I need a voltage source controlled by a 0 to 5 volt input. The source must run on 16.5 volts dc, the minimum and maximum voltage must be adjustable by 2 potentiometers, for example, one pot would control the starting voltage, probably somewhere between 3 to 12 volts when the control input is at 0 volts and the other pot would control the max voltage somewhere between 10 to 16 volts when the control input is at 5 volts. As the control voltage varies between 0 and 5 volts the output would vary between the minimum and maximum set voltages. It needs to be able to handle about 1.5 amps. it needs to be simple and reliable, efficiency isn't important. Can't I take a power transistor, put it on a heatsink and bias it with the control voltage through the potentiometers and some resistors to get the effect I want? I'm just not sure as to how I would exactly do this. This circuit will drive a resistive load. I need this in a bad way, it's for a really cool project that I can't disclose yet.
Sounds like a job for one or more LM317 Google around there are lots of voltage control circuits for it and its so easy to work with even i can. I keep a stock since they are so handy.
This is what I came up with. Could I use a circuit like this?- I would adjust P1 until the load had it's minimum required power and then apply 5 volts to the 0 to 5 volt input and adjust P2 until the load had it's maximum required power. Then I hope it doesn't catch on fire and when I vary the control from 0 to 5 volts that I would see the power across the load vary from its min setpoint to it's max setpoint. DO I really need op amps and regulators? If I dissconected the pots from the 0 volt line would it work better?
http://www.daycounter.com/Circuits/Voltage-Servo/Voltage-Servo.phtml one pot is R3 in the schematic, the other pot would go on a resistor divider into the drain of the n-channel fet
Not as you require. Without negative feedback and controlled gain the transistor will basically be on or off.
doesn't the amount of current going through the base to the emmiter flow a proportional but larger amount of current through the emmiter and collector? I would I implement the feedback and controlled gain you mentioned?
