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Power supply switch for boombox project...

Could someone help me with some simple wiring questions?

I've built a little boombox using a Lepai amp and some speakers. At the moment the back is off the box that houses the amp, so I can plug in a mains power adapter, but I've got a housing for 10 x rechargeable NiMH AA batteries making a 12v battery pack with maybe 20 amphours of life in it. I've only just ordered the batteries so I'll see. However, I was thinking that I'd still like to have a socket that I can plug the mains adapter into.

So I was thinking about mounting a DC socket on the back plate, and some sort of switch to select the power source.

1. Does the switch need to be a 3 position one? There's an on/off switch on the front of the amp, so maybe a 2-way switch would be OK?

2. Does the switch need to be some sort of special one because it's switching power. Would something like this one do?

3. The switch has 3 terminals. How do I connect it up? I'll have +ve and -ve from the battery pack, a +ve, -ve, and earth from the DC socket, and a +ve, -ve and earth going to the amp.

...or maybe there's an easier way of doing it?

Thanks.

TobaTobias4 years ago
For 12 V the kind of switch doesn't matter. I recommend for what you you're doing, a 3 postion switch (DPDT). It has 3 terminals, you would connect both ground to middle pin and then positive 1 to one side pin and then positive 2 to the other side pin.