Found in a Westinghouse Silicon Power Handbook from the 60s, this circuit makes use of period components. Special high voltage transistors are used. Zeners are 15 V.
In fact, the 556 consists of a double 555, which can be replaced by these integrated ones. The...
Found in a 1964 Electronic Design, this circuit makes use of period components. The components are from...
This polarity test or indicator indicates the polarity of a power line by LEDs. The circuit is...