Sinclair ZX80 / ZX81 / Z88 Forums

I just saw a BBC news article about the Spectrum next.
That has the possibility of driving a large number of people to the second kick starter.

I've never owned a spectrum or really looked into them. And it caught my attention

https://www.bbc.com/news/amp/technology-53765852

I have altered my original post here as I've come to the conclusion that on my board, who ever assembled it has reversed R2 and R7 I shall reverse their position and report back as to whether it works or not. EDIT. Have now reversed R2-R7 as per the schematic and can report it all works ok. Thank y...

"R" is the decimal notation in the BS1852 format. https://reviseomatic.org/help/e-resistors/Resistors%20-%20BS1852%20Codes.php R47 = 0R47 = 0.47 Ohm. 47R = 47R0 = 47 Ohm. 470R= 470R0 = 470 Ohm. Maybe it was for me :D It was something I didn't know (at least the R47 one - never run across that notat...

[edit] http://www.computinghistory.org.uk/det/52940/Maplin-ZX81-Talk-Back-GB18U/ Link to Maplin magazines : https://worldradiohistory.com/Maplin-Electronics.htm TalkBack_SPO256al2.jpg Zx81 Talk-Back : Maplin #5 https://worldradiohistory.com/UK/Mapelin/Maplin-Electronics-1983-03-05.pdf Have fun. Tha...

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...

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

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!

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/Periphe...

I guess any oscilloscope in the usd375 range as that will do the job :lol:.. I wonder if there is a Chinese model in the usd 50 to 100 range .. it could be even £100 is capable enough? You used to be able to find a good basic 10-20mhz oscope on eBay or the want ads for usd 50. But, these days they ...

I've been meaning to add a quality oscilloscope to my workbench for a while now. My research suggests that an entry level Rigol DS1054Z is a good unit. Would this be sufficient for any diagnostics I would need to do on a TS1500? Your research is correct. The DS1054Z is quite capable (even without, ...