This circuit also detects IR, providing LED indication. The circuit is used to indicate humidity in bench tests. We found it in the Radio Electronics magazine of February 1990.
An FM receiver with good sensitivity and with acceptable sound quality in the strongest stations, can...
This filter has a factor Q = 10 (selectivity), and its frequency can be changed as shown in the...
With the capacitor used, this circuit provides delays of 40 to 60 seconds. Larger capacitors can...