Advice about AC/DC power adapter required

PSUs: The source of DC power for all components in the PC & often a big noise source.

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Jordan
Posts: 557
Joined: Wed Apr 28, 2004 8:21 pm
Location: Scotland, UK

Advice about AC/DC power adapter required

Post by Jordan » Thu Sep 18, 2008 3:03 am

OK, this isn't actually PC related but seemed like the most fitting forum...

I just got myself a SpeakerCraft SL-One speaker A-B switch for sharing my pair of front speakers between my AV and stereo amps. The switch arrived today but doesn't include a power supply! :evil:

The requirements are 12V (2.1mm) and 120mA so I thought fine, I'll just get an adjustable one from Argos or Maplin. However, it seems that while voltage adjustment is common I can't see anything about current adjustment and 120mA seems very uncommon. Then I started reading about regulated adapters to control current then polarity was mentioned and now I'm completely confused!

Please help! :cry:

Aard
Posts: 46
Joined: Mon Nov 19, 2007 1:13 am
Location: New Zealand

Post by Aard » Sat Sep 20, 2008 5:58 pm

Hi

A power supply will supply only the power required to power the device. P=IV and the voltage is fixed (in this case at 12 V), so to vary the power we must change the current, which may be anything from around 0 A to potentially above the maximum current specified by the power supply.

With this in mind you can now buy almost any 12 V DC power supply available to you and have to work.

Maplin for example have:

http://www.maplin.co.uk/Module.aspx?ModuleNo=19160

http://www.maplin.co.uk/Module.aspx?ModuleNo=13453

Note one is regulated and the other isn't, the advice that I've been given is that since its a speaker buy a regulated power supply if the speaker is unregulated, or buy a unregulated power supply if the speaker is regulated, if your unsure buy a regulated one.

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