I have a device that requires 48V at 2.5A. I found another adapter that says it provides 48V at 2.5A. When I use my voltmeter to probe it, I get 55V at no load. If I remember correctly, wall warts and similar simple adapters push more volts than they are rated at until you load them - or at least they have a tolerance. Am I correct on this?? I dont want to fry my equipment.

For those curious, it's a Cisco Small Business poe switch. I have had no luck at all finding a replacement adapter on ebay, craigslist, etc - most likely because they were all garbage and failed. If you have a better suggestion of how to replace the power supply, feel free to offer it up.

4/10/2012 8:41:26 PM

There are various power supply designs, generally regulated or unregulated. The former will maintain a constant voltage up to a particular load, the latter will provide a given voltage at a particular load. What you have appears to be unregulated.

The appropriateness of the supply will depend on what the original was. If it was unregulated, you can use either type. If it was regulated, then it's a crap shoot. The device might not mind some overvoltage, it may operate erratically, or it might just not work at all.

4/10/2012 10:20:56 PM

pm sent. I may be able to find the right wall wart for your switch.

4/11/2012 3:31:28 PM