I want to control a 0-to-40v output DC voltage linearly with a 0-to-5v variable DC voltage

Thread Starter

Zakaria Mansouri

Joined Sep 29, 2017
2
i have a 40 volt DC voltage source ( VH ), and i want to control how much voltage to output from 0 to 40 volt by another DC voltage source ( VL ), from Arduino pin witch provides a range from 0 to 5 volt, so the output voltage ( VO ) must be proportional to VL
This equations is the goal:
VO = VL * 8 witch is < VH

See the photo to understand more

am waiting for any answers or advice
and thanks in advance
 

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AnalogKid

Joined Aug 1, 2013
10,986
How stable (well regulated) is the 40 V source?
What power source is available for the regulator circuit? Only the 40 V input?

Do you need a true 0 V output? With either linear or switching technology, regulating down to 0 V is a bit more tricky when there is no negative supply voltage for the regulator circuit, but there are several ways around this.

There will be some minimum voltage drop across the regulator, so with a 40.00 V input you will not get a 40.00 V output. Depending on the regulator circuit complexity and cost, that voltage differential can be as little as about 0.2 V (big p-channel power MOSFET) or as much as 3 or 4 V (LM723 controlled).

ak
 

alfonsoM

Joined Nov 8, 2017
41
The output of the arduino is PWM with average of 0-5 V to get the same PWM on the 40V you need a N chn power mosfet with the drain connected to the +40V supply and source to the + output. The arduino output is connected between the source and the gate. This will work only if the arduino, the 40V supply and the output dont have a common earth, If the earth is common then you need a high-side switch which requires P chn mosfet with a transistor or two and some resistors. If you wish I can suggest a circuit.
 
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