[ 3 / biz / cgl / ck / diy / fa / ic / jp / lit / sci / vr / vt ] [ index / top / reports ] [ become a patron ] [ status ]
2023-11: Warosu is now out of extended maintenance.

/diy/ - Do It Yourself

View post   
File: 10 KB, 465x359, 21121212121121.png [View same] [iqdb] [saucenao] [google]
127666 No.127666 [Reply] [Original]

Sup /diy/, so I decided to do this project
http://www.instructables.com/id/Music-LED-Light-Box/

which is a lamp that lights up to the beat of the music you play.

I was thinking of making 4 of these lamps, stacking them and having them with different levels of sensitivity so the bottom one lights up first, then the second and so on.

Ho do I do this with this circuit? Can I just add a resistor to each circuit with different resistances? Where would I put it?

pic related, its the circuit

>> No.127670

>>127666
also, how could I connect the LED's in parallel?

>> No.127677

>>127670
bottom one is parallel, top one is series

>> No.127678
File: 22 KB, 714x538, 1327206838981.png [View same] [iqdb] [saucenao] [google]
127678

>>127677
stupid captcha!

>> No.127680

>>127670

I'm no electrician, but I've done some similar projects.

Don't think you could do parallel with that design. The way the series circuit is working is that the power level of the music is allowing a corresponding amount of current into four series LEDs, each consuming voltage along the way. Presumably, a high enough volume from the headphone jack will allow the full 12V battery power to flow through, hitting all four LEDs if each causes a voltage drop of about 3V.

If you were to do it in parallel, then all four LEDs would light up at once depending on the volume of the music, which totally defeats the purpose.

A resistor at the start of each LED should be enough.

>> No.127681

>>127680

Wait, I'm sorry, I misunderstood. I thought the lights would be lighting up like a volume meter, not just tapping to the beat. Your bottom design will light them all up tapping to the beat, while the top design should be like a volume meter, methinks.

>> No.127687

I was thinking of something like this, I just dont know how or where to place the resistors or which resistance they should have

>> No.127689
File: 34 KB, 413x377, 2121212121.png [View same] [iqdb] [saucenao] [google]
127689

>>127687
forgot the pic

>> No.127691

>>127689
I don't see a change in the pics. Am I missing something or was there an image editor error?

>> No.127693

>>127687

If you have the right formula, you can calculate how much resistance to use to get the desired brightness, but with LEDs, it is just important that you have *some* resistance because the element wasn't built to withstand a lot of current. I get away with just using 1k ohm. 1 resistor at the anode of each LED should be fine (wire goes into one side of the resistor, resistor is connected to the LED).

A few times when I had to hook up a lot of LEDs and ran out of 1k ohm resistors, I had to use lesser ones. It worked, but they just get hotter than the higher rated resistors.

Hopefully a more knowledgeable EE guy will come along and tell me if I am full of shit or not.

>> No.127694

>>127691
I supose you add a resistor at the anode of the first led, I just dont know the Ohms value the resistor should have

>> No.127697

>>127694
Ohhh, gottcha.

>> No.127715
File: 223 KB, 468x1500, untitled.jpg [View same] [iqdb] [saucenao] [google]
127715

>>127678
If you do this the LEDs in parallel will burn out when the transistor outputs enough power to run the LEDs in series, and also the LEDs in series will not light up. Also connecting LEDs in parallel like that without load balancing resistors is never a good idea.

There are some chips designed for this sort of application like the LM3915. However if you want to do something simpler without a dedicated chip Pic related.

>> No.127723

>>127715
that is exactly what i was looking for, thanks

>> No.127729

>>127723
Be warned I pulled the resistor values out of my ass. You want them increasing at a constant interval, but 1k,2k,3k,4k may not be best. If the resistors are too big the topmost LEDs will never light up. If they are too small even a quite sound will make them all turn on.

>> No.127767

>>127729
Also if they're too small, the LEDs may actually die.

>> No.127797

Why not run them the audio through an equalizer IC (the MSGEQ7 for example). This chip will take sets of frequencies and output a DC voltage relating to the amplitude of the sound within the interval of the frequencies. Of course you would need current limiting resistors on the led's anyway (330 ohm is usually what i use).

>> No.127801

>>127767
OP's original picture had no resistor at all; so we can safely assume that no matter how small the resistor is the transistor will not allow too much power through.

>> No.127805

http://thecreatorsproject.com/en-uk/blog/rig-up-your-own-light-up-led-organ-instructables-how-to

>> No.127809

>>127666
you should follow the other diagrams (like the last one) instead.

>> No.128579

FYI none of these circuits will work because:

1. diodes don't let any current through until there is enough voltage to forward bias them, the LED's are diodes, not regular incandescent lights. So they will either all be completely off or they will all be on at the same time once the forward voltage reaches the amount needed for all 4 in series.

2. The sound coming in will be operating at multiple frequencies simultaneously; once music gets complicated the lights will just stay on and not really do much flashing. This is seen in the instructables video, only nigger music with big gaps in between really work for this.


What you guys need is a VU meter driver IC which is easy enough to get, but a little expensive for a single component. Combine multiple IC's with audio filters, possible R-C or L-C circuits and you will have a real audio spectrum analyzer. Or if you really want the instructables version to work properly, attach it to an audio filter designed to pass only low frequencies.