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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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11th May 2022, 11:19 pm | #1 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Transformer or choke and RC unit
These are starting to intrigue me, in a bits box is an old transformer of unknown make and a Bullphone radio products RC unit.
The transformer has no label on the top as it is missing, but the three terminals from left to right are :- HT+, C , P&C1. The terminal on the side is labelled Earth. Typically around 400 Ohms between HT+ and C and C and P&C1 so 800 Ohms in total, In inductance approx 3.7H per section, but 18H total across HT+ and P&C1. No resistance to Earth, guess it could connect to the laminations or it is open circuit. The next unit is basically a holder for glass style resistors, grid leak and I am guessing Plate load resistor. Terminals are HT, P, G and GB, guessing grid bias battery? The caps in the unit are not very well when being read with my TC1 so I assume very leaky. Perhaps I should warm the unit up to remove the wax and see what is in there. I have several caps in Bakelite cases and guess they will all be duff by now all in wax so should be reasonably easy to replace. I have a couple of 4 pin valve holders and valves etc so thinking of adding a 1920/1930's early battery style project to my list of to do's. If anyone knows details of the two objects I would appreciate the information. Adrian |
12th May 2022, 1:22 am | #2 | |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Transformer or choke and RC unit
Quote:
Last edited by radiograham; 12th May 2022 at 1:27 am. Reason: atachment |
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12th May 2022, 1:32 am | #3 |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Transformer or choke and RC unit
Telsen Mag.
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12th May 2022, 7:40 am | #4 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: Transformer or choke and RC unit
Thank you Graham, I will have a good look through that mag.
Adrian |
12th May 2022, 8:22 am | #5 |
Octode
Join Date: Jan 2004
Location: Southport, Merseyside, UK.
Posts: 1,156
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Re: Transformer or choke and RC unit
Other than posting this scan from a 1930-31 catalogue showing something similar, I can't offer any other info' about them.
John |
12th May 2022, 11:34 am | #6 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: Transformer or choke and RC unit
Thanks John
I have just taken the R.C Unit to pieces, well melted out the bitumen, was really hoping it was a hard wax. Found where the cap was connected. Looking through the magazine from Graham, I guess it makes building a radio a bit like a Meccano build, bolt things down and wire between the connections. I have downloaded all six of the Telsen Magazines and will print off and have a good read. Adrian |
12th May 2022, 12:17 pm | #7 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Transformer or choke and RC unit
The RC coupler was a low cost alternative to an audio intervalve transformer. You will find similar markings for P (plate/anode), HT, G (grid), GB (grid bias battery) on the transformers. The disadvantage with the RC coupling is lower load impedance and loss of gain from the transformer turns ratio.
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12th May 2022, 12:18 pm | #8 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,107
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Re: Transformer or choke and RC unit
It may have been high grade 'stockholm tar', ie derived from wood not crude.
Dave |
12th May 2022, 12:35 pm | #9 | ||
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: Transformer or choke and RC unit
Quote:
Quote:
I have approx 9, 4 pin valves, a couple of holders, some other chokes and variable caps, even what looks like a NOS Cossor 2P output valve, should be able to come up with something as a project. Adrian |
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12th May 2022, 1:07 pm | #10 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
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Re: Transformer or choke and RC unit
Stockholm tar has a very strong smell of kippers even if it is just a little smudge around the tin lid.
I know because I have seen and smelt it used in a non electronic setting. |
12th May 2022, 1:52 pm | #11 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: Transformer or choke and RC unit
Then I think it is bitumen, no particular smell to it.
Acetone not working well may try turps. Adrian |
12th May 2022, 5:50 pm | #12 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 4,107
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Re: Transformer or choke and RC unit
Or wd40. It's bakelite-friendly.
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12th May 2022, 11:29 pm | #13 |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Transformer or choke and RC unit
Hi,the imposing looking building on the front of the telsen mags is still there or it was in early 90s.Not as impressive as on the mags,artistic licence much in evidence.Took me a while to find it nestling under a flyover in aston birmingham.
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13th May 2022, 10:00 am | #14 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: Transformer or choke and RC unit
Oh I don't know the building looks OK to me, courtesy of google street maps.
I have been checking out so caps or condensers to give them the term of the time. All basically short circuit, the best i have managed to recover is a 2 mF but at 180 Volts it has 400uA leakage. So at some point I will melt out the bitumen on them and fit modern internals and then try to reseal. I have some smaller mica caps that may test OK. A long term idea for a project I think. time to get on with some smaller projects and get them out of the way. Adrian |
13th May 2022, 1:05 pm | #15 |
Dekatron
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
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Re: Transformer or choke and RC unit
The less messy way to remove bitumen is to freeze it then chip it out, just beware that the bitumen chips don't end up on the carpet as when thawed they stick like tar.
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13th May 2022, 7:29 pm | #16 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,195
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Re: Transformer or choke and RC unit
Hi Adrian, plenty of designs in the Radiomags to use the parts on, but you will need to build your own baseboard and source some material for the front panel
Ed |
13th May 2022, 7:32 pm | #17 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: Transformer or choke and RC unit
Thanks PJL and Ed.
Yes there are lots out there, I could do with some interstage transformers but have time to try and find some, it is not an urgent project idea. Adrian |
13th May 2022, 7:34 pm | #18 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: Transformer or choke and RC unit
Forgot to add looking through the Telsen magazines, the loudspeaker must have been in the hundreds if not K Ohms range?
Adrian |
14th May 2022, 3:28 am | #19 | |
Hexode
Join Date: Oct 2017
Location: Manchester, UK.
Posts: 363
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Re: Transformer or choke and RC unit
Quote:
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14th May 2022, 7:54 am | #20 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: Transformer or choke and RC unit
Graham as an aside, I found another Matsui remote, pm me your address and I will get it to you.
Adrian |