This circuit was found in a 1965 Radio Shack documentation. The transistors are from that time. The circuit can be implemented with current transistors and lower voltage supply.
This sophisticated remote field strength meter circuit was found in a 73 magazine for radio...
This amplifier for electrometer can work with currents of 0.1 pA in a band of 1 Hz. The circuit is...
This circuit is from an operating manual from the 1990s. The circuit generates sinusoidal and cosine...