Latching Touch Sensitive Alarm Electronic Circuit

UTSOURCE Electronic Parts

Soldering iron (generic)

<h3 > Latching Touch Sensitive Alarm</h3><h3 > Electronic Circuit</h3>The latching mechanism is involved in this electronic circuit, when the probe is touch by an external source the buzzer keeps in ON position until the state is changed by a momentarily push button, though output is connected to the 555 timer IC. The latching is intensively used in burglar detection, capacitive touch detection circuits etc. it also detects with the negative touch of an object also when they are very near. So let’s make our latching circuit and understand the concept behind it. <figure><img src=https://projects.arduinocontent.cc/cec49b39-c75b-4f80-a455-d1895d0bfa00.JPG /><figcaption> </figcaption></figure><h3 >Principle</h3>When we touch the open wire probe, the voltage across the circuit 555 timer regulates and buzzer makes sound, until it is turned OFF with the help of momentarily push button. It has wide range applications and uses in burglar and home security system. When the negative object are bring close to the probe, the buzzer makes a sound. Let’s do the project in sequence to grab the points effectively.<h3 >Components Required:</h3>1. 555 Timer IC (1) get it from <a href="https://www.utsource.net/category/elec-component/transistors">here </a>2. <a href="https://www.utsource.net/category/passive-components/inductors-ferrite-beads-transformers">Buzzer (1) </a>3. <a href="https://www.utsource.net/category/elec-component/transistors">BC547 Transistor (1)</a>4. <a href="https://www.utsource.net/category/led-lighting/led-modules">LED (1)</a>5. <a href="https://www.utsource.net/category/sensors/other-sensor">Momentary push button</a>6. <a href="https://www.utsource.net/category/passive-components/resistors">10k, 270 ohm resistor(1)</a>7. <a href="https://www.utsource.net/category/accessories-tools/breadboard">Bread board</a>8. <a href="https://www.utsource.net/category/accessories-tools/wires-cables">Connecting wires</a> (asrequired) 9. <a href="https://www.utsource.net/category/accessories-tools/battery-case">DC Power supply(5-12)V</a> Circuit Diagram:<figure><img src=https://projects.arduinocontent.cc/a2d82c97-03b0-4d3a-b0f7-02d316fbbc14.JPG /><figcaption> </figcaption></figure>Procedure:1. Place the 555 Timer IC on the bread board with its notch facing up <figure><img src=https://projects.arduinocontent.cc/520e21af-7e6a-4af1-9022-b06ead8646df.JPG /><figcaption> </figcaption></figure>2. Connect pin 4 of the IC to the positive rail of the bread board<figure><img src=https://projects.arduinocontent.cc/a5e09105-52f8-43e1-ac0a-5672c2663e0a.JPG /><figcaption> </figcaption></figure>3. Connect pin 1 of the IC to the negative rail of the bread board and reset pin to <figure><img src=https://projects.arduinocontent.cc/5b46acfc-7ab2-4937-b2a6-e59bd871faf5.JPG /><figcaption> </figcaption></figure>4. Connect pin 6 to the positive rail of the bread board and touch contact to the pin 2 of the 555Timer IC.<figure><img src=https://projects.arduinocontent.cc/157c9296-b8da-465e-a020-5975f30c4aaf.JPG /><figcaption> </figcaption></figure>5. Place an LED on the bread board <figure><img src=https://projects.arduinocontent.cc/7c6e2a82-64c5-46de-9d86-ff37f5961a81.JPG /><figcaption> </figcaption></figure>6. And connect anode to the 555 Timer IC <figure><img src=https://projects.arduinocontent.cc/e4865ac2-e4bb-4b76-90bd-d83ce3957c88.JPG /><figcaption> </figcaption></figure>7. Connect cathode of LED via series resistor of 270 ohm <figure><img src=https://projects.arduinocontent.cc/7429195f-046d-4538-aecc-a0531fecb58c.JPG /><figcaption> </figcaption></figure>8. Now connect the buzzer between the output of 555 timer IC and negative rail.<figure><img src=https://projects.arduinocontent.cc/eb33626c-a35f-4c44-b82f-f2b678f485db.JPG /><figcaption> </figcaption></figure>9. Now connect the transistor (BC547) such that emitter is connected to negative pin of 555 timer IC<figure><img src=https://projects.arduinocontent.cc/d3797ac4-b0d6-46a3-8557-09200916573a.JPG /><figcaption> </figcaption></figure>10. Connect 10k resistor between the transistor and the timer IC <figure><img src=https://projects.arduinocontent.cc/f5af2cc7-b7bb-4941-82d2-77d4f6708e72.JPG /><figcaption> </figcaption></figure>11. Connect the collector pin of transistor to pin 2 of IC<figure><img src=https://projects.arduinocontent.cc/bf85a6fd-8755-4853-8aa2-94955e4c4ca1.JPG /><figcaption> </figcaption></figure>12. Now insert momentary push button on the bread board, with terminal connected to collector and positive rail.<figure><img src=https://projects.arduinocontent.cc/1042bde7-33c0-4a16-bfd5-0f0646ec7075.JPG /><figcaption> </figcaption></figure>13. Connect the power supply to turned ON the circuit <figure><img src=https://projects.arduinocontent.cc/d3cd8517-30b5-4856-9355-7d14b202ba69.JPG /><figcaption> </figcaption></figure>14. And when we place our hand or object closer to the probe, the buzzer makes the beep sound and LED flashes indicating the circuitry operation is performed. <figure><img src=https://projects.arduinocontent.cc/eed331c5-6e7a-4416-8414-90c49faccc51.JPG /><figcaption> </figcaption></figure>when we push the momentary button the LED turned OFFand buzzer stops making sound, the circuit is shifts to quasi state. <figure><img src=https://projects.arduinocontent.cc/356416a6-62b8-45d5-93db-914bc9605fc3.JPG /><figcaption> </figcaption></figure>So this is the basic latching operation for the touch detection circuits, having intensive application in home security system and burglar action protections. What are you waiting for make the project to understand the concept perfectly.Thank YouAlso visit - <a href="http://www.robocircuits.com">www.robocircuits.com </a>

Latching Touch Sensitive Alarm Electronic Circuit

When the probe is touch by an external source the buzzer keeps in ON position until the state is changed by a momentarily push button.