This weekends projects

Discussions about Sinclair ZX80 and ZX81 Hardware
mcarlson_sb
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Location: San Francisco

This weekends projects

Post by mcarlson_sb »

This weekends project has been to recreate the Maplin GB18U "Talk-Back" board in Eagle Cad.
TalkBack.jpg
I tried to make this one fairly close to the original, so that the instructions made sense and could be followed.
For more info on the original see https://k1.spdns.de/Vintage/Sinclair/80 ... vzx81.html


I plan to make another version that uses the LM386 as the amplifier for a slightly more modern alternative.
That one will be black to differentiate them

Those will be sent of for fabrication soon along with several other utility boards
(male-male edge adapter)
ZX81-M2M.jpg

And possibly a in/out parallel port based on the 8255 depending on how much I want to sleep tonight :D
I don't think I'll get around to the AY soundcard yet (have to save some fun for another weekend)

I tend to batch boards because shipping is more than the cost of making the PCBs these days.
The minimum order is also 5. So, I'll have spares of most everything.
Feel free to DM me if yone have a SP0256-AL2 and need a board.


Cheers,
Matthew
mcarlson_sb
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Location: San Francisco

Re: This weekends projects

Post by mcarlson_sb »

I just noticed in a picture on a Jupiter Ace that someone has a M-M edge connector adapter with what looks like a reset switch and power LED indicator.

I'm going to have to add a version with those!
zx-heinz
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Joined: Thu Apr 27, 2017 8:56 pm

Re: This weekends projects

Post by zx-heinz »

Interesting project. What about the software? Will it be as powerful as the CurrahµSpeech software?
Moggy
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Joined: Wed Jun 18, 2008 2:00 pm

Re: This weekends projects

Post by Moggy »

zx-heinz wrote: Mon Aug 10, 2020 5:02 pm Interesting project. What about the software? Will it be as powerful as the CurrahµSpeech software?
I have one of these and if it is going to have the original software then no not like the Currah-speech, no typing of strings and it doesn't have the Currahs inflection capability.

It is just like the Cheeta sweet talker or similar devices insofar as you have to put allophone codes together in some kind of data stream and feed it to the chip,usually a big REM or in my case a pre programmed EPROM on an EPROM board.
You could also use the ZXpand data block save/load feature to load pre programmed speech have the device speak it then quickly load another block from the SD card alowing for a quite lengthy if somewhat monotonous chat. :lol:

It is slightly different in that it doesn't use the standard allophone number set(why I don't know).
Without checking I think this device uses the standard allophone numbers with 90 odd added to them.

With a bit of ingenuity you could create a ZXpand serial to PC USB link use a PC program such as chip talk,some clever ZX81 software and transfer the typed speech straight into the speech card if you didn't fancy typing out lots of numbers.
Attachments
SANY0198.JPG
stroebeljc
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Re: This weekends projects

Post by stroebeljc »

Here is another peripheral called the Parrot that is based on the same speech chip. There are some nice design references contained in this thread.
John
mcarlson_sb
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Re: This weekends projects

Post by mcarlson_sb »

stroebeljc wrote: Mon Aug 10, 2020 10:40 pm Here is another peripheral called the Parrot that is based on the same speech chip. There are some nice design references contained in this thread.
Ooooooo!
Thank you. I plan to make one of those also.
I just happened to run across the Talk-Back :D
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1024MAK
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Location: Looking forward to summer in Somerset, UK...

Re: This weekends projects

Post by 1024MAK »

Oh my! I can see it now... He’s gonna have multiple Sinclair machines chatting to each other :lol:

Like some kind of elderly Sinclair retirement home for chatty computers instead of chatty old men and women!

Mark
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XavSnap
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Joined: Sat May 10, 2008 4:23 pm

Re: This weekends projects

Post by XavSnap »

Hi mcarlson_sb,

Thanks for sharing.

Are there more readable scans of this magazine?
I can't read the pin number on the linked web page…
:mrgreen:

I plan to rebuild it on Kicad.

[edit]
http://www.computinghistory.org.uk/det/ ... ack-GB18U/

Link to Maplin magazines :
https://worldradiohistory.com/Maplin-Electronics.htm
TalkBack_SPO256al2.jpg

Zx81 Talk-Back : Maplin #5
https://worldradiohistory.com/UK/Mapeli ... -03-05.pdf

Have fun.
Xavier
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XavSnap
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Re: This weekends projects

Post by XavSnap »

Something's wrong with R7=470R
Surely 470k , due to a compression error from the native "Djvu" format document…
:o

This format used to get all black zones (characters, lines, drawing…) and put them on the page and get the similar character to use it in the document.
The "Djvued" document, in a book, just get the main characters profils… but, if a character is "dirty", the character is replaced by a wrong character…
"1" by a "i", a "L"...

OR

(Is's really a "R", seen on other diagram)
R7= 470 (OHM)
R7= 47 OR (GOLD quality value in french)


OR

R7= 470 (Rounded)
R7= 470 (Reversed)
R7= 470 (Roger)
R7= 470 (Rotated)
Xavier
mcarlson_sb
Posts: 122
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Location: San Francisco

Re: This weekends projects

Post by mcarlson_sb »

XavSnap wrote: Thu Aug 13, 2020 11:20 am Something's wrong with R7=470R
Surely 470k , due to a compression error from the native "Djvu" format document…
:o
Last weekend I did the CAD work based off of the fuzzy scan.
This week I've been breadboarding it to tests.
:( it didn't work :(

I'm currently redoing the breadboard version slowly and testing as I go to find faults and adjust as needed.

I'll update my schematic - and share - once I have a working version
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