On Sun, 6 Jun 2004 11:56:19 +0100, "Owain"
wrote:

"T i m" wrote
| I should have taken note of the make / model on the existing handsets
| shouldn't I ;-(

Yes, and until you do we're not really much further forward.

| The BPT one looks like it might do (subject to the technical stuff) ..

If it's a BPT (or is it BTP I can't remember offhand) panel and speech unit,
and power supply ...

| ? Do these things normally come with a line cord or are they hard
| wired?

Hard wired. BPT and I think Entryphone provide adapter bases that can be
used on a cord.

| I can now also add there are also separate12V DC and / 12V AC supplies
| to this system (DC for door entry mech / phones / panel, AC for
| camera?).

More likely DC for panel speech and camera, AC for the lock or some systems
use AC buzzers in the handsets.

Owain

Ok, thanks for the above and all noted.

So, the PTM switches 'switch' 12V DV (looking at the bunch of wires
that are connected in what looks like a home made PSU box with a std
12DC PSU in there). So that might activate a relay in the door entry
panel and that in turn switches the 12V AC through the door release
solenoid?

I haven't traced (or measured) the PSU feed to the camera but it could
well be AC. I have some pro CCTV cameras here that run from an
low(ish) voltage AC supply and hence the guess?

Assuming I (we) can recognise the maker of the two phones (that are in
parallel), could I just measure the 'line' voltage actoss pins 2-5 and
see if it's 12V as suspected? If so wouldn't that be a big clue as to
what was needed? (I havent been inside the door entry panel yet but
didn't think I saw a mains lead going in there so assumed it was
unning from one of the external PSU's?)

If they were running from 12V DC and in parallel wouldn't that tell us
a lot (impedance etc)?

All the best .. and thanks again Owain ..

T i m