Changing Led Colors On Vu Meter Kit - Help

 
#1

OK I picked up this kit for like 20 bucks. Got it together and working with LEDs included. However I want to swap to all blue LEDs. The blue LEDs use 3.2 volts but the green only take 2.2 volts. Anyone think I can make a small change and up the volts enough to power a blue led? Here are pics.
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#2

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Back of the tracing...
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#3

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Here's a close up on the integrated circuit. I will try to find a data sheet real quick. Take in mind I'm only going to use the pos output pins from the yellow and green LEDs. This is because the red almost never light up and I want the led bar to light up all the way when Jarvis speaks.

#4

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#5

Try it without changing anything, since the voltage rating for the new LEDs is higher it wont damage anything but you may find they still light up well enough.

Or you may be able to change the resistors in it, depending on the input voltage (I haven't looked at the data sheets)

#6

Just found a bit more info on it, 12dv input so you should be able to change the resistors so they power a 3.2v led rather than 2.2v. You need to calculate the values, google for led resistor calculator. Then follow the traces on the board and replace as necessary.

#7

Hmm OK I will research it this weekend when I can get out to RadioShack. Today I believe I will be working to wire up the air soft much warriors since MAkerfaire NC is coming in a little over two weeks.

#8

I tried undervolting a 5mm led rated for the same voltage and that was a no-go. I may just save the time and wire them to a switching transistor to all come on with sound servo or something. Think I could do that? I wonder if I could just use one of the led outputs from the unit to trigger a switching transistor if I can't do it directly from ezb.

@rich. Do you know if there's a option that will trigger something from sound in ezbuilder? Thx.

#9

Sound Servo does, from what I remember it basically does the same as PWM but with the sound controlling the PWM value. I used it on Melvin's single LED lamp in his mouth on the first head I did. It picks up all sound on the PC though, so system sounds, speech synth. sounds, mic sounds (if enabled)...

You also have sound movement which can run scripts, I've not used it at all though so not sure how it works, I guess it makes variables depending on the sound level so you could easily use those as triggers in a script, or even us a change in volume as a trigger with the WaitForChange command.

Edit: It looks like Sound Servo has changed since I used it and now specifies a servo, which may not be what you need.

#10

Hmm well a servo is still pwm in itself. I'm not sure how I can finagle this. I will try to "raise" voltage first. My meter is auto ranging and the pulse is to brief to accurately measure. Worse case I should be able to use the led output to trigger a switching transistor. Do ya think 2.2 volts is enough to trigger one?