VT100 preventative maintenance?

tony duell ard at p850ug1.demon.co.uk
Sat Aug 22 23:53:51 CDT 2015

> > Also note that we use the term 'valve' for  diodes, triodes, etc, but
> > 'tube' for CRTs, nixie tubes, dekatrons, voltage stabilisers,
> > probably trochotrons, etc.  There seems to be no obvious reason for
> > what is a 'valve' and what is a 'tube'.

> Based on your examples, it sounds to me as though a "valve" is a vacuum
> device whose major purpose is to control current flowing elsewhere in
> its circuit, whereas a "tube" is anything else - a CRT's major purpose

Possibly. But diodes are normally called 'valves' over here, in fact I think
the term 'valve' came from the fact that a diode acts like the one-way
valve, say on a tyre. And not necessarily vacuum devices. Thyratrons
(gas filled triodes) are 'valves'. So is the infernal 0Z4 :-). But not voltage

I am trying to think what we call tuning indicators -- magic eyes and the
like. Probably valves (even though they don't control anything and are
display devices).

> is display, with the current flow incidental to that; Nixies,
> dekatrons, and voltage stabilizers are cold-cathode gas-filled devices.
> A trochotron...that's an interesting case.  On the above (speculative)
> basis I could argue for either "valve" or "tube".

> Incidentally, thank you for mentioning trochotrons.  I was not
> previously aware of them, and now that I've read up on them a tiny bit
> I'm glad I have.

I wonder if they were ever used in early computers. Dekatrons were, both
in the Harwell Dekatron machine, and in some Anita calculators. But I've
only come across trochotrons in digital voltmeters and the like.


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