Found in a 90s Popular Electronics, this mixer can be expanded to more channels. Transistors can be modern general-purpose equivalents.
Found in a 1990s American technical brochure, this circuit is intended for alarms that use as...
We found this circuit in a Japanese 1968’s documentation. The circuit makes use of transistors from...
This useful circuit is used to test the insulation of cables, appliances, leaks in high voltage...