ZX81 denigrated! (was Re: Approaches to projects)

From: Gordon JC Pearce <gordon_at_gjcp.net>
Date: Wed Dec 1 02:43:10 2004

Jim Brain wrote:
> Glen Goodwin wrote:
>> One transistor + one resistor + one monitor = rock solid display.
> Any links? A dormant unit sits on the shelf.

 From memory, desolder the resistor inside the UHF modulator that goes
to the middle pin of the phono. Poke one lead of a 75 ohm (or
thereabouts, 68 is common and close enough) through the polythene
through the polythene bush, and solder it to the socket instead. Solder
the emitter of a small NPN tranny to the other end. Solder the base of
the tranny to the video lead, the other one that goes through the bush,
and solder the collector to the +5 supply where it goes into the
feedthrough cap. Finally solder another 75 ohm resistor between the
junction of the first one and the emitter, and ground. You may need to
adjust those values, I may be wrong.

>> Scraps from the junk box and 30 minutes time will yield a cable which
>> provides enough distance from the ZX81 to eliminate the "wobble"
>> problem.
> Again, links?

Get a 2x23 edge connector, a bit of circuit board etched and shaped to
match the edge connector on the ZX81, and a bit of ribbon cable. Wire
them together.

Received on Wed Dec 01 2004 - 02:43:10 GMT

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