Query: Sterdy Door Access/Intercom

[sandman1600]

Hi,

First post here so apologies if I'm doing something wrong.

I've just moved into a house that was built in the late 50s/early 60s and one of the features we loved was the door access system.

There's a metal (not sure if it's copper/brass/bronze) door bell/buzzer on the front door and a phone handset upstairs to answer and unlock the door.

Sadly it no longer works and the handset end is badly damaged so would need replacing. We'd love to find out more about it and hopefully get it working again.

The door plate is labelled "Sterdy" and I think I've found a note of the item on this webpage

I've uploaded a few images of the item too. I'd love it if anyone has seen these before if they could give me anymore information or possibly a pointer to where I might be able to find a replacement handset.

Many thanks.
Steve

[mike_newcomb]

Hi Steve, Google is your friend in such matters. See:-

sterdy.co.uk

They appear to still be trading, and are in Caterham.

Suggest emailing with photos. Presumably any modern equivalent handset will function.

If you want the same model handset, suggest you advise such and also would be happy with a used one (or replacement parts?) if that is all they have.

Please advise back on progress.

Good Luck - Mike

[Phil G4SPZ]

Hi Steve,

The handset looks similar to the very common types used in military field telephones. There may, of course, be other faults - have you found the power supply? This may be little more than a large bell transformer, possibly with rectifier, hidden away somewhere together with an amplifier for the door speaker and intercom. The most awkward problems could be with the door detent/latch mechanism.

Hopefully the manufacturers will be willing to help you, but sadly it is common to find nowadays that manufacturers have no interest in their own 'legacy' products, and will simply try to persuade you to buy a new one!

Good luck anyway, it will be interesting to hear how you get on.

[G6Tanuki]

Handset's bound to be a carbon-mic with balanced-armature earpiece. There will either be a mains power-supply [some sort of transformer and probably given the age of the thing a Selenium or copper-oxide rectifier] or given that the thing only consumes power when bell-ringing or speaking, it could be powered by a "Flag Battery".

[Nickthedentist]

Originally Posted by sandman1600

Sadly it no longer works and the handset end is badly damaged so would need replacing.

It looks like part of the cradle that the handset sits on is broken off, but it would be feasible to make a reasonable repair in modelling putty or car body repair stuff, I would have thought, using the intact part to make a mould, maybe.

I note that the housing looks to be "cream-coloured Bakelite" (actually urea formaldehyde) but has been painted black. This could be removed with paint stripper if you had the patience.

I bet that electrically, there's not much wrong with it, other than the handset cord and absent power supply.

If you can't manage to mend the internal station, I would keep an eye on eBay as I would imagine that these turn up from time-to-time, perhaps not identified as door entry systems but merely as phones.

If restoration of everything isn't your goal, it would be fairly easy to conceal the guts of a modern unit behind the external station's fascia, and its bell push could be linked to any old doorbell you fancy. This might be your best option if you're not au fait with restoring old tech.

Nick.

EDIT By the way, do any of your neighbours have similar systems? If so, it might be worth asking if anyone's getting rid of theirs, as most people would have no hesitation in binning something like this.

[dagskarlsen]

Does the indoor unit have quite many wires?
1 common wire + 2 to the handset + 1 to the button, and 1 to the ringer/buzzer?

The outdoor unit should have a transmitter element, a loadspeaker, and ringer button.
In addition it may be a magnetic door lock.

This may be nearly the right schematics.
dsk

[Herald1360]

To make the most of the carbon mike output into a loudspeaker I would expect there to be some sort of matching transformers in there as in the induction coils in an old telephone.

[dagskarlsen]

Yes,,,,,,,,and NO!
Yes it would have made it better, and you could not hear loud and clear in these old intercoms. It was a matter of cost, know-how, and simplicity to make it easy to install by less qualified people.

They often used loudspeakers of high impedance, where the dc resistance was measured in the range of 40-120 ohms. This was a rough impedance match, (at least by idea)

To increase the volume the voltage, and current was raised, and the life-length of the carbon transmitters was considerably shortened, even when using bigger carbon granulates.

If this was my home, I would try to repair the indoors telephone, or replace it with an other old one. (they dont differ much by make)
Whats behind the outdoors metal faceplate would have been replaced with substitutes including an amplifier. A charger and a 12V battery could support both this, and a wired burglar and fire alarm unit with a GSM sender, then I got covered in all hence regarding electr(on)ic safety devices.

dsk

[dagskarlsen]

Even when this are a door telephone system, I believe you may get may get lots of answers at Rotary phone forum.

This company seems to be able to help with parts: http://www.intercomsrus.com/intercoms.htm Never tested them, but they have a great page.

dsk

[Aaamusements]

I don't know if the OP still needs one of these Sterdy handsets/bases but if so I dug one out of my perpetual pile of junk just the other day. It's not perfect but its very much more serviceable than the one that they have pictured. I think it's probably a bit later and fortunately it's not been painted black...