If you want a photophilic Jitterbug (that is, one that gets the shakes in the dark instead of jittering out of the light), then just swap the positions of the 4.7k resistor and photoresistor in the schematic in Figure 22-6. If you want to play with the Jitterbug’s photo-responsiveness in either configuration, try using different resistors in place of the 4.7k resistor. For a truly advanced Jitterbug, double up on the motors, resistors, and transistors, and build two brains (one to control each motor independently). Since the transistor gradually lets more power go to the motor as the photoresistor senses more light, it’s possible, if you rig up the body carefully, to make the bug exhibit meaningful positive (or negative) phototaxis. Or, consider a major shift in the Jitterbug’s basic body: Use a normal 3-volt motor instead of a vibrator motor, glue a toy car’s rim and tire to the shaft, and build a zippy little Monowheeliebug.