Now day’s wireless control of appliance is in practice, because of its advantage like no wire is needed, multiple controlling is less complicated. By considering these all, the innovative group Dreamlover Technology designed and verified the circuit of wireless Doorbell. The controlling range of wireless doorbell is 100M.

Circuit Description

As the wireless doorbell is wireless based project, it is divided into two major section i.e. transmitter and receiver.

Transmitter:- This transmitter section is designed around oscillator transistor (BF194B) T₂ followed by two transistor (BC148) T₁ and T₃. Transistor T₂ generate special radio frequency determined by trimmer (variable capacitor) and coil. Transistor T₁ is used as pulse generator. The output from transistor T₃ is given to emitter of transistor T₂ in order to get radio frequency from its collector. Trimmer VC₁ is used to adjust the transmitter frequency.

Receiver: - The receiver section is further divided into two main sections i.e. RF amplifier section and bell trigger section.

An aerial is used to receive the transmitted frequency from remote which is further amplified by amplifier and trigger circuit. The whole receiver circuit utilizes seven transistors. Transistor T₄ get frequency from hand unit and further send to tuned circuit made from capacitor C₆ and coil L₂.

Transistor T₅ is used as comparator which further send amplify voltage to capacitor C₁₁ for filter. The filter voltage is passed through detector stage i.e. rectify and given to base of transistor T₆. Transistor T₆ is adjusted in amplifier mode for amplifying the signal voltage.

The amplified voltage from transistor T₆ is given to base of transistor T₇, used in complementary mode. The positive voltage at collector of transistor T₇ let transistor T₈ in conducting state and T₉ in non- conducting state. The positive voltage available at collector of T₉ is given to base of transistor T₁₀. Transistor T₁₀ is used here in blocking oscillator mode which further produces bird sound combining with output transformer.

PARTS LIST

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