Capacity Measured in 'Jars'

['LIVEWIRE?']

Many years ago in the early 1970s, I worked with an elderly Scottish Gentleman, who, when not regaling us with tales of how he joined the Navy in WW1 because of the 'Lusitania' sinking, would talk of the time when capacitance (of 'condensers') was measured in 'Jars' When was this changed and what, in this context was a 'jar'?

[Julesomega]

I gather a Jar was about 1nF
I once went to Leyden and had a jar of lager in one of the pubs

[Aub]

Something to do with Leyden jars, perhaps?

[Radio Wrangler]

Originally Posted by Julesomega

I once went to Leyden and had a jar of lager in one of the pubs

How much were you charged?

David

[G6Tanuki]

"Jars" was certainly still being used well into the 1930s: I've got a copy of the green "Admiralty Handbook" here where capacitance is in Jars and inductance in Mics.

[russell_w_b]

Originally Posted by 'LIVEWIRE?'

'When was this changed and what, in this context was a 'jar'?'

In the 1938 Admiralty Handbook a paragraph in the Prefatory Note states that the 'Jar' has been discontinued, having being considered obsolescent for 'a few years'. But they still used it in there!

A Jar equalled 1.11nf.

[kalee20]

I believe a jar is about 1nF - the amount of capacitance a typical Leyden jar gives.

Capacitance has also been measured in centimetres. 1cm = 1.1pF approx. See this thread.

[Dave757]

Hi

I can remember seeing a B19 (or possibly a B13) receiver dated 1942 or 3
with a brass plate on the front showing the circuit with the capacitances marked
in jars.

Bearing in mind of course that this would have been a prewar design.

Kind regards
Dave

[Orakle42]

As already pointed out the Admiralty Hand book March 1938, Vol 1, page 167-169 quotes jars.
It states that 1uf=900 jars.
It goes on to state "The jar is now obsolete as the service unit, having been replaced by the Farad..."
The reprint in 1944 also has a "Prefatory Note" regarding -bringing the unit of capacity into line with commercial practice-.

Orakle42

[dsergeant]

When I was playing with antennas for the amateur 136kHz band I invented a related term. The Bucket for inductance. A 100m reel of wire wound on a British Standard Bucket had an inductance of around 1mH - or One Bucket.

Never seemed to catch on. But quite appropriate for that band if a Jar is 1nF as
1 Jar and 1 Bucket resonates at 159kHz, nearly exactly what is needed...

[Electronpusher0]

We used to refer to capacitors as "buckets" and high capacity ones as "FGCs" or "rather large" capacitors (insert expletive as appropriate).

Peter

[Bobdger]

Hi Peter.

Don’t forget the elephant’s.....

Bob.

[Herald1360]

Originally Posted by Electronpusher0

We used to refer to capacitors as "buckets" and high capacity ones as "FGCs" or "rather large" capacitors (insert expletive as appropriate).

Peter

I remember "CFT" as the TLA for a large valued Capacitor...... "Capacitor Farads Tremendous" of course