This circuit with its light source was found in American documentation two years 70. Or transformer of the type found in small transistor radios of the time. The transistors are general-purpose.
This circuit is from a 1967 US publication. The configuration can serve as a basis for designs...
This ultrasonic insect repellent was found in American documentation from the 1980s. The...
Oscillators up to some megaherts can be made with comparators like the LM139, 239 or 339. Theses...