UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Reply
 
Thread Tools
Old 22nd Apr 2024, 11:59 am   #1
GMB
Dekatron
 
GMB's Avatar
 
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,119
Default Educational 'scope ?

Has anyone seen these small and strange oscilloscopes or knows what they were made for? (Panel is 6 inches square, only 4 inches deep)

I bought a couple of these from a closing-down equipment supplier.
I assume they are meant to be educational as they are really too crude to be very useful although I have finally thought of a use - to make a component analyser.

It offers just 3 modes of operation...
OFF gives you a simple X and Y plotter.
SIN puts mains (literally, I recently found out) on the X plates.
LIN puts a ramp signal on the X plates - made by a neon oscillator.

The 1CP31 tube gives a really sharp display that astonishingly is in focus and OK brightness whatever the supply voltage (over bonkers range I found when running up on variac). Its only proper valve just buffers the neon oscillator.
Attached Thumbnails
Click image for larger version

Name:	ScopeSmall.JPG
Views:	241
Size:	36.4 KB
ID:	296719  
GMB is offline   Reply With Quote
Old 22nd Apr 2024, 2:29 pm   #2
m0cemdave
Octode
 
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
Posts: 1,236
Default Re: Educational 'scope ?

Could they have been built for modulation monitors, ex AM radio transmitters?
m0cemdave is online now   Reply With Quote
Old 22nd Apr 2024, 4:57 pm   #3
GMB
Dekatron
 
GMB's Avatar
 
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,119
Default Re: Educational 'scope ?

Quote:
Originally Posted by m0cemdave View Post
Could they have been built for modulation monitors, ex AM radio transmitters?
I doubt it although that could be another use for it.

The very crude X scan options suggests it was to demo Lissajous figures from a signal generator (no sync for waveform view though).

It does need ±50V to drive the deflection. No amplifiers!
GMB is offline   Reply With Quote
Old 22nd Apr 2024, 8:44 pm   #4
paulsherwin
Moderator
 
paulsherwin's Avatar
 
Join Date: Jun 2003
Location: Oxford, UK
Posts: 28,149
Default Re: Educational 'scope ?

Strange device indeed. It does seem to have been professionally made, so may have originated from some long forgotten lab requirement.
paulsherwin is online now   Reply With Quote
Old 23rd Apr 2024, 9:03 am   #5
GMB
Dekatron
 
GMB's Avatar
 
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,119
Default Re: Educational 'scope ?

It is professionally made but I suspect as a one-off batch.

It is built using a peg-board with through connection pins inserted as required. The valve and crt are mounted on metal brackets. There is no branding or rating plate but they are crudely numbered.

I can't see lab use for it as it is way too simple.
GMB is offline   Reply With Quote
Old 23rd Apr 2024, 9:10 am   #6
Simondm
Pentode
 
Join Date: Nov 2020
Location: Bristol, UK.
Posts: 166
Default Re: Educational 'scope ?

The hardware looks 1960s-1970s.

Please could you give an idea of dimensions?

I can think of three possible sources (although there must have been dozens):

- Some school demonstrator kit as discussed.

- A display for synching a generator to the grid (hence the mains on one pair of plates), but mechanical phase meters were common, and probably much cheaper.

- Something to do with the BBC Natlock system for synchronizing Outside Broadcasts to London.

Natlock used phase comparison between audio tones (phone-bandwidth circuits), to drive the OB's pulse chain to time-in with London. I only vaguely remember the system (we used it in CMCR3), but this ETD sheet on a later development (tweaking it to do colour signals) says it could take up to six minutes to sync-up.

I don't remember any visual display on the OB end (rack space was quite valuable), but it might have been for the monochrome version (ours was PAL), in which case it would probably have been early 1960s. The mains toggle switch mounting arrangement (to a sub-panel, with a clean hole surrounding it on the front) is something I've seen before on BBC kit of that era, sometimes where a Maltese Cross mains indicator was removed and replaced with a switch.

Last edited by Simondm; 23rd Apr 2024 at 9:28 am.
Simondm is offline   Reply With Quote
Old 23rd Apr 2024, 11:40 am   #7
GMB
Dekatron
 
GMB's Avatar
 
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,119
Default Re: Educational 'scope ?

As I said, the dimensions are 6 inch square front and 4 inches deep. So quite a small object with no external mounting holes at all and two pairs of feet with deeper ones at the front so looks like it was for being on a bench as it slightly looks up at you.

It uses RS components.

I dug out my other one and it has a green "test" label (a bit like a modern PAT label). It has a date but it was put on with rubber stamp and the result is that the year is last century but hard to read (1960 or 1980? Looks like 1900 but obviosly not).

Everything on the panel is actually behind it as noted, except for the mains neon that looks like an afterthought as it makes it hard to access the underside of the board.
Attached Thumbnails
Click image for larger version

Name:	insideSmall.JPG
Views:	118
Size:	80.0 KB
ID:	296767   Click image for larger version

Name:	circ.jpg
Views:	77
Size:	51.3 KB
ID:	296768  
GMB is offline   Reply With Quote
Old 23rd Apr 2024, 12:14 pm   #8
paulsherwin
Moderator
 
paulsherwin's Avatar
 
Join Date: Jun 2003
Location: Oxford, UK
Posts: 28,149
Default Re: Educational 'scope ?

The components look mid 60s.
paulsherwin is online now   Reply With Quote
Old 25th Apr 2024, 7:29 am   #9
Oldmadham
Pentode
 
Join Date: Sep 2019
Location: Perth, Western Australia, Australia.
Posts: 207
Default Re: Educational 'scope ?

The sinewave signal on the H plates was part of what was called a "quasi-linear" scan, based on the idea that the lower sections of the sinewave signal situated around zero volts were a reasonably close approximation of a ramp.

The only such device I ever saw "in the flesh" was at an "open day" at the old Perth Technical College, but the ARRL Handbook had one as a Project for years

The one you have might be for showing students basic operation of a CRT in a 'scope, & as a bit more advanced lesson, how much more linear the neon oscillator is.
I very much doubt it would have had any use other than educational.
Oldmadham is offline   Reply With Quote
Old 26th Apr 2024, 8:17 am   #10
cmjones01
Nonode
 
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,686
Default Re: Educational 'scope ?

At school in the 1980s I remember we had a device a bit like this languishing at the back of one of the physics labs. It was more or less just a a CRT in a box with the deflection plates brought out to terminals. It had the ability to apply mains to to the X plates, I think, for a simple sweep, and also had a coil wound round the CRT itself. Connecting orange 'Unilab' signal generators to the plates and coil we made all sorts of interesting patterns! I think it was somewhat older than this example, being built on a wooden board with the CRT horizontal, definitely of the wood-ebonite-brass and cotton-wrapped enamelled wire era.

Chris
__________________
What's going on in the workshop? http://martin-jones.com/
cmjones01 is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 4:21 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.