I have built a PWM motor controller board as found on www.eleinmec.com. I have substituted a 556 for the two 555 chips, and added another transistor to create a Darlington pair for more current to power larger 12v motors from cordless hand drills. What I want to do now is control the speed with a PC via the parallel port. I have a VB program that I made about a year ago for a relay board to control power outlets via the parallel port. I also have a voltage regulator that was intended to be used with a car cig-lighter outlet but have 1.5, 3, 4.5, 5, 7, 9, or 12 volts selectable out. Inside, the car regulator has a voltage regulator, a bunch of resistors, and a switch to select which resistor is used. Vs goes through the switch, through the selected resistor, and then the output of the resistor is fed into the voltage regulator "Sense/Reference" pin, which in turn makes the regulator output the voltage required at 1 amp. Can I use the voltage regulator instead of the potentiometer on the monostable circuit, by using 8 resistors that would work nicely with an 8 bit system coming from a parallel port, or would a voltage regulator even work in this instance? |
