This compact, battery-free, high-range radiation monitor was developed for long-term maintenance-free operation in 1963 by a Chalk River technician, Walt Woytowich. The monitor, which measures 5 cm by 7.5 cm by 12.5 cm (2” by 3” by 5”), is based on a compact (5 mm diameter by 25 mm long) Geiger tube and weighs only 650 g. The Geiger tube operates at a voltage of 550 volts which is supplied by a capacitor that is charged via a hand-cranked generator. One charging usually lasts 15-18 hours.
The monitor has a clip to allow it to be worn on a belt or clothing and has an output that can feed an earphone. The monitor was designed for Civil Defence applications at the time of the Cold War and has a range of up to 5 Roentgens/hour. The meter also acts as a voltage indicator during charging. This commercial model, named the Algonquin, came on the market in 1963.
