Geiger counter (1)

This circuit is built around a 4049 hex inverter (U1), a pair of 555 oscillator/timers (U2 and U3), two transistors, a Geiger-Millern tube and a few additional support components. The first 555 (U2) is set to run without steady state. The output of U2 at pin 3 (a series of negative pulses) is going to the parallel inverters (U1-a, U1-b, and U1-c). The forward output pulse of the inverter is to the Q1 gate so that it switches or turns off.