Home-brew 405-line TV

[Ian - G4JQT]

Having just seen Panrock's work on the NBTVA website with the Argus TV, it's reminded me of a long-term project I had in mind years ago, which is...

...If forum members were to build a TV from a published home-brew 405-line design, which one would it be?

I guess important criteria to consider are:

Design must use a fairly easily available, reliable tube
Design must be known to work, including any corrections/updates
Ease of making the scan coils and any other wound components
Availability of IF transformers, if required
Oh, and picture quality

So... any ideas? Would it be the Argus? This would be a long-term but rewarding project.

Regards,

Ian

[ntscuser]

Is electrical safety a consideration?

If so I suggest that rules out the Argus:

http://www.radiocraft.co.uk/agus.htm

[FERNSEH]

Make a copy of the Baird T29 "Everyman". A very simple TRF receiver, only eleven valves, even this valve count can be reduced.
The signal circuits consist of a 6F12/EF91 common vision and sound amplifier which is followed separate RF amplifiers. Same type of valve was used for the video and audio output. The line output stage employed only one valve in a self oscillating circuit. CRT can be a 9 or 12" round type.

DFWB.

[Brigham]

Plans for a Complete Television Outfit appear in the Book of Practical Television (ed. G.V. Dowding- 1935 edition). Design is by K.D. Rogers, who was made a Fellow of the (Royal) Television Society in that year.

Tube is the Ediswan AH, or the larger CH, with suitable chassis modification. Valves are a mixture of Marconi and Cossor in the receiver stages, with the close-coupled mounting of the special 'ultra-short' X41 shown in great detail. Vision receiver is superhet, sound appears to be TRF.

Some demand must have been anticipated; the chassis plates were available ready-punched from Burne Jones & Co. Ltd. The cabinet is delightful. Perhaps someone with computer skills could reproduce the photograph here.

Has anyone seen a constructed example?

[Ed_Dinning]

Hi Gents, I think an electrostatic tube such as the much used green VCR97 would be a good way to go as there is then not the problem of scan coils.
This tube is still available as are other ES scope tubes.
The added advantage is that it is very easy to alter the timebases for 625 lines or any other standard.

Ed

[Peter.N.]

I built a Denco kit TV in the '50s, that was pretty straightforward, don't know if there is any information available on that still.

Peter

[Neanderthal]

Hello All. I built a View Master circa 1950. This was a TRF on channel 1 using war surplus metal can EF50s, and a 9" tube. It was prone to oscillate, as pins and bases on these valves did get tarnished rapidly. However it served for a number of years and my mother watched the Coronation on it, while I was doing national service. I don't know if any info exists today. I remember the VCR97 green tubes, and did construct a timebase unit using one of these, but the 2.5 KV EHT with a 0.5uF reservoir capacitor scared me somewhat and the project was abandoned in favour of the View Master with its line flyback EHT.

[Ed_Dinning]

Hi Neanderthal, yes there are still some of these sets and units about. Some of the members of the Forum have even built them in the last few years.

Why not have a go again and re-build it?
No problems with mains derived EHT as there are now small modules available and there were also circuits in TV that showed RF EHT units for this type of set.

Ed

[Radio Tech]

Hello gents

Anyone got the circuit for the view master? if not the baird t29, I am always on for a challenge.

regards

Ken

[llama]

I've got most or all of the original build instructions. Also a few original parts.
Graham

[Anthony Thomas]

Originally Posted by Radio Tech

Anyone got the circuit for the view master? if not the Baird T29, I am always on for a challenge.

Indeed does anyone have this circuit and if possible post it here please

Tusen Takk
Tony

[llama]

Yes but it might take a few days.
Graham

[BGmidsUK]

I too would be interested in doing a project like this. I have been thinking of converting an existing 1980s monochrome portable for dual-standard or even single-standard 405-line operation, my only concerns being how to deal with the EHT as I don't currently have any way of measuring this .. I'd need to make small adjustments to the line frequency and measure the EHT in order to work out what compensation may be needed.

This could be done with a colour set to display 405-line NTSC color* and would be a great way to see how modern sets would perform in terms of picture quality, as a direct comparison with PAL and NTSC on the same (type of) receivers.


Brian

*Spelling is intentional

[Anthony Thomas]

Originally Posted by llama

Yes but it might take a few days.

Thanks Graham

Tony

[Anthony Thomas]

F J Camm gave out a book "Practical Television Circuits" in the early 1950s mine is a reprint from 1954, it contains The Argus and several other television build projects including one titled (to the effect) Build a £9 television reciever.

Does anyone know if this is the same or a similar circuit to the "View Master" by any chance?

Tony

[Anthony Thomas]

Today I came across the building details of the View Master, it contains all the pertinent details of chassis and circuits.

http://www.g4dmp.co.uk/viewmaster.pdf

I think I will stick to the Argus Project as I already have the CRT for that, I thought the View Master used an electrostatic deflector CRT but I was wrong.

Tony

[greenstar]

Hi, be interested to know how you get on. If you have not already seen it, there is some info here, with suggested modifications:
http://www.radiocraft.co.uk/agus.htm

And of course here:
http://vintage-radio.net/forum/showthread.php?t=81446

Also Tony

[Neanderthal]

Hi Ed. Sorry to be so late getting back. This is a large forum, and in starting a thread about TV engineers, I lost this one. I doubt I have the space available to build another Viewmaster, but did build a second while in the RAF. Would need to source a lot of EF50s! Good to know the design still lives on.
Mike G4BIY.

[Anthony Thomas]

Originally Posted by greenstar

Hi, be interested to know how you get on.

Thanks Tony

Indeed I have seen that excellent site and not forgetting the three page list of mods performed to the original design to enhance its performance.

I am not exactly one to saddle and ride the same day so I have been collecting as many components that I can for the Argus build up, I have a CV2810 and a VCR97. The former from Gerry (Crowthorne tubes) ages ago and the VCR97 I found here in Norway for NKr 60,- or about £6. I have VR65 valves and the Mazda octal bases. I now have two CRT bases and the only real limit is the mains transformer but I have a solution for that which might work, since I have a VCR97 I might use that first for my prototype buildup on the chassis for the Argus. The CV2810 is for the final version.

I was wondering about the View Master since I had seen it mentioned several places but the lack of a suitable CRT with deflector coils precludes me from attempting that build, finding the transformers to drive the deflector circuits are also a challenge for my poor old head. They would be a special wind job to suit the tube deflector coils which I don't have anyway, I will be satisfied with the Argus project or the £9 television receiver because those I can probably work out solutions for from my spares collection.

Best wishes Tony

[Anthony Thomas]

Here is one that I built earlier, its from FJ Camms book of Practical Television Circuits the "building a 3" television" from about 1952. see thumnail photo. It has not been powered up in years so it will need to have its capactors checked and perhaps reformed first and one or two mods to bring things in line with the original design.

Tony