Oxygen sensor Circuit Post 3:

Oxygen sensor circuit:

The task we had to was to build a oxygen sensor using the flowing components.thses components have to be put in all together to build the circuit

12v Battery
3 LED's:
1x Red led
1x Yellow led
1x Green led
1x Op Amp  LM324
3 diodes 1N4001
7 resistors (R2=1KΩ, R3=1KΩ, R4=1KΩ, R5=380Ω, R6=10KΩ, R7=270Ω, R8=470Ω)
1 zener diode 9v1
2 capacitors  0.1uF




Calculation:


R2, R3 & R4
I= 9.5mA =0.0095A
The voltage drop in R2 is at 9.6v, Vd=12 - 0.6 - 1.8 =9.6v
R=V/I =9.6/0.0095 =1010.5Ω
The voltage drop in R3 is at 9v, Vd=12 - 0.6 - 0.6 - 1.8 =9v
R=V/I =9.6/0.0095 =947Ω
The voltage drop in R4 is at 9.6v, Vd=12 - 0.6 - 1.8 =9.6v
R=V/I =9.6/0.0095 =1010.5Ω


R5=
Power supply voltage is at 12v, Vd of crossing diode D2=0.6v, Vd of zener diode D1=9.1v
Vd of R5 = 12-0.6-9.1= 2.3v
I=5.6mA=0.0056A
R=V/I =2.3/0.0056 =411Ω


R7 an R8


R6=10KΩ Voltage drop in crossing R6 is at 8.47v 
The volage are at 9.1v and 0.63v before the R6 and after the R6 each. 
So, Vd=9.1-0.63 = 8.47v
ohms law I=V/R =8.47/10,000 =0.000847A


R8=
VD= 0.4
Vd= 0.63 - 0.23 =0.4v
R=V/I =0.4/0.000847 =472Ω
R7 consumes the voltage which voltage drop is at 0.23
Vd= 0.23 - 0 =0.23Ω
R=V/I =0.23/0.000847 =271.5Ω
Total resistance RT=R6+R8+R7 =10,743Ω
I=9.1/10,743 =0.000847A


The calculation is shown in the diagram blew please click on the image to view it larger as it might be harder to see.

here is picture of it after i built on breed board .

I also recored a short clip it showing how its working for example when its running lean or when its running richer or when its in between and this had be also on breed board .

Here is some pictures after i built it on pcb board it shows the emission of how the car is running it has 3 different color LEDs so they represent when the car is running lean or when its rich or when its in between

                                                  The LED shows when its Rich mixture

                                         The yellow LED shows whens its running in normal mixture

                                            And the green LED shows that when its running in lean mixture

                                           The is the picture of my oxygen sensor

And here is the video clip i recored when i finshd building and then i connected to check if its working and here is the video you can see it your self to its working fine.

Oxygen sensor

Since oxygen sensor mainly control the fuel mixture of the engine by measuring the oxygen content parameter for the engine computer (ecm), it is necessary for us to understand how this sensor circuits works.

In the early 1980s when oxygen sensor was first introduced, it has only one signal wire. This sensitive wire was designed so that it only takes low voltage signal under 1 volt. This crude design has a major flaw; it takes too much time for the sensor to give signal to the engine computer.

It is the computer’s job to regulate the fuel mixture after the sensor warms up which sometimes takes about 10-15 minutes. This time delay can gets worse when the weather gets cold and would dump a lot of raw fuel to the catalytic converter (CAT). This leads to premature CAT failure and high fuel .But since 1994 to 2006 the oxygen sensor has been upgraded to solve this problem.

The O2 sensor is mounted in the exhaust manifold to monitor how much unburned oxygen is in the exhaust as the exhaust exits the engine. Monitoring oxygen levels in the exhaust is a way of gauging the fuel mixture. It tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen).

Reference

http://blog.automotivetroubleshootingsecrets.com/hho-gas-tips/fix-oxygen-sensor/