Hi friends.

I think i should give more detailed information.
What I need is to uso a PIC microcontroller, so using 2 push-buttons, I can increase / decrease the voltage level from 0VDC to 60VDC. The PIC output range is 0-5VDC, so I need an interface to convert this signal to 0-60VDC.
Current output needed 2.5 or 3A. Load is a magnet, with the following voltage/current measured:

40V - 2.08A
34.8V - 1.85A
30.3V - 1.26A
24.5V - 0.69A
18.4V - 0.12A
17V - 0.01A

The idea is to replace actual boards to get 50 or 60VDC in order to achieve a stronger magnetic force.


Thanks!

Best regards.

 

What sort of power supply do you have to supply the ~80W required?

You want each button press to increment voltage by some amount?

Also, something is wrong with your data or your description: The current through a magnet coil should be proportional to voltage with a zero intercept. Why no current in your magnet with <17V ?

My approach would be to pass the current through a low ohms shunt resistor in series with the coil and compare the ∆V across the shunt to the set point reference voltage given by the controller. Use an op amp and power transistors to close the feedback loop.

 

For that value of current and voltage I would use PWM from the PIC to control a MOSFET which would vary the current with low losses.

 

I was thinking of that but wouldn't you then also need a low pass filter to avoid sending a square wave to a giant inductor? The OP's odd data also makes me wonder if this is more than a simple coil, and might have electronics on board.