I have included this description of the ShokPopper circuit from Grant McKee for your
convenience here. The list of components was changed slightly to reflect the parts
that were used at the workshop.

ShokPopper V1.0 (click for circuit diagram) - GrantM Aug 2001

Theory of operation:

"Shok" architecture is a technique pioneered by Mark Tilden describing controlled
state changes of Bicore style circuits via chip power or enable toggling. When a
Bicore circuit is powered on, it will resume a state opposite to what it was when
it was powered off, this effect can either be duplicated by pulsing the enable line
or by pulsing power to the chip itself. This is called "shoking" the Bicore. The
power-on state can also be pre-determined by biasing the voltage across the Bicore
capacitors. A photodiode attached directly across the Bicore charge capacitor will
pre-bias the shoked output. The addition of tactile sensors is easily implemented by
attaching a switch from the input of the Bicore to +Vdd. When the switch is closed,
it forces that side high, presetting the state of the Bicore on the next pulse cycle. 

Probably one of the simplest photovore circuits to date, the core circuit consists of
a 6 part count and a solar-engine. Either 74AC240 or 74HCT240 will work but we recommend
using the AC series for better output drive current. The ShokPopper will not work under
battery power unless the enable line is pulsed.

Solar Engine to use with Shok:
The best solar-engine to use is the Miller engine. For the ShokPopper Photovore we used
a Miller engine consisting of:
CP3300uf cap 
1381J
CP1uF timer cap
ZVN2106 Transistor 
SC3733 Solarcell 
D1 1N914 Diode 

The Bicore Circuit Consists of:
74AC240 Octal Buffer Chip 
TR100k Trimpot 
2 x 0.22uF Capacitors 
2 x IR1 Infrared Sensors 
2 x RM1 Motors 
TACT2 Spring Sensor Kit

The Miller engine switches the ground line of the circuit.