Radiospares Tapped Choke - UK Vintage Radio Repair and Restoration Discussion Forum

M0FYA Andy · 24th Oct 2019, 2:18 pm

Can anyone suggest what would have been the intended application for a Radiospares Tapped Choke, 150mH at 0.9Amps, please?

When did Radiospares change their name to RS Components, that dates it to a degree?

Many thanks,

Andy

ms660 · 24th Oct 2019, 2:32 pm

Scroll down:

http://www.electrojumble.org/passives_013.htm

Lawrence.

M0FYA Andy · 24th Oct 2019, 3:41 pm

Lawrence, thanks. Although I'm not really any wiser how it would be used, other than as a simple smoothing choke in a low-voltage high-current supply. Was there a Radiospares application note of any sort?

Andy

ms660 · 24th Oct 2019, 3:57 pm

Quote:

Originally Posted by M0FYA Andy

Lawrence, thanks. Although I'm not really any wiser how it would be used, other than as a simple smoothing choke in a low-voltage high-current supply. Was there a Radiospares application note of any sort?

Single ended Class A transistor OP stage is all I can think of at the moment like what was used in some car radios (high Q current) I suspect there would have been a data sheet, not sure about application sheet(s) with circuits

Lawrence.

m0cemdave · 25th Oct 2019, 12:29 am

Quote:

Originally Posted by M0FYA Andy

Lawrence, thanks. Although I'm not really any wiser how it would be used, other than as a simple smoothing choke in a low-voltage high-current supply. Was there a Radiospares application note of any sort?

Andy

The info on electrojumble is much the same as that in the 1967 "Radiospares"
catalogue (83 pages of 9-1/4 x 6"). I don't think they produced datasheets in those days.
Looks like it was tapped to allow matching to different impedance speakers in car radio applications etc.

Here's a scan:

trobbins · 25th Oct 2019, 2:52 am

Given it provides a 1:1 winding with 15 ohm tap as CT, and it is nice audio quality, there may be a push-pull output stage arrangement with each end of the choke connected to PP cathodes, and the CT connected to ground or bias as a common-cathode point.

The only vintage scheme I can recall that is 'somewhat' related was the Parry Cathamplifier, but it used a transformer.

https://dalmura.com.au/projects/Cathamplifier.html

Paul JD · 25th Oct 2019, 8:02 am

Quote:

Originally Posted by M0FYA Andy

When did Radiospares change their name to RS Components

1971

https://uk.rs-online.com/web/general...boutRS/history

M0FYA Andy · 25th Oct 2019, 8:15 am

Many thanks for the replies. I bought one recently simply because it had me puzzled and I find vintage components fascinating!
In some ways it seems like a solution looking for a problem, but that's not how Radiospares worked, they supplied the parts which everybody wanted. So there must have been a good market at the time.

Andy

24th Oct 2019, 2:18 pm	#1
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Radiospares Tapped Choke Can anyone suggest what would have been the intended application for a Radiospares Tapped Choke, 150mH at 0.9Amps, please? When did Radiospares change their name to RS Components, that dates it to a degree? Many thanks, Andy

24th Oct 2019, 2:32 pm	#2
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Radiospares Tapped Choke Scroll down: http://www.electrojumble.org/passives_013.htm Lawrence.

24th Oct 2019, 3:41 pm	#3
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: Radiospares Tapped Choke Lawrence, thanks. Although I'm not really any wiser how it would be used, other than as a simple smoothing choke in a low-voltage high-current supply. Was there a Radiospares application note of any sort? Andy

25th Oct 2019, 2:52 am	#6
trobbins Heptode Join Date: Oct 2009 Location: Melbourne Australia Posts: 901	Re: Radiospares Tapped Choke Given it provides a 1:1 winding with 15 ohm tap as CT, and it is nice audio quality, there may be a push-pull output stage arrangement with each end of the choke connected to PP cathodes, and the CT connected to ground or bias as a common-cathode point. The only vintage scheme I can recall that is 'somewhat' related was the Parry Cathamplifier, but it used a transformer. https://dalmura.com.au/projects/Cathamplifier.html

25th Oct 2019, 8:15 am	#8
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: Radiospares Tapped Choke Many thanks for the replies. I bought one recently simply because it had me puzzled and I find vintage components fascinating! In some ways it seems like a solution looking for a problem, but that's not how Radiospares worked, they supplied the parts which everybody wanted. So there must have been a good market at the time. Andy