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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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13th Sep 2012, 11:22 pm | #1 |
Retired Dormant Member
Join Date: Nov 2011
Location: Deal, Kent, UK.
Posts: 21
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Ideas for a Trimphone switch
Hello
Unable to find a blanking plate for the front of a dial 722 Trimphone, I have slotted in a Switch No. 13A-2 (“Single pole, non-locking, change over”). Although this serves the purpose from a cosmetic point of view, I wonder if it would be possible to connect the switch to do something useful such as temporarily silencing the microphone during a call. My extremely limited knowledge of electronics is such that I don't have a clue what is or is not feasible. I would be very grateful for any ideas and/or guidance. I attach some images of the present set up. John |
14th Sep 2012, 12:20 am | #2 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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Re: Ideas for a Trimphone switch
Try connecting the blue and slate grey wires from the switch, to the blue and white wires from the handset (T3 + T10 with standard wiring). This will give a muting function while the switch is held down.
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If I have seen further than others, it is because I was standing on a pile of failed experiments. |
14th Sep 2012, 11:01 am | #3 |
Heptode
Join Date: Aug 2009
Location: Worthing, Sussex, UK.
Posts: 662
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Re: Ideas for a Trimphone switch
Best to use the switch as a change over with a 300 ohm resistor to keep the microphone circuit ok.
eg 300 ohms +-----white---microphone----blue-------+--------\/\/\/\/\/\/\----------+ | | | +---------------------------------------------/\----------------------------+ switch Hope that helps.... |
14th Sep 2012, 1:30 pm | #4 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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Re: Ideas for a Trimphone switch
I doubt that's strictly necessary. The dial off-normal contacts just short-circuit the microphone.
__________________
If I have seen further than others, it is because I was standing on a pile of failed experiments. |
14th Sep 2012, 2:22 pm | #5 |
Octode
Join Date: Jul 2011
Location: Stockport, Greater Manchester
Posts: 1,217
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Re: Ideas for a Trimphone switch
I have used a switch to silence the microphone in several Trimphones - due to the design of the handset, covering the holes at the bottom doesn't work! Just connected across the blue and white wires works fine...
Robert |
14th Sep 2012, 8:44 pm | #6 |
Retired Dormant Member
Join Date: Nov 2011
Location: Deal, Kent, UK.
Posts: 21
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Re: Ideas for a Trimphone switch
Thank you all for the comments. I have now connected the blue and grey wires from the switch to T3 & T10 and it works perfectly.
Many thanks John |