Protecting my new power supply Answered
I've got a 12vdc 500ma power supply that I'm using to trigger a few solid state relays. I'm also using the same power supply to provide input current to a little micro PLC (Automation Direct DL05). Both the relays and the PLC have a wide range of acceptable input voltages and their current requirements are about 15ma per channel at 12 volts. The count is 6 relays and 8 PLC inputs, if all are on thats about 210ma. I once killed a similar power supply by allowing the leads to touch and short-out. I would like to protect this power supply from the same fate by protecting it from short circuit. I thought about attaching a reisistor to the end of one lead and covering all but the outlet of the resistor with heat shrink tubing... problem is, it would have to be a big, bulky power resistor to handle the wattage. Is there a simple component available that will limit the current upon short circuit that I can place in series with my loads to protect the power supply? As I said, it doesn't have to be precise and it doesn't matter if it jerks the voltage around a little.