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Re: ZX81 rebuild

Posted: Tue Feb 06, 2018 1:23 pm
by 1024MAK
Oscillator design is one of the parts of electronics that is considered a black science!

Mark

Re: ZX81 rebuild

Posted: Tue Feb 06, 2018 7:53 pm
by Lardo Boffin
Oh good. At least it is an easy one to sort then.

Maybe one of these?

https://www.cricklewoodelectronics.com/SFE6M5.html

Not much detail on their site though.

Re: ZX81 rebuild

Posted: Tue Feb 06, 2018 8:21 pm
by 1024MAK
Other 'black arts' in electronics include switch-mode power supply systems and boost and buck DC-DC converters... (well, before special 'easy to use' chip came on the market).

As to which is the most suitable ceramic resonator, it's a case of buy it and try it as far as I can tell. The normal use of these is as part of a filter circuit, not as oscillators.

Mark

Re: ZX81 rebuild

Posted: Tue Feb 06, 2018 10:06 pm
by krowne
Lardo Boffin wrote: Tue Feb 06, 2018 7:53 pm Oh good. At least it is an easy one to sort then.

Maybe one of these?

https://www.cricklewoodelectronics.com/SFE6M5.html

Not much detail on their site though.
Lardo PokeMon has them on S.M.R.

https://www.sellmyretro.com/offer/details/3469
Brian

Re: ZX81 rebuild

Posted: Tue Feb 06, 2018 10:19 pm
by Lardo Boffin
Thanks!

Re: ZX81 rebuild

Posted: Thu Jul 05, 2018 2:33 pm
by Lardo Boffin
Well, after a brief pause to move house (if only the builders had finished it before we moved in :evil: ) I have finally got back to this!

I fitted a turned pin socket for the oscillator and put in an original zeddy one:-

D79CD3CB-BA24-4A3C-B0ED-6DC0B5CED185.jpeg

Its alive!!! :lol:
And yes I have been relegated to the garage. Something to do with melting holes in worksurfaces...

60F52597-E256-4F42-9C8B-FDFBB16394C7.jpeg
Bouyed up by this I fitted a new one from Sell My Retro and....
7A3CBDB3-3C0A-4939-9321-C9E9BC30A700.jpeg

Still alive! I have a new ROM and hopefully a new ULA from Andy at some point at which time the only original component will be the PCB and case. Hmmmm....

Re: ZX81 rebuild

Posted: Thu Jul 05, 2018 7:33 pm
by 1024MAK
Image

Re: ZX81 rebuild

Posted: Thu Jul 05, 2018 9:06 pm
by McKlaud
:geek: well done, well done :geek:

Re: ZX81 rebuild

Posted: Thu Jul 05, 2018 9:20 pm
by Lardo Boffin
McKlaud wrote: Thu Jul 05, 2018 9:06 pm :geek: well done, well done :geek:
Thanks. One of your ROMs will be going into it!

Re: ZX81 rebuild

Posted: Thu Jul 05, 2018 9:27 pm
by Moggy
Lardo Boffin wrote: Thu Jul 05, 2018 9:20 pm
McKlaud wrote: Thu Jul 05, 2018 9:06 pm :geek: well done, well done :geek:
Thanks. One of your ROMs will be going into it!
Hopefully not the X2 ROM (it's packed with C-4 and a certain keypress combination sets it off) :lol:

Apologies it's whisky night.