Need help with 7 segment display, ULN2x03

neoteric

OK, I researched and researched, and I just cant get it.· I just cant find the solution....· I am no Electrical Engineer, but I thought I knew how to do this.

I have several large size 7 segment displays.· I have one display working.· I want to use a bs2p.· The 7 segments are common anode, 15v, so the segments are common.··I'm driving the segments with ULN2803.·What do I use to turn off the displays I want off?· My thought was to rapidly rotate through the displays so they all "appear" to be on at the same time...

I did figure out how to do this with a common cathode and a 7 segment IC, but the large ones I have are common anode.

Any help is appreciated.



THANKS!!

PJAllen

The 2803 pin 9 needs to go to GND, not to +15 as you've shown.

You will need a limiting resistor between·each 2803 output and the segment it's connected to.

neoteric

PJ, yes, thank you.·Thank you SO MUCH!·I misdrew it.· (Shockingly--pun intended--, the simulator runs this model correctly for·one 7 segment display.)

Still trying to figure out how to cycle through the 7 segment displays, since they are common anode and I can't use the max7219...· maybe h bridge?

David H.

neoteric,
You could use an inverter IC, and you would wire them like a common cathode, because the signal will be inverted.
Good luck.

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David


There are 10 types of people in this world,...
Those that understand binary numbers, and those that don't!!!

PJAllen

neoteric and I got this working this afternoon via P-M.

Attached are the schematics.

Hopefully, neoteric will share his program and knowledge will increase.

neoteric

10 Cheers to Mr. Allen for his tremendous amount of help teaching me this.·· My ultimate goal is to have a readable display of the temperature in my Kiln, which is in the back of my yard.· Because it gets dang cold in the winter walking the distance to see what the temperature of the Kiln is.

Attached is code that runs through 0-99 on a 7 segment display.

kingspud

Hello guys,

I set this circuit up and used the source code but all I get are the entire digit lighting up.· Meaning I get an 8 that flashes on and off.

Is my circuit correct or am I missing something?

Could you please show the entire circuit?

Thanks


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“Intellectual growth should commence at birth and cease only at death”
Albert Einstein

Forrest

Don't see the 1K inline resistors shown on the hand drawn schematic.

PJAllen

kingspud,

in re. Could you please show the entire circuit?

The schematics are complete (nothing has been withheld.)

kingspud

The way proteus works you don't need the 1K resistors to make the circuit work or have any affect on the display.

What I meant by "can you provide the entire circuit"... can anyone provide a complete, working circuit diagram of the 12V seven segment display!

Thanks



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“Intellectual growth should commence at birth and cease only at death”
Albert Einstein

PJAllen

I don't know from "proteus".· If you build the circuit, the resistors are required.

The circuit for the "12V display"?· I guess what you're asking for is a pin-out of the 7-segment display/s.· These vary, there isn't a standard pin-out arrangement for 7-segment displays, every manufacturer does his own thing.

So, what to do?
Well, to find out what you've got, I outlined a process-of-elimination procedure to pin-out your display/s --
http://forums.parallax.com/showthread.php?p=705685

Post Edit -- As you're probably using some circuit simulator, I guess you may have to wing it and use separate LEDs (with their anodes tied together), arranging them in a "7-segment fashion."

Post Edited (PJ Allen) : 4/8/2008 2:44:09 AM GMT