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Subject: Re: [Homebrew_PCBs] TV Typewriter: Custom G10 copper clad

From: Harvey Altstadter <hrconsult@...>
Date: 2016-03-21

Tom,

Your description of the modified TV for use as a monitor triggered my memory.  Although I didn't build the TVT, I used the  handbook to modify a small screen TV for use as a monitor.  Yes, it had a hot chassis.  I used it with a computer board that I read about in Radio Electronics. The CPU was the Signetics 2650. I bought the board from Central Data and stuffed it myself. It came with the ROM listings in a poorly printed book.  I manually programmed a 4K X 8 PROM. Much to my amazement, got through it with no errors and the computer worked.  I remember one quirk of the monitor.  Alternating lines of text angled to the left and right.  I wanted to troubleshoot the system, expecting that there were some sync issues, but with the monitor having a hot chassis, and the scope having a grounded chassis, I didn't try.  The board came with a version of BASIC on an audio cassette. That was loaded from a modified audio tape player.  Soon enough, the system was replaced by a Commodore 64, and the 2650 board relegated to long term storage bin in the sky.

(Another) Harvey

On 3/19/2016 10:12 AM, 'Tom Crawford' ah983@... [Homebrew_PCBs] wrote:
 

This TV Typewriter thread has triggered some interesting thoughts, that might be of interest.  I recall building one of these, so took a look through my project files (I keep stuff way too long...)
 
Found a picture of what I built, dated May, 1980.  The photo note says it was a CT-1024, actually, not an original TVT.  Photo includes a large aluminum box I hand-built from flat stock to hold all the electronics, power supplies and connectors, and a separate Keyboard, with a cable connection to the box.  I made all the PCBs myself from the plans, and soldered a wire into every via of the set of 2-sided boards. 
 
Behind is a modified BW TV to use as a CRT (prob. hot chassis, as I remember!  I hope I had a polarized plug wired correctly to it!).  Sitting next to it on the table is a home-made “Pennywhistle” 300 baud acoustic coupled modem.  The phone handset cradles were made from cut-down soup cans, lined with weather-stripping foam.
 
After looking at the photo, I realized I had seen that big aluminum box recently, so after some poking around my workshop, I found the entire CT-1024, and it’s keyboard!  (The modified TV and Pennywhistle I knew were gone, replaced quickly with a safer and clearer surplus CCTV monitor, and a faster 1200 baud direct connected modem...)  I’m tempted to plug it in, and see what happens, but I don’t really need another project.  Maybe someone else wants to try...?  I also took some new pictures, including the insides and the circuit boards, I will see what’s involved in posting them, if anyone is interested.  Sorry, don’t know what type of PCB material I would have used at the time [g].
 
This device replaced a modified IBM Selectric (From a “Computyper” device, as I recall), which never did work very well.  Used for some online BB access locally, and with my first microcomputer, a “Tek-1802” (RCA 1802 cpu, ram, hex keypad, 7 segment displays...)
 
I moved on fairly quickly to a hand-built “Big Board” (Z80, 64K RAM, 80x24 display generator, 2x 8inch floppy drives (cost a fortune, even surplus!), running CP/M.  Used this for “serious” software development in C.  Was followed by a hand-built clone Apple II with floppies, then my first purchased IBM PC....
 
fyi,
Tom Crawford
 
 
 
Sent: Friday, March 18, 2016 5:01 PM
Subject: Re: [Homebrew_PCBs] TV Typewriter: Custom G10 copper clad
 
 

I built one to replace my clunk model 45 Teletype, eventually I replaced it with a Televideo 950.

On 3/18/2016 3:37 PM, 'Brad' unclefalter@... [Homebrew_PCBs] wrote:

Also on the original front – I don’t think anyone harboring an original TVT project would be willing to give it up for less than lots of money, given how rare and important historically they are. So that’s why I’m not holding my breath there.

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Friday, March 18, 2016 10:35 AM
To: Homebrew PCBs mailto:Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] TV Typewriter: Custom G10 copper clad

Yeah

And besides, there are scant few folks around in hobby electronics nowadays that have ever actually

laid eyes on a finished (or unfinished) Lancaster TV Typewriter. It is totally obsolete by todays standards and state

of the art.

And, as Lancaster envisioned, the thing was to be enclosed in a kind of wooden desk-top enclosure, so

nobody sees the circuit boards anyway.

Too bad that a search can't somehow be made on the internet, inquiring if there is some

"old-timer" (like me) that has a Lancaster TV Typewriter in a dusty pile of forgotten projects,

and that way, you could get the "real" item and bring it back online.

These are just suggestions.........now, don't everbody jump on me with snide remarks.

Regards.

Roland F. Harriston, P.D.

∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗

From: "Stefan Trethan stefan_trethan@... [Homebrew_PCBs]" mailto:Homebrew_PCBs@yahoogroups.com

Snip:

Most people are going to look at you as if you are crazy for wanting a specific colour and weave of material. That is because you are crazy of course, and nothing to worry about.

It will not help your quest at all, but consider buying double sided laminate (with copper on both sides). I found it much easier to obtain and just etch one side away completely for single sided boards. Of course it makes impossible to see the inside.

Also mind that in any case the copper on the other side will severely change the colour you see, even if the seller provides a photo of the board side. The copper layer is actually a dark red underneath, completely different colour from the shiny top surface.

ST

Posted by: "Brad" mailto:unclefalter@... 











-- Cecil - k5nwahttp://thepartsplace.k5nwa.com/