Surprisingly much, can turn on – shut down electric devices with a whistle sound.
This is simple sound control circuits, that different from a little common circuit is Requires high frequency noise Such as whistle sound etc.
The heart of working in this circuit is IC1 (UM3763) that is designed for this particular work. Figure below shows a circuit in actual use.
How circuit works.
The IC1 needs to used a voltage only 3 volts. However, for convenience to using with a voltage relays up to 12V. I so use the R3 and the ZD1 are reduced voltage for IC1 to only 3 V, as needed.
The R6 is used to adjust the frequency of the oscillator circuit internal IC1. In this case sets frequency at 18Khz. Input frequency using be in the range 1/10 – 1/15 of the frequencies in above. In the frequency used in the 1.8-1.2khz.
The Output of the circuit will change state each time to get input signal comes. The output signal as said at 8 pins’ And supplied to the base of Q1 to drive the output of the transistor Q2, which acts as a relay to drive the pace of the sound input signal.
IC1__________UM3763__Analog IC – Datasheet Reference
Q1___________NIO is BC547___45V 100mA NPN Transistor
Q2___________BC337 50V 800mA NPN Transistor
C1___________0.0068uF 63V Polyester Capacitor
C2___________4.7uF 16V Electrolytic Capacitors
C3___________10uF 16V Electrolytic Capacitors
D1___________DRL is 1N4148 75V 150mA Diodes
ZD1__________Zener Diode 3V 0.5W