You were lucky.

Quite often AC supplies are alternately half-wave rectified to provide + and - supplies. I've also seen them used to feed voltage multiplier cicuits to give very much higher voltages than the 9 - 12V from the transfomer.

A DC supply would not work at all in either of these instances.

Well I was going to say... but it looks like I'm too late (just add me to the list)

I wonder if anyone else is unable to listen to them without immediately thinking of John Peel. Sad loss.

Been following this with interest (but little knowledge of your gear), when re-reading your initial comment a thought occurred to me. You said a WHINEY hum. Does that mean it's a fairly high pitch? Say around 5kHz? If so, then it's almost certainly the inverter in the UPS that's the culprit. If not,...

Or c) <censored>

Is this a can of worms I see before me?

Well now, you never know
Was Mr Anderton scribing during the early to mid 1970s?

Chris Edwards wrote:

Mixedup wrote:Not sure about the Macs, but PCs tend to have a battery

All computers maintain their clock when powered off.

The ones at Bletchley Park don't

OKok

Sheesh! Some people get up early in the morning :ooo: Well I wasn't being ironic, but now I realise that (ironically) I've just made work for myself. This drawing was in a bunch rescued from the loft, that were all copied from Practical Wireless, Practical Electronics & Wireless World many moons...

Place I used to work for used sequential delay socket strips. Don't know where they got them from but I'm sure they're still around. They used bi-metal switches and cost about 3-4 times that of an ordinary socket strips. They were euro sockets and I think there were 8 in a strip. Also I've heard you...

Hey! I wouldn't mind a bitter, old man :) Incidentally {la la l'la la} I've found an old circuit of a compressor {la la} That uses 741 Op Amps, and diodes as the variable element (1N914 to be precise, 6 of them). {la la l'la la} and I'm going to try rebuilding it with modern-ish bits. betcha all jea...

Hi Guys.
I'm in North Kent, but freqently travel to Dorking, and occasionally to Farnborough, and even more occasionally to Thatcham.

P.S.
I'm also looking for another excuse to go up Milton Keynes way, where there just happen to be some old computers