Hey all,

Any thoughts on a simple circuit that would allow 0-10v DC to adjust a 0-12v DC output?

I'm looking to use a 0-10v controller to vary the output of a 12v power supply.

Thanks

 

How much current do you need?

 

I think 500ma will be more than sufficient.

 

Do you need the output to be adjustable right down to zero volts? That would complicate the design.

[Edit] Also do you need a circuit to limit the maximum output current or would you be happy with just a fuse?

 

The relay cutoff voltage is 1.5v so anything below that will work.

 

The circuit below will do the job. It has a minimum output voltage of 1.2V, will supply 0.5A and is short circuit proof.

 

Is there any fashion to build this using only a lm317? I'm in a time crunch and am trying to work with componemts I have. I included a circuit that worked for a 4.5v output. Is there any way to use this to adapt to my current needs?

 

If you put the 0-10V directly into the LM317 ADJ pin, the output will go from 1.25V to about 10V output with a 12V supply (the LM317 has about a minimum 2V dropout input to output).
Note that Albert's circuit has that same limitation.
Would that be sufficient?

 

I do belive it would. It'll be very close. I'm gonna hit the breadboard and see what happens.

Thanks all!

 

Did you catch my edits to my previous post?

 

I did. Could you please explain "minimum dropout"?

 

The control pin of the LM317 would need to be at 10.8V to get 12V out and you can't do that with a 10V input. You can get 1.2V to 11.2V by simply connecting the control voltage direct to the LM317 control pin.

I selected the LM317M as it is rated to supply 500mA and will limit the current to just a bit more than that.

 

I did. Could you please explain "minimum dropout"?

That's the minimum voltage between the input and output for the regulator to regulate, as shown below for the LM317.
For a 500mA output the curve shows about 1.7V, depending upon the junction temperature.
Thus with a 12V supply, the maximum output will be about 10.3V.