Author Options:

How to add a op amp to this circuit? Answered

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.



4 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.

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.