Re: Op Amp Hookup Help Please

On Mon, 28 Nov 2005 16:19:35 +0000, stilltrying wrote:

> I'm not an experienced electronics person, and so have a "stupid question".
> I have a device that provides an "on" signal intermittently at 2.7 volts DC.
>
> When the "on" of 2.7 volts is available, I need to have a "sub-circuit"
> receive an "on" of 5.0 volts. I have a source of 5.0 volts on the board.
> I've been told I need to use an op amp to do this, so I bought two NTE 928M
> op amps. I've tried to get this to perform as I need, but can't. HELP
> please!!! I put resistors in somewhere, but where and how big?
> tanksalot
> S.F.

An opamp is a super high gain amplifier. So amplify the difference between
your input and a reference. Your NTE928M won't be able to pull the output
up to 5V unless you give it about 7V Vcc. A better way would be to use a
comparator with an open collector output. Google for comparator. Also
google for 'hysteresis'.

---
Regards,
Bob Monsen

The chief aim of all investigations of the external world should be to
discover the rational order and harmony which has been imposed on it by God
and which He revealed to us in the language of mathematics.
- Johannes Kepler
.