Audio Fx Sound board ACT pin turns off LED rather than on

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rfender
 
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Audio Fx Sound board ACT pin turns off LED rather than on

Post by rfender »

Loving' the Audio FX Sound board and wanted to try combining the playing of an audio file with the lighting u of an LED. So I built a circuit that has an external on the ACT pin. When I power on the board, the LED is on by default (because the ACT pin is LOW by default?) but when I play the audio file, the LED turns off.

I would like the achieve the opposite. When Audio file plays, the LED turns on and when no audio is playing the LED is off. Something like what you would want in the space blaster project: trigger pulled, audio plays, barrel lights up, trigger released, no audio, no lights.

I am a total noob with circuit building so bear with me. I did read somewhere about the use of an NPN transistor to reverse the pinout of ACT so that the LED is off by default and on when audio is playing ... but it didn't work .. or I miswired it.

Any ideas?

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mikeysklar
 
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Re: Audio Fx Sound board ACT pin turns off LED rather than o

Post by mikeysklar »

@rfender,

There are some good examples of using the ACT LED or other button press based LEDs in this thread.

viewtopic.php?f=19&t=120155
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rfender
 
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Re: Audio Fx Sound board ACT pin turns off LED rather than o

Post by rfender »

Thanks, @mikeysklar. I'll try these. I thought I did something like this and the led was still on by default and off when the button is pressed. But the way I prototype is kind of chaotic.

Don't laugh, but I also tried both NPN and PNP transistors in the circuit because I thought my interpretation of what I read would be they reverse the pin "output". Is that right? If a pin is LOW and you use a PNP transistor would treat the pin as HIGH?

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rfender
 
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Re: Audio Fx Sound board ACT pin turns off LED rather than o

Post by rfender »

@mikeysklar, I just tried the simple circuit you have with the "hot" to resistor to led to ACT pin and it worked like a charm!!! I have no idea what I was doing wrong before but this is fantastic!

You would laugh at my working prototype using a trinket m0 triggering an led and the audio fx sound board at the same time. But the LED wouldn't stay lit as long as the audio is playing.

Thanks again!!!!

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