D201 1N914 or similar (not at all critical)
D202 1N914 or similar (not at all critical)
D203 LED (not at all critical)
RESISTORS (1/4 WATT, 5%):
R103 1Meg variable *
R202 1Meg variable *
R205 100 (The LED in the Solid State Relay seems to need a lot of current.)
* Keep leads short in this high impedance part of the circuit.
Pulser 555 Timer IC (or 1/2 556)
Timer 555 Timer IC (or 1/2 556)
Relay Sharp S101S05V (Radio Shack stocks this, part number 275-310)
Small 5 volt DC supply (e.g the Radio Shack 273-1454 6 Volt 150mA "wall wart" style -- about $8.00). It doesn't need to put out much current, but should be well regulated. Just about anything should do.