This low power circuit was obtained from an American 80's documentation. The circuit indicates the voltage of a battery being trimmed by the trigger point. The transistors can be the BC549.
The integrated circuit of this amplifier is not very common today. The output transistors can be...
This circuit is from a1970 documentation. R1 may have 10k and P1 47k. The transistors can be BC558...
This circuit is from a 1977 documentation. It is powered by the power supply of the circuit under...