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Dictograph breakthrough?

Started by gpo706, November 07, 2009, 10:33:43 AM

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bingster

What about a small capacitor across the switch to alleviate the sound?
= DARRIN =



gpo706

#16
What value capicitor would you recommend, I'm up for a bit tweaking.

Incidentally I found some old circuit diagrams on the net and the buzzer runs off the 12V transformer from the mains (I have one from the original post) but running out of electrical sockets I bought a GPO buzzer 33 to hide inside it and wire to the ringing circuit, assuming it fits inside OK I should be able to make it buzz on demand through the PBX, if not no doubt I can use it for some other scrapper!

Like so:

http://www.britishtelephones.com/buzz33.htm
"now this should take five minutes, where's me screwdriver went now..?"

gpo706

#17
Anyone want a whole office set?

I would but Cambridgeshire isn't exactly local to me.

http://cgi.ebay.co.uk/Dictograph-Telephones-/250699851915?pt=UK_Collectables_RadioTelevision_Telephony_SM&hash=item3a5ee0288b
( dead link 03-27-21 )

Well at least there is one bid so they wont be getting skipped as the seller threatened.
"now this should take five minutes, where's me screwdriver went now..?"

gpo706

That last batch went for 21.28, so at least its all been rescued.

My buzzer arrived today, so after a lot of trial and error wired it in parallel with the switch, and eventually it works, I sealed the unit in a crimp bag to avoid shorts and it has plenty of space to sit on the top of the chassis without interfering with the up and down switchkeys.

I expected a loud buzzing noise but it more like a strangulated Trimphone warble, or maybe a subaqua Trimphone, anyway it buzzes now, so next stage is rewire the thing so I can get a ringing tone when you pick the handset up, and then you flick the switch to connect, and pull out the single bulb unit fitted on it and try to get it to flash when I dial through from the PBX, apart from that happy so far.

Here's the buzzer again, it has one positive terminal and three other marked "loud"/"medium"/"soft", I wired it up to "loud" seeing as it is enclosed in a plastic bag and housed inside the wooden cabinet, well you would, wouldn't you?

http://www.britishtelephones.com/buzz33.htm
"now this should take five minutes, where's me screwdriver went now..?"

gpo706

I'm a dufus, official.

The 3rd scrapper 706 linesmans phone I used to get a second running, yeilded this rattling about in the bunch of bits sitting in its base:

http://www.britishtelephones.com/buzz26a.htm

It had totally detached itself from the upper moulding before I got it, so extraction was at least easy!

Experiments later.

"now this should take five minutes, where's me screwdriver went now..?"

KeithB

You're no doofus  :D  But that's not surprising it was loose.  I'm certain some of these ringers and buzzers could eventually shake themselves loose over a number of years.

gpo706

I'm still a dufus Keith, but as you say the buzzer had errr "detached itself" from the top plate by virtue of the plastic leg having broke off, and all the bits sitting in the base!
"now this should take five minutes, where's me screwdriver went now..?"

gpo706

Got another GPO 33A buzzer the other day, so wanted to try and get the table-top set working.

Darn't thing was dead RX end, so I swapped the handset from the wall-mount, and result - now can listen and talk, added the buzzer and its now sitting on the desk with its larger cousin and the two run off two separate lines from the Pana 616

The sound quality is quite low, but I guess thats down to the bakelite style slide on RX cap.

I might mix and match RX/TX components to see if it boosts the sound, got plenty of donors here...
"now this should take five minutes, where's me screwdriver went now..?"

gpo706

Just swapped the RX capsule from another set, its interesting in that the mounting screws also are the circuit connection, the two screws go into the holes which are mounted in the bakelite handset, so the RX wires are embedded into the handset.

Its a lot less fiddly than any other handset I've encountered, you just unscrew it and rescrew a new one in.

I'm wondering if any US models had this type of mounting for an RX?

Anyhow, its still quite low with the replacement RX so more experimenting to do.

The RX diaphragm is marked thus:

"RICHARD THOMAS & BALDWINS LIMITED"

"No. 24"

"FERROSIL"
"now this should take five minutes, where's me screwdriver went now..?"

gpo706

It's Welsh!

http://llanelli-history.co.uk/chronology%201900-2002.htm

"1947 By this time the Labour Government had nationalised many industries. The coal mines were operated by the National Coal Board.

After long drawn out negotiations with the Government, proposals to establish steel production plants at Trostre and Velindre were underway.

An amalgamation took place between Richard Thomas & Baldwin's tinplate division, Llanelly Associated Companies, Lysaghts and Guest, Keen & Baldwins to form The Steel Company of Wales at Margam."

"FERROSIL" doesn't get much results though.
"now this should take five minutes, where's me screwdriver went now..?"