The Solenoid Engine electronics Only built and tested .
Piston timing comes from a slotted-opto sensor. The speed regulation comes from the small embedded CPU. This gives a wide range of running speeds which are adjustable with a pair of push buttons on the back of the PCB to increase/decrease the speed.
The speed is regulated by ‘missing’ power strokes when the flywheel is moving over the pre-set speed. This is similar to the way a gas engine is regulated.
It is capable of running from 5-18V supply with an average current draw as low as 20mA, depending on the solenoid choice, speed and supply voltage. An LED indicates the solenoid output.