adding a load shut off circuit to a basic PSU-is it possible?

[GreyWoolfe]

I see a lot of the higher end PSUs have a load shut off switch.  I've tried to find information on it on the Internet but I haven't been successful.  Is there a circuit that is fairly easy to implement?  I built and modded an Elenco XP720K and I think that is something I would like to add.  I also have an Agilent E3610A PSU on the way that I would like to add the circuit to.  Has anyone done this and can you point me in the right direction?

Tom, NW0LF

[tsmith35]

Possibly similar to the automatic load shutoff for a UPS? When the battery charge falls below a user-specified level, the UPS will shut off power to the load while still remaining active.

[TMM]

You can simply add a switch or relay on the output but then you have to deal with contact bounce - look up RC snubber circuits. Also the PSU itself may produce some undesirable effects if it is suddenly connected to a load (under/overshoot).

A better solution would be to simply have a switch that sets the PSU voltage to 0V. Obviously there is no 'one circuit fits all' solution for that, you have to reverse engineer the PSU to find out how the voltage is being set.

[nctnico]

Just put a switch across the volt setting potmeter. Shorted means the output goes to 0V. I recently modified one of my HP6024A PSUs with such a switch.