Experiment 2, Throttle Position Switch

 

Q. Explain the internal operation of this sensor and why the resistance changes?

A. In switch type TPS sensor there is a two contact points inside the throttle.There is a arm in the middle inside it, that makes the connections at two points. One point is for close postion and other for wide open (WOT)  At Idle, throttle is closed and the resistance is infinite and when it starts open, the resistace at once jump to 0.1 ohms with any variations in between. In other way around, when it closing down from its fully open postion, the resistance jumps to infinite.

Experiment 1: Sensors: Throttle Position Sensor

Q. What types of TPS is this?
A. Potentiometer.

Q. Explain its internal operation and why your voltage changes?
A. There is a variable resistance located inside it. When the throttle is fully opened,  the variable resistance will be at that position where it gives lowest resistance and when the throttle is closing down, the resistance will increase as well.

After connecting this sensor to the power supply of 5 volts, there are some following voltage outputs obtained at different throttle angles.

Graph

Wiring up ignition systems

Wire up an ignition module using a function generator to trigger the module.
Have a coil and spark plug in the circuit so the spark plug can fire

Draw a wiring diagram of how you wired the circuit

Wire up an ignition module using a distributor to trigger the module
Have a coil and spark plug in the circuit so the spark plug can fire

Draw a wiring diagram of how you wired the circuit

Wire up the wasted spark ignition system using the function generator to trigger the modules.

Have the coils and sparks plug in the circuit so the spark plugs can fire.

Draw a wiring diagram of how you wired the circuit

Wire up the coil over ignition system using the function generator to trigger the module
Have the coil and spark plug in the circuit so the spark plug can fire

Draw a wiring diagram of how wired the circuit.

Building a simplified ignition module
Build the ignition circuit below on a breadboard using two 2N2222 transistors

Q. Find the maximum current value of the transistors from the data sheet, the resistancne of the coil. Then calculate the resistor need to protect the circuit. Show calculations.

Calculation for B1 resistance:
Base current at B1(Ib) = 1A
Supply voltage = 5 V
Voltage drop Vbe = 0.7 V
Voltage at base Vb = 5-0.7 = 4.3 V
V=IR
R= 4.3/1 = 4.3 ohm
Calculation for R3:
V = 12 V
Ic = 3 A
V= IR
Resistance of ignition coil is 1.2 ohm
V = I(1.2 + R3)
(1.2 + R3) = 12/3=4
R3 = 4-1.2= 2.8 ohm
So R3 = 2.8 ohm
Instead of the calculated values of R and R3, we used in our experiment 4.7 ohm and 3.3 ohm resistance respectively as available in the Lab.

Q. What difficulties did you encounter in building this circuit?
A. At beginning, we faced difficulty in finding resistance R and R3 but we struggled with and finally we found those.

Q. If you were going to build this circuit again what would you do differently?
A. we would try to find the resistance instantly