How to Test 7 segment display LEDs with Digital Multimeter:-
STEP-1: Connect:-Digital multimeter (Testing common anode OR cathode)
DMM + probe to Common Pin ( To 5 pins in the centre see animation picture)
Connect: DMM – Probe to ‘a’ segment,
SEVEN SEGMENT FND 507 CA PDF DETAILS: 7 segment FND507-datasheet
VERIFICATION: This connection is forward bias to “a” segment LED so that ‘a’ segment will glow with low bright, LED bright changes DMM TO DMM because DMM battery type may changes with company vice.
CA= COMMON ANODE PIN ( Center pin of the Top 5 pins or Center pin of the bottom 5 pins)
If the (‘a’ Segment )LED not glow……………………………………..
VERIFICATION:– Above condition the 7 segment display Led “a” segment is common cathode or that common anode segment ‘a’ segment LED is open or short.
when testing is need to common cathode, change polarity of the multimeter probe and above result is the same.
Power supply test:- connect +5 v power supply in series with 330 ohms Resistor to common pin and Negative supply to ‘a’ segment LED cathode. The LED will glow if the testing 7 segment is common Anode or does not glow because is it common cathode or open LED or LED shorted.
COMMON CATHODE:- In common cathode type all the cathodes are connected together to get a common cathode display and it should be connected to ground.
COMMON CATHODE DISPLAY: FND 508 DETAILS: seven segment FND508-datasheet
A 7-segment indicator consist of 7-LEDs arranged and named as a,b,c,d,e,f,g the LEDs emit light (glow) when forward bias. By forward biasing different LEDs, we can see the digits from 0 -9. For example 0, the segments a,b,c,d,e,f are to be lighted up.
COMMON ANODE:- In common anode the anodes of all segments are tied together, a common anode is made available and it should be connected to 5v.
A BCD-to seven segment decoder is a combinational circuit that accepts a decimal digit in BCD and generates the appropriate ouputs for the selection of segments that display the decimal numbers.
TRUTH TABLE TO SEVEN SEGMENT
7 SEGMENT LED ARRANGEMENT A seven-segment display, or seven-segment indicator, is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot-matrix displays. Seven-segment displays are widely used in digital clocks, electronic meters, and other electronic devices for displaying numerical information.
BCD TO 7 SEGMENT CIRCUIT
HUMAN DECIMAL NUMBER=>(0-9) TO BCD=> (0000 – 1001) =>DECODER IC => 7-SEGMENT DISPLAY ELECTRONIC NUMBERS.