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Common Cathode 7-Segment

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Deathshead

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What exactly does common cathode mean in terms of a seven segment display. Im trying to display numbers on a 7-segment that i placed on a breadboard . Im using a 7493 binary counter through a 7447 bcd to seven segment display decoder, but all im getting is weird readings on the 7-segment. How do i wire this?? Does the counter have to be negative edge or use a diff decoder??
 

Exo

Active Member
Common cathode means all the leds have their cathodes connected to each other and it comes out of the 7-seg as 1 single pin.

To see the connections of a 7447 see the datasheet:
**broken link removed**

As you will see in the datasheet 7447 is designed to drive common anode displays, wich is why you get strange readings

use 7448 to drive common cathodes, or buy common anodes to go with your 7447's
 

Deathshead

New Member
Thanks for that info
Also, If the 7-Seg display has 2 common cathode pins, can i just wire them together and connect them to ground or just wire both to ground?
 

Exo

Active Member
normally, they are internally connected to each other, so connect one of them, or both, it doesn't mather.
 
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