We will guide you through the construction of a simple alcohol detector circuit in this post.
Here LEDs, resistors, capacitor, a MQ-3 alcohol sensor, an IC LM393 dual comparator, components are used in the circuit.
An alcohol detector is a gadget that detects if there are alcohol vapors in the atmosphere and gives an alert, either visual or auditory.
We will talk about the MQ-3, one such sensor in todays post.
A common alcohol sensitive sensor used in breath analyzers is the MQ-3.
A 5V supply, which is often accessible from a variety of power sources including USB charges or regulated power supplies, will power the circuit.
Circuit Working:
Parts List:
| Component | Value | Quantity |
|---|---|---|
| Resistors | ||
| 1 watt | 5Ω | 1 |
| 1/4 watt | 47k | 1 |
| 1/4 watt | 1k | 2 |
| Potentiometer | 10k | 1 |
| Capacitor | ||
| Ceramic | 0.1µF | 1 |
| Semiconductors | ||
| IC | LM393 | 1 |
| LED1 | Trigger 5mm 20mA | 1 |
| LED2 | Power 5mm 20mA | 1 |
| MQ-3 Gas Sensor | 1 |
The circuit schematic for the Simple Alcohol Detection Sensor Module is shown in above circuit diagram.
The design of this module is rather simple, requiring just a few parts to assemble.
In the event that you need to quickly construct this circuit, the schematic that is provided above will be useful.
The schematic shows an LM393 op-amp, which is a low-power, low-offset voltage op-amp that can be driven by a +5V supply.
However, utilizing 3.3V to power the circuit is not practical since the MQ-3 Sensor requires 5V to operate.
The purpose of this operational amplifier main is to convert an input analog signal into a digital signal.
Apart from that, the MQ-3 Alcohol Sensor module triggering voltage sensitivity may be adjusted thanks to an included 10k potentiometer.
There are two LEDs in addition to that.
The first LED1 is the trigger LED, while the second is the power LED2.
The power LED2 turns on when the board receives electricity.
The trigger LED1 turns on when a certain threshold is reached.
Lastly, the board has one input capacitors that aid in reducing noise.
Formulas:
The following are some important formulas for a basic alcohol detector circuit that make use of the MQ-3 alcohol sensor, LEDs, resistors, capacitors and an LM393 comparator integrated circuit:
Formula for Voltage Divider:
To provide a reference voltage for the MQ-3 alcohol sensor, a voltage divider is usually needed.
The following formula can be used to get the reference voltage or Vref:
Vref = Vin × R2 / R1 + R2
where,
- Vref is the reference voltage for the comparator input.
- Vin is the supply voltage to the voltage divider for 5V
- R1 and R2 are resistors in the voltage divider network ( in this circuit diagram it is VR1 pot).
Voltage Threshold of Comparators:
The output from the MQ-3 sensor is compared to a reference voltage by the LM393 comparator.
To determine the comparators threshold voltage Vth, use:
Vth = Vout−VLED / RLED
where,
- Vth is threshold voltage where the comparator switches its output state.
- Vout is the voltage from the MQ-3 sensor.
- VLED is the forward voltage drop of the LED
- RLED is the resistor with the LED
LED Current Estimation:
To guarantee the LED functions correctly when the comparator output is high, determine the LED current I LED using ohms Law:
ILED = Vout−VLED / RLED
where,
- ILED is the current through the LED.
- Vout is the voltage at the output of the comparator.
- VLED is the forward voltage drop of the LED
- RLED is the series resistor value.
MQ-3 Sensor Reaction:
The output voltage of the MQ-3 sensor may be used to determine the alcohol content by utilizing its distinctive response curve, which often has a power law shape.
If Vsensor is the sensors output voltage and Calc is the alcohol concentration, then the relationship may be roughly expressed as follows:
Calc ∝ 1 / Vnsensor
where,
- Calc is alcohol concentration.
- Vsensor is the output voltage from the MQ-3 sensor.
- n is the sensor specific constant
These formulas help in the circuit design and calibration of the alcohol detector, guaranteeing precise and dependable detection.
How to Build:
To build a Simple Alcohol Detector Circuit using IC LM393 following are the steps for connections:
- Gather all the components as mentioned in the above circuit diagram.
- Connect IC LM393 pin 1 to trigger LED1 and resistor R3 to 5V power supply.
- Connect IC LM393 pin 2 to the MQ-3 sensor output.
- Connect IC LM393 pin 2 to capacitor C1 for noise reducing and ground, connect resistor R2 from pin 2 and ground.
- Connect IC LM393 pin 3 to center leg of VR1 pot, upper leg to positive supply and 3rd leg to ground.
- Connect IC LM393 pin 4 to GND.
- Connect IC LM393 pin 8 to positive supply of +5V.
- Connect one end of heater coil of the MQ-3 sensor to ground through resistor R1, and connect the other end of the heater coil to positive supply and connect the upper A terminal or B terminal of the sensor with the positive supply
- Connect resistor R4 and LED2 power from positive supply to ground.
Testing:
- Switch the circuit on attach the circuits power supply to it.
- Add alcohol vapor to the MQ-3 sensors exposure.
- If there is alcohol present, the red LED should illuminate.
Conclusion:
Using widely available electrical components, this simple alcohol detector circuit offers a basic yet effective method of detecting alcohol fumes.
Utilizing the MQ-3 alcohol sensor and LM393 comparator IC, you may construct an efficient alcohol detection system fit for a range of uses.
These instructions will help you construct a basic alcohol detector circuit that you may use for monitoring the environment or breathalyzers, among other uses.