This detector uses an unusual sensor today. The circuit is from an 80s documentation. Its sensitivity is 10 ppm. The transformer has two secondary voltages.
Using the 4001 integrated circuit, this latching relay can employ any general-purpose transistor. The...
Suggested by a 90s Electronic Design, this circuit drains only 0.25 mA from its source. Listening...
The frequency of this oscillator depends on the amount of light incident on the LDR. The circuit,...