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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 17th May 2019, 10:58 pm   #21
SiriusHardware
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Default Re: Sinclair Microvision from the NVCF

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Originally Posted by Richard_FM View Post
I know Sinclair made some other test equipment, particularly a digital multimeter which used a case from one of their calculators.
That would be the PDM35, and they also sold the PFM200 Frequency meter made in the same 'Cambridge' calculator body as well. I have an 'acquired' example of the former and a from-new example of the frequency meter although that is in very heavily used condition now. I also have a digital storage unit in the same type of case as the SC110 scope and intended as an add-on for it, although that is Thandar branded and I'm not sure if that was ever a Sinclair product.

For a few years I worked as a field engineer, including on door entry systems, and as McMurdo pointed out, the side-entry tube used in the later generation of Sinclair mini CRT TVs was widely used in video type door entry phones which let the tenant see who was at the door. I also had a portable leather cased monochrome monitor - intended as a CCTV engineer's tool - which used the same type of side-entry CRT.
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Old 17th May 2019, 11:52 pm   #22
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Default Re: Sinclair Microvision from the NVCF

Thanks for filling me in, I wasn't sure what Sinclair related test equipment was released.

I have a Sony FD-250B which was one of the last sideways CRT Watchmans. I picked it up at last November's Golbourne meet.

Oddly it has an AV connection but no input for an external aerial.

It produces a sharp picture, but is slightly out of line, which Studio 263 reckoned would be more trouble than it's worth to try to get right.
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Old 18th May 2019, 11:08 am   #23
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Default Re: Sinclair Microvision from the NVCF

Thanks for that fascinating post- I'd wondered about what went on in these ground-breaking little boxes, it certainly broke the mould.

I'd also wondered about the tube commonality between it and those portable 'scopes that appeared in its wake and the thread at least implies what I had also supposed- whilst a tiny telly is a superficially appealing concept to us tech-heads, I did wonder how many people would actually spend a fair amount of money on something that produced a not-much-bigger-than-postage-stamp-size monochrome picture for a short time on expensive batteries, and with all the vagaries of portable analogue reception from directional signals on a less-than-optimum aerial arrangement.

This sort of thing is now definitely worth preserving as an illustration of what was necessary in the past, though- nowadays we're all accustomed to taking high-definition, bright, colour, moving images on flatscreen smartphones/media players for granted and for near-trivial money.
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Old 18th May 2019, 3:36 pm   #24
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Default Re: Sinclair Microvision from the NVCF

I was working at Sinclair on the Pandora display (which had the phosphor on the glass front) just before the Amstrad buyout and had loads of the flat screen TVs given to me by my line manager. Gave them all away in the end, the Fresnel magnifier to heighten the picture was particularly awful. I still have a Microvision (first version) TV somewhere.
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Old 19th May 2019, 9:42 pm   #25
Andy Green
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Default Re: Sinclair Microvision from the NVCF

I remember playing with one of these in a shop in Edgeware Road back around 1978. Not a hope of buying one as a 17year old I recall I was interated what I could see what I could get on VHF (nothing in the middle of London!
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Old 20th May 2019, 1:09 pm   #26
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Default Re: Sinclair Microvision from the NVCF

Hi Studio 263,
I enjoyed the write up.

Can I ask how you open the case? I have one which is lacking in height slightly.

I also have the later flat screen version and I would say that the battery life of the AA cells in the MTV1B is much longer than for the expensive polaroid battery of the later sets.

Cheers
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Old 20th May 2019, 2:33 pm   #27
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Default Re: Sinclair Microvision from the NVCF

The old Polaroid instant cameras used these batteries in their film cassette, they just needed a bit of tin foil to "adjust" the contact positions. Plenty of life left after using the film, and they had quite a good storage life.
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Old 21st May 2019, 11:13 am   #28
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Default Re: Sinclair Microvision from the NVCF

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Can I ask how you open the case? I have one which is lacking in height slightly.
There are two screws under the rod antenna, another one hidden under the foam in the battery compartment and one hidden under the stickers opposite the aerial underneath at the back. If you warm the sticker first it won't get ruined when you peel it off (maybe...).

You will have to remove the PCB from the casework bottom to reach the height control. You can wriggle it out once the plastic holder for the speaker has been removed, disengaging the shafts from the line and frame hold makes it easier. Make sure that the tube base wires don't short out on anything and that none come adrift, there are lots of volts up there and the ICs will be ruined if anything shorts.
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Old 23rd May 2019, 8:27 am   #29
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Default Re: Sinclair Microvision from the NVCF

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Quote:
Originally Posted by Studio263 View Post
I very much doubt that. They made a 405 line prototype in the 60s but the ones you could actually buy were all 625 or 525 line. The earlier version had a UHF / VHF tuner but all the timebases were single standard.
I heard Sinclair proposed a portable TV in the 1960s which never went into production, only getting as far as some print ads, which I presume was the 405 line prototype.
There was a write-up in the Radio Constructor, Oct 1966 which interestingly describe the thing as having magnetic deflection (in contrast to Post #6), so maybe this was dumped in favour of a more complex tube by the time the TV went into production? Certainly electrostatic seems more attractive from a low-power circuit point of view!
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Old 23rd May 2019, 9:48 am   #30
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Default Re: Sinclair Microvision from the NVCF

Thanks Kalee20 for the article,

That was an interesting read.
Does anybody have any schematics of any of the Microvision sets as their "non standard" circuitry in a bid for miniaturisation is certainly a point of interest.

Cheers
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Old 23rd May 2019, 10:31 am   #31
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Default Re: Sinclair Microvision from the NVCF

Service manuals for at least one version of the 'conventional CRT' Microvision and the 'flat CRT' microvision are on-line somewhere. They include the circuit diagrams, but of course not detailed information of what is inside the custom ICs.
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Old 23rd May 2019, 11:52 am   #32
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Default Re: Sinclair Microvision from the NVCF

https://www.vintage-radio.net/forum/...ad.php?t=54997
https://www.vintage-radio.net/forum/...ad.php?t=43257
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Old 26th May 2019, 5:27 pm   #33
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Default Re: Sinclair Microvision from the NVCF

The Radio Constructor article suggests that it only draws 50 mA. Is that true?

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Old 26th May 2019, 5:46 pm   #34
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Default Re: Sinclair Microvision from the NVCF

Hi Peter,

Indeed, that is a bit unlikely, but perhaps not totally impossible.
My MTV1B draws a total supply current of 120 mA @ 6VDC, but the FTV1 only about 80...90 mA @ 6VDC.
I haven't seen any circuit information of the 1966 proto/show-type.

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Old 26th May 2019, 6:13 pm   #35
kalee20
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Default Re: Sinclair Microvision from the NVCF

Might be a Sinclair exaggeration, maybe 50mA with brightness at zero, volume at zero, and tuned to a strong signal so that AGC action biases the transistors right back.

The circuit description indicates it is entirely discrete, no IC's (well, it is 1966) whereas what went into production in the 1970's used three custom IC's.

All the same, it was an achievement!
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Old 26th May 2019, 6:43 pm   #36
G8KBG Tony
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Default Re: Sinclair Microvision from the NVCF

Short clip of the 1966 Sinclair working HERE.

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Old 27th May 2019, 2:50 am   #37
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Default Re: Sinclair Microvision from the NVCF

Thanks Jac and kalee,

Certainly a bit of exaggeration there but at 720 mW it's a lot more impressive than the 4.9 Watts that my "modern" 3" Casio draws from AA cells.

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