How to understand Laptop Adapter power ratings?

[tezza]

Is that 12V unloaded? As regarding power supplies, the ones in the UK were built for 240V and could get overheated if run at a lower voltage. The Swedish Sinclair importer already from the beginning rejected UK power supplies and instead bought German ones which were built for 220V and of a different build quality.

Hmm...the PSUs are different. The European one I got was from the Netherlands. It came with the Spectrum which I won on e-Bay. It's a genuine ZX power supply but it says "Euro 1400" in the fine print on the specs label. It also says 220v not 240, which would support what you say. This is the one that gives 15V unloaded on the meter.

The one from New Zealand (with a NZ/Australian plug) is also a genuine Sinclair ZX PSU but this one is called "UK 1400" and the input is 240v. It's unloaded output on my meter is 12V.

Both packs say the output is 9v pulling at 1.4amp.

Perhaps the load from machine does pull it down to what it should be. I've run the unit with both adaptors and for many hours. It doesn't seem to get hot and runs just fine.

 

[nige the hippy]

One thing that you've got to watch using european 220V stuff on 240V.
Some (unfortunately most!) transformers were made down to the last penny. For a real transformer putting 15% extra volts on the primary won't just up the secondary voltage by 15%. It will also tend to saturate the core leading to over current & overheating.

On a modern transformer with a thermal fuse it's usually terminal (for the transformer) but not serious, on an old transformer without a thermal fuse it can be terminal for all the occupants of the house when it bursts into flames!

Keep an eye on those recent acquisitions, just in case!


This shouldn't be a problem with laptop supplies, as they are switch mode (just different technology).

 

[tezza]

One thing that you've got to watch using european 220V stuff on 240V.
Some (unfortunately most!) transformers were made down to the last penny. For a real transformer putting 15% extra volts on the primary won't just up the secondary voltage by 15%. It will also tend to saturate the core leading to over current & overheating.

Thanks for the advice. That 220v Euro transformer I got with the machine is now going nowhere near it!