The views above show an old battery charger/eliminator (covered in half an inch of dust when I picked it up) which I bought at an Antique Fleamarket in Antwerp (see also the meters, I got from another stall at the same place ...elsewhere on this website).
Similar devices to this one could be used to replace the HT battery in an old radio in the late 20s and early to mid-30s. This one has a nice metal label which proclaims that it's a "REDRESSEUR DE COURRANT B.B DEPOSE" for 110 volt 50 Hz mains and provides 40-80-120 volts @ 0.1Amp and and 2 to 12 volts @ 1.3Amp. It originally had two Philips tubes, types "1010" and "1011" fitted in the pair of B4 sockets in the ebonite top. There's a nice three way knife switch on the top and four screw terminals for connecting up to the radio. When the switch is one position an accumulator from 2 to 12 volts may be charged. When in the other the unit can replace the radio's HT battery (or maybe charge an HT battery, which were not too common). In the latter position it's a battery eliminator and in the first it will charge the filament supply 2 volt accumulator. One cannot do both at the same time as it explains on the label. I suppose it can also charge lead acid HT batteries (these were not very common)...maybe that's it's prime purpose, just charging either battery as it may be a source of hum without additional components for smoothing?
I wonder if the unit just pre-dated the disk or electrolytic rectifiers which were available in 1928?
I asked the chap if he knew what it was and he just shrugged but he said wanted 300BF for it. I offered 200 (£3.50) which he accepted but I felt very guilty as the smallest I had was a 2000 Franc note. As I took the very heavy dusty old box, with its mains lead cut off short and the handful of change in notes. which he very deliberately counted out, I jokingly asked if it was guaranteed. He replied after a few seconds of thought (with a "poker face"), "two years". I found most Flemish Belgians invariably had that sort of sense of humour. I was at a small bar in Tournai three months earlier with a couple of friends and my 14 year old son. We ordered three Jupilers and asked the barman what he'd recommend for Jeremy. He thought for a few seconds and said a lot of flemish words then ushered us back out to a pavement table. Soon he appeared with three beers and then disappeared back into the bar to reappear. a moment later, with the same beer but in a glass the size of a thimble. We proceeded to quench our thirsts (it was very hot) and Jeremy who looked a bit taken aback sipped daintily at his. After a few moments there was the sound of merriment inside shortly followed by the barman who emerged with a tray, on which was a fourth (normal sized) Jupiler.
This is a small unit
for charging a wireless accumulator from 200 to 250 volt 50 cycle
mains. It comprises a small transformer connected to a simple
disk type metal rectifier and can charge an accumulator from 2volt
to 6 volt at a half to a third of an amp.
Heayberd also made battery eliminators.
See even more battery eliminators