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Battery eliminator info please

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Battery eliminator
Picked this up at the weekend for a couple of quid
No makers plate anyone seen one before or got any information please
Note if you can not read the o/p markings they are


Topic starter Posted : 08/08/2013 10:55 am
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LT is probably 2V or 4V, but probably only correct with a suitable load (between 4 and 12 Ohms depending on what it was for and voltage.)

It's for a battery radio with valves for Lead Acid battery power for filament. Such radios still released as new models up to 1950 though we think of them as 1930s!

I'd not use ANY vintage battery eliminator as the LT regulation is very poor they can wear out the valves too quickly even if working properly.
The 90 & 60 may be for screen voltages. Older sets using a Winner 120
(something like this ) might have a resistor in HT- for grid bias or a 9V GB battery or a GB tap on an HT battery. If it used a GB supply then a 9V tapped battery
would be used too. The GB battery can last for over a year.

Posted : 08/08/2013 11:10 am
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... The GB battery can last for over a year.

Interesting, Michael.

I hadn't really thought about this before but, assuming no resistive path to earth due to the variety of bias voltages available, shouldn't the GB battery life be, effectively, shelf life as no current should be drawn from it ...?

Posted : 08/08/2013 12:11 pm
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Shelf life would have been 18 months. But often there would be resistors. Also Power Amp stage DOES use grid current on audio peaks.

Actually in 1905 shelf life was about 6 months but by 1945 with better purity and manufacturing Zinc Carbon shelf life and capacity was about what it is today. About 2 years for useful capacity. Depends on temperature. Can be 6 months in extreme heat to 5 years in chiller. Alkaline is about x5 longer shelf life at same temperature and about 1/2 the internal resistance, hence the x5 capacity is only true at very high currents where NiCd (now NiMH) is better.
All GB used "B" cells. These are about 2500mAH at 50mA drain. So if we take 10uA the life might be 2700,000/10 hours = 30 years! So we can take about 0.25mA and still not wear out much faster than shelf life for traditional Grid Bias batteries The tapped HT packs were up to 98 identical "B" cells ( 7 x 14 layout for largest I think, a GB battery is 6 cells, giving 10.5 grid bias at the end and 0V at a corner)
Something like

To avoid expensive resistors early sets used a tap for EACH HT voltage needed. Mostly Screen Grids, but on earlier triode only sets the earlier stages used lower HT.
-9V tap and various HT taps.

As far as I can tell ALL Winner and Portable packs used exclusively "B" Cells. The AD3 used 60 x B cells and 8 x F cells. Layer cells (somewhat between Zinc Chloride and Alkaline in performance and seem to be closer to Zinc Chloride than Zinc Carbon) appear some time in 1940s, possibly even 1938 or 1939. Certainly some 1940s B7G US sets used them and after 1945 the Portable 61 and AD3 seem to be the only non-Layer cell pack in common use, though some new models up to 1950 used 2V lead Acid LT and "Winner" type B cell based packs. The Portable 61 seems to be the last "B" cell HT pack in use in new models, used in Vidor CN420A. The B103 is a somewhat lower capacity (6 rather than 8 F cells I think) Layer Cell replacement of AD3.
A quality Lithium coin CR2032 cell is about 220mAH but maybe 15 years shelf life. Mercury button cells invented to be "built in" Grid bias even on mains radios (mid 1930s I think by Mr Compton). The packaging invented is what modern button and coin cells are based on. They also used as Grid Bias in WWII in munitions as the Mercury button cell has an extremely long shelf life (in cool conditions maybe 15 years)

Posted : 08/08/2013 12:51 pm
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It wasn't Crompton. It was Samuel Ruben and he got involved with Mallory (Now Duracell).

Union Carbide (U.S. Eveready, now Energiser) actually invented the the Alkaline battery, but were not interested in marketing it.

Oddly Mallory Ireland made the UK Ever Ready batteries in Ireland but was eventually bought by Duracell. UK Ever ready had originally (before 1905!) belonged to US Eveready / NCC /UC and in mid 1990s bought by Energiser, the holding company of US Eveready after Union Carbide and National Carbon Company.

Posted : 08/08/2013 4:21 pm