This circuit for the 60 kHz range was found in 73 magazine and published in 1995. The circuit uses a ferrite rod. Note the direction of the coil windings.
Available at Mouser Electronics this component of Diodes Incorporated consists of a voltage...
Found in Radio Electronics this circuit uses a fotodiac to drive a triac. The circuit can use...
The first circuit was suggested by Analog Devices (www.analog.com) in its Application Note AN-411...