Two standard, 19-inch (48 cm) wide, 1970s vintage, electronics racks used at Chalk River by Warwick Knowles for his gamma ray measurements. These racks display the typical Nixie counting tubes used in that era to display counts. The lower rack consists mainly of three Nixie tubes displaying “Units, Tens and Hundreds” along with multiple switches to adjust and set counting periods.
The rack of electronics behind the panel holds three E.P. Clare rotary switches that drove the counting tubes. The upper rack housed the circuit boards that prepared the signals for driving printers or paper-tape punch units. The boards were the forerunners of Nuclear Instrumentation Module (NIM) bins that became industry standard around 1970. These boards were designed and manufactured at Chalk River.
