Philips 3003 Battery Eliminator

Many early radios were battery powered, as many homes were not connected to electricity. The batteries were expensive and replaced regularly. When homes became connected to electricity, they could still use their radio, by connecting a "B" battery eliminator, such as this one. This usually supplied the "C" bias as well. The "A" battery eliminator was not successful as  large electrolytic capacitors had not been developed. It was quite common to have a trickle charger connected to a large accumulator, for the "A" supply.

The Philips eliminator was made in Holland and was very popular in Australia, costing 9 pounds and 15 shillings in the 1920s. Quite a few still survive and are usually in good condition.

The unit is connected by plugging banana plugs into the appropriate sockets, to select the B and C voltages. The top row is labelled "B" for the B battery supply. The extreme left socket is the common and labelled "-", the extreme right is the 200v DC and labelled "+6", and the others are taps in between, labelled "+1, +2, +3 ,+4,+5". The voltage varies with load and goes down to 100 vDC with a 50 mA load, but the radios didn't seem to mind. The bias is connected from the second row and is labelled "C" for the C battery supply. The extreme left socket is labelled "+" which is the common and is internally connected to B-. The extreme right socket is the maximum negative voltage labelled "-III", varying depending on load. The sockets in between are labelled "-I,-II". They get their voltage from the 3 rows below, which are arranged in a matrix. The left column is labelled I, II, and III which corresponds to the three C terminals, and the top row is labelled 0,2,4,6,8,10,15,20,25,30,35,40 which is various negative voltages up to -40 volts. You plug a special plug into the front and this selects a tap and connects it to the bias socket. In this way, you can select 3 bias voltages the same, or any voltage in small steps. These are a special banana plug with a spring loaded tip.

This 3003 model (serial number 13432) has a good paint coat on its steel box, and the insides were clean. I had to break the seals to open it, which indicates that it had never been serviced. The power cord was replaced, and the unit powered up slowly. The transformer, rectifier valve (type 506) and choke were good, but the capacitors required a little time, before they came good. Two of the resistors for the voltage tappings were open circuit. I found the break and joined the wire, which was fine resistance wire wound on a glass rod. The "C" supply has its own rectifier diode valve type 3006 (labelled "Sold for amateur use only), capacitors and resistors. These were all good.

The 3009 model (serial number 505352) generates its negative bias from resistors in the HT negative lead, in the traditional back bias method. It has only one rectifier valve, type 506. The capacitors in this one required a great deal more time to come good. It also had several open circuit resistors, but I could not successfully repair these, so I soldered a replacement across them. I had 6 to fix. I replaced the mains cord and plug. The case was very good but the paint was chipped and dull. I resprayed it with black Satin paint which preserved the crinkle finish, and gave it a new sheen. It has a top row of sockets for the B supply, labelled "-,+1,+2,+3,+4" and has no common for the C supply as it is internally connected. The second C supply row is thus labelled "-I,-II,-III". The matrix below has only 2 rows to select the C bias voltages for the I and II sockets. The socket III has the maximum C voltage on it. The top row of the matrix is labelled "0,2,4,6,8,10,12,15,20". It is used in the same way as the 3003 model, which selects the voltage for the C sockets by plugging in a special spring tipped banana plug.

I recently bought a model 372, which has the valve visible on the top. I have not yet done any work on this one.


Philips Battery Eliminators, Ray Kelly, HRSA Newsletter, January 1991, page 15-18.
Vintage Radio, Battery Eliminators, Peter Lankshear, Electronics Australia, February 1990, Page 102-103.
Circuit 3003 , VVC Electroacoustics, Sydney, 1989

Ray Robinson