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TV Typewriter replica project

falter

falter

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Joined
Jan 22, 2011
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Vancouver, BC
Hey guys,

So I am pretty much decided on a attempting to do a 'replica' of the Don Lancaster design TV Typewriter. I have been getting more and more fascinated with PCB fabrication, and I think, even if I don't end up with a perfectly functional unit, it'd still be a great learning experience. I've always kind of had mixed feelings about replicas, but in this case because people could elect to build their own from scratch using only the plans from the magazines, my mind isn't classifying it as pure replica.

I have some questions for more experienced hands though.

1) What PCB stock would get me closest to what someone would have had in 1973, esp. in terms of appearance?
2) I notice in photos of period-made TVTs, the traces end up being a kind of silver color rather than copper..?
3) Is there any likelihood of finding most of the correct, original chips used? I understand some were already scarce back when this project was created and I imagine have only gotten harder to locate since then. If you guys have any good sources for the rarest bits I'm all ears.
4) I have seen two distinct keyboards used with the original TVT -- the one shown on the cover of RE, and the weird 'blue circles' kind that I understand is on the prototype (I think they called it 'Surplus' -- is that a brand or?). Anyone have any recommendations on how I might source one of the two, or something appropriate to the period?

Think that's it for now. I plan on doing a video documentary of the whole thing. For me it's about as close to going back in time as one can get.
 
The silver colour is tin plating over the copper. Bare copper will tarnish over time and will become difficult to solder. Production PCBs were generally tin plated. If you decide to make your own PCBs - and you do the construction soon after etching - the tin plating is not strictly necessary. You can, however, by chemicals to tin plate the bare copper after etching if that is a must.

Dave
 
PS:

The 2513 is a 'generic' number.

The 2513N is a plastic DIP package.
The 2513I is a ceramic DIP package.

The same silicon 'logic' can be encapsulated into different packages (hence the additional suffixes).

You should also be aware that there were custom versions of the 2513 that could be programmed to user's specifications. There should be another identifying mark on your package. CM2140 is the 'bog standard' ASCII character set. CMxxxx (where XXXX is anything else other than 2140) implies that the character generator contents is probably not what you are expecting!

Dave
 
daver2 said:
PS:

The 2513 is a 'generic' number.

The 2513N is a plastic DIP package.
The 2513I is a ceramic DIP package.

The same silicon 'logic' can be encapsulated into different packages (hence the additional suffixes).

You should also be aware that there were custom versions of the 2513 that could be programmed to user's specifications. There should be another identifying mark on your package. CM2140 is the 'bog standard' ASCII character set. CMxxxx (where XXXX is anything else other than 2140) implies that the character generator contents is probably not what you are expecting!

Dave
Click to expand...

I got my 2513s in today. They are CM3030. According to the datasheet info I can find online, Signetics refers to it as: Old ASCII Character Generator, Upper Case, 7X5, Horizontal Scan -- the only difference I can see between it and CM2140 is the word 'old'. I don't see a CM number anywhere in the original TV Typewriter specs.. not in the parts list anyway.. re-reading the article.

Just for kicks, I took out one of the chips and swapped it for the 2513 that's on my Apple II rev 04 board.. worked as normal.. don't know if that tells us anything..
 
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So I'm working on acquiring parts for my TV Typewriter project. I'm having a bit of a hard time understanding what I need parts wise. For example, for the main transformer, the magazine specifies: Dual 12v center tapped secondaries, 1.5a, signal 24-1a.. I've tried some searches but I'm not seeing anything with exactly those specs.. wondering if there's anything out there I can use to educate myself a bit on transformers so I can understand what to search for or what modern day equivalent would be acceptable.
 
falter said:
Dual 12v center tapped secondaries
Click to expand...
That equates to:

Transformer_dual_12V_center_tapped.jpg


falter said:
1.5a
Click to expand...
The load will draw up to 1.5 amps from each secondary. Therefore, when seeking the above transformer, look for one that can handle 1.5 amps, or more, being drawn from each of the secondaries.

falter said:
signal 24-1a
Click to expand...
???
 
I do have the manual for the SWTP PSU kit that came with the CT1024. I think dual 12VCT secondaries would make for a lot of excess heat. Even the SWTP PSU was a bit underpowered. Those 2102s are pretty power-hungry and ran hot.

But I've already said this somewhere else on another TVT thread...
 
Yeah... I'm trying to get as authentic as possible on this one though. But some of the parts in the parts list are a bit unclear. I know nothing about transformers so it was a bit of a toughie understanding what all that meant. I have no idea what the 24-1A meant either. Wish I could just find an example part number someone used to work with. Easier to compare for us rookies.
 
Here are the ICs I've acquired so far (and have a few others in my inventory from previous purchases):

20140311_112717.jpg

A few vintage chips in there.. the char gens are 1973, couple other chips are 73 74 vintage. The idea is to get what I need to get it running, and then over time find date-correct replacements. I'm going with socketing the chips.. I'm assuming that will be fine?

For the basic design, I'm going with the original prototype. Haven't had much luck on the keyboard for that, but I did score some teletype keys:

http://www.ebay.com/itm/320552452076?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2648

All the same key 'REPT', but I think are generally the right shape and could be repainted? I'm wondering if that's what was done on the prototype? None of the keys on that unit have lettering. Letters are placed on the black plastic (?) surround. I understand that keyboard was an actual keypunch keyboard of some kind (still not clear on model -- Don said EBCDIC but that's just the encoding type?). It may turn into a hybrid situation maybe where I have to borrow a keyboard design from elsewhere (like the earlier 73 article Don did with the custom made key switches) and then put those keytops atop it.

Going to buy the wood anyway and build the case so I have that to motivate me. It looks like he covered the wood with some kind of wallpaper/decorative covering?

Here's a closeup shot: http://www.computerhistory.org/revolution/personal-computers/17/296/1135

Was going to ask Don again but I don't want to wear out my welcome peppering him with questions. :)
 
Got my teletype keytops today:

20140402_094530.jpg

Was lots of fun removing all those from their single packages. :) The plan is to paint them the solid blue and red like the TV Typewriter prototype. I've not been able to find the actual keyboard/PCB that Lancaster used, so I'm thinking my best bet may be to try to recreate the keyboard project he did in an earlier Radio Electronics article and then modify it to have these keytops. I'm not sure how I'll make the stalks for these keytops yet. Probably use styrene cylinders and then glue them in place.

Actually thinking about building the case first, just to provide motivation and something to look at. Still soliciting opinions on the construction of the case in the link above. Really would like to know what that 'covering' material over the main body parts are.
 
I do have the SWTP construction guide for Lancaster's keyboard for the TVT. It includes a "shadow" PCB layout showing component locations, if that's any help. The tough part is that it used two RTL ICs--MC789. They're pretty thin on the ground, aren't they?
 
No, this was in Popular Electronics in a 1974 article titled "A low-cost, fully professional ASCII Keyboard and Encoder you can build". Like the TVT, this was picked up by SWTP and sold to accompany the TVT. The hex-inverter MC789s are used as output buffers as well as some wired-OR logic.

Believe it or not, Don still has the article online in his tinaja.com site here
 
Chuck(G) said:
No, this was in Popular Electronics in a 1974 article titled "A low-cost, fully professional ASCII Keyboard and Encoder you can build". Like the TVT, this was picked up by SWTP and sold to accompany the TVT. The hex-inverter MC789s are used as output buffers as well as some wired-OR logic.

Believe it or not, Don still has the article online in his tinaja.com site here
Click to expand...
Every time I read Lancaster's stuff it takes me right back to my youth; the man was/is a genius at doing complicated things in the simplest and cheapest way and explaining complicated things in the simplest and clearest way; who knows how much many of us learned from his articles and projects. I had his cookbooks and devoured his articles in PE and RE, and even today get a kick out of and even (re-)learn something from perusing old back issues.
 
Chuck(G) said:
No, this was in Popular Electronics in a 1974 article titled "A low-cost, fully professional ASCII Keyboard and Encoder you can build". Like the TVT, this was picked up by SWTP and sold to accompany the TVT. The hex-inverter MC789s are used as output buffers as well as some wired-OR logic.

Believe it or not, Don still has the article online in his tinaja.com site here
Click to expand...
It's also one of the circuits in his TV Typewriter Cookbook. Also on Holley's site:
http://www.swtpc.com/mholley/PopularElectronics/Apr1974/PE_Apr1974.htm
 
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falter said:
Cool! Never seem that keyboard before? Do yoi have the foil patterns in what you have?
Click to expand...
I thought you were going with a 2513?

I'm pretty sure I've got one of those keyboards with blue and red round keys but haven't managed to find it. What are you using for the key switches? Are you building them from scratch as in the RE article?
 
What I am doing is acquiring parts to create something similar, at least in look, to the prototype's keyboard. If I understood Don correctly in his email to me.. the one used on the prototype was a complete IBM keypunch keyboard reconfigured for that use. No mention though of model number. He did say it used EDBDIC encoding. I'm keeping my eye open on the off chance one comes up on ebay or something (don't know what to look for of course so i just search through all vintage keyboardds there from time to time.)

The closest I've seen online is this:
 
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