We found this circuit in the July 1969 Radio Electronics magazine. The circuit uses a coupler made with a lamp and an LDR. The power of the lamp determines the types of diodes.
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...