This circuit was found in the October 1987 Radio Electronics magazine. The circuit is a PWM control with a 555. It appears that the 555 is missing a connection that would be pin 4.
In the figure below we have the main configurations of power supplies with the most used...
This circuit is a high voltage source for a gas LASER. We found it in a documentation from the...
This integrated amplifier was used in televisions from the 70s, with good sensitivity...