SparkFun Forums 

Where electronics enthusiasts find answers.

Have questions about a SparkFun product or board? This is the place to be.
By Silent77
Sorry for the late reply but yeah angelsix your right, I created a short. I got everything close to working now but I'm still having a little trouble. The LED's are staying on constantly so I added in a potentiometer into the circuit like this picture shows....

But when I gave it power and an audio signal it started to smoke the potentiometer.

This circuit is suppost to make the LED's pulse with the audio signal. So with that said does anyone have any idea on how to make this actually work?

By angelsix
The LEDs brightness with vary with current, and you are not really varying anything. Audio line levels (if that is what you are using) vary the voltage I believe, so all you will be doing is adjusting the saturation level of the NPN, which really isn't going to vary the output current. It would if you hit the right edge but its not designed for that at all.

You would probably be better using an op amp in a voltage-to-current setup making sure either the amp can handle the total power, or lower the output current and then use a transistor to boost the current gain. For an example of a v-c op amp setup take a look here: