How to add a op amp to this circuit?

I built this circuit a while ago but the only problem i have with it is that i have to use electronics like my iPod, laptop, or anything with a high volume output. So I started reading about op amps and hwo they "jack up the signal" and I stated wondering could I somehow integrate it into my circuit so that my audio input is higher therefore allowing me to use my cellphone, tablet, and e.t.c? Currently I have a LM324 Quad amp i know fr sure i wont need all those pin. I also have a tip31 and 2N3904 transistors.

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iceng3 years ago

Try this high gain Darlington configuration before you tackle op-amps

aa gain.GIF

That's what I said....he can use both his existing transistors.

Yes you did.

Since he was already using my first drawing, I had to give him was the second :-)

What are you using for schematic generation for Ibles ?

Iv gotten really good at using the very simple windows paint plus every image is stored in a like subject file.

tramont (author) 3 years ago

I used a 2N3904 for one led box I made and a tip31 for the other. I thought since the HFE was higher on the 2N3904 it wouldn't require such a high audio signal output but I guess I was wrong.

Wire BOTH transistors into a Darlington connection. Put the TIP 31 to the LEDs, and the 3904 on the input stage. Now your gains MULTIPLY

Like this


Which transistor did you use ?

Look into a clap circuit. That will show you how to use an op amp to use an audio signal to flash an LED.

tramont (author)  mpilchfamily3 years ago

Thanks i'll look into it