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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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4th May 2020, 5:58 pm | #21 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
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Re: Plan 105 with external extensions
The Converter Ringing 9A is only powered when a 'calling' key is pressed (battery -ve is then connected to the Converter Ringing 9A via contacts KA2 or KB2 in the Planset, see N4507 for more details). It was possible to run the Planphone system off a battery rather than the mains power supply (Power Unit 53B), the official battery was 8 'Flag' cells in series. I've run mine off 8 D cells in series at least for testing/demonstration.
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4th May 2020, 7:02 pm | #22 | |
Octode
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Location: Saltburn-East, Cleveland, UK.
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Re: Plan 105 with external extensions
Quote:
Andrew Last edited by AndiiT; 4th May 2020 at 7:21 pm. |
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4th May 2020, 9:28 pm | #23 |
Dekatron
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Location: West Cumbria (CA13), UK
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Re: Plan 105 with external extensions
Sorry, Andrew, I was mistaken about the bell ringing in the main. Listening a little more carefully while muffling the sound of the extensions ringing, I realise that only the buzzer in the main is sounding, not its bell - despite having a capacitor between the A leg and earth.
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5th May 2020, 7:52 am | #24 |
Dekatron
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Re: Plan 105 with external extensions
I seem to remember that's what it should do. Diagram N1450 has a comment to this effect too. You get the buzzer sounding at Main if the extensions are ringing.
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5th May 2020, 2:14 pm | #25 |
Dekatron
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Re: Plan 105 with external extensions
It seems that even the lack of ringing was down to that broken wire, and the connection between A leg and earth wasn't needed after all.
While trying to track down a severe crackle that has developed while switched to the default speak to extension, I disconnected the capacitor that I'd inserted between the A leg and earth. Lo and behold, the main still rings on "spk to exch", and the extension rings, with the main buzzing, on "extn to exch". Oh, and the crackle is probably down to the switch contacts, but my Servisol 10 has chosen this moment to run out without warning! Project on hold until a new can arrives.
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5th May 2020, 9:30 pm | #26 | |
Octode
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Re: Plan 105 with external extensions
Quote:
I'm off work till Friday so may well have a play about in the next couple of days. Andrew |
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6th May 2020, 7:54 am | #27 |
Dekatron
Join Date: Jun 2015
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Re: Plan 105 with external extensions
I seem to remember that when I worked through the Plan 105 External circuits, you do need the A leg to be earthed for the ringing circuit to be completed. It was assumed this was done at the exchange, but when I was running the setup on a line simulator on the bench it did not ring until I'd made that connection.
Of course the A leg would normally be essentially earthed at the exchange so it will work without extra connections on a normal telephone line. |
6th May 2020, 8:04 am | #28 |
Dekatron
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Re: Plan 105 with external extensions
I'm beginning to wonder whether the A leg is inadvertently shorting to the earth (which isn't physically earthed by the way, continuity merely maintained within the setup). I'll do a bit more continuity checking.
As far as earthing at the exchange is concerned, I should say that all my testing is done on extensions of my house PABX.
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6th May 2020, 8:56 am | #29 |
Dekatron
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Re: Plan 105 with external extensions
Resistance measures as ∞ in all switch positions, so it would appear not. As a certain Alice would have said, "curiouser and curiouser".
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6th May 2020, 6:01 pm | #30 |
Triode
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Re: Plan 105 with external extensions
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