This circuit is from Mullard 1969 documentation. The circuit operates at a relatively high supply voltage and has a 10 Vpp output. The transistors are of the time, but admit equivalents.
This oscillator, from an old Argentine publication from 1973, uses the inductance of the 500 ohms...
This circuit consists of an adapter that allows the reading of low currents at various scales. A...
This circuit was suggested by Philips in an old publication. The coils, made with wire 14 to 16...