APPENDIX 



now returned to a point at 100 V positive the timing accuracy is good. 

 The circuit then flops, rapidly returning to the quiescent state because Ri 

 is shunted by the diode F^^j. In this manner a 240 V negative-going square 

 wave is generated at the anode of V2 and is fed back via C^ to the Geiger 

 tube. 



The load of V^ is tapped so that only a fraction of the 240 V is passed on 

 to the scaling equipment. This prevents loading of the circuit by e.g. the 

 output cable capacitance. The reduced square wave appearing at the 

 junction of the 3-9k and 56k resistors is differentiated and either the negative- 

 or positive-going component is suppressed by the diode Fj^, leaving a 

 monophasic output of the required polarity to operate the scaler. 



ED. 



445 



