capacitor discharge time

I can remember often getting belts from caps when I used to come across fly-tipped TV sets at the local gravel pits, and dismantled them.

I used to take the PCBs home, and desolder the useful components. I think almost 50 yaers on, I've still got some of those salvaged components in my junk box !

I've still got various things from my teenage years All sorts of stuff from my two uncles who worked for IBM

-- Things I found on the tip

-- Things we nicked

-- Things I bought from army surplus stores

-- Things from school

-- Things my dad's customers gave me

Bill

You must remember picking up a CRT with ~500pf capacitance and charged up to 25kV.....I do!

The 'prentices at a local TV repair shop were known to put a charged capacitor in the foreman's pocket. Incidentally he was a Pole (left over from the war I believe) and he once came out with the immortal bellow: "You tink I I know f*ck notting! I tell you I know f*ck all!"

Does this ring any bells with Donny lads?

Bill

Yes these are probably low voltage ones perhaps? I'd not expect the device to have an ac motor. Brian

It used to be the tubes that held the charge. I was always told to wrap the neck in duct tape and hit it with a hammer to break the vacuum if disposing of them. Brian

Brian Gaff expressed precisely :

My two seater recliner uses ac motors, though I think I heard some disability type recliners use a dc motor and battery backed operation.

Yes the engineers at Rediffusion used to leave such capacitors on the girls work bench over lunch. Most only got caught out once. These ladies were excellent desollderers and solderers. Brian

If it used AC then why the big psu? Brian

I used to just lob a brick/rock/or similar at the ones in tellies I found fly-tipped, though quite honestly in 95% of the cases someone else had already beaten me to it

Brian Gaff pretended :

I don't know, but without checking - I think mine runs directly from

At school we connected a charged CRT to the brass doorknob of our study room - of course hilarity ensued. The HT transformer produced pretty corona discharge too.

The one I had, a La-Z-Boy that I got dirt cheap on eBay, there were three PP3 batteries whose job was to bring the chair upright if the mains power failed, so you weren't stuck in it. I never fitted good batteries and anyway I doubt there was a power cut in the time that I had it, so I don't know how well that worked, if at all.

While watching the billion pound railway I was suprised the elizabeth line used 25KV. I wouldn't want to touch that though :-)

What else would it use? It's a continuation of the normal railways but in really big tunnels.

All London Underground Lines (including the W & C) operate at 630 volts DC using third (positive) and fourth (negative) current rails. The current rails are positioned so that the contact surface is higher than the running rails.3

All wondering if they use voltage or ciurrent or some PWM in the cab to change speed.

The HS1 trains use(d) both 25KV for France and 3rd rail DC for the Kent stretch. Originally they created such a lot of EMF, it interfered with the trackside signalling boxes until some sort of remedial action was undertaken.

Ditto Thameslink trains. The changeover occurs at Farringdon stn and provides a nice fat spark as the pantograph rises.