The difference between this circuit and the previous one is that it uses PNP transistors. The circuit is from Radio Electronics magazine from July 1968. The frequency depends on R1 and C1.
The integrated circuit used in this power supply is no longer very common in power supplies today....
This circuit is basically the same as the previous configuration (CB15616E) with a power stage with...
This 2003 circuit was designed to be installed on a guitar, taking advantage of the magnetic...