Sinclair ZX80 Keyboards

[Moggy]

I thought about that and have now uploaded a picture of the motherboard of the ZX80 - as you will see the switches are printed directly onto the motherboard itself, so you could not easily replace them.

The replacement keyboard is just an adhesive overlay which provides the actual keyboard.

Sorry If I appear a bit thick Rich but Your pics are only showing one half of a set of contacts ,like a modern remote control for example, something has to bridge the circuit if memeory serves and it was thirty years ago, when I built my zx80 kit the keyboard comprised a top graphic overlay then the switchable membrane which was a seperate item that operated on the m/board (see link).
Can You confirm that it is the ovelay only for sale

Regards Moggy


http://www.mango-a-gogo.com/scot/zx80/zx80const.pdf

[RWAP]

Sorry If I appear a bit thick Rich but Your pics are only showing one half of a set of contacts ,like a modern remote control for example, something has to bridge the circuit if memeory serves and it was thirty years ago, when I built my zx80 kit the keyboard comprised a top graphic overlay then the switchable membrane which was a seperate item that operated on the m/board (see link).
Can You confirm that it is the ovelay only for sale

It is not just the keyboard graphic, no - from that useful picture (never seen the ZX80 assembly instructions on line before by the way!) I would say it is classed as "keyboard pre-assembled".

It is difficult to describe I guess - especially as I am only guessing!!

Underneath each key, the adhesive layer is cut away to produce a circular cut out with a silver backing. Presumably the electrical circuit is made by that silver backing covering the electrical spiral on the circuit board (I can't test it, as the ZX80 motherboard does not belong to me and lacks a modulator!).

The spiral comes from the front and back of the PCB, without the two trails touching, so I guess that is how it works in effect - the silver backing on the keys connects the two trails.

[Moggy]

Sorry If I appear a bit thick Rich but Your pics are only showing one half of a set of contacts ,like a modern remote control for example, something has to bridge the circuit if memeory serves and it was thirty years ago, when I built my zx80 kit the keyboard comprised a top graphic overlay then the switchable membrane which was a seperate item that operated on the m/board (see link).
Can You confirm that it is the ovelay only for sale

It is not just the keyboard graphic, no - from that useful picture (never seen the ZX80 assembly instructions on line before by the way!) I would say it is classed as "keyboard pre-assembled".

It is difficult to describe I guess - especially as I am only guessing!!

Underneath each key, the adhesive layer is cut away to produce a circular cut out with a silver backing. Presumably the electrical circuit is made by that silver backing covering the electrical spiral on the circuit board (I can't test it, as the ZX80 motherboard does not belong to me and lacks a modulator!).

The spiral comes from the front and back of the PCB, without the two trails touching, so I guess that is how it works in effect - the silver backing on the keys connects the two trails.

Thanks for prompt reply Rich thats covered it completely although my zx80 is ok at the moment ( purchased from Your good self) I will order one after christmas when post is back to normal. Although it wont be fitted till Mine is kaputt I will be able to let other forum members know my opinions on it; looks feel etc I bought a couple of zx81 versions which were superb so I see no reason to doubt this one.

Thanks again Rich

Regards Moggy

[sirmorris]

Now that we have these I shall be asking Lee to update his zx80 design so we can use these overlays...!

[RWAP]

Now that we have these I shall be asking Lee to update his zx80 design so we can use these overlays...!

Well I did wonder what Lee was using!!