Categories: Electronics

Multi-Function Wire-Loop Safety System

This multi-purpose safety system utilises wire loops to safe objects. Wire loops might be employed in varied methods for safety functions resembling baggage safety, bike safety, bicycle safety, room safety, and door safety. A wire loop, when hooked up to safety objects and alarm mechanisms, detects and alerts in case of unauthorised makes an attempt to tamper with the wire loop.

Fig. 1: Writer’s prototype on breadboard

Use a skinny, versatile, and sturdy conductive wire to create a loop across the space you need to safe. Set up the wire loop across the desired perimeter, whether or not it’s a doorway, window, or every other entry level. When a breach is detected (e.g., somebody cuts or breaks the wire loop), the alarm system prompts.

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Elements Record
Semiconductors:
IC1	-UM66 melody generator
IC2	-LM386 low energy amplifier
T1	-BC327 pnp transistor
ZD1	-3.1V zener diode
LED1	-5mm LED
Resistors (all 1/4-watt, ±5% carbon):
R1	-1-kilo-ohm
R2	-10-kilo-ohm
R3	-220-ohm
Capacitors:
C1	-470μF, 25V electrolytic
C2	-10μF, 25V electrolytic
C3	-220μF, 25V electrolytic
Miscellaneous:
JACK1	-DC socket
S1	-SPDT change
CON1	-2-pin connector
Batt.1	-9V battery
LS1	-8-ohm, 0.5-watt speaker
	-9V DC adaptor
	-Versatile wire for loop (size as per requirement)

Circuit and dealing

The circuit diagram of the multi-purpose safety system is proven in Fig. 2. It’s constructed round transistor BC327 (T1), melody generator UM66 (IC1), low-power audio amplifier LM386 (IC2), 8-ohm half-watt loudspeaker (LS1), 9V battery or 9V adaptor, and some different parts. Round one metre of versatile wire is used as a sensor, forming a loop to attach the article (resembling baggage) to CON1 within the circuit.

Fig. 2: Circuit diagram

The melody sign produced by the UM66 melody generator is weak. To amplify the sound alerts, the widely-used audio amplifier LM386 is employed.

To know the working of the circuit, first comprehend the pin descriptions of LM386. Pins 1 and eight are used for gaining management of the amplifier. Pins 2 and three feed the enter sign for amplification, with pin 2 for unfavourable enter and pin 3 for constructive sign. Pin 4 is used for floor, whereas pin 6 is used for the constructive 9V DC energy provide. Pin 5 is the output, linked to a loudspeaker via a capacitor. Pin 7 is just not utilised on this configuration.

– Commercial –

The system’s operation is easy. When energy is provided through a battery or adaptor, the musical IC UM66 (IC1) will get activated and begins producing musical sound at its output pin 3. The speaker might be instantly hooked up between pin 3 and floor of IC1 to listen to the musical sound. For louder sound, LM386 is used. The three.1V zener diode ZD1 is linked at pin 2 of IC1 to guard it from voltage past 3.1V.

To amplify the alerts, modify the achieve issue via pins 1 and eight. If left open, the achieve will probably be 20dB, as internally set within the IC. By including a 10µF capacitor (C2) between pins 1 and eight, the achieve might be various as much as 200dB. Feed the required alerts to pin 3 of IC2.

The musical sign output from IC1 is linked to pin 3 to acquire amplified output on pin 5 of IC2. Capacitor C3 acts as a coupling capacitor, eradicating DC alerts and passing audio alerts via it. The amplified alerts are then output via speaker LS1.

– Commercial –

First, join a versatile wire as a loop between CON1 and the article (resembling baggage) to be protected. The system operates with both a 9V battery or 9V adaptor, relying on the appliance. After connecting a battery, change S1 probe in the direction of the battery aspect. If LED1 glows, the system is able to use.

After utilizing the ability supply, preserve the mode change in the direction of the supply used. Now, 9V is on the market within the system. When somebody breaks the loop, transistor T1 begins conducting and IC1 receives 3.1V to activate it.

On this system, a versatile wire loop is interfaced as a sensor with the musical IC UM66. LED1 is used within the system as an influence provide indicator.

The versatile wire has two terminals which should be linked throughout CON1 through the merchandise throughout safety measures. When the loop is lower or damaged, it supplies a low voltage on the base of transistor T1. Transistor T1 then conducts, enabling IC1 to activate the melody generator sound. The output of IC1 is additional directed to IC2 for louder sound.

Building and testing

A single-side PCB structure for the musical safety alarm is proven in Fig. 3, with its part structure displayed in Fig. 4.

Fig. 3: PCB structure

Fig. 3: Precise-size PCB structure

After assembling the circuit on the PCB, enclose it in an acceptable field. Repair LED1 and CON1 on the entrance aspect of the field, and the mains energy connector JACK1 and 9V battery on the rear aspect. Join the versatile wire loop between factors A and B (confer with CON1 in Fig. 1) through the merchandise to be secured, guaranteeing that the loop would break simply when somebody makes an attempt to tamper with it.

Bonus. You may watch the video of the tutorial of this DIY challenge at https://www.electronicsforu.com/videos-slideshows/make-multipurpose-security-system

S.C. Dwivedi is an electronics fanatic and circuit designer at EFY

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