Introduction
Have you heard of breathalyzer or Alcohol level tester gadgets before? They are gadgets that calculate how much alcohol a person has consumed. Basically, it aids in the detection of an intoxicated driver in order to avert accidents. And, this is the topic of this article. Because in this article, we are going to discuss the “Alcohol level tester bar graph”.
In the making of the circuit, we are using the MQ3 Sensor. Basically, It’s a metal oxide semiconductor sensor, also promoted as a chemiresistor. Because it works with the change of the resistance. Hence, it senses the alcohol concentration by voltage dividing network
Hardware Components
The following components are required to make Alcohol Level Tester Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | IC | LM3914 | 1 |
| 2. | Alcohol Sensor | MQ3 | 1 |
| 3. | LED | – | 10 |
| 4. | Variable Resistor | 20KΩ | 1 |
| 5. | Resistor | 500Ω, 2.7kΩ, 3.9kΩ | 1,1,1 |
| 6. | Connecting Wires | – | – |
LM3914 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LM3914
Alcohol Level Tester Circuit
Working Explanation
In this Alcohol level tester bar graph circuit we are utilizing the alcohol sensor MQ3 having the sensing part sense the alcohol.
The tabular sensing part of the sensor is made up of aluminum oxide which has a coating of tin dioxide(SnO2). When this layer of SnO2 is heated at a high temperature, oxygen gets adsorbed at the surface. So, when there is no alcohol, the electrons from the conduction band of SnO2 get attracted to the oxygen. Thus, this forms the depletion layer below the surface of the SnO2. Hence, worked as a potential barrier that allows no current to flow. When the layer senses the alcohol, oxygen is reacted with the alcohol, and the density of adsorbed oxygen gets decreased. This reduces the potential barrier and electrons are allowed to release into SnO2. As a result, the current starts to flow in a sensor.
The LM3914 bar graph decoding IC is used to drive output. LEDs are there in the circuit to show the output. Know that circuit operates on a +5V power source and the sensitivity level may be adjusted using the VR1 variable resistor.
Application and Uses
- Firstly, in breathalyzers.
- Further, in portable alcohol detectors.
- Also, in environmental sensing or monitoring devices.
- Moreover, In gas level alarms.
