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 Post subject: Homebrew Electrostatic TV Set.
PostPosted: Jan Tue 21, 2020 8:43 am 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 172
This homebrew project might of some interest, though it could also be posted in the TV section too.

I became fascinated with the notion of home made electrostatic deflection TV sets. I looked at a few designs with scope CRT's (like the 5BP1) and some of the English ones. Practical Television (PT) magazine in the UK published an interesting one using a VCR97 Radar CRT, they called it the Argus.

I had also remembered from my childhood seeing the bright red pentode, the EF50. These really are "eye candy" on the account of the color.These are said the be "The Pentode that won the war" that is explained in the article below.

So I designed and built this TV partly based on the Argus, but I changed some of its circuitry and the entire mechanical design. The original had sub-chassis. I went with a single chassis, machined to my design by Landfall Systems in TX. I painted it myself. It is strong enough to support the large Hammond power transformers & chokes.

It has a few interesting features. I used a Neon tube transformer for the EHT and opened its magnetic gap. I wound all the RF coils myself and went mainly for bifilar types (the reasoning is in the article). The deflection oscillators & scan output design is an uncommon configuration in the USA for electrostatic deflection, a Miller-Transitron type, but this was very popular in the UK for home brew TV's.

There is a lot more detail and better quality images here:

http://worldphaco.com/uploads/ARGUS.pdf

Also in that pdf are some CRT screen pictures from one of my favorite Sci-Fi movies, with Al Hedison and Vincent Price; The Fly. A very interesting message in this story, that one very small thing (in that case a fly) can foul up a large project and I think when building any large project it pays to remember that the Devil is in the detail.


Attachments:
arg1.jpg
arg1.jpg [ 673.48 KiB | Viewed 456 times ]
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 Post subject: Re: Homebrew Electrostatic TV Set.
PostPosted: Jan Tue 21, 2020 5:31 pm 
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Joined: Dec Sun 21, 2008 3:59 pm
Posts: 37
Your skill and dedication to the art of Homebrew is incredible!
Merrill Yeager


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 Post subject: Re: Homebrew Electrostatic TV Set.
PostPosted: Jan Tue 21, 2020 6:31 pm 
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Joined: Aug Tue 28, 2018 9:22 pm
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Location: Sanford Fla 32771
Outstanding work ACORNVALVE.
Seeing those green screen shots of TV programs reminded me of a lashup I did when stationed at a remote USAF transmitter site. The mountain top I was stationed at could only receive one TV station (somewhere in Newfoundland) and our set had a very weak CRT. So I lashed up one of our oscilloscopes to stand in for our black and white CRT. It worked very well, just every TV picture was now in green.

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Last edited by pauls.ironhorse on Jan Wed 22, 2020 8:39 pm, edited 1 time in total.

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 Post subject: Re: Homebrew Electrostatic TV Set.
PostPosted: Jan Tue 21, 2020 6:50 pm 
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Joined: Mar Sun 11, 2007 6:55 am
Posts: 11425
Location: Mission Viejo, southern California
Wow, it appears to be factory-made, and from a superior quality maker! How about a photo of the bottom of the chassis?

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 Post subject: Re: Homebrew Electrostatic TV Set.
PostPosted: Jan Tue 21, 2020 10:22 pm 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 172
FStephenMasek wrote:
Wow, it appears to be factory-made, and from a superior quality maker! How about a photo of the bottom of the chassis?


If you look at the link to the pdf I posted and scroll through the detailed article on it, you will see a good under-chassis photo with a lot of the major components labelled.


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 Post subject: Re: Homebrew Electrostatic TV Set.
PostPosted: Jan Wed 22, 2020 5:59 am 
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Joined: Mar Sun 11, 2007 6:55 am
Posts: 11425
Location: Mission Viejo, southern California
Thanks, I did, and it is outstanding.

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many of my radios http://s269.photobucket.com/user/FSteph ... t=3&page=1


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 Post subject: Re: Homebrew Electrostatic TV Set.
PostPosted: Jan Wed 22, 2020 7:56 am 
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Joined: Feb Sun 05, 2012 5:12 pm
Posts: 938
Location: North Syracuse NY 13212
I built a TV using a 2AP1. Here's the prototype:
Attachment:
hbtv1.jpg
hbtv1.jpg [ 121.74 KiB | Viewed 315 times ]

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hbtv2.jpg
hbtv2.jpg [ 131.81 KiB | Viewed 315 times ]


I later built it up with two vertically stacked chassis, but I still haven't taken a photo.
It did work, but the signal level dropped off after the rebuild. I built the tuner from scratch.
At the time, we had channels 3 and 5, so I only built enough to get 3, 4 for the VCR, and 5.

I picked up this one a few years ago:
Attachment:
HBTV3.jpg
HBTV3.jpg [ 207.49 KiB | Viewed 315 times ]


I removed the 7JP4 before I took it home.
There were many parts floating around the CRT circuits, and the voltage doubler had one side of an electrolytic on the AC line, and the other end on the B+. Of course there was more ripple than DC. I don't believe it ever worked.

I drew up the schematic and rebuilt it. It needed lots more B+ to get a reasonably sized image, and I didn't bother with the tuner and IF.
The horizontal sync works great even with a VCR, and the video quality is very good:
Attachment:
Timing.jpg
Timing.jpg [ 124.79 KiB | Viewed 315 times ]



Bob

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 Post subject: Re: Homebrew Electrostatic TV Set.
PostPosted: Jan Wed 22, 2020 5:44 pm 
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Joined: Sep Wed 10, 2014 2:01 am
Posts: 2032
Location: Costa Mesa, California
Acornvalve, I think you may be in the wrong forum--this should be in the "Radio as Fine Art" forum. Have you had these projects in a gallery? They should be on display in an art museum.

Norm

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