Posted on Saturday, May 21, 2011 • Category: Power Supplies
Here's a laboratory power supply with output voltage continuously adjustable from 0 V to 24 V DC, remote voltage sense capability (Sense internal/external), output current limit is continuously adjustable from 0.04 A to 4 A and output current can be limited continuously or output shut down (Limit/cut).
Remote sensing means there are two additional wires which sense the delivered voltage at the load and compensate for any voltage drop along the cables which carry the delivered current. This improves voltage regulation at the load considerably but requires two additional wires for the sensing. A switch allows internal sensing at the output terminals for simpler operation when remote sensing is not required.
I like to have a switch which lets me choose between limiting the output current continuously (useful for charging batteries), or shutting down the output if the current limit is reached (useful for protecting equipment being repaired).
Another thing I like to have in the power supplies I build is a push button switch which multiplies the current scale by a factor of 10. That way one can momentarily press the button and get a much more precise reading of current. By making the switch a push button one cannot forget to turn the function off and risk the instrument being damaged when a large current is put through it. In this case and for now I am not installing this function because I am using the instrument's shunt resistor to sense the current for the electronic control system and I would have to change several things. I might do this in the future.
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