noniverting transistor amp

[Martin Czech]

> If you take a P-channel FET with the source tied to ground and the drain tied to +12V via a resistor and take out the signal at the drain. Wouldn't  that work?
> 
Maybe. Depending on threshold voltage, you will not get down to ground.
Same with pnp emitter follower. MOst applications require pretty low
voltage for a "0". High level is not so important.

A dual npn inverter can also be wired as Schmidt-Trigger.
Gives clean transitions.

A LF311 comparator with open collector is the best choice,
if you have a proper supply.

m.c.