Using a 4046 PLL we found this circuit in the December 1989 issue of Radio Electronics magazine. The circuit operates at 220kHz, but this frequency can be changed by changing C3.
The basis of this circuit is the HA2400 released at the time. The circuit is from a Radio...
This circuit with TTL output was found in a 1968 EEE. The transistor can be of general use. The...
This circuit can be found in a 1970 Motorola documentation. The circuit can be implemented with general...