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Old 5th Jun 2020, 10:07 am   #21
peter_sol
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Hi Nick
I would imagine you could connect a low impedance speaker to where the primary of the 100V line transformer connects to. leaving it in place as I suspect that some negative feedback comes from the primary.
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Old 5th Jun 2020, 10:48 am   #22
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Strange transistor mix for 1966. Maybe they had a big box of OC44s they wanted to use up.
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Old 5th Jun 2020, 11:25 am   #23
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Quote:
Originally Posted by Nickthedentist View Post
The sockets in our classroom were these Belling Lee ones (pic from eBay):

Good point about the cable distribution system, but I always thought that was TV rather than radio.
Thanks for a picture of the sockets, the one I was remember had 3 round holes, with the central one lower than an earthed 5 amp socket.
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Old 5th Jun 2020, 11:50 am   #24
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

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Strange transistor mix for 1966. Maybe they had a big box of OC44s they wanted to use up.
My impression of Clarke & Smith from my former colleague and their service manager was that their equipment was solidly made but not state of the art - I don`t think they had an extensive design and development department.

I do remember our school music room had quite a nice C & S record player in their trademark polished wood - it always sounded quite good on the rare occasions we got to hear it. (circa 1961 - 66)
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Old 5th Jun 2020, 12:03 pm   #25
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

That brings back memories of being at school in the 60s, I went to a normal primary school despite being severely sight impaired. The head master knew I loved anything to do with radio so as I couldn't take part in games etc he'd let me sit in his office and record stuff from one of those onto a massive tape recorder (Ferrograph?). I was in heaven!
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Old 5th Jun 2020, 12:13 pm   #26
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

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Originally Posted by Essexsteve View Post
That brings back memories of being at school in the 60s, I went to a normal primary school despite being severely sight impaired. The head master knew I loved anything to do with radio so as I couldn't take part in games etc he'd let me sit in his office and record stuff from one of those onto a massive tape recorder (Ferrograph?). I was in heaven!
It could have been a Clark & Smith - they did produce a tape machine using the Wearite (Ferrograph) deck - in a polished wooden case, of course.
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Old 5th Jun 2020, 12:23 pm   #27
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Hi Nick,

Do a search on the web, the Goerler unit documentation for the IF-strip and tuners are out there somewhere (or at least they were some time ago).
If you can not find them let me know, I have it stashed away somewhere on my computer.

Regards, Peter
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Old 5th Jun 2020, 12:26 pm   #28
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Very interesting, Nick. I have never seen one of those, but then I come from Lancashire and it seems they were made for the London area.

I remember C&S equipment being used at primary school and the big speakers being lugged round to be plugged in in the classrooms. In my last year at primary school the class which was expected to pass the 11+ was housed in the former staff room as the school was overcrowded. This had an 8812 radio on a side table and I was appointed as radio monitor to switch it on and off as required. There was also a record player with an oval speaker aperture which was used every morning to play an EP of sheep may safely graze whilst the children were coming in to assembly. It was the same record every morning and I can never hear it now without thinking of school assembly.

Needless to say I have acquired both the radio and record player, although I have managed to damage one of the rather fragile IF transformers on the radio whilst attempting to align it!
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Old 5th Jun 2020, 9:41 pm   #29
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Thanks to everyone for their comments
Quote:
Originally Posted by 1100 man View Post
Hi Nick,
Thanks for an interesting write up on an unusual piece of equipment. I rather like the C&S stuff, but I don't remember any of my schools having any radio gear. In fact, I don't recall ever listening to a radio broadcast at school!

Glad you have finally managed to find one!

All the best
Nick
Glad you appreciated my post, Nick

Quote:
Originally Posted by crackle View Post
Nice write up Nick.
I look forward to seeing your proposal for this radio in the Radio Museum.

Mike
And thanks Mike too. I might PM you about the best way to do that, if I may, please.

Quote:
Originally Posted by peter_sol View Post
Hi Nick
I would imagine you could connect a low impedance speaker to where the primary of the 100V line transformer connects to. leaving it in place as I suspect that some negative feedback comes from the primary.
Thanks Peter, that did cross my mind. The internal transformer has a very low resistance primary (~0.6R) though I can't easily measure its impedance. So presumably, sticking an 8R speaker in its place should be OK as far as the power amp is concerned. Did you mean feedback from the high-Z secondary, by the way?

Quote:
Originally Posted by barrymagrec View Post
Quote:
Originally Posted by paulsherwin View Post
Strange transistor mix for 1966. Maybe they had a big box of OC44s they wanted to use up.
My impression of Clarke & Smith from my former colleague and their service manager was that their equipment was solidly made but not state of the art - I don`t think they had an extensive design and development department.
Thanks both. I agree with that, their products looked old-fashioned even when new, and I suspect the technical aspects were the same. But schools wanted tried and tested and robust, not innovative.

Quote:
Originally Posted by orbanp1 View Post
Hi Nick,

Do a search on the web, the Goerler unit documentation for the IF-strip and tuners are out there somewhere (or at least they were some time ago).
If you can not find them let me know, I have it stashed away somewhere on my computer.

Regards, Peter
Thanks Peter. I had a quick search but couldn't find anything with those codes, and Radiomusem.org has nothing either. But I spelled the name without the umlaut or e, so maybe that's where I went wrong. So yet, if you find anything, please do PM me.

Quote:
Originally Posted by PaulR View Post
Very interesting, Nick. I have never seen one of those, but then I come from Lancashire and it seems they were made for the London area.

I remember C&S equipment being used at primary school and the big speakers being lugged round to be plugged in in the classrooms. In my last year at primary school the class which was expected to pass the 11+ was housed in the former staff room as the school was overcrowded. This had an 8812 radio on a side table and I was appointed as radio monitor to switch it on and off as required. There was also a record player with an oval speaker aperture which was used every morning to play an EP of sheep may safely graze whilst the children were coming in to assembly. It was the same record every morning and I can never hear it now without thinking of school assembly.

Needless to say I have acquired both the radio and record player, although I have managed to damage one of the rather fragile IF transformers on the radio whilst attempting to align it!
Yes, this was definitely a London special.

Nice to hear you're a fellow C&S nut and have tracked down some mementos too!
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Old 5th Jun 2020, 10:30 pm   #30
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

The junior school, built on the early '60s, that my children attended and more recently where we went to vote still has a centralised installation with a stepped volume control in the hall and speaker sockets high up above it with little shelves next to them. The volume control and speaker sockets are finished in the same coloured paint as the C&S radios and I wonder whether they were supplied by them. I would love to take my radio there to try out the old installation.
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Old 5th Jun 2020, 11:24 pm   #31
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

My primary school had a Coomber (I think) stereo on a trolley, with a turntable and tape deck and largish speakers. I can't remember if it had a radio built into it. There was also an input for microphone, which could be mixed into the different inputs.

We used to have a different classical piece of music every week for walking into assembly, & the headmistress used to get a bit angry if whoever was playing the music just stopped it rather than fade it out.
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Old 6th Jun 2020, 8:59 am   #32
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Quote:
Originally Posted by Richard_FM View Post
We used to have a different classical piece of music every week for walking into assembly, & the headmistress used to get a bit angry if whoever was playing the music just stopped it rather than fade it out.
Rather more imaginative than Sheep may safely graze every single morning!

My friend's mother was a school secretary and we used to "help" during the school holidays. They had a box of new classical records delivered from an upmarket record shop in Southport during each summer holiday.

Our church was given two Coomber PA speakers previously from a school. One has an FM radio and cassette player fitted into the cabinet. Oddly it also has a clock and timer fitted to it. I can't imagine what that would be used for.
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Old 6th Jun 2020, 12:40 pm   #33
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Quote:
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Quote:
Originally Posted by Richard_FM View Post
We used to have a different classical piece of music every week for walking into assembly, & the headmistress used to get a bit angry if whoever was playing the music just stopped it rather than fade it out.
Rather more imaginative than Sheep may safely graze every single morning!

My friend's mother was a school secretary and we used to "help" during the school holidays. They had a box of new classical records delivered from an upmarket record shop in Southport during each summer holiday.

Our church was given two Coomber PA speakers previously from a school. One has an FM radio and cassette player fitted into the cabinet. Oddly it also has a clock and timer fitted to it. I can't imagine what that would be used for.
Maybe it was designed to record off the radio?

This would be useful for recording schools programmes.
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Old 6th Jun 2020, 1:01 pm   #34
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Hi Nick
Re the negative feedback.
I think it will either come from the same low impedance winding as the pilot speaker or a seperate secondary winding.
if the 70v winding is centre tapped/balanced it wouldnt do to upset that.
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Old 6th Jun 2020, 2:11 pm   #35
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

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Maybe it was designed to record off the radio?

This would be useful for recording schools programmes.
Yes that's probably it. I had to disconnect the clock as it kept switching the speaker off. No problem for ordinary use of course.
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Old 7th Jun 2020, 12:45 pm   #36
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Hi Nick,

I did check my records, and I did find the Goerler documents, but unfortunately those are different from those used in your radio.
The IF-strip that I have has four stages vs. the three in yours, the circuit is probably quite close to yours.
The documentation for the four stage unit can be found on RM too.

Regards, Peter
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Old 7th Jun 2020, 3:48 pm   #37
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Thanks you for looking, Peter!
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Old 8th Jun 2020, 9:19 am   #38
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Hi Nick,

Jeffrey Borinski has been following your thread and tells me he has the schematic for this set if you need it. http://www.borinsky.co.uk/

Peter
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Old 10th Jun 2020, 9:18 pm   #39
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Default Re: Introducing the Clarke & Smith 747 schools receiver from 1966

Thank you so much for the tip-off, Peter!

JB and I have been in touch, and I now have the original C&S circuit diagram! If anyone wants to see it, he tells me it's available at Golborne Vintage Radio.

I got a Canford "MP 10-4" 100V 10W transformer from eBay, and fitted it into a redundant Mordaunt Short MS077 3-way loudspeaker from c.1970, then installed the pair in my workshop-cum-garage-cum-junk pile. I've just had Saint-Saens' Organ Symphony blasting out for the last half hour or so, and I have to say, I've never had so much fun from a mono reproducer

N.
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