how to check seven segment working or not using sensors?

Thread Starter

Nanda Kumar 1

Joined Aug 25, 2016
40
Hi every one.
Is there any chances to check the seven segment working or not ,with any sensor ?
 

GopherT

Joined Nov 23, 2012
7,983
@Nanda Kumar 1
Connect a 1k ohm resistor to a 9V battery and then connect a black wire to the battery (-) and a red wire to the end of the resistor that is NOT connected to the battery.

Then touch red and black wires to two pins of the 7-segment display. Connect every combination. LEDs have a polarity so they will not light up if the red and black wires are connected "backwards" so you need to test every combination in both possible polarities.

This will light only in segment at a time.

How many digits is your display and how many pins?
 

Thread Starter

Nanda Kumar 1

Joined Aug 25, 2016
40
@Nanda Kumar 1
Connect a 1k ohm resistor to a 9V battery and then connect a black wire to the battery (-) and a red wire to the end of the resistor that is NOT connected to the battery.

Then touch red and black wires to two pins of the 7-segment display. Connect every combination. LEDs have a polarity so they will not light up if the red and black wires are connected "backwards" so you need to test every combination in both possible polarities.

This will light only in segment at a time.

How many digits is your display and how many pins?
@GopherT thank you for u r clear explanation but i dont want that type i want check each segment with any sensor like LDR .
 

DickCappels

Joined Aug 21, 2008
5,760
Drive each segment according to GopherT in post #8. Take 8 phototransisotrs, each one pointing to one segment plus the decimal point if that exists. You can then "And" the outputs of the phototransistors such that you only get a true output when all segments light.

You can also do that with a video camera but it would be more difficult.
 

blocco a spirale

Joined Jun 18, 2008
1,535
Measure the current to each LED; a faulty LED is likely to draw significantly more or less current than a working one. By measuring the current in the common line it would be possible to check all the segments either together or individually.
 

dl324

Joined Mar 30, 2015
8,769
Another option is to use one optical sensor and turn on each LED separately. Position the sensor so it can "see" all segments, or use a light pipe to redirect light.
 

Thread Starter

Nanda Kumar 1

Joined Aug 25, 2016
40
Another option is to use one optical sensor and turn on each LED separately. Position the sensor so it can "see" all segments, or use a light pipe to redirect light.
@d1324 i want to check all segments in one time
 

Thread Starter

Nanda Kumar 1

Joined Aug 25, 2016
40
Drive each segment according to GopherT in post #8. Take 8 phototransisotrs, each one pointing to one segment plus the decimal point if that exists. You can then "And" the outputs of the phototransistors such that you only get a true output when all segments light.

You can also do that with a video camera but it would be more difficult.
Thank you i will try this
 

hp1729

Joined Nov 23, 2015
2,304
@d1324 i want to check all segments in one time
???
In actual operation or at the bench not connected? Single digit or multiple digit?
What are you trying to confirm? Forward voltage? brightness?
 
Last edited:

Thread Starter

Nanda Kumar 1

Joined Aug 25, 2016
40
???
In actual operation or at the bench not connected? Single digit or multiple digit?
What are you trying to confirm? Forward voltage? brightness?
i want to check multiple digits at a time like (a ,b,c,d,e,f,g pins).And Brightness
 
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