HT and LT Battery Eliminator to convert vintage battery Radio sets to 230V mains.
The eliminator, is designed to replace the now long unobtainable HT battery AND
the LT batteries that were used in many valve portable sets of the 1950's and early 60s.
It will fit into the space for, and indeed the casing of, an EverReady B126 90V battery.
The Eliminator provides an HT supply (see table below) and a regulated LT supply for the filaments.
You can order the LT voltage from 1 to 8V as required, normally I would build to 1.4V.
as this is the design heatrer voltage of most single cell battery valves. The HT voltage is unregulated (but smoothed)
the actual voltage is not very critical as battery sets were designed to cope with a reducing HT voltage over
the life of the battery.
I can fit a buck converter for the same price, instead of the LM317T linear regulator
this will supply up to an Amp of LT in the range 1.4v to 3v (adjustable), the downside of this is,
it is a switching part and can introduce some RF noise, but in practice I have never found this to
be a problem on MW/LW sets as the fundamental switching frequency is around 65Khz.
|HT Volts||LT Volts||Max LT Current||LT ONLY version|
|140v||1v..12v||160 mA||320 mA|
|120v||1v..10v||160 mA||320 mA|
|90v ||1v..8v ||200 mA||400 mA|
|68v ||1v..6v ||315 mA||630 mA|
|45v ||1v..5v ||400 mA||800 mA|
Email me your HT/LT voltage combination requirements.
The LT side can supply the maximum current specified above (unless buck converter fitted) which is suitable for most sets
that use a dry battery for the valve heaters, sets with a rechargeable lead/acid battery
usually take a higher heater current, Pye/Vidor/EverReady etc. sets with a valve line-up of
typically DK96,DF96,DAF96,DL96 will work fine with 90V HT 1.4V LT, I can check your set for
suitability before ordering I have most schematics in my collection and am happy to send to you.
The 230V mains input, HT and LT connection are all made using screw terminals,
so no soldering is required. The Eliminator provides full isolation from the mains input,
and will allow the set to pass PAT tests. The mains input Live/Neutral can be connected
either way round, it does not matter. Be aware that mains voltage is present at a few points
on the PCB underside, so care should be taken when mounting, using stand off bushes on the
mounting screws or making other provision for the board's underside to be insulated from
the set's case or chassis (not usually a problem with a wooden case!).
There is no mains voltage accessible from the component side apart from the connector screw terminals.
The PCB dimensions are 92mm x 64mm x 37mm high, by comparison, a B126 battery is 2.5 x 4 x 2"
(102 x 64 x 51 mm) and a B141 is 198 x 119 x 37mm. The LT and HT supplies are electrically isolated from each other.
I usually wire these up with an inline switch (table lamp switch) in the mains cable (not supplied)
so no alteration is required to the set for a mains on/off switch, suitable made up cables can be
rescued from table lamps as found in charity shops etc. for around £2.
The batteries are shown for illustrative purposes only, these are the types or similar that this unit replaces.
I can also build
HT only or
LT only versions with £10 off the price i.e. £20.
Postage is £3 to the UK, See table above for international rates, although be aware that
only 230VAC models are currently available!