This amplifier with the EL84 tube is a European commercial type from Corpim mounted on a printed circuit board. The diagram appeared in a September 1958 Radio Electronics magazine.
This signal injector and tracer (follower) was found in an old American documentation. The...
The basis of this circuit is the HA2400 released at the time. The circuit is from a Radio...
Found in a 1980s English magazine, this trigger circuit can have different types of inputs...