Thursday, April 9, 2009
Go Kart Controller
I have finished the hardware for the Go Kart Controller. It consists of the potentiometer, (for pedal location detection), the MOSFET array, (for switching), and the PICAXE, (the brain).
I haven't yet finished the code for the PICAXE. The program will monitor the resistance of the potentiometer. When the resistance rises, the motor will accelerate/decelerate and vice versa. To change the speed of the motor I will used PWM on the MOSFETs. I have tested this with an LED and it works just fine. The PWM in this case is at 10,000Hz. This means the circuit is switching on and off 10,000 times a second! The duty cycle is determined by the potentiometer.
These four MOSFETs are IRF1405. According to their data sheet they are capable of about 100A at about 100°C. Having four of them wired in parallel means I can have 400A at 100°C. Most sites I've been on state that starter motor current peaks at about 300A. 400A should be plenty enough!
Not much news on the data logger just yet. Bought some more parts of Andrew (wireless units!). I have NO idea how to get the Casio working... I've done it before, but it doesn't want to work just yet.