This circuit was found in 1980's Radio Electronics. The circuit produces a 1500 Hz modulate 35 kHz. The components used are still common.
This circuit makes use of a special LM195 power transistor not very easy to obtain. The circuit is from...
Found in documentation from the 90s, this circuit can employ other comparators in the series such as...
Suggested by Philips in a 1970 publication, this circuit uses components from that time. No...