Application Guideline for Guard Door with Solenoid Locking ...
Little Door Guard
2
CIRCUIT IDEAS ELECTRONICS FOR YOU SEPTEMBER 2005 • 1 0 3 WWW.EFYMAG.COM Fig. 3: Back view of the door assembly Fig. 2: Pin configurations of UM3561 and transistors 2N5777 and BC547 Fig. 4: Suggested enclosure with major components layout I f some intruder tries to open the door of your house, this circuit sounds an alarm to alert you against the attempted intrusion. The circuit (Fig. 1) uses readily available, low-cost compo- nents. For compactness, an alkaline 12V battery is used for powering the unit. Input DC supply is further regulated to a steady DC voltage of 5V by 3-pin regulator IC 7805 (IC2). Assemble the unit on a general- purpose PCB as shown in Fig. 4 and mount the same on the door as shown in Fig. 3. Now mount a piece of mir- ror on the doorframe such that it is T .K. HAREENDRAN LITTLE DOOR GUARD S.C . D W I VED I Fig. 1: Circuit of the door guard exactly aligned with the unit. Pin configurations of IC UM3561 and transistors 2N5777 and BC547 are shown in Fig. 2. Initially, when the door is closed, the infrared (IR) beam transmitted by IR LED1 is reflected (by the mirror) back to phototransistor 2N5777 (T1). The IR beam falling on phototransistor T1 reverse bi- ases npn transistor T2 and IC1 does not get positive supply at its pin 5. As a result, no tone is pro- duced at its output pin 3 and the loudspeaker re- mains silent. Resistor R1 limits the operating current for the IR LED. When the door is opened, the absence of IR rays at phototransistor T1 forward biases npn transistor T2, which provides positive supply to IC1. Now 3-siren sound generator IC UM3561 (IC1) gets power via resistor R5. The output of IC1 at pin 3 is amplified by Darlington-pair transistors T3 and T4 to produce the alert tone via the loudspeaker. Rotary switch S2 is used to select the three preprogrammed tones of IC1. IC1 produces fire engine, police and ambulance siren sounds when its pin 6 is connected to point F, P or A, re- spectively.
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this a pdf on the little door guard useful for the electrical gradutes for their project
Transcript of Little Door Guard
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CIRCUITIDEAS
E L E C T R O N I C S F O R Y O U S E P T E M B E R 2 0 0 5 1 0 3W W W . E F Y M A G . C O M
CMYK
Fig. 3: Back view of the door assembly
Fig. 2: Pin configurations of UM3561 and transistors2N5777 and BC547
Fig. 4: Suggested enclosure withmajor components layout
I f some intruder tries to open thedoor of your house, this circuitsounds an alarm to alert youagainst the attempted intrusion.
The circuit (Fig. 1) usesreadily available, low-cost compo-nents. For compactness, analkaline 12V battery is used forpowering the unit. Input DC supplyis further regulated to a steadyDC voltage of 5V by 3-pin regulatorIC 7805 (IC2).
Assemble the unit on a general-purpose PCB as shown in Fig. 4 andmount the same on the door as shownin Fig. 3. Now mount a piece of mir-ror on the doorframe such that it is
T.K. HAREENDRAN
LITTLE DOOR GUARD S.C. DWIVEDI
Fig. 1: Circuit of the door guard
exactly aligned with the unit.Pin configurations of ICUM3561 and transistors2N5777 and BC547 areshown in Fig. 2.
Initially, when thedoor is closed, the infrared(IR) beam transmitted byIR LED1 is reflected (by themirror) back tophototransistor 2N5777 (T1).The IR beam falling onphototransistor T1 reverse bi-ases npn transistor T2
and IC1 does not getpositive supply at its pin 5.As a result, no tone is pro-duced at its output pin 3and the loudspeaker re-mains silent. Resistor R1limits the operating currentfor the IR LED.
When the door isopened, the absence of IRrays at phototransistor T1forward biases npn
transistor T2, which provides positivesupply to IC1. Now 3-sirensound generator IC UM3561 (IC1) getspower via resistor R5. The outputof IC1 at pin 3 is amplified byDarlington-pair transistors T3 and T4to produce the alert tone via theloudspeaker.
Rotary switch S2 is used to selectthe three preprogrammed tones of IC1.IC1 produces fire engine, police andambulance siren sounds when its pin6 is connected to point F, P or A, re-spectively. z
