This experimental circuit with Nixie tube was found in the Radio Electronics magazine of March 1969. The circuit serves for demonstrations and also for testing these digital indicator tubes.
We find this circuit in an American 80's documentation. It makes use of IC sensor which is mounted...
This is a configuration obtained from an old manual, using an operational amplifier of the time....
In the figure we have the way to add hysteresis to an operational amplifier. The relationship...