Found in 1980s Electronics Design, this circuit covers 4 decades of frequencies with a unique control. A multi-turn trimpot is used for fine adjustment. The frequency range depends on C1.
The A3906 integrated circuit from Allegro Microsystems (www.allegromicro.com) consists of a PWM...
This analog TV circuit can be used on a small transmitter. The circuit is from an 80's American...
This circuit is from an Electronics Now from the 90s. It applies to almost any operational...