The sensor of this circuit found in Popular Electronics can be formed by a piece of fabric between two bare wire screens. When wet, the fabric will pass the current between the screens, triggering the alarm.
We find this simple circuit that operates at a frequency of 5 to 10 MHz in an old English...
This tester was found in a 90’s Popular Electronics. The integrated circuit is CMOS 4011. The...
We found this circuit in a 1980 publication. It can be applied to Triacs of the TIC series and the...