David Denness
What happened to B size batteries?
We have AA, AAA, AAAA, C, D.
Geoff Fletcher
There is or was a B size battery – also known as a U10. It was used in two battery mini torches.
John Howell
These letters stem from the requirements of valve (tube) radios.
The ‘A’ battery supplied filament current at 1.5 Volts, the ‘B’ battery HT at 67.5 to 120 Volts, and the 9 Volt ‘C’ battery provided grid bias voltages at typically 3, 4.5, 6, & 7.5 Volts.
But it’s got out of hand now with 1/2 & 2/3 AA, Lithium DD (£48 from RS) and not a ‘B’ battery in sight! (unless you count the Eveready ‘Bijou’ 3 Volt).
Dave Mundy
My TMK500 analogue multi-meter has a B154 battery (15 volts, square section) for the higher resistance ranges. I don’t use the meter any more since Lidl sold some nice digital ones: it was used in the past on ‘real’ TVs etc. (i.e. valve stuff!).
John Nottage
I’ve got one of those TMK500 analogue multi-meters! I think I paid £9.19s.6d for mine so it was pre-decimal. I think I still have the receipt somewhere! Still use it too – though there’s a space where the 15V battery is supposed to go. I seem to remember having to chuck the battery years ago when it died and being unable to find a replacement. I’ve an Altai Digi meter too, also years old.
Dave Mundy
John probably bought at the same shop as me – Gilberts in the Grampians, Shepherds Bush! I bought mine after someone else on my crew got one, they were very popular (£8.10s.!)
Keith Wicks
It’s much safer to use a low-voltage digital meter for the higher resistance ranges. A 15-volt resistance meter can damage modern solid-state circuits. I learnt this the sad way.
Not quite so severe as my ancient (1950s?) oscilloscope, which puts a pulse of several hundred volts on the circuit being investigated if you change ranges while the probes are connected. I have a fried detector diode to illustrate this.
Mike Jordan
My hand wound and my mains operated Meggers (seem to have OB section 5 on them – whatever that means) both are 500v units. Made by Mr Evershed and Vignoles who had the factory in Acton Lane.
Mr Vignoles was also famous for inventing "flat bottomed rails" which, as opposed to figure 8 ones, didn’t rock and roll when trains went around corners and fall out of the sleepers. There are some of those used as handrails in Brentford Station – so there!
Their sportsground was across the road from us and, since they became AVO and moved to Dover, has been a club, a 7th Day Adventist school and soon to be a free school.
Dave Plowman
We probably all remember the AVO 8 as being the meter of choice for our studio engineers, etc at one time.
They were still on sale new last time I looked – but at about £700.
I picked up a very good condition used one – complete with real leather case – at an autojumble not that long ago, for a very modest sum.
