Experiences with a composite video mod for a Sinclair ZX81

Terry Stewart terry.stewart296a at gmail.com
Sat Jan 2 20:06:12 CST 2016

On 3/01/2016 2:50 pm, "drlegendre ." <drlegendre at gmail.com> wrote:
> Thanks Terry, fair enough. =)
> Has it been done with the ubiquitous 2N2222A? That one is probably in
> everybody's kit.. it might be even more common than the 3904
> Wondering.. is there a way to re-purpose that Chan. 3/4 switch as an RF /
> Composite switch? That way you'd still have a correct (local) RF output,
> well as the Composite video.

Actually you probably could if you wanted to keep RF.  You'd have to make
sure it's hardwired to the right RF channel of course but yea..

It's interesting that none of my present TVs would tune properly to the RF
of the ZX81 but they will with some of the other RF only computers like the
Coco 1 and Atari 400?  More circuitry in the latter perhaps...

Terry ( Tez )

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