous No.715568]

>>715566
So you're saying the gaps between pins are too large?
I guess I should have expected it.
It's too bad, I hoped I could use them as breakaway female headers, instead of buying 10000 sizes.

[Anonymous No.715572]

>>715568

The gaps between the pins are correct, but the male pins are too large to get in, they are intended for chips and similar.

[Anonymous No.715573]

>>715568
You should buy these.

[Swifts !WiNDUPyWhk No.715577]

How would you go about making a timer with 15 minute intervals?

I'm assuming a 555 timer wouldn't be exactly accurate for such an application?

[Anonymous No.715579]

>>715577

>I'm assuming a 555 timer wouldn't be exactly accurate for such an application?

Define accuracy, the 555 can lose around half a minute or so, but it's a repeating cycle, so that time is more or less constant, if you want it for example for Halloween props it would work just fine.

If you want a precision down to a millisecond an ATTINY85 will do the job, it costs around $2 and you can easily program it, add buttons, LED indicators...

It also needs less voltage than the 555, you can easily power it with 3 AA batteries, and with a power saving function it can work for months.

The drawbacks is you need an arduino or an AVR programmer to program it, but the code is so simple I could write it for you in a minute.

[Swifts !WiNDUPyWhk No.715580]

>>715579
>the 555 can lose around half a minute or so
Well that's perfectly acceptable then.
Apparently the guy that need this wants to have his fridge or w/e on his boat running at an interval like that (15 minutes on, 15 off), so I was thinking of just using a 555 circuit with some pretty big resistors and running an impulse relay off of it.

[Anonymous No.715716]

>>715580
> fridge running on an interval
I don't quite understand this. I'm not a fridge expert, but I believe the compressor pump only turns on when the internal temperature of the fridge climbs above what is set.

(Sorry for offtopic, OP.)

[Anonymous No.715720]

>>715716

Maybe is a 12v portable fridge with no temperature control.

[Anonymous No.715852]

so I have a dual usb charger and a 2 pronged laptop cord, would anything happen if i stripped the 2 prong and connected it to the usb charger? I want a cord for this fucker thats portable

[Anonymous No.715862]

>>715852
Be more clear about what you mean. Is the USB charger meant to plug into a wall outlet, or into a computer's USB port? Is the laptop cord just a cord, or does it have a power brick on it? How does adding a cord to a USB charger make it any more portable?

[Anonymous No.715866]

>>715862
usb charger plugs into wall, i want to extend its range to power a pi and a external hard drive, should be putting out no more than 1.2A
2 prong has no brick or anything

[Anonymous No.715877]

>>715866


Your plan will work, but I have no idea why you've decided not to use an extension cord or USB extension cable. Don't leave your USB charger's prongs exposed unless you like being electrocuted.

[Anonymous No.715879]

>>715877
need this to be portable as possibly, smaller cord means less space taken

[Swifts !WiNDUPyWhk No.716011]

>>715720
I'm fairly sure it's like this.
Would make sense since we're talking about a small sailboat.

[Anonymous No.716305]

So, guys, was reading the dc biasing chapter of Boylestad's book.
Think i found an error, in the excercise about the voltage divider kind of transistor biasing. Vce seems to be calculated wrong, or i am doing something wrong?

[Anonymous No.716307]

>>716305
hurr i'm a retard. Forgot pic.
ere it is

[Anonymous No.716319]

>>716305
compare early editions of the book to latest editions. if its still the same then its probably right.

captcha : 555 timzu

[Anonymous No.716321]

>>716305
Boylestad is for High School, stick to Neamen if you are serious about electronics

[Anonymous No.716366]

>>716321
Hmm guess i'll take a look at that.Problem is that it may be too complex mathematically for me.

[Anonymous No.716388]

need a transistor or fet for a switch that begins opening around .02 volts and opens fully around .1 volts. any ideas, or a suggestion for a voltage quadrupler

[Anonymous No.716484]

>>716307
Skimmed it and it looks right, but I didn't look over it thoroughly.
How do you think it should be calculated?

[Anonymous No.716488]

>>716484
The equation underlined in red, doesn't make sense to me.
The transistor is almost saturating at that current, it can't have such a big Collector emitter voltage.
I know it's not important, because its was stated that it was unaccurate to do it that way, but that error is unrelated to that.

[Anonymous No.716491]

>>716488
>The transistor is almost saturating at that current,
At what current? 2.59mA? That's not the base current, if that's what you were thinking.

The equation underlined in red is saying that the voltage drop across collector and emitter is 18V minus the voltage drops across the two resistors, which is calculated using V=IR.
Look above at the exact analysis, the equation takes the same form in the last step.

You can put this circuit into simulation (ltspice is free and fairly easy to use) if the math doesn't convince you.

[Anonymous No.716496]

>>716388
You won't find any mosfets that meet that requirement.
Instead build a gate driver with an opamp or two that does what you need.
Also you can "quadruple" voltages using opamps if that's what you were getting at.

Hard to succinctly say what would help in your situation without knowing what your ultimate goal is.

[Anonymous No.716543]

> Hard to succinctly say what would help in your situation without knowing what your ultimate goal is.

i'm pretty sure this is the same faggot who wanted to light some LEDs using music but wanted a magic 1-transistor solution, rather than building a proper conditioning circuit like pic related.

[Anonymous No.716549]

>>716488
Calculations seem to be right and yes, you wouldn't bias transistor that way if you wanted to maximize the output voltage swing.

[Anonymous No.716640]

>>713237

>I stripped the cables myself with sandpaper

NIGGER WHAT

[Anonymous No.716660]

>>716640
They're thin single core wires.
Sandpaper is the easiest way to strip them, if you don't have a wire stripper, which I now have.

[Swifts !WiNDUPyWhk No.716664]

>>716660
>wire stripper in the mail, expected to come in two days

Soon

[Anonymous No.716705]

Why is this SR's output oscillating? I put those three gates there to "filter" the input so 1&1 would give 0&0, but it doesn't seem to work.

[Anonymous No.716720]

>>716660
I like to strip wires by putting the right amount of pressure on a dull pair of wire cutters and pulling them through. It works just as well as a stripper.

[Anonymous No.716761]

How do you make a memory register?
I couldn't find guides, so I "hacked" this one together.
If LOAD is high, the INPUT is written.
The way it works is that LOAD resets the OUTPUT to 0 while INPUT is being delayed by 2x D-flip flops, after that input sets OUTPUT to 1 If it's HIGH (otherwise OUTPUT remains 0)

[Anonymous No.716862]

>>716761
I realized I'm an idiot.
There was a simple way to do this: by modifying a D-FlipFlop.
>pic related
As you can see I made two different versions: One with the full D-Flip flop, and one with the last part removed.
I'm not sure whether not removing the last part would be advantageous, it works the same.

[Anonymous No.716866]

>>716491
I know it is the collector current. But if you do the math you see that the result is wrong.

[Anonymous No.716871]

>>716705
It's because it has a swastika

[Anonymous No.716873]

>>716871
Why are latches so racist?

[Anonymous No.716932]

> I know it is the collector current. But if you do the math you see that the result is wrong.

I've checked it, and at least one other dude has too, and we both found the math correct. Show us how it's wrong.

[Anonymous No.716943]

>>716866
18 - (0.00259) * (5600 + 1200)
=.388

Okay I see what you're saying. I thought your issue was with the equation, not that they computed the answer incorrectly.
I missed that.

[Anonymous No.716944]

>>716932
Actually, on the second look, the given result would be the collector voltage. However, it is supposed to be the voltage across the transistor and when you count in the 1.2k emitter resistor, the transistor is, indeed, more or less saturated.

[Anonymous No.717037]

> the given result would be the collector voltage

nope, it's the supply voltage minus the voltage drop across the two resistors, so the result is indeed Vce.

[Anonymous No.717063]

Guys I have to do some research on the 555 timer ic, anyone know of a good project or something interesting about it?
Bistable projects look pretty cool in my opinion.

[Anonymous No.717069]

>>717037
And if you put in the given values, the result is much nearer the collector voltage than the Vce. Yeah, only nearer, the true error is the decimal point position. The result should be 0.388V, like the other anon said.

[Anonymous No.717137]

>>717063
Google "555 contest".

[Anonymous No.717140]

>>717063
look at the links in the OP. Adafruit has some neat circuits.

[Anonymous No.717189]

>>708779
I want to power 5v (most of the time uses 400ma, _MAY_ peak up to 1A, can't really measure) with a solar panel and a battery. This is in a regulated environment and with a plug always near (solar power for 'marketing reasons'), should everything fail.


I found a solar panel that outputs 17v 0.58A.. Google tells me I need a step-down converter (something like this, http://www.adafruit.com/product/1065 , I don't know if I can get one of these though). What about the charging circuit? What kind of battery do I get? If i'ts not very expensive I can buy most stuff but I don't know what am I even looking for

[Anonymous No.717194]

>>717189
Why don't you use a panel closer to your needs?

Look for a 5v step down converter at auto parts stores. They're used for putting USB chargers in cars and other thing. They'll say "12v/24v input", but work fine at anything from 6-26v.

[Anonymous No.717202]

I want to run 15 IR LED's on 36kHz pulses and the maximum current PEAK for each one is 80mA, should I use 70mA (as a precaution measure since the max is 80mA) and multiply that current by 15 to drive the LED's? (It would be 1.05 amps) Or is 0.80mA safe enough?

I plan to add a 10uF 25V capacitor to help to drain the batteries, since I think 3*AA Ni-Mh batteries (around 3.5v ) can't deliver that amount of current so fast, should I use a bigger value? The period of the signal is 0.027 microseconds, so the capacitor should be charged in half that time in order to have the right value.

I'll add a small resistor in series to avoid going above 1.05 amps, something like 4 ohms should do the job.

I want to make an actually "super" super tv-b-gone (see pic related)

[Anonymous No.717220]

>>717202
Are the LEDs in series or parallel? The current for a group of LEDs in series is the same as a single LED, it's the voltage drop that goes up. If they're in parallel you should have a balancing resistor on each one.

Are you even using a current source?

[Anonymous No.717246]

>>717194
Because I'm from Argentina, That's the only panel I can get (others, even smaller cost at least 5x that).

I can get that 17v 0.58A panel for ~40usd and a "Lm2596 Ajustable Step Down 1,25v to 30v 2a" for 7-12usd.
I'll look for the auto part converter, thanks for the tip.

I still need a battery and a battery-charging-circuit. I'll look if I can get one premade, but this starts getting "expensive"

[Anonymous No.717415]

>>717220

Parallel, I didn't know I had to put resistors at each LED, I've tested them conecting the thing to a power supply and it works fine, all the LEDs emit the same light. I don't really care if this can damage the LEDs at long term, I'll just use it a few times.

I don't know what you mean by a current source, a capacitor?

[Anonymous No.717418]

>>717415
A current source is a power supply where current remains constant and voltage varies with power. A voltage source is a power supply where voltage remains constant and current varies with power. Batteries, wall warts, etc are voltage sources.

Your post makes it sound like you are working from a current source.
> should I use 70mA
If you are working from a voltage source you set the voltage so the LED draws the right current from that.

[Anonymous No.717450]

I just want to fix a through-hole DC jack on a PCB.
Can I use a desoldering braid for that, or will it be a pain in the ass? Can I use any solder?

I eventually want a heat gun/hot air gun. What can I get when it comes to quality+good price?

[Anonymous No.717451]

>>717418

I did that, more or less, the batteries charge a small capacitor, when all the current is released a resistor I controls it so it stays around 1 amp.
I don't know how fast will a 10uF charge under 3,5 volts, so i don't really know if that's the best capacitor for this application.

I guess the resistors at each LED are to control the current individually, since one LED could draw more than another, but mantaining the current somewhat lower than the maximum the treshold should be enough so they don't fuse after a day.

Also, how inductive are 0,5 or 1 watt resistors, I say this because they might reduce the current flow at the beginning of the pulses.

[Anonymous No.717459]

>>717450

Buy a desoldering pump, they are very useful when desoldering components.

[Swifts !WiNDUPyWhk No.717587]

Yay, it's done!

[Anonymous No.717695]

>>717587

Motor driver I guess.

[Swifts !WiNDUPyWhk No.717703]

>>717695
It's going to be a PLC once I get the PIC.

[Anonymous No.717861]

>>717450
You can use desoldering braid, but you will probably need a high-powered iron. Avoid using force when removing the jack or you risk lifting traces.

[Anonymous No.718092]

For what would you guys would you use an ARM cortex m3 dev kit? I was looking for embedded jobs, and a few of them want people with experience with arm cortex m3 and other 8bit micro controllers. So i was looking through them, and the only thing i know about them, is that they can get easier connection with the internet and they are more powerful. So what would you guys use them for? Also some recommended dev kits?

[Anonymous No.718095]

>>718092
I've used them at work for power plant control panels and UAV flight controllers. They're powerful enough to run a light version of Linux, and development can be done primarily in c++. With less powerful microcontrollers you've got to write firmware in C/ASM to squeeze out all the efficiency possible.


>and other 8bit micro controllers.
Cortex-M are 32 bit.

>get easier connection with the internet
You need a TCP/IP stack and Ethernet transciever like every microcontroller. Cortex-M makes it easier because you've got an OS providing standardized networking functions.

[Anonymous No.718186]

>>708844
don't know if anybody still cares about this question but use 2 555s one controls duty cycle the other frequency

[Anonymous No.718217]

>>716705
why are you trying to reinvent the SR latch?

when you are attempting to switch from reset to your "hold" via 1&1, a race condition occurs where the AND gate will output a 1 briefly causing it to set before the hold

consider adding a buffer to the two inputs of the AND gates to account for the delay of the XOR gate

[Anonymous No.718324]

>>718186

Yes, still lurking, thanks!

[Anonymous No.718448]

Hey /ohm/.

What's your favorite 555-based project? It can either be something genuinely useful or just a neat little gadget. Links or circuit diagrams are appreciated.

[Anonymous No.718451]

I really want to become a master of solar power. I have all sorts of neat do-dads that I would like to make solar-powered to put in geocaches. I think it would be neat to have a box that chirps every few minutes to let people know they are near the cache, but batteries are an issue. Can anyone help me out? I need solar chargers/power supplies that can put out between 3 and 12 volts for different projects.

[Anonymous No.718473]

>>718448

[Anonymous No.718474]

>>718473
what does 8R speaker means? 8 resistance? 8 ohms?

[Anonymous No.718476]

>>718474
8 ohms

[Anonymous No.718584]

>>718451

you can use a solar garden lamp, and connect a circuit to boost the 1.2V battery voltage to 5V, or whatever you need, using a circuit similar to this: http://www.electroschematics.com/6232/portable-5v-power-box/

[Anonymous No.718586]

>>718474
"R" is a stand in for the ohm symbol omega (Ω) used in computing, which is not available in any standard keyboard layouts. It kind of does mean "8 resistance", or 8 units of resistance, that unit of course being an ohm (though that's kind of like referring to a 20 horsepower engine as a "20 power" engine). Where kilo and megohm values come into it, "R" is replaced by "K" or "M". These characters are also used to replace decimal points in the value, making it all look a little neater when you have a list of values.

> 10R = 10 ohms
> 1R2 = 1.2 ohms
> 4K7 = 4,700 ohms = 4.7 kilohms
> 56K = 56,000 ohms = 56 kilohms
> 1M2 = 1, 200,000 ohms = 1.2 megohms

> tfw you type a word that many times that it starts to look like its spelt wrong, even though you know its right.

[Anonymous No.718589]

>>718586
>making it all look a little neater
Also replaces the decimal point with something which is likely to remain readable even on low quality or dirty prints.

[Anonymous No.718592]

>>718589
Huh. That never occurred to me, makes perfect sense.

[Anonymous No.718621]

>>717703
Is the switching electronic? no Relays n shit?

[Swifts !WiNDUPyWhk No.718639]

>>718586
In some cases R is also replaced by E.

Apparently using E is a more modern way, atleast that's how I was told in school.

[Anonymous No.718645]

How would i go about programming this thing: http://www.icstation.com/product_info.php?products_id=3586 ?
It looks like it doesnt have an spi interface, only jtag and serial(probably), would that mean i would have to get a jtag or serial programmer?

[Anonymous No.718659]

>>718448

#1-Flyback driver
#2-Mini piano
#3-5 minute timer

[Anonymous No.718661]

>>718659
I remember making this 10 years ago. I had a line of microswitches so it even had a piano-like keyboard.

[Anonymous No.718684]

So this is my first time working with transistors.
Apparently If you connect current to the gate it flows straight to the emitter, even if there's nothing on the collector.
>pic related
I did not expect this.
How am I supposed to make a working AND gate with this?
The one I made doesn't work because of this unexpected phenomenon.

[Anonymous No.718695]

>>718684
It depends on what kind of transistor you have. Post more information.

[Anonymous No.718696]

>>718695
It reads "S8050"
And then there's "D 331" on the second line but I guess that's less important.
I googled S8050 and found various datasheets.
Here's one:
http://html.alldatasheet.com/html-pdf/154210/WEITRON/S8050/292/1/S8050.html

[Anonymous No.718703]

>>718684
base current has to go somewhere, where did you think it went?
and gates are much easier with two transistors, bases are inputs then put them in series i suppose is how to describe it.

[Anonymous No.718712]

>>718703
That pic wasn't a gate.
It was meant as a demonstration.
I made a proper AND gate with two transistors, but it doesn't work because of what I said.

[Anonymous No.718724]

>>711477
that's an NPN transistor. use a PNP. NPN are closed with no current in the base. PNP are open

[Anonymous No.718725]

>>718724
>>718684
quoted wrong person. chanu went full retard

[Anonymous No.718737]

>>718712
out will increase however wont reach 6v until both are on.
adjust resistors to find a value that works for you.

[Anonymous No.718849]

>>718712
when the b input is high but A is low, it works like a voltage divider, try higher values of Rb with little Re.
But it's gonna create mor heat that way, that's why TTL is sooo outdated. CMOS is the shit

[Anonymous No.718980]

we're at 300.
new thread when?

[Anonymous No.719041]

>>718849
Yeah, I played with the resistor values a bit and it worked. R of A and B just have to be much higher that the one to ground.
>that's why TTL is sooo outdated. CMOS is the shit
I don't really get this.
What I understand is that TTL is transistor transistor logic, like what I used, and it's also in ICs like the 7400s.
CMOS is the more modern technology in ICs and it's inside my CD4011s.
While I realize that CMOS is a different way of making chips, I don't get how it's not "transistor-transistor logic".
Isn't all logic in computers made with transistors?
Does it somehow implement logic gates without transistors?

[Anonymous No.719075]

>>719041
It uses MOSFET's, nMOS and pMOS in a complementary way.
these don't require resistors to work. that makes it consume WAY less than TTL.
TTL is still used for some stuff i think.
someone post new thread pl0x

[Anonymous No.719083]

>>719075
But it still works with transistors, right?

[Anonymous No.719095]

NEW THREAD
>>719089
>>719089
NEW THREAD