Re: Comfort / Analogue Input / Op-amp ?

["Nick" <nick@xxxxxxxxxxxxxxx>]

> I can't view the schematic

Damn Yahoo --- just lose the "." off the end of the URL, that's
supposed to be the end of the sentence, not part of the URL!

> I don't know Comfort but
> if this is an analog input
> connecting the opamp output
> to it should not be a problem.
> Low impedance into a high
> impedance will be alright.
> And if it's an A/D input
> nothing should come out of it.

That might be the problem.  The Comfort zones work both as
"normal"
zones to which you connect PIR contacts etc and as A/D inputs.  That
is why I am suspicious that something will be coming out of the
input!

> The op amps also don't like going
> negative in respect to V- but feeding
> it with +5V as you do would make
> sure that its not. Do you still have
> +5V on the faulty board?

Yes, the faulty board still has 5.03V exactly as before.

> Also try to replace the opamp
> and check if it gets hot.
> If so something in the circuit
> might be wrong.

I was suspicious of my circuit at first, but as it worked properly
until the output of the op-amp was connected to Comfort's input....

I can try changing the op-amp (and would appreciate your advice on
whether the TL071 is a good choice or not) but need to wait until I
can get to the shops.

> Do you have a schematic for the Comfort A/D input?

Unfortunately not - it doesn't seem to be published and there is
very little documentation apart from "0 - 5V input".

As usual, many thanks for the prompt response and for trying to help.

Nick