STOP PRESS  This is my old site last updated June 2005.  Enjoy the pics here but it is best to shift direct to the new site. Looks the same but lots more stuff and regularly updated.  The full size pictures  are only available there.

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Solar car (Photoelectric) 2003

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A model  for a school project. Features include two 1 Farad supercapacitors which give an ability to charge in relatively low light and also to drive about 10 yards through a shaded area out of direct sunlight.  The solar panels can be tilted to either side to best catch oblique sunlight. Two LEDs indicate the charging with the high intensity blue LED being visible in sunlight. It can be charged in low light from a light bulb.

Solar Car (Steam powered!)  March 2004
The next childs Dad-assisted school project. Not really electronic but is a contrast with the car above.  This utilised a model steam engine for marine use that I bought 20 years ago. The sunlight is focused by 2 Fresnel lenses (used for reading magnification).  Each beam is reflected to strike the boiler on each side which is blackened to absorb heat. The lens and mirror structures are able to be tilted to aim towards the sun. So far the engine works when externally heated with a burner and has a satisfying red flywheel.  Not enough power to work with sunlight without extra heat assistance.  Note the focusing of the overhead light by the lenses.  A Stirling engine would work better.

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Robotic car (PICAXE programmable)

This model car is programmed via a PICAXE 28A chip 168F72 with Basic language. Transfer of the program is via a serial cable output. It is simple enough for kids to be able to program.   The 4 MHz development board has 8 outputs buffered on board by a darlington driver chip ULN2803A and a L293D motor driver chip.   There are 8 inputs and 4 analogue inputs as well.  It all runs on 4.5 V.  There is a 256 line limit and 15 gosub limit

Mechanically it has two independent rear motors and a front castor (a small furniture one) all mounted on a 23 x 17 cm acrylic chassis. 

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So far it has inputs of 2 switches and a light dependent resistor and outputs of two motors and two LED's.