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.
Found in an old Radio Electronics, this circuit uses common components today. The resistors of the IC...
Found in a 1965 General Electric circuit manual, this circuit uses SCRs from that time. Modern...
The modified Hartley oscillator, seen in figure 2, can generate signals ranging from 3 MHz to 10...