Hi all. I would like to be able to regulate current (around 4A @ 17.5V). I have a constant voltage supply that seems pretty stable but I want to be able to regulate the current. Google searches only seem to return low current circuits, or suggest to use small current regulation devices.
Which is the best direction to turn guys?
Thanks in advance
Hy Dan,
Care to tell us your county.
I think many of us have been holding off suggesting a circuit to meet the requirements of your request due to a concern about safety. Now that you have told us a bit more about your application I fell a bit easier.
To answer your question, yes there are circuits that will provide a constant current with the following general characteristics, all within reason that is (reasonable limits in brackets):
(1) any value of constant current (10uA to 20A)
(2) any accuracy of constant current (+- 0.5%)
(3) any input voltage range (6V to 50V)
(4) any output voltage range (0V to 50V)
(5) arbitrarily low dropout voltage (100mV)
(6) modest cost (£2 UK to £20 UK depending on specification)
Obviously, the characteristics are interdependent. For example, without using switch mode techniques, it would be difficult to provide a constant current of 20A with an input range of 6 to 50V and an output range of 0V to 50V because of the resulting dissipation in the series pass element of 1KW.
I am about halfway through a design which should meet your requirements and will post a schematic soon for your consideration.
spec