Cheap alcohol tester circuit
My friends who live in California, USA, said that he likes to party with friends. With alcoholic beverages. And the need to drive a car. He does not want illegal traffic and to ensure the safety of everyone, so thought to buy this alcohol tester to the car. I agree. But he wondered how, Can we build it? I highly recommend this circuit.
Advantage of it is easy to use, show the alcohol level with the 10 LED. Use the parts less. So is not difficult to build and cheaper.
The working principle of the circuit.
The heart of the circuit in Figure 1 is an alcohol sensor(sensor1), which features sensitive to the substances of alcohol. When we apply the power supply of 12 volts into point J1 then turn ON switch S1 to provided the voltage supply to this circuit. The voltage is maintained level of voltage constant of 5 volts by IC1-LM7805. This voltage will be feed into all power of circuit.
When considering that sensor1 pin 2 and pin 5 will be parts of heating coils inside the sensor body. It will be connect with the positive voltage to ground makes generate heat up. The input of the sensor is pin 1 and pin 3 is connected to voltage as well. The output of the sensor is the input pin 4 and pin 6 is connected to pin 5 of IC2-LM3914. To apply the changes. From the sensors to manage with the LED2-LED11. To measure the alcohol content From the breath the test on the sensor.
The resistors R2 and VR1 serves to calibrate the voltage output from the sensor.More details, see the customization and the test projects.
When who tester blowing Breathing that within the alcohol onto the sensor unit. The vapors of Alcohol into contact with semiconductor components in the sensor, the Resistance to change within the sensors. And have the output voltage to be applied to us. The heating coil will get rid of the alcohol vapor residues. Until the end From the first test. To ready for the next the test. For the first time after the calibration.
The Customizing and test Project.
First need to understand for those creation of this project. To is a personal alcohol tester only. Customization does not compare to the actual standard. But the volunteers really drink beer.
When Turn on will see the LED1 glow. Use hand covering the sensor, it will feel warm. Indicates that the machine is ready or waiting for 10-15 seconds. We measure the level of alcohol. Divided by the breath.
The normal level.
The first is that we adjust VR1 until LED2, LED3 lights when the sensor is in its normal environment.
The middle level.
In this test. Our Volunteers drank beer number two canned drinks on the wait 20 minutes before blowing. The test results can be seen LED4, LED5, LED6 bright yellow.
This means that Our body has alcohol in blood.If necessary, drive the vehicle. Should stop drinking immediately. And body stay about 20 minute before driving on.
The high alcohol level.
If you continue to drink more. Blood alcohol level of the drink will be higher.
Test by the volunteers drank beer cans, three and four cans. When again try blowing found that the dismissal order LED7-LED11 will light up red. the test have shown that the level of alcohol too. Not suitable for driving any vehicle. Intoxication as a result of the slow and error. Should stop drinking and relaxing.
This is just an example circuit, I suggest. If you do not cumbersome, and save cost. It may buy from amazon, there are many more.