Hello,
I have a voltage source that will be outputting voltages between -20V and +20V. I need a circuit that will regulate this voltage between +0.5V and around +14V. Anything below 0.5 must stay at 0.5 while anything higher than 14 must be kept at 14...all voltages between must be their actual values.
I know I can use a zener diode regulator circuit to keep it below 14V but I am not sure what to do with the minimum voltage value, espically once it goes negative. Any negative value must be held at 0.5V.
Any suggestions????
Thanks for your help!
Hi there,
Assuming you dont need super accuracy and you want super simplicity, you can clamp
the voltage to +14v with a zener and resistor. For the +0.5v clamp you could use a
+1.2v power supply with a diode (anode connected to the +1.2v supply) and other
end to the zener and that will clamp the output to approximately +0.5v if it tries
to go negative or even below +0.5v.
Since you probably dont have a +1.2v supply sitting around you can use, you can
make one with a +5v supply and a resistor and two diodes. The two diodes get
connected in series and also in series with the resistor. The cathode of the end
diode goes to ground, the resistor to +5v. The voltage at the second diode anode
will be roughly 1.4v, not 1.2v, so that means the output will actually be clamped to
about 0.7v instead of 0.5v. If that's not good enough, then use three Schottky
diodes instead. Two in series with the resistor to construct a +1.0v supply, and
one diode connected to the upper diode and the zener. That will clamp close to
0.5v but of course it wont be perfect.
If you need really accurate clamp points we'd have to design a more precision
circuit...please advise. You should at least also tell us what output impedance
you need so we can determine if these kinds of solutions will even work at all
or you need a more robust output control.