/diy/ - Do It Yourself

>>816106

dont use a higher-wattage pot, your circuit is the problem. pin 7 of the 555 is used to discharge the timing cap. it does this by essentially shorting pint 7 to ground when appropriate. if your pot is at the min value, you're shorting it across the power supply which will cause it to burn. solution: put a fixed resistor in series, like 1K, which will limit the max current thru the pot to Vcc/1000.

this is one of those things that are often omitted from schematics coz it's assumed you know it. sucks if you dont.

>>806093
> You are an idiot

Circuit simulator says I'm right.

>>806082
>Circuit breakers prevent that from ever happening.

except there are no circuit breakers on the neutrals. see pic.

what actually happens, as mentioned in >>806040, is that the two loads are effectively put in series across the 240V lines, and if they're of diff wattages, the neutral takes away any excess current so that they each have exactly 120V each.

e.g. two loads of 10A and 8A wont put 18A on the neutral, only 2A. coz math.

>>802785

reminds me somewhat of a gravity-wave detector I built a few years ago. it used the surface plates of a capacitor to (theoretically) detect theses waves. so, maybe the big metal plate is capturing something unworldly.

http://www.keelynet.com/gravity/grav3.htm (this is a diff circuit than the one I built)

if I recall, if I swung a large metal object around in a circle near it, the circuit would react to it. spooky!

good thing you mentioned dying, because, as a matter of fact, dying fixes all problems, cures all disease, pays all debts, neutralizes all insults and slights suffered. no one is more carefree, loved or respected than those who are gone.

it should be added to the sticky as the go-to solution to every problem.

by sticking two polarized caps back to back, you get a non-polarized cap at half the capacity. then you can parallel the couples to get higher capacity. no, it wont blow up.

https://electronics.stackexchange.com/questions/21928/can-you-make-a-non-polar-electrolytic-capacitor-out-of-two-regular-electrolytic

another possible solution is to start the motor manually since starting is all the capacitor is needed for.

sticking an inductor in series with the motor may fix this. an inductor opposes changes in current, so the inrush current will be tamed. a capacitor wont help in this task, nor will a freewheeling diode. as for the size of the inductor, that's determined by trial-and-error. you want the smallest number of turns that works reliably.

the inductor thing worked for a previous poster who had a similar problem a few months back.

you should jam an X-acto knife under one side and twist to provide lifting force. this should lift off one side as you heat the solder. (you should have added extra solder to make it more malleable.) then repeat on the other side.

if you dont have an X-acto, you could plug in a sacrificial micro USB cable and use that to lift.

>>797571

get yourself a heavy duty BBQ brush and scrub away. I mounted mine on a wood pole, so I could use it standing up.

>>796066

if the source of a signal has an internal impedance of, say, 1000 ohms, and you connect it to a 16 ohm load, that creates a voltage divider that reduces the signal by 98.4%, but if the load is 2000 ohms, it only reduces it by 33%.

>>796066

if the source of a signal has an internal impedance of, say, 1000 ohms, and you connect it to a 32 ohm load, that creates a voltage divider that reduces the signal by 98.4%, but if the load is 2000 ohms, it only reduces it by 33%.

>>795920
the thickness of the antenna is irrelevant, as is the type of wire (solid or stranded).

you cant use regular headphones to listen to a crystal radio, coz they require too much power. you need either an amplifier or high-impedance speakers, around 2000 ohms. ordinary earbuds are 32 ohms.

I'm pretty sure the speaker from these vintage 1970's type phones would work. I have one, and it's very high impedance, and very sensitive.

>>795920
the thickness of the antenna is irrelevant, as is the type of wire (solid or stranded).

you cant use regular headphones to listen to a crystal radio, coz they require too much power. you need either an amplifier or high-impedance speakers, around 2000 ohms. ordinary earbuds are 32 ohms.

I'm pretty sure the speaker from these vintage 1970's type phones would work. I have one, and it's very high impedance, and very sensitive.

you dont need an Arduino to light some LEDs, FFS. this simple circuit will give you infinitely-variable color from an RGB LED.

> so electrical wire soldered to banana plugs would be fine?

whenever you're choosing a banana plug, it's good to consider this type of solder-less plug (pic related). the little screws on the side act as Darwin filters, eliminating those hobbyists who are a danger to the herd. if they're careless enough to handle plugs that have high voltage on them, the little exposed screws on the side will quickly make them ex-hobbyists, and that will make Darwin smile.

> it'll be easier to find an old vcr and rip out the rf modulator from that.

nope, you just use the VCR as is. plug your video + audio into the input jacks, set source to LINE1, or whatever it's called in your unit, and you should get an RF signal out the RJ45 connector in the back on channels 3 or 4.

you need to put a plug cover on them or else the electrons spill out of the holes.

there's some big money to be made from mummified cats. pic related.

one way to avoid the melting nightmare when cutting acrylic is to use a scratching blade, and then snapping the piece. i'm guessing there are youtube videos showing how to do this. i usually use 5mm sheets, and will scratch a line into it of 1mm depth. at that depth, i've never had a sheet not break perfectly.

>>544677

assuming you dont have solder wick, or a solder pump, you can use the following technique.

lay the iron sideways so that you're making contact with all three pins to desolder. dump a lot of solder on the pins so that there is one big blob covering all three pins. pull the part out from the opposite side. or, you could attach a weight to it, so it drops off by itself. the use soldering iron to remove all the solder.

> So do i apply the gun directly to the pins

if you're actually using a soldering gun, like the 100W Weller ones, you shouldnt be doing this at all. you're gonna destroy the PCB traces. you need a soldering iron of 15 - 40 Watts, ideally 25W.

>>543673

having a leg electrode is a pain in the ass coz it's a long-ass wire, and people have to pull down their socks.
a better idea is to have two electrodes, LEFT+GROUND on one hand, and RIGHT+GROUND on the other hand

>>543618

using a 300-ohm bridge is nuts. the signals you're measuring have a significant output impedance, in the 1000's of ohms. by shorting them with 300 ohms, you are attenuating them significantly.
you need a large input impedance, like the 1meg in the >>543659 schematic.

>>543673

having a leg electrode is a pain in the ass coz it's a long-ass wire, and people have to pull down their socks.
a better idea is to have two electrodes, LEFT+GROUND on one hand, and RIGHT+GROUND on the other hand

>>543659

WTF is that? you have R1 =10K so the gain of the instrumentation amplifier is 0.1. Where the hell is the big gain necessary to amplify the tiny voltages?

>>543618

using a 300-ohm bridge is nuts. the signals you're measuring have a significant output impedance, in the 1000's of ohms. by shorting them with 300 ohms, you are attenuating them significantly.
you need a large input impedance, like the 1meg in the >>543659 schematic.

this will work

you can double the voltage using this circuit which is not a multiplier, but just two half-wave rectifiers. seems to me it should be more efficient than a multiplier.