Now, for our life today, it is a very important product. If there is no electric light, our night will fall into the darkness, and it will make us unable to carry out a lot of work. Therefore, the installation of the electric light is in ours. The life is already very common, mainly to install the electric light, we must install the light switch, this article we will introduce for everyone: the working principle of the light switch and how the voice control switch works.
How does the light switch work?
1. When the external light is strong, the photoresistor R4 exhibits low resistance, and the triode VT6 base is extremely low, and the triode is cut off. The light does not light up.
2. When the external light is weak, the triode VT6 base is extremely high, and the triode VT6 is turned on. When the metal piece M is touched by hand, the human body induces an electromotive force from the M input, and the VT5 is amplified by the triode VT4 and VT5 to charge C in a short time. At the same time, the VT7 has a base current and the VT7 is turned on. The electric light is shining. When the finger leaves M, the capacitor C3 starts to discharge, VT7 remains on, and the delay starts. When C discharge is completed, VT7 is turned off, the bulb is extinguished, and the delay ends. The delay time is determined by the values of C3 and R5.
3, voice control. Vigorously pat the palm of the hand, so that B receives the sound signal, then converts the sound signal into an electrical signal, and then transfers it to the triode group. The amplified current of VT1, VT2, VT3 acts on capacitor C3 to charge it, and turns VT7 on. If the VT6 is also turned on at this time, the light bulb will light up. The discharge charging of capacitor C enables the delay function. This circuit can be used for occasions such as stairway aisles. Manual operation and voice control can be easily realized if it can work normally.
4. It is worth noting that R4 must be installed in a place where the EL light cannot be used. Otherwise, the light bulb will turn off automatically after it lights up.
How does the voice switch work?
This circuit uses a six-in-one integrated circuit CD4069, in which the gate 1, the door 2, the door 3 and the R1, R2, and R3 form a three-stage signal amplifier. Each time the palm is hit, the applause is picked up by the MIC of the electret microphone. After the sensitivity is adjusted by RP, the signal is amplified by the subsequent three-stage amplifier, and then the C5, D5, D6, and C6 are detected to obtain the DC control voltage. After 4 inversion, control the subsequent bistable circuit flip. The bistable circuit consists of a gate 5, a gate 6 and surrounding components, the flip level of which is a negative pulse. When there is no clapping trigger signal, the input of the gate 4 is grounded to a low level via R4, then the gate 4 outputs a high level, and the bistable circuit does not flip. When there is a high-pitched trigger signal, the input of the gate 4 is high, and the gate 4 outputs a low level, and the falling edge of the negative pulse causes the bistable electronic switch to be turned over.
. Assume that the gate 5 outputs a low level and the VT is turned off at the previous time. At this time, the gate 5 outputs a high level, the VT saturation is turned on, the relay is energized, the normally open contact JK is pulled, the light circuit is turned on, and the light H is illuminated. . At this time, the control level of the detected wave of C6 is gradually released by R4, and the gate 4 outputs a high level again. When the palm is hit again, the input of the gate 4 is detected again, and the gate 4 outputs a low level. The falling edge of the negative pulse causes the bistable electronic switch to flip again, and the gate 5 outputs a low level, and the VT is turned off. JK jumps off, the light H goes out, and the cycle is turned on, which realizes the opening and closing control of the electric lamp with the applause sound.