A point-contact transistor scaling circuit with 0.4 microsec resolution

There is a wide choice of scaling devices which will operate at maximum counting rates up to several hundred kilocycles per second, but for counting rates in the region of megacycles per second, the choice is limited almost entirely to special thermionic scaling devices or circuits using thermionic valves. Such circuits tend to be rather complex and have a relatively high power consumption. The paper describes some scaling circuits using transistors which will resolve 0.4 microsec and hence count at a maximum rate of 2.5 Mc/s. The transistors are the normal point-contact type, and the circuits are simple, they have wide tolerances and are economical in power consumption. Features which contribute to the short resolving time are the prevention of bottoming of collector potential and the absence of capacitors. A typical scale-of-10 circuit uses seven transistors, seven pulse transformers and 14 crystal diodes.