This is the receiver for the previous transmitter. The microphone is of the high impedance ultrasonic type. The circuit activates a relay. The operational amplifier supports equivalent.
This circuit, obtained from old documentation, doubles the frequency of the pulses applied to the...
The passage of an object in front of the LDR, producing a shadow or even turning off the ambient...
The CMOS TLC555 [equivalent to the bipolar 555] can be used as a monostable in the configuration...