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.
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.
Resistors (all ¼-watt, ~+mn~ 5% Carbon)
R1 = 100 Ω
R2 = 330 KΩ
R3 – R5, R10, R25 – R27 = 2.7 KΩ
R6, R18 = 47 KΩ
R7 = 33 KΩ
R8 = 100 KΩ
R9, R24 = 22 KΩ
R11, R19, R28 = 1 KΩ
R12, R21 = 15 KΩ
R13 = 470 KΩ
R14, R16 = 1 MΩ
R15, R22, R23 = 10 KΩ
R17 = 8.2 KΩ
R20 = 4.7 KΩ
R29 = 4.7 Ω
R30 = 100 Ω
R31 = 27 KΩ
C1, C3, C8 = 0.001 µF (Ceramic Disc)
C2 = 0.022 µF (Ceramic Disc)
C4 = 100 pF (Ceramic Disc)
C5, C13 = 0.02 µF (Ceramic Disc)
C6, C7 = 3.3 pF (Ceramic Disc)
C9 – C11, C17 = 0.002 µF (Ceramic Disc)
C12 = 220 µF/25V (Electrolytic)
C14, C18 = 0.04 µF(Ceramic Disc)
C15 = 22 µF/25V (Electrolytic)
C16 = 100 µF/16V (Electrolytic)
VC1, VC2 = 100 pF (trimmer)
T1, T2, T6, T8, T9 = BC148
T3 = BF194
T4 = BF195
T5, T7 = BC158
T10 = BEL187
D1 = 1N4446
L.S. = 8 Ω speaker
X1 = O/P transformer
AERIAL = 2
L1 – L4 = coil
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