This circuit was obtained in a 1964 Electronic Design. The transistors are from the era and the instrument is 100 uA full-scale.
Originally this 2000 circuit was designed to be a switch to the parallel port, but with 5 V or...
Activating a relay from pulses (from a monostable, for example) can be useful in many types of...
This circuit converts the voltage from small fixed sources of 6 V or 12 V into 3 V for powering...