This circuit was found in a 1966 EEE. What it does is it converts the logic levels of 0 V and +4 V into -6 V and +6 V. Some older type transistors can be replaced by modern equivalents.
The Texas Instruments INA826S Instrumentation Amplifier Evaluation Module is available from Mouser...
This ultra-low power metronome was found in a 1991 documentation. The output transistor is general...
We have in the figure as a monostable a proximity switch where our body capacitance (estimated at 200...