Found in a 73 magazine for radio amateurs of the 90s, this circuit provides a 2 kV voltage with 7.5 mA of current for HeNe laser.
This circuit was obtained from a 1977 magazine, but can still be mounted using BC548 for TR1 and...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
The figure shows how to add a Darlington stage to an operational amplifier in order to obtain a...