3,6,12,13,24

On a light load I would expect the 6V unit to provide 9V.

Have you tried measuring it's output?

I did just that . All (presumably) items that require a "wall wart" have one included with the item when bought new. If I get one second hand I have one (a couple actually) of those multi-voltage multi-tipped things . If I have an item not very much used that I have chucked out the "wall wart" of then a quick Google to find which one I need and buy it on Amazon (other shopping sites are available). Or I could use the multi-voltage thing

Watch this strategy bite me in the bum.

Use the 3V and 6V ones and put the outputs in series?

As a diagnostic, maybe ...

A few years ago, I had a similar experience with a box of mobiles. I can't remember the exact number (more than 8) but despite every single one working, I couldn't actually use any. Either a lack of charger (looks at Nokia with their 1,000 charger variants) or a network lock. The worst was a £10 Orange phone that EE wanted £35 to unlock.

It's hard not to feel we really are heading towards something final with wastage like that.

And hope that the ground of the DC output isn't connected to mains earth, otherwise one adaptor's 9V will be connected to earth on the other adaptor and be shorted out.

With modern electronic devices having no mains earth connection, you'll probably get away with it. I like Heath Robinson arrangements like that!

The other problem is finding a PSU that can supply the right voltage *and* the right current. The PSU on our video recorder failed (weird symptom: the PVR would display menus but not play or record, probably because there was insufficient current to drive the hard disc). I found lots of 12V PSUs in shops, but none were rated to supply as much as 2A (as the failed one as rated) and a 1A PSU that I had spare would not do the job. Luckily the PSU for an external hard disc was the right connector and the right current rating.

I now have a collection of PSUs in my cupboard, just waiting for something to fail... Along with neatly coiled-up cables in different boxes/bags - USB with full-size square connector, USB with mini end or micro end, mains leads (kettle lead, clover-leaf, two-pin figure-of-eight, etc). When I needed a kettle lead connector, I could found loads of others but not the one I wanted... Like when I needed a spare HDD to try a new installation of Ubuntu - I had loads of ancient IDE discs but no spare SATA ones, so I spent half a day moving data from one backup drive to another to free up one for testing. I remember having loads of "small" ones ("only" 80 GB) but I think I threw them away thinking I'd never need anything that small. I kept the IDE discs simply because those are probably not sold any more.

Now if you have a calculator that does not need a 9V supply, you have a solution :-)

AB From the well pummelled keyboard of Archibald Tarquin Blenkinsopp Esq

I was going to say 17, as that's the only other meal that comes with egg fried rice at our local takeaway. ;-)

Cheers, T i m

Are any of them regulated? Could be as simple as fitting a different regulator if its an analogue wall wart. Brian

They used to make switchable wall adapters.

I would not expect those to be available today, that style. Too easy.

You can also make your own, using available material from the junk room. Even a 12V adapter and a 7809 would do.

Its not the only missing one. 7.5v was very popular for a while for rechargeable devices. Also what I did many years ago is bought an lm317T, bolted it into a metal case with a pot and a couple of capacitors. One end had the socket for a 12v adaptor, the other end a wire with the usual combination of things on it. One could just set it to 9v and carry on regardless, made a nice hand warmer as well. Brian

I have far more than that. Even my collection of switched mode ones is now getting quite large.

I'm getting tempted to put all the "transformer" ones in the metal bag for the next tip trip.

Given they are cast iron / copper, don't you have a metal recyclers near you as you may be surprised what they might be worth (for the copper etc)?

Ours give £2.50 for any electric motor (washing machine size) for example.

Not worth a specific trip for one motor etc but if you are taking any other stuff in, it all adds up.

At a different place (we were going past anyway), a smallish box of old PCB's got me 27 quid. Better than taking them to the tip. ;-)

Cheers, T i m