Common anode or common cathode display?

[IC71]

Hello,

I am on Module 3 of my electronics 11 course, and I am on section 12: Running a 7-segment Display, lesson 39: Introducing the 7-segment Display, pages 147 and 148 in my “Electronic Circuits for the Evil Genius” guidebook . I am trying to map out the pins, but I can't tell what 7-segment LED I have. Is it a CA or a CC? I'll send pictures.

 

[KrisBlueNZ]

It would help if the markings on the display were readable! Find the part number on the side of the package, and look it up using Google or on http://www.digikey.com.

 

[Gryd3]

It would help if the markings on the display were readable! Find the part number on the side of the package, and look it up using Google or on http://www.digikey.com.

Or, if for whatever reason, you dont have the internet
You could poke and prod with the diode setting on a multi-meter.

You should be familiar enough to determine common cathode/anode based on these results.

 

[IC71]

Thanks again!

 

[hevans1944]

... You could poke and prod with the diode setting on a multi-meter.

I would poke and prod with a 1.5 V D-size dry-cell connected in series with a 100 Ω 1/4 W resistor. Some segment will light up and the reverse voltage applied by the dry-cell should not be enough to damage reverse-biased segments. You should then be able to determine if this is a common-anode or a common-cathode display. Better yet, find the datasheet and compare to that.

 

[IC71]

It would help if the markings on the display were readable! Find the part number on the side of the package, and look it up using Google or on http://www.digikey.com.

Here is a clearer picture of the part number

 

[hevans1944]

@IC71 : Nice photo! Unfortunately, a Digi Key as well as a Google search returned... nothing. Try my " D-size dry-cell and 100 Ω current limiter" suggestion to find the pins for each of the segments and the decimal point. Should take you all of a two minutes to find the segment LEDs, once you have one end of the resistor soldered to one end of the dry cell and a "test probe wire" soldered to the other end of the dry cell. Use the free end of the resistor as a "probe" while you hold the dry-cell in your hand. Let us know what you find out.

 

[Arouse1973]

I think the A might denote common cathode. Give that a try.
Adam

 

[IC71]

Thank you all for the help, the middle pin on both sides are ground, but does that mean it's a CA or is i a CC? I think it might mean it's CC, but please tell me if it is the other way around.

again, Thank you all for the help

 

[(*steve*)]

If the common pin must be negative to make the segments light up, the device is common cathode. Conversely, if it must be positive, the device is common anode.

 

[IC71]

If the common pin must be negative to make the segments light up, the device is common cathode. Conversely, if it must be positive, the device is common anode.

Thank you