How to get negative pulse from open collector output? Circuit to generate needed negative pulse to reset 74142 nixie driver from open collector output. Logic source on left represents 0-9 open collector output from 74142. Three inverter gates give 30 ns delay. Output of last inverter passes through needed low pass filter to block short transient pulses which commonly appear from output during counting. Top right voltmeter represents CLR input to 74142 which is kept at 5V to count and resets to 0 with ground. Turn logic source on/off to generate pulses (represents any active 0-9 output from 74142.
