"Dave Baldwin" writes:
>You should get app note AN-72 from National Semiconductor. It's title is
>"the LM3900: A New Current-Differencing Quad of +/- Input Amplifiers". The
>first important thing to know is that the inputs are never connected
>directly to a voltage source. Second, they are Single supply devices with
>both inputs one diode drop above ground.
Thanks. I will get that application note. What you tell me
matches what I observed about that chip. I just hadn't synthesized it
in to something coherent yet.
This explains why you sometimes find the LM3900 in tape head
preamps and it makes a pretty good dynamic microphone preamp. These
are all applications where one may have very little voltage to play
with but a fair amount of current relatively speaking.
Again, thank you.
Martin McCormick
--
Author: Martin McCormick
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Fat City Hosting, San Diego, California -- http://www.fatcity.com
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