7 segment sed driver/decoder circuit help

Ive looked all over, and have already tried 3 circuits, but none work. They have either the wrong ic, wrong led display, etc. So, I want to make a circuit that, by using a decoder, I can flip 4 dip switches and make the display make certain numbers. I have a 7447 ic, common cathode led display, but I can only either find a circuit with a 7447 and a common anode, or a circuit with a common cathode but a different decoder (a latch/decoder/driver). Here is the first site I tried:


And when I finally flip the switches, nothing happens even though I made it exactly as shown. But it has a CMOS, so thats probably a big problem. I also tried this site:


But it has a common anode, and when I tried it it didnt work. I have exactly ELS321HDB. And I have a power unit that can go from 5 - 18 volts. Can anyone show me how to make this? Im not too good yet at reading circuit diagrams, because I seem to make it way more complex then it should be.

harryjri5 years ago
I've been playing with 7447 chips over the last few days, and it does seem like it is only for common anode 7 segment displays.

The allaboutcircuits.com link you list above uses a 4511 chip, which my research tells me is good for common cathode 7 segment displays.

If anyone wants to add to or discuss my answer, feel free. HTH
101yummYYummy101 (author) 8 years ago
By the way, I also have 74248 and 74347