AC/DC Adapters for Equipment

jimi_t

Although this probably really belongs to the electronics forum, I thought I'd try here first.

I've (another) bit of gear with no adapter. I've noticed before that if the voltages on a piece of gear were the same, that then I could use an adapter with a different ampere rating (although the adapter would get hot quickly if the original adapter had a higher ampere rating).

Now I need an adapter rated @ 7.5vAC 1a. I've a few different adapters rated from 9vAC 200ma to 9vAC 780ma. Would any of these be safe to use? The next closest adapter in terms of voltage would be either 10vAC or 5vAC... Will things blow up or what if I do? (I presume trying to use a DC adapter would lead to baaaad things?)

Voodu Child

The voltage supply will be decided by the adaptor, the current draw will be decided by the device.

So you should match the voltage of the adaptor and the device bang on, I wouldnt use a 9V adaptor with a 7.5 V device personally.

Using an adaptor that is rated at 750ma means the adaptor physically isnt capable of supplying the max current that the device potentially could draw. You'll only get into trouble if the device is running flat out, in which case more current will be coming through the adaptor than it is rated for, the PSUs transformer will overheat, and possibly be damaged.

And, yeah, dont use a DC instead of AC or vice versa

Eoin Madsen

At 9V the device should draw proportionately less current (assuming it works properly at 9v to begin with) and items are generally rated to err on the side of caution. So I think you could probably chance your arm with the 9VAC 780mA... but I'd try it to get out of a fix, definitely not as a permanent solution. And the official, responsible, and not-liable answer would have to be no - just get a suitable adaptor, exactly 7.5VAC and 1A or higher.

jimi_t

Eoin Madsen wrote:

...get a suitable adaptor, exactly 7.5VAC and 1A or higher.

Any idea where I'd be able to get one (reasonably cheaply) on the southside of the city? I'm based in Ranelagh

Voodu Child

jimi_t wrote:

Any idea where I'd be able to get one (reasonably cheaply) on the southside of the city? I'm based in Ranelagh

If you're having trouble finding one, im sure Argos have multi-voltage adaptors.

Dennis2011

you have to be a bit careful about this around non-switching adapters. Most of the non-switching type wall warts are also unregulated. They are designed to put out the rated voltage at the rated current, and can typically put up to 30% more voltage out at low current draws.

This is one case where more isn't always better. Replacing a 5V 100mA adapter with a 5V 2A wall wort may in fact feed more like 8-9V in to your equipment at the lower current draw you actually use. This can easily cause damage if the device isn't designed to account for possible higher input voltages.
good luck.

gotBass

jimi_t wrote: »

Although this probably really belongs to the electronics forum, I thought I'd try here first.

I've (another) bit of gear with no adapter. I've noticed before that if the voltages on a piece of gear were the same, that then I could use an adapter with a different ampere rating (although the adapter would get hot quickly if the original adapter had a higher ampere rating).

Now I need an adapter rated @ 7.5vAC 1a. I've a few different adapters rated from 9vAC 200ma to 9vAC 780ma. Would any of these be safe to use? The next closest adapter in terms of voltage would be either 10vAC or 5vAC... Will things blow up or what if I do? (I presume trying to use a DC adapter would lead to baaaad things?)

I'd only use a correct PSU fpr what you have.
If it was a DC input I'd be ok as most of the time there's a protection diode in there.

7v5AC 1A
http://www.maplin.co.uk/Module.aspx?ModuleNo=43055
these guys have shops in Blanchardstown and on Henry street.

they also have good customer support.
bring your device in and they'll read the back panel for you I'm sure

darrenw5094

Dennis2011 wrote: »

you have to be a bit careful about this around non-switching adapters. Most of the non-switching type wall warts are also unregulated. They are designed to put out the rated voltage at the rated current, and can typically put up to 30% more voltage out at low current draws.

This is one case where more isn't always better. Replacing a 5V 100mA adapter with a 5V 2A wall wort may in fact feed more like 8-9V in to your equipment at the lower current draw you actually use. This can easily cause damage if the device isn't designed to account for possible higher input voltages.
good luck.

Dennis the Menace.

Dragged up a 3 and a half year old thread.:)

I hope the OP has the power supply sorted by now.