Transistorized 10-Mc Decade Scaler

A space-saving, standard, transistorized 10-Mc decade scaler of modular construction has been developed to replace assorted earlier types of scalers. For high reliability, silicon planar transistors are used throughout, except for readout drivers. Two complete scalers are contained in a standard, rack mounting frame of 3-1/2-inch front panel height. A power supply module on the rear panel powers both scalers. Each scaler comprises nine modules. One module contains a tunnel diode pulse height discriminator with a threshold variable from 0.1 to 2 volts, and temperature coefficient less than 1 mv/°C. Another module contains a diode gate for gating the discriminator output, and the reset circuitry for the scaler modules. A third module contains a 10-Mc decade counting unit (DCU). Six identical 1-Mc DCU´s complete the scaler. Ten-digit front panel readout of the DCU´s is provided by neon lights in column configuration. External DCU readout is provided by four-line binary-coded decimal signals in 1-2-4-8 code.