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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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20th Nov 2020, 11:41 am | #1 |
Heptode
Join Date: Aug 2016
Location: Dumfries, Scotland, UK.
Posts: 549
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Circuit wanted for 1920s style Battery powered Amplifier
Right I have a very nice two valve radio from 1925 I want to build a seperate amplifier for it using 2v battery valves anyone built anything like this or in possession of an original design for one ??
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20th Nov 2020, 12:16 pm | #2 |
Dekatron
Join Date: Sep 2007
Location: Oxfordshire, UK.
Posts: 4,311
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Re: Circuit wanted for 1920s style Battery powered Amplifier
It's claimed that although push-pull was known about by this stage, the first commercial PP radio amp only appeared in 1924 https://en.wikipedia.org/wiki/Push%E2%80%93pull_output. A more primitive single-ended amp is detailed in this series of Godfrey Phillips cigarette cards, including all the instructions for building one http://www.r-type.org/articles/art-028.htm. I like the way that the two cards which cover the subject of the valve more or less boil down to saying "Get a valve" .
Cheers, GJ
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20th Nov 2020, 12:48 pm | #3 |
Dekatron
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 3,274
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Re: Circuit wanted for 1920s style Battery powered Amplifier
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22nd Nov 2020, 12:27 pm | #4 |
Dekatron
Join Date: Nov 2006
Location: London, UK.
Posts: 3,496
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Re: Circuit wanted for 1920s style Battery powered Amplifier
There are pages and pages of ads first, but if you scroll down to the 12th page, that’s where the circuit diagram is. It is marked in the upper left hand corner as (page) 3.
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Al |
23rd Nov 2020, 9:46 pm | #5 |
Heptode
Join Date: Aug 2016
Location: Dumfries, Scotland, UK.
Posts: 549
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Re: Circuit wanted for 1920s style Battery powered Amplifier
I'd quite like to make a push pull amp struggling to find a.schematic for push pull using directly heated battery Triodes though.
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23rd Nov 2020, 10:15 pm | #6 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,195
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Re: Circuit wanted for 1920s style Battery powered Amplifier
Hi lloyd, have a look at QPP circuits. They use a single valve with 2 electrode assemblies inside
Ed |
23rd Nov 2020, 10:18 pm | #7 |
Dekatron
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 3,274
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Re: Circuit wanted for 1920s style Battery powered Amplifier
How about these?
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24th Nov 2020, 10:00 am | #8 |
Hexode
Join Date: Mar 2009
Location: Cirencester, Gloucestershire, UK.
Posts: 391
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Re: Circuit wanted for 1920s style Battery powered Amplifier
Looks like a worthwhile project.
Suitable output valves, even twin triodes and QPP twin pentodes, are fairly easy to find. Suitable driver and output transformers with intact windings are harder to find. Unless you intend to build the transformers yourself, I suggest you look for the transformers first. best regards ... Stef |
25th Nov 2020, 9:39 pm | #9 |
Heptode
Join Date: Aug 2016
Location: Dumfries, Scotland, UK.
Posts: 549
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Re: Circuit wanted for 1920s style Battery powered Amplifier
Yes I have some transformers non push pull so I think we'll stick to single ended
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26th Nov 2020, 6:03 pm | #10 |
Heptode
Join Date: Aug 2016
Location: Dumfries, Scotland, UK.
Posts: 549
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Re: Circuit wanted for 1920s style Battery powered Amplifier
OK I'm still really struggling with this one I can find load of single valve designs bit for the sake of vanity and looks I really want two valves they're going to be visible ideally what I want is something switchable between one valve and two I have a pile of good period ( ish ) 2 volt Triodes pm2 PM2a p220 and some 220-ot to play with I've got 2.5:1 4.5:1 and 5:1 transformers sitting about and a fair selection of period caps grid resistors and switches terminals Rheostats etc.
So the aim is to make something that looks good and works fairly well. |
26th Nov 2020, 11:26 pm | #11 |
Dekatron
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 3,274
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Re: Circuit wanted for 1920s style Battery powered Amplifier
If you cannot find a couple of vintage transformers with with centre tapped windings it might be worth the effort to strip a couple of old coupling transformers and rewind them with centre taps. There are plenty of old coupling transformers available. Probably quite a few worthless ones with corroded (open) windings.
Peter |
27th Nov 2020, 12:20 am | #12 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: Circuit wanted for 1920s style Battery powered Amplifier
This set has a choice of using a single or two audio valves by switching and the info is
available "up top" http://www.kbmuseum.org.uk/kb_images...set3a_late.htm |
27th Nov 2020, 9:29 pm | #13 |
Heptode
Join Date: Aug 2016
Location: Dumfries, Scotland, UK.
Posts: 549
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Re: Circuit wanted for 1920s style Battery powered Amplifier
Well I found a circuit so I've started building it coming along quite nicely though I can't decide if the transformer should stay on top or go underneath I quite like the look of it up top.
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