This circuit was obtained from a 90s Radio Electronics. The integrated circuit used HAA11508 is not a common component today.
This one is from an 80's EDN. Transistors can be general purpose types. The frequency is...
We found this circuit in the April 1975 Radio Electronics magazine. The circuit has a latch and...
The circuit presented, from a 2005 documentation, can provide from 1 W to 2.5 W of output when...