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How to wire Illuminated buttons so that they light up when pressed ?

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MonMotha:

Yegads, there's a few simple ways of doing this, and that circuit with the inverter is something of a wtf of overengineering, like Andy said.

If you've got LEDs without integral resistors or resistors sized for close to the pull-up voltage of whatever encoder/controller input you're using, you're in luck.  The circuit BobA posted should work fine.  Just be sure you measure the pull-up voltage on your encoder/controller input (hit it with a multimeter on voltage test with no button pressed).  It's probably 5V or 3.3V. Use that as the supply voltage for your LED, and size the resistor accordingly.

If you want to use a different voltage for your lamps than your encoder/controller uses (e.g. you've got 12V lamps or LEDs with integral resistors sized for 12V that you can't replace), the best approach is a couple MOSFETs, but a bunch of diodes also works.

All that said, I'm betting the mini-PAC is 5V, and since your LEDs are also 5V, you should be good to go with that circuit BobA posted.  Just confirm the voltage of the miniPAC first.  Most 3.3V devices don't take too kindly to having 5V dumped on their inputs (though you're unlikely to damage things - you'll just end up with an LED that's bright/dim instead of on/off).

drventure:

hehe. I always sucked at EE..

DaOldman's circuit is far simpler. So what I said still stands. I'm Bookmarking this thread!  ;)

MonMotha:

I'm sorry, I meant DaOldman's circuit, not BobA's.  Unfortunately image attachments don't show up in the summary while you're typing a post :)

BlueScreenJunky:


--- Quote from: DaOld Man on October 22, 2010, 09:12:22 am ---Wouldnt something like this work?
Of course if youhave more than one or two buttons you may want to get the 5 vdc for the LEDs from the computer power supply. USB is limited to half a amp in best scenario, Im sure.

--- End quote ---

Thank you !
That's more like what I was thinking about, and thank you Andy for confirming since my main concern was to fry my brand new mini PAC.
I will probably try that today and tell you how it went.

And yes I think USB from a computer is 500mA max, but the controller in the video is actually using USB to light the 7 buttons and the LEDs from the turntable so I guess it could work ? I have no idea how much the LEDs need.


--- Quote from: MonMotha on October 22, 2010, 06:33:04 pm ---All that said, I'm betting the mini-PAC is 5V, and since your LEDs are also 5V, you should be good to go with that circuit BobA posted.  Just confirm the voltage of the miniPAC first.  Most 3.3V devices don't take too kindly to having 5V dumped on their inputs (though you're unlikely to damage things - you'll just end up with an LED that's bright/dim instead of on/off).
--- End quote ---
Assuming I'm using my multimeter correctly (yes, I'm that bad with electronics  ;) ) the miniPAC is indeed 5V. Thanx for the heads up !

saloonstudios:


--- Quote from: drventure on October 22, 2010, 06:56:19 pm ---hehe. I always sucked at EE..

DaOldman's circuit is far simpler. So what I said still stands. I'm Bookmarking this thread!  ;)

--- End quote ---

Yeah me too. I'm glad there was an easier way-

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