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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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31st Dec 2020, 11:58 am | #1 |
Tetrode
Join Date: Dec 2020
Location: Chelmsford, Essex, UK
Posts: 69
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Connecting U43 to an Electric Bell
I have just restored and converted a French U43 Ericsson dated 1964.
I was amazed at just how little I needed to do to get this working on our phone line - a BT line cord, two diodes and a quick clean up of some oxidised contacts. The sound from the earpiece is a bit quiet and the sound from the Mother-In-Law speaker is about 50% too quiet (any ideas? I might remove the added rectifier to see if this helps - I chose random diodes!) Apart from this the phone looks and performs really well. But to the main question - I have a vintage electric bell (see attached) that I would like to use as a bellset for the phone. I know it will not give a traditional twin-bell tone, but this car boot find deserves a purpose in life. I cannot find much in English on the U43, and nothing about bellsets for the model. Can anyone suggest a circuit that can connect the two? [The bell dings nicely with a tired 12V battery, but too aggressively with a 12V 2.5A smoothflow model train supply] HAPPY NEW YEAR TO US ALL Last edited by Xyience; 31st Dec 2020 at 12:05 pm. Reason: attach photo |
31st Dec 2020, 12:41 pm | #2 |
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,127
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Re: Connecting U43 to an Electric Bell
The problem is that the bell shown is a DC trembler bell (rated, as you say, at 12V), whereas the ringing current from a telephone line is 25Hz AC at around 75V or so.
Incidentally, I am unclear what the diodes described are for.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
31st Dec 2020, 12:52 pm | #3 |
Tetrode
Join Date: Dec 2020
Location: Chelmsford, Essex, UK
Posts: 69
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Re: Connecting U43 to an Electric Bell
That is an issue. It doesn't sound like compatibility would be easy or cost-effective.
Would the bellset/bell from a junked GPO phone work with the U43? These seem easy to come by. The diodes are instead of a No 205 rectifier as suggested by https://www.britishtelephones.com/tranchan.htm Phones are entirely new to me, and I didn't want to blast my families hearing, so I went with the instruction. |
31st Dec 2020, 1:05 pm | #4 | ||
Dekatron
Join Date: Feb 2005
Location: West Cumbria (CA13), UK
Posts: 6,127
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Re: Connecting U43 to an Electric Bell
Quote:
Quote:
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Mending is better than Ending (cf Brave New World by Aldous Huxley) |
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13th Jan 2021, 11:52 am | #5 |
Tetrode
Join Date: Dec 2020
Location: Chelmsford, Essex, UK
Posts: 69
|
Re: Connecting U43 to an Electric Bell
I found a perfect donor telephone for my purposes. A stinky, discoloured cream 706. The smell off this phone actually made me gag once or twice!
I stripped off all of the components and mechanical items one by one until I was assured that I had just enough left to operate the bell. This left the metal chassis, the circuit board, but only to mount the striker mechanism, and the two gongs. I added a resistor to correct the REN and wired up directly to the U43. This works perfectly. When I get some more time I will give the bellset its own BT plug and add a nice cover to keep fingers away from the exposed terminals. This is hung high up on a wall so it is safe enough for now. Everyone in the house loves the sound of the metal bells. Takes me right back to the 70's. I experimented with the phone by taking out the DIY 205 rectifier. This does allow some unpleasant transients to reach the receiver, so the diodes stay. Thanks for the tips Dave |