Power supplies - again!

[dave2010]

I've asked similar questions before, but need to check. Also, having read recently of a board member who apparently blew up a Logitech Touch by connecting the wrong power supply, I figure one can't be too careful.

If I connect a device rated at 12V 2 amp to a power supply (switched mode) which is rated at 12V 2.5 amp, will there be any problems? Is it possible to blow either the PSU or the device? [Both! :steam:]

At present I have a Logitech loudspeaker - this one - see Amazon - Logitech Rechargeable Speaker S715i for iPod and iPhone or here - http://www.pixmania.co.uk/uk/uk/10320220/art/logitech/s715i-portable-ipod-iphon.html, which is 12 V 2 amp.

I also have a Logitech Squeezebox Boom box, 12 V 2.5 amp.

The power supply for the S715i has (temporarily I hope) gone walk-about.
I'm guessing that the psu for the Squeezebox Boom will work OK with the speaker, but thought I'd confirm here.

[Ali Tait]

Nope, no problem. The device will only take what current it requires. You do need to make sure that the power supply you use will supply at least the current that the device requires, but it is better to have a supply capable of supplying much more, say 10A supply for 2A device, as the power supply will have an easier time and give a cleaner supply (less ripple)

[Ali Tait]

Make sure the polarity of the jack is correct!

Usually center is positive.

[chrism]

Should be ok pending checking the polarity of the connector and the device (is it positive centre etc). Also double check the voltage before plugging in.

Sorry beaten to it by a better man!

Regards

Chris

[dave2010]

Thanks guys.

Now found an appropriate PSU which seems to work - exactly 12 V 2 A. I wonder if it was the original for this unit. Barring the mains cable - one of those 2 pin continental types - it seems fine. I don't recall Logitech selling brick type (Chinese?) psus for this device, but maybe that's exactly right.

Most psus now have the voltage, amps, and the pin layout printed on them, but some "cleverly" (!!!) manage to avoid putting the pin diagram on. I'm not sure whether the solid line above the dotted line shown on some PSUs has signficance. I prefer to see a + and a - linked to a diagram of the plug. If the solid/dotted line notation is useful it'd be good to know what it means, though it could be more helpful than Chinese.

The one I'm using does have a positive centre pin layout. Also, unlike a previous occasion, there is no slight burning smell from using an under rated psu, so I think the rule must be to always match or exceed the device current rating at the psu, as Ali says.

[Ali Tait]

Yep, at least match, preferably exceed.