Microammeter (T465E)

Found in a 1948 MIT documentation, this circuit uses a 0 to 100 uA microammeter as an indicator. The power supply is 150 V.

Precision Current Monitor (CB3995E)
This circuit is from the 1990 Motorola Linear Databook. The integrated circuit used is the LF355,...
20dB amplifier (CB20656E)
This high impedance amplifier is from 1985 documentation by General Electronic. The amplifier with...
Tone control and preamplifier (CB8506E)
Based on the TCA6600 or TCA5500 this circuit was found in a 90’s European documentation. The...