Found in an old English publication, this circuit applies to the 240 V network, but can be changed to lower voltages. Transistors are mostly general-purpose, admitting modern equivalents.
Found in Radio Electronics from the 90s, this circuit uses a thermistor as a sensor that can have...
The scale of this scale uses LEDs, and its accuracy depends on the number of LEDs. We found this...
Found in American documentation from the 90s, this circuit generates sound bursts according to the...