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 was found in the PC documentation from 1996. The maximum current of the motor is...
This circuit is from the time when the 741 was first introduced. It was published in the February 1971...
Only two transistors are used in this preamp for low-sensitive transducers, such as guitar and...