Based on a design by Peter Holland, Radio Control Models & Electronics, December 1964.
Probably the first published design for a phototropic vehicle which didn't follow Grey Walters design of a scanning turret coupled to the front wheel. Instead Fred's turret independently rotates and a sensor integrates the light level over the Port and Starboard sectors and directs the steering to head to the brightest sector.
Built May 1990.
Size - 5" * 3"
Operational area - 3ft * 3ft.

Fred was built using parts that either were or could have been in my bits box in 1964 which is the date of the original article. The transistors are GET103.

The original Fred was obviously made in a hurry as a magazine article because in operation the steering head would end up travelling right round wrapping the suply wires round itself. I made two limit switches with fine phosphor bronze spring wire and the 'L' shaped wire on the front pulley just pushes them and breaks their contact. I also changed the rubber band, from the steering motor to the steering head, to a push rod.

   

Magazine: Radio Control Models & Electronics, December 1964

Magazine article fred-RCMEDec64.pdf

Fred circuit as built