This oscillator uses a small IF transformer taken from an old transistor radio. FET admits equivalents. The circuit can be used to calibrate radios.
We found this circuit in a publication from the 1970s. The circuit has a logarithmic gain...
This simple low-power circuit uses, in the original version of 1965, germanium transistors. The...
This circuit triggers a relay when a light beam that hits the phototransistor is cut off. The...