Digital Logic Design ECE-103
Mini Project
LED VOLTMETER CIRCUIT
Submitted to: -
Submitted by:-
R.Anitha, Asst. Prof.(Sr), SENSE, VLSI Design Division, VIT University, Vellore.
NAVEEN.Y 11BEC0077, KAUSHIK REDDY.A 11BEC0285
CONTENTS:1. OBJECTIVE 2. WORKING PRINCIPLE 3. COMPONENTS COMPONENTS REQUIRED 4. COMPONENTS COMPONENTS DESCRIPTION 5. PIN DIAGRAM 6. PIN DESCRIPTION 7. CIRCUIT DIAGRAM 8. CIRCUIT WORKING 9. APPLICATIONS 10.DRAWBACKS 10. DRAWBACKS 11.DIFFICULTIES 11. DIFFICULTIES ENCOUNTERED 12.CONCLUSION 12. CONCLUSION 13.RESULT 13. RESULT 14.REFERENCES 14. REFERENCES
LED VOLTMETER CIRCUIT OBJECTIVE:To design a circuit for measuring the voltage level in a battery using comparator and LEDs.
WORKING PRINCIPLE:The circuit is based on four comparators made of quad op amp LM324.The inverting inputs of IC are kept at reference voltages 100%,75%,50%,25% that is 12V,9V,6V,3V as we are using a 12 V battery respectively at pins 2,6,9,13 by using resistors R1,R2,R3,R4. The battery voltage is fed to the non-inverting input pins 3, 5, 10, 12 respectively. When there is variation in the battery voltage level, the output of each op amp goes high accordingly as they are wired as voltage comparators and the corresponding LEDs glow.
COMPONENTS REQUIRED:Name of the items Comparator Resistors PCB board DC Power supply
Specification IC_LM324N 1K Ohms
Quantity 1 4 1
COMPONENTS DESCRIPTION:IC_LM324N
independen t operational amplifiers (op-amps) LM324 is a 14pin IC consisting of four independent compensated in a single package. packag e. Op-amps are high gain electronic voltage amplifier with differential input and, usually, a single-ended output. The output voltage is many times higher hi gher than the voltage difference between input terminals of an op-amp. These op-amps are operated by a single power supply and need for a dual supply is eliminated. They can be used as amplifiers, comparators, oscillators, rectifiers etc. The conventional op-amp applications can be more easily implemented with LM324.
PIN DIAGRAM:-
PIN DESCRIPTION:Pin No
Function
Name
1
Output of 1st comparator
Output 1
2
Inverting input of 1st comparator
Input 1-
3
Non-inverting input of 1st comparator
Input 1+
4
Supply voltage; 5V (up to 32V)
Vcc
5
Non-inverting input of 2nd comparator
Input 2+
6
Inverting input of 2nd comparator
Input 2-
7
Output of 2nd comparator
Output 2
8
Output of 3rd comparator
Output 3
9
Inverting input of 3rd comparator
Input 3-
10
Non-inverting input of 3rd comparator
Input 3+
11
Ground (0V)
Ground
12
Non-inverting input of 4th comparator
Input 4+
13
Inverting input of 4th comparator
Input 4-
14
Output of 4th comparator
Output 4
CIRCUIT DIAGRAM:-
CIRCUIT WORKING:A single IC LM 324 is used to measure the voltage level in the battery. battery. each op amp receives voltage through the potential divider chain R1 to R4. So depending on the input voltage, each op amp compares it with the reference voltage at the inverting input. If the voltage in the non inverting input is higher than the reference voltage at the inverting input, output of each op amp goes high and the corresponding LED turns on. If the battery voltage is above 12 volts, all LEDs remain on. Thus, more more and more LED's are lighted up as the the input voltage rises. More LED's may be added by adding more op-amps connected in a similar manner. Voltage level
LED indication
Above 12 V
All LEDs turn on
9V-12 V
I,II&III level LEDs turn on
6 V-9V
I&II- level LEDs turn on
3V-6V
I-level LEDs turn on
Below 3 V
All LEDs turn off
APPLICATIONS:
This is a very useful circuit which when installed in your car gives the voltage of your battery your battery in a LED dot display form.
The main use of the car battery voltmeter is to monitor the life and performance of batteries. It can be mounted on the dashboard that shows the battery condition to easily monitor the electrical system voltage while driving.
The battery is full charge if the voltmeter reads 12 V or more while a voltmeter reading of much less than 12 V signifies the battery is either discharged or failing.
You can also use it as a voltmeter in case your digital voltmeter is faulty or damaged.
DRAWBACKS:
We can only measure if the voltage is greater than 3,6,9,12V,but not the actual voltage value. It’s not calibrated instrument.
DIFFICULTIES ENCOUNTERED:ENCOUNTERED:
For 3V voltage, LED blinking is too dim to be noticed.
CONCLUSION:
IC LM 324 consists of4 op amps in one package, so power supply is common and is
shown once (pin 4 and 11). To setup, connect the circuit to battery, adjust R6 so that required voltages are available
at the inverting pins (refer description to get the required v oltages). Fix the LED’s on the dash board and mark the voltages near to it as shown in circuit
diagram. The gadget is now ready. LM324 is referred to as quad device this is because it contains four Op-Amps. So instead of getting four uA741 u can use only one LM324.
RESULT:Thus the LED VOLTMETER CIRCUIT is designed and the battery level is measured.
REFERENCES:
http://www.electronicsforu.com/electronicsforu/circuitarchives/view_article.asp?sno=710&title =LED+Voltmeter&article_type=1&id=643&tt=unhot
http://circuit-electronic.blogspot.in/2007/06/led-voltmeter-for-car-battery-by-lm324.html
http://circuitdiagramwiring.com/led-voltmeter-for-car-battery-by-lm324/
http://www.circuitstoday.com/car-battery-volt-meter-circuit-using-led
