This circuit was described in an article in the February 1993 Radio Electronics magazine. The frequency depends on the crystal and L1 is optional.
This circuit activates a machine to dry hands (fan and heater) when the sensor detects the...
The operational used is like the 741. The circuit is from the datasheet and the formula that...
The second order filter shown in the figure is suggested by Texas Instruments, based on the TL081...