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DIY kit, anda harus merakit sendiri.
Warna speaker bisa berbeda dari gambar.
The kit is a circuit for a bell that can make "ding, dong" sound. It is composed of a time base circuit integrated block and peripheral components. It has a beautiful sound quality, easy to install, low cost and low power consumption. Its working voltage is DC3V-12V. It is usually powered by a 9V laminated battery. The higher the voltage, the louder the sound. Since the speaker is not in the box, the sound phase in the front and back of the plate counteracts the volume and the volume is smaller. You can load the carton to raise the volume.
The core C1 is the time base circuit integrated block NE 555. It forms the unsteady multivibrator. Press the button AN (mounted on the door), the oscillator oscillates, the oscillation frequency is about 700Hz, and the speaker makes a "ding" sound. At the same time, the power supply is charged by diode D1 to C1.When the button is released, C1 is discharged through the resistance R1, maintaining the oscillation. However, due to the disconnection of AN, the resistance R2 is threaded into the circuit, which changes the oscillation frequency, about 500Hz, and the speaker makes a "dong" sound.Until the voltage on C1 can't sustain the 555 oscillation. The length of the sound of "dong" can be changed by changing the number of C1.
The kit circuit is fairly simple. You will get a about 5*7cm universal board or process PCB board. Due to the cost limitation, the loudspeaker will be a little rusty for the inventory. (and different batches may not be the same, generally 23-50mm speakers). However, it does not affect the use and experimental effect. If you mind, please select a new product.
Doorbell NE555 Electronic Transformer Sound Circuit DIY