This circuit was found in a 90s Wels' Think Tank. The frequency depends on C2 and R3. The handset or speaker must be at least 80-ohm. Observe the low supply voltage.
This circuit was found in a 1967 documentation. The switch diode is a component of the time and is...
As in the previous case (CB5045E), we have in the circuit of the figure the use of the polarized...
The configuration of this circuit was suggested by an old English publication that comes to...