We found this circuit in a 1969 General Electric documentation. The circuit uses transistors of the time and the diodes in the dotted board must be mounted on the output transistor heatsinks.
This 80's circuit has an input resistance of the order of 880 M and gain 10, using operational...
We found this circuit in the Audio Handbook of the National Semiconductor of 1977. The circuit is used...
Published in 1988 in Hands-On Electronics, this circuit converts the 12 V of a battery into 120 V...