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Last edited by shahidali55; - 18th October 2006 at 18:21.
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I believe UDN2981 would be cheaper since you would have to use many transistors.
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"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
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Hi everyone, thanks for all your help.
I made my LED clock using transistors cause i couldn't get the UDN2981.
It works great. I added an hourly animation and a battery battery backup also ( i cant belive i'm getting more than 20 hours out of a 60mAh rechargeble battery {with display off}).
I've attached a picture of it...
Last edited by shahidali55; - 24th October 2006 at 17:50.
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Good to see something is working!
FYI: Upon the chip info above, I checked the prices.
The price of UDN2981 is around US$1.60-1.70 (for 1000s lots), which is a lot more expensive then traditional ULN2003 types.
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"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
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sayzer, It probably is but I don't think you can source current with a ULN2003.
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Yes, of course Dave.
I had no info about this UDN2981 before, but now I will consider it when the project allows me to use it (cost & hardware etc.).
Thanks for the info.
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"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
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shahidali55,Originally Posted by shahidali55
May I get your schem about the final Common Anoda display 7 segment (12 V) to me, couse i've same problem with you before.
thanks for helping ...
[email protected]
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Hi Zhao Hui.
Check post #20.
That schematic will drive the high current consumption at the common anode pin.
The individual cathodes can be driven by a single NPN trasistor buffer each.
Check the schematic below (for seperate cathode drive).
This circuit will invert the PIC inputs so dont forget to correct this in software.
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Zhao Hui and mdaweb, here is the schematic.
The display should be a common anode display.
The 9.6v input shown in the schematic should not exceed the display max segment voltage.
I have shown the connection only for the 'a' segment. The patern just has to be repeated for the rest of the segments.
I have been using this circuit for some time now. It works great.
But the operating logic is a bit different.
Logic 1 on both p.1 and p.2 will turn segment 'a' on.
p.1=1 and p.2=1 --> seg'a' on
p.1=1 and p.2=0 --> seg'a' off
Last edited by shahidali55; - 4th June 2007 at 18:06.
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shahidali55 and all you guys in this forum......... thank's alot for technical information my job almost done now...
once again thaaaaankkkkkkkkk's
pic 16F628 with 4digits (10 inc) 7seg 12 Volt
zhao hui
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