That is a very clever circuit, and cleverly laid out as well.

BD 433 is a 22 volt GP NPN transistor, E C B left to right on top surface.
It does the switching.  Its base is connected to presumably the emitter of
the next transistor (if it's an NPN type as well).

It would be really nice to know what's written on the fronts of those two
transistors, also the complete legend on the diodes.

Yrs,
d

On Sat, Aug 5, 2017 at 1:32 AM, Alistair Bell <albell@shaw.ca> wrote:

> Dick,
>
> That looks nice and compact, david or others, what's going on there beside
> the obvious?
>