Wimshurst machines.

[Techman]

Originally Posted by Hartley118

Brilliant - even without any recapping!

Martin

Great comment!

I'm thinking you know me too well! No blanket cap changing from me - I think those yellow 630 volt things wouldn't do too well in place of those jars

Regarding the last two posts and Philip Harris, I certainly remember the large Leyden jars having to be removed from service and destroyed for safety reasons and also issues regarding the Wimshurst as it was capable of storage with its albeit smaller jars.

Below in the pictures is, in the first one, the original Philip Harris 'Bible' from 1960. No prices in this edition (second picture) but it does say that spare parts for the machine were available. Updated price lists were issued until a new updated full catalogue was issued. The third picture shows the entry in the 1964 catalogue, a flexible covered ring bound item with prices shown. The last picture shows the updated price list from 1966 with the Wimshurst machine price shown right at the bottom, so we can see the price gradually starting to rise, but at £132 all in today, in real terms it's actually come down in price. Philip Harris were always high quality and you paid the price for it, also the fact that it was manufacturing for supply to a 'relatively' limited market. The modern machine won't have the high quality of manufacture of the original, but will be adequate for the intended use - I guess they've had to drop the probably over engineered quality side and also their relative prices to stay competitive in todays market.

Silly me - it says that the discs are made of Perspex...should have checked my own books for the answer to that one!

[Techman]

It says that a 10 cm (that's almost 4 inches) spark is possible. I've just tried that and it can't make it. The best it can do is 7 cm (just under 3 inches) and on a very slow shutter speed I've managed to capture it on the first attempt with the camera - picture below. If I get those missing segments replaced and some good gripping belts, then the full 4 inches could possibly be achieved!

[Dave Moll]

Assuming it's not motorised, I have a lovely mental image of you cranking the machine with one hand while operating the camera with the other.

The spark has come out quite nicely - presumably as its brief nature suits the slow shutter speed.

[Techman]

Originally Posted by Dave Moll

I have a lovely mental image of you cranking the machine with one hand while operating the camera with the other.

That's exactly right, I think you must have been outside looking in through the window, just to the left of that curtain!

I tried to keep the camera as still as I could, but you can see the movement in the surrounding 'scenery' - it's as you say, the spark itself is so brief that it's captured nearly perfectly. You can actually see a difference in the spark as it's captured left to right (or right to left) if you look closely. Making a 'mini' thunderstorm in your house - it goes with a good 'crack'!

It's interesting to see how the price increased over the years. Below is first shown the rather attractively covered Philip Harris 1990 catalogue where the machine is now priced at £212.10. There's no sign of Leyden jars being offered as separate items by this time, the same as in the link provided previously by Simondm (post#40), if you look further you'll note that Leyden jars are conspicuous by their absence - link:- https://www.philipharris.co.uk/produ...ic-electricity

Griffin also did a version of the Wimshurst machine, as shown in their 1980/82 catalogue, shown in the last two pictures below, at £39.55. Leyden jars were still available from them at that time, but made in cheap and nasty plastic by then, although arguably less likely to get smashed!

The biggest danger with those large Leyden jars was that they could be charged up to 50KV and then dismantled with an insulated 'tool', and the parts left lying around, only to be picked up and reassembled by an unsuspecting person and 'zap', the charge being stored in the dielectric. The component parts are harmless when handled individually...it's not until they come together that there's a nasty 'shock' in store for the unsuspecting!