This circuit was found in an 80's Electronic Design. It amplifies TTL fast signals for a coaxial cable. TTL is from the S (Schottky) line and transistors are types of the time.
This circuit is valid for other comparators of the same series. In this case, a lamp is excited, but...
This circuit is from a Radio Electronics from October 1963. The transistor is a power transistor of the...
This test circuit for transformers connected to the power grid makes use of a variac. We found it in...