This circuit is from an old American documentation from the 70s. Transistor 2N3904 can be replaced by BC548. The relay must have 100 mA of maximum current.
This circuit uses the first commercial Darlington transistor, the 2N626. We found it in Radio...
This multimeter with FET and 709 operational amplifier was found in the July 1972 Radio...
January 2017 - Texas Instruments' new TPS54200 integrated circuit for excitation of LEDs with a...