Using the 2N2646 this circuit was found in a Radio Electronics magazine from July 1968. The transistors are from the time and the lamp can be replaced by a high-power LED in a current version.
This circuit from an 80's publication also features low input capacitance. FET can be a modern...
This old version of analogue switch was found in a 1969 documentation. Components of the time are...
In this circuit the gain decreases as the input signal intensity increases. The circuit is from a...