On Sun, 29 Oct 2006 08:30:28 +0000, Andy Wade
wrote:

Andrew Gabriel wrote:

A friend of mine bought a ZX80 or XZ81 kit (can't recall which).
The diodes for the power supply bridge rectifier were rejects
because the band was marked on the wrong end, it turned out
after he powered the thing up...

Ah...

Remember the germanium "micro alloy transistors" used in many of his
earlier efforts (I still have an original X10 (PWM) amplifier
somewhere)?

Did it work? I was at uni at the time studying electronics. The
lecturers poured scorn on it because the output transistors and diodes
did not have good enough characteristics to switch off the current
pulse through the inductive voice coil of the speaker without a lot of
power loss. Sure enough the only one I ever saw had burnt out output
transistors.

Those are documented somewhere as being a job lot of
rejects he bought from AEI.

Legend has it they had been used as hard core under a new drive.
Sinclair bought them and paid to have them dug up.

Thinking back it must have been just before the UK semiconductor
industry went over to silicon. They could have been the tail end of
Ge. transistor production ??

DG