What is Ammeter?
An ammeter is an electronic device that measures the electric current in a circuit. The name is derived from the name for its SI unit, amperes “A”. We will discuss about simple digital LED ammeter using ICL7107 . First let’s know about ammeter.
For an ammeter to measure a device’s current, it should be joined in series to that device . This is must for objects in the series are experienced the same current. They should not be connected to a voltage-source ammeters are designed for working under a minimal burden (which refers to the voltage drop across the ammeter, typically a small fraction of a volt).
Ammeter in Series
An ammeter (A) is always placed in series to measure current. The whole current in the circuit flows through the meter. The ammeter would have the same reading if located between points d & e or between points f & a, as it does in the position shown. (Note that in the script capital ‘E’ stands for ‘EMF’ & ‘r ‘stands for ‘internal resistance’ of the source of potential difference. )
Parts List
0.01 Ohm - 1.5mm / 5cm long copper wire 0.1 Ohm - 5W Resistor 1 Ohm - 5W Resistor 1x - 220 Ohm Resistor 1x - 10K Resistor 1x - 15K Resistor 1x - 47K Resistor 1x - 100K Resistor 1x 10K Pot 1x - 100pF Capacitor 1x - 10n Capacitor 1x - 100n Capacitor 1x - 220n Capacitor 1x - 470n Capacitor 2x - 10uF Capacitor 3x - 1N4148 Diode 1x - ICL7107 IC 1x - 7660 IC 2x - MAN6910 2-digit LED 7-segment Display
Technical Specifications:
Supply Voltage: 5V
Current Consumption: ~ 25mA
Measurement Accuracy:
10A – 100mA Resolution – 99.9 A
5A – 10mA Resolution – 9.99 A
2A – 1mA Resolution – 1.999 A
About this Circuit
Ammeter is really a great addition to any Laboratory-Power-Supply because it measures the current consumption and helps you determine if there are any problems with the circuit that you’re going to build or test. This ampere meter is able to measure the current consumption up to 10A with selected 100mA, 10mA & 1mA accuracy, and consumes only about 25mA of current. The ammeter is based on single ICL7107 chip & 3.5-digit seven segment LED display. It is possible to fit it on a small 3cm x 7cm printed circuit board because of a relatively small number of components that the circuit is using.
Construction Notes
0.01 Ohm resistor must be made out of 1.5mm thick / 5cm long copper wire. 0.1 Ohm and 1 Ohm resistors must have 5W ratings. For the highest accuracy, it is recommended that the ICL7107 ampere meter module mustbe supplied with its own voltage supply. If measurement of the current of same supply is needed then ICL7107 ampere meter would have to sample negative not positive voltage supply. Brightness of LED displays can be varied by adding or removing 1N4148 small signal diodes that are connected in series. Use two 1N4148 diodes for higher brightness. The use of 7805 5V voltage regulator is highly recommended to prevent the damage of ICL7107 and 7660 ICs. Dot on the seven segment LED display can be also moved with addition of a dual switch as below.
10A – 100mA Resolution – 99.9 A
5A – 10mA Resolution – 9.99 A
2A – 1mA Resolution – 1.999 A
Calibration
Use 10K potentio-meter to set the reference voltage between ‘PIN 35’ & ‘PIN 36’ of the ‘ICL7107 IC to 1V.
Seven Segment LED Display Of Simple Digital LED Ammeter Using ICL7107
Prototype Images
Read Also>> Digital Ammeter Circuit Diagram Using Microcontroller
