Gain of LM3900

Thread Starter

Neil Groves

Joined Sep 14, 2011
I have just completed the first stage of my project and have a question regarding the LM3900 chip, on the input i have such a small sinewave it is barely visible with the scope, meanwhile i have a thumping great sinewave on the output pin, it's beautiful!!!

So what is the gain of the LM3900? it must be huge?



Joined Dec 20, 2007
That very old LM3900 amplifier is not an opamp, it is different.
I am surprised that it is still being manufactured.
Why don't you modify the circuit a little so an ordinary opamp can be used?


Joined Nov 22, 2011
I am surprised that it is still being manufactured.
I am pretty certain that most of these ICs are no longer actually in production. They couldn't be, there is next to zero commercial demand.

I mean, the preparation work / tool cost to do a run of chips is probably only a few million dollars :eek:

But 0.0000001 cents a piece after that initial fee.
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