> various interesting guesstimations re: component values

Referring to my ASCII schematic, R1 = 220R 2W ceramic body wire wound FR.
Zener rated 1.5 A peak repetitive current (I think it was a 1 Watt Zener,
5V6). R2 = 470K 0.5W FR. The rectifier diode and the capacitor chosen to
suit the circuit. If a clock is required it can be derived directly with a
resistor from the Cathode of the Zener and injected into the circuit. It
is guaranteed to swing ABOVE and BELOW the Vcc and GND by exactly 0.6 V
;).

R1 dissipates ~0.2 W in normal operation. Note WIRE WOUND AND FR. Use
other types at your own risk. Such resistors are made and available for
switching mode PSU's and other applications, in the usual white
rectangular ceramic case (short).

R2 dissipates ~0.1 W in normal operation. NOTE FR type.

C1 is calculated for 30 mA through the Zener.

hope this helps, and USE AT YOUR OWN RISK,

Peter