quick walwart power supply question

Chris_B · « **on:** 8 Jan 2006, 06:44 pm »

I need to replace a walwart power supply for an external crossover. The crossover power input specs are: 15VAC 300mA

I have a 12VAC .67A walwart sitting around doing nothing. Would it be OK to use the 12V one?

If no, I am guessing that I need to go buy this:

15V 1000mA AC Switching Adapter

http://www.radioshack.com/product/index.jsp?parentPage=search&cp=&productId=2049696&kw=15v&tab=techSpecs

Am I correct in saying that any power supply that delivers 15VAC and can supply at least 300mA is what I need?

thanks for the advice,

Chris

Chris_B · « **Reply #1 on:** 8 Jan 2006, 11:22 pm »

bump to top -- anyone?

Occam · « **Reply #2 on:** 8 Jan 2006, 11:35 pm »

The RadioShack wallwart you referenced is a dc supply, as the specs clearly indicate (read down), and its description as a switching regulator generally indicates that its a dc supply.

Your 12vac supply might work, might not. With a minimal load (300ma) the regulation of a 8va transformer should bring the voltage up substantially, 10-30%. It depends whether your line voltage runs high or low (mine typically runs 124vac), and if that voltage, after rectification, is regulated and how much voltage headroom is required for regulation.

Ideally, measure the 12vac warts output with a multimeter. I wouldn't think (but certainly am not guaranteeing) that even if the voltage is too low that it would harm your crossover.

mgalusha · « **Reply #3 on:** 8 Jan 2006, 11:40 pm »

Chris,

The 12V supply that you have might work. It's a certainty that it's being converted to DC internally and 12V with a higher current rating might be fine. It shouldn't hurt anything to try.

The Radio Shack model linked to outputs 15 volts DC, not AC. The product title is misleading.

If the 12V supply doesn't work (I would try it) you can get a 14 or 16 volt wall wart from Jameco.com for 5-10 bucks. Either of those voltages should be fine as it's going to be rectified and probably regulated internally.

Mike

Occam · « **Reply #4 on:** 8 Jan 2006, 11:44 pm »

Hey Mike - beat you to it. Daft minds think alike....

mgalusha · « **Reply #5 on:** 8 Jan 2006, 11:46 pm »

Yeah, I saw that as the page reloaded. A good example of saying almost the same thing with different words. Daft indeed.