USB to RS232 without using any line driver IC

This prototype is a total replacement of line driver IC & works very well. Used discrete components in place of line driver ICs. I’ve taken reference from Sparkfun tutorial¬†

I have used USB to TTL converter (CP2102) module for interfacing with laptop. Now when I prototyped the circuit it was not working. I wondered what’s going on.

After replacing components & some tweaking I had found out that it’s the transistor who is responsible for jam. Actually every transistor has beta (current amplification factor) value which changes from transistor to transistor. So I replaced PNP transistor base resistor with a potentiometer of 10k value. Continue reading