A pocket-sized TV is not a big deal today. But in 1983, cramming a CRT into your pocket was quite a feat. Clive Sinclair’s TV80 or FTV1 did it with a very unique CRT and [Dubious Engineering] has a teardown video to show us how it was done.
A conventional CRT has an electron gun behind the screen which is why monitors that use them are typically pretty thick. The TV80’s tube has the electron gun to the side to save space. It also uses a fresnel lens to enlarge the tiny image.
The device was not successful in the market since it cost about 4 million pounds to develop and sold around 15,000 units. The advent of the LCD killed off these kinds of devices, altogether.
The CRT is a marvel and doesn’t look like a normal CRT. The TV converts its 5V input to about 20KV and uses it to shoot and deflect electrons parallel to the screen’s surface. While a normal CRT has the electrons hit the screen from the rear, the TV80 uses an electrode on the front screen to push the electrons down to the front of the imaging surface. A voltage multiplier generates several high voltages for the CRT.
There is only one IC in the entire device, apparently. Hard to imagine these days where there are almost no discrete components in anything anymore.
Another place to find tiny CRTs is in old camcorder viewfinders. We were sad to see Sir Clive Sinclair passed away recently. While the TV might not have been a success, it was certainly creative and innovative.
there were 2 models, the first version was bigger, about the size of a ST:TOS Tricorder, that one used a camcorder CRT
Sinclair also made a small oscilloscope in the same form factor
the battery life is ok
my mate has one that still works, he also has the Citizen(?) LCD Pocket TV, that unit is what killed off the Sinclair ones
Not a camcorder CRT. No camcorders came with an electrostatically deflected CRT.
the larger model, the first one has a normal tube
this unit has the electrostatic deflection tube, just like the larger Phillips door monitor system, which they invented
Nope. The Sinclair MTV-1 uses a Telefunken Electrostatically deflected CRT. I know because i have one of both.
Guess it would have been easier to use coils than to try to produce the necessary high voltage signals. I’m pretty sure I’ve still got a couple of miniature CRTs in a junk box somewhere, if memory serves me they are coil deflection and at least three or four inches long. Nothing comparable to the thin construction of this portable TV tube.
I remember seeing the 2″ Leader o-scope back in 1979, and the lust it produced.
I had to look up what a Tricorder was. The microvision is from the late ’70s and so predates camcorders. Discrete video cameras, to be pedantic, usually have detachable CRT electronic viewfinders unless they are low end, and they would have been around at the time. I didn’t know they did an oscilloscope. Thanks. I don’t think one particular Citizen model killed off Sinclair TVs. There are tonnes of different LCD TVs, mostly Casio and Citizen.
Anyone else get nervous when he used the metal screwdriver to indicate parts of the tube by tapping on it or waving the tip around it?
Most ASMR videos are totally driving me mad with their horrible sounds and stressful behaviour, but this one is actually the thing to me… There is nothing as refreshing as poking with a screwdriver around some high voltage stuff! Same with machining videos or other technical things
If you want more details regarding the operation, look at EEVblog:
https://www.youtube.com/watch?v=qCJPF6Ei3Vw
If you want to see it show Doom, look at CPU Galaxy:
https://www.youtube.com/watch?v=fEcs52lAI3E
But, can it play….
Never mind, I wasn’t listening.
B^)
There was a mid to late 60’s cover article on one of those “pop” sci or tech zines had a proposal or mock up of such a TV.
When they developed digital TV they left out that people would soon have portable small screens. So the system is not fit for mobile reception.
The screws in the picture resemble the letters “TV”… :-D
The voltage is not 20 kilovolts, it’s 2.4 kilovolts. Also the lens is not a fresnel, it’s a standard lens molded into the front. A fresnel lens will have ridges molded into it to save on material. This is not the case here.
I’m seeing the ridges pretty clearly.
Wikipedia claims it is a fresnel, but I don’t know how accurate that is. The video says 20KV, but you are probably right — I thought when I heard that it seemed high to be in a handheld case. Not that 2.4KV is much better :-)
I recall from Electronics class in the late 1970s, a rule of thumb 1Kv / diagonal inch of viewing.
I have one of these TV’s and i can assure you that it’s not a fresnel :)
The interesting note is that the Sony 4″ CRT I have here is very similar apart from being a lot larger.
This one has dual scan coils and no electrostatic deflection, thus limiting applications.
I did try and hack it using conductive paint but it didn’t have the desired effect.
With modern circuitry and piezo based IHVT the thing may live again.
I see CRTs very similar to this in older New York City apartments. They’re used in video door intercoms I’ve always been fascinated by them.
I’m not 100% sure who bought what from whom, but those video intercoms used tubes that looked exactly like the Sony 4″ Watchman TVs, which unlike the Sinclair shown in the article, used magnetic deflection.
they were originally developed by Phillips
Emily Velasco has a few videos
They are indeed the same tube. My recollection is that Sony developed their TV, and later Watchman products designed for reviewing camcorder tapes on the move, around the intercom CRT.
I designed the electronics for the FTV1 – everything that isn’t the tuner, IC or the tube itself – so I guess I ought to do my own teardown one of these days. The CRT design was driven by a desire to make it easy to mass-produce, primarily, and also to make it more power efficient by having the electron beam strike the viewing side of the phosphor. The so-called “flat screen” was in some ways a by-product; as you can see the TV isn’t particularly slim anyway, especially if you compare it to a smartphone.
The lens on the front is a Fresnel type, which produces the effect of a cylindrical lens magnifying only in the vertical direction. This was done to reduce power consumption in the vertical scan circuitry, which has to handle more complex waveforms than in a conventional TV because of the need to correct for the ‘keystone’ effect caused by firing the electron beam in from the side.
The screen voltage is designed to vary according to the battery state, and the scan amplitudes track with it to maintain a roughly constant picture size. On the external DC power pack (rated 5.9V @ 100mA, by the way) it *would* have been around 2.4kV if I remember it right. It’s difficult to measure accurately anyway. We used to use a 1 Gigohm probe, and even that 2μA or so loaded the supply somewhat. The normal operating beam current was only in the μA region anyway; there isn’t enough energy in those tiny capacitors to give you a serious shock, unless you were at death’s door already. My record is 5kV from a test rig I built for the CRTs. :)
do you know anything about the first model or the CRO?
they are about the size of an original Star Trek tricoder
my mate still has the “pocket TV”,
I had the CRO but it was stolen, it wasn’t that flash, maybe 10 Mhz, but ok for field work
If you mean the late ’70s models with the AEG Telefunken CRT, I worked on the TV1A (the metal cased version with the multi-standard buttons on the front) and the TV1B (the plastic cased single standard model). I don’t have any information on those sets, unfortunately. I did have a TV1a, but I foolishly lent it to someone who was promptly made redundant and I never saw him or the TV again. So it goes.
The oscilloscope was developed by Bill Hardman around the same CRT. I remember seeing him working away at the design but wasn’t personally involved. There was also a monitor version of the TV1A. Both that and the scope were steady sellers for some time.
I’m being careful with my nomenclature because the original Sinclair Microvision TV dates back to 1966, before my time. It used magnetic deflection and received 405 line transmissions in VHF bands I and III, for those who are old enough to remember those! To the best of my knowledge only two sets ever existed, both hand built by Jim Westwood (of ZX80/81 fame), so they would be worth a mint today.
Just remembered this. There’s an interview with my colleague who worked on the TVs here: http://polymathperspective.com/?p=408