Bit by bit I think we'll get there.

It does not have to be a ceramic disc, any 10nF capacitor should work. Sinclair used a ceramic disc because this type (for this value) is the cheapest.patters wrote: ↑Tue Apr 06, 2021 5:40 pm I'm ready to order a bunch of components to attempt various remediations. Is it ok to replace C10 on the ZX81 with something this physically small?
https://www.bitsbox.co.uk/index.php?mai ... cts_id=207
I kind of need a wider leg pitch ideally but I can't seem to find that in a ceramic.
Well, it may be, but in this circuit, the voltage will be well below the 50V rating of the 10nF capacitor that you linked to.
When I get some time, I’m going to try a 1kΩ resistor in parallel with R3 or in parallel with R2 on the composite video board to see if I can get the black in the picture to be a bit darker (more black).
Moggy wrote: ↑Sun Apr 04, 2021 2:34 pm There is something you can do to increase the output of the 386,if it hasn't been done already by the makers and will take a bit of confidence on your part to try.
Like most op-amps used for audio they rely on a bias circuit to control the strength of the out-put.
The 386 is a bit unusual in that it already has a small bias built in which gives it an amplification of X20.
The addition of a 10uf electrolytic cap' can boost this to X200 (the chips max out-put) and would certainly put to bed any thoughts of the out-put being too low.