This circuit was found in American documentation from the 90's. The transformer determines the output voltage. The transistor must be equipped with a heat sink.
The shield circuit shown is from the 1994 Linear Applications Handbook by National Semiconductor of 1994....
This configuration was found in a 1990s documentation. Modern operational amplifiers can be used...
The LED frequency flashes depends on the value of the capacitor tested according to the table. We...