Radio remote doorbell circuit schematic

Photocoupler

This example introduces a radio remote control “叮咚” doorbell with the TWH630/631 remote control module. When the guest visits, press the doorbell button on the door frame, the doorbell will make a crisp and pleasant bird song, and inform the guests to visit outside the door. If the owner goes home, just press the remote control switch in his pocket and the doorbell will make a "beep" sound. It is especially suitable for children who have primary school at home. Children don't need to bring keys when they go to school. Just wear a small remote control and just press the remote control when you get back to your door. Parents will know the child.

The child is back home.

working principle

The remote doorbell is divided into two parts: a remote control transmitter and a receiver. The circuit schematics are shown in Figure a and Figure b, respectively.

The main component of the transmitter is a TWH630 miniature radio transmitter that radiates high frequency signals into the air through the built-in antenna when the transmit button SB1 is pressed. The transmitter modulation oscillator adopts a common 555 time base integrated circuit and is connected to a self-excited multivibrator. The output square wave frequency f=1.44/(R, + 2R2)C1, according to the data shown in Figures a and b. Calculated to be approximately 1 kHz, the square wave signal is applied by resistor R3 to the input terminal IN of TWH630 to modulate the radiated high frequency signal.

The receiver consists of TWH631 radio receiver, LM567 audio decoder and KI-156 ASIC. The TWH631 receives the signal from the transmitter module and then amplifies it first. Decoding to LM567, the center frequency of the decoder is mainly determined by RRP+R4 and C4, Opf=1.1/( RRP+R4)C4, adjust the potentiometer RP, so that the center frequency is equal to the modulation frequency of the transmitter is 1 kHz. At this time, the 8-pin output of the integrated block outputs a low level, and is applied to the low-trigger terminal TG2 of IC5, so that it is triggered to emit a "叮咚" signal and is amplified by the transistor VT to drive the speaker BL to sound. IC5 is a "叮咚-Bird." music integrated circuit, it has two trigger terminals, one is the high level trigger terminal TG1, it is triggered by the high level, the OUT terminal is the bird ringing signal, the trigger end It is inactive for low level; the other is low level trigger terminal TG2. When triggered by low level, the output of OUT is “叮咚” signal, which is invalid for high level. The SB2 is a button mounted on the door frame. When the guest touches, the SB2 is pressed. At this time, the high-level trigger terminal TG2 is triggered, so the speaker BL emits a "bird" sound.

Component selection

ICl can use NE555, SI555 or p, A555 and other time base integrated circuits; IC2, IC3 should use TWH630/631 type radio transmitting and receiving module; IC4 is LM567 audio decoder; IC5 is KD-156 "叮咚-Bird "Special music integrated circuit, the integrated block is packaged in black paste, resistors R6-R8, capacitor C5 and transistor VT can be soldered to the small printed circuit board of the chip. VD1 and VD2 are common 1N4148 silicon switching diodes. Their function is to use the forward diode step-down to make the KD-156 operate under normal voltage.

VT can use 9013 type silicon NPN transistor, which requires current amplification factor β>l00.

RP is best to use WSW organic solid trimmer potentiometer, other RC components have no special requirements, only the volume should be smaller.

G1 is best to use a 12V battery dedicated to electronic lighters. G2 is connected in series by four 5th dry batteries, and the voltage is 6V.