Peter P. wrote:
> In continuation of this thread, I have hinted before that I have a clamp circuit that uses generic parts and works well. I have posted it before on this list (eliciting no reaction). It is hardly ground-breaking, and it works very well. It can be implemented in several variants, and a zero power version is possible (by adding a MOSFET like a 2N7000 in series with R1, controlled by a voltage monitor or by a microprocessor output).

Hi Peter,

Another thing to point out about the circuit you posted, the transistors
are reverse biased B-E, so don't expect to use this circuit above 5
volts because of the zener effect. Of course nobody would, but it's
sometimes an easy thing to forget.

But it is a well-tested circuit, I have used it many times in situations 
where I have an amplified transducer running from opamp (+-15V)
voltages going into an ADC.

Cheerful regards,

Bob
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