This timer was found in Japanese documentation from the 1960s. The transistor can be replaced by an equivalent and the relay must be of the sensitive type with voltage according to the power supply.
This amplifier was found in a Japanese publication in 1972. Transistors are uncommon today, and...
The current of this source is 200 mA at the most, and the output depends on the zener that may...
Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The...