The extra capacitors are the blue ones. The brown disc capacitor is a part originally fitted by Sinclair. The position of this varies between different boards, so it may not be in the same position on your board. It may also be a different style.
Back to the blue capacitors, they are 100nF multilayer ceramic types. They are rated at 50V, but 100V types are okay as well. They come with the leads in two pitch spacings. 2.5mm/2.54mm and 5mm/5.08mm, I used one of each. These may also be classified as Radial Ceramic. I got mine from Rapid many years ago, the particular brand I bought has been discontinued, but all electronic suppliers should be able to offer equivalents.
For example, from RS, these are suitable:
Vishay 100nF Multilayer Ceramic Capacitor MLCC 50V dc ±10% , Through Hole K104K15X7RF53H5,
RS Stock No.: 852-3270
Link
https://uk.rs-online.com/web/p/mlccs-mu ... rs/8523270
Vishay 100nF Multilayer Ceramic Capacitor MLCC 50V dc ±10% , Through Hole K104K10X7RF53L2,
RS Stock No.: 852-3261
Link
https://uk.rs-online.com/web/p/mlccs-mu ... rs/8523261
There are also various models from RECOM, as they have improved their designs over the years.
The RECOMs are available in various ratings. The type we are discussing have a 5V DC output are typically rated at a maximum current output of 1A. But other current outputs are available.
I've not done the calculations, but, yes, I believe it should be possible to run a ZX81, and a Pi Zero. Yes, you should be able to run a 5V fan as well. Just not sure you actually need a fan if you are using a RECOM. Without the 7805 and it's heatsink, the board will run much cooler.
Mark
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