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St. Paul MN 55112 |
An AC powered battery eliminator is very helpful when working with antique radios that were intended to be operated from dry cell based batteries. Typically the radios required an A battery, usually 5 to 6 volts but just 1.5 volts for the Radiola III and others. A tapped B battery with the high tap possibly as high as 90 volts, and lower taps at 67.5, 45 and most often at 22.5 volts. Many radios also required a C battery, typically 5 volts but again the Radiola III required 1.5 volts. This AC powered battery eliminator utilizes readily available plug in power supplies for the A and C voltages. A nixie tube power supply is used for the B voltages, providing about 120 volts and reduced to taps at 90, 67.5, 45 and 22.5 by a series of zener diodes. Since the Nixie supply uses a switching circuit at high frequency, the outputs are heavily filtered to keep the switching noise from the radio. This Nixie supply was purchased complete on Amazon and replaced an earlier kit that failed after several months use. Similar supplies are now available from many sources. Refer to the parts list below for details of the unit I used.    A list of parts follows. The total is quite expensive primarily due to the enclosure and terminals . The basic circuit is quite affordable and many of the parts can be found at much lower cost than the listed source.
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