Quad 7-segment display

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Armagon

Member
Deal all:

Some weeks ago, I built a Quad-7segment display, I used 4 digit (18mm), the pins are multiplexed, 8 pines for segments and 4 pines for common anodes, and it work excellent, but now I tried to build the same display with a big display 25mm and the intensity is very low, Could someone explain me how can increase the intensity?

Armagon
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Mycroft2152

Senior Member
As Tim the Toolman once said. " MORE POWER!"

Post your circuit, you may be limited by the driving capabilities of your chips.

Myc
 
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inglewoodpete

Senior Member
Your circuit is incomplete. It also needs some explanation as to what is to be connected to the connectors on the left and right of the diagram.

Also note that conventional circuits "flow" from left to right. (Inputs on the left and outputs to the right)
 
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moxhamj

New Member
"The inputs are come from PIC, to Anodes and catodes"

I don't understand. Which pins do they connect to on the pic? Also I still can't read the circuit diagram. Some of those resistors look like 1k. But maybe they are 10k. If they are 150R then the circuit simply won't work properly, but without a complete circuit it is hard to advise how to fix this. You may need transistor drivers on both sides of the display. I think you might be better with different transistors - the one on the right is a low side transistor and you have it connected to 5V. I can't read the part number, but if it is a BC547 you may be better with a 557 on the high side, and 547s on the left side of the display. What does R17 do? Which is the anode of the display - is it a common anode or common cathode? I'm guessing common anode.

You can do this with 11 transistors and get lots of brightness! Is that going to be ok, or is it too many devices to solder? If not, we can look at driver chips where you get 8 drivers in one chip. Or dedicated 7 seg display chips.

As an aside, check out http://stores.ebay.com/Sure-Electronics and scroll down till you find this "1.5" Character Height 7-segment LED Information Board". $8US. Big display. But the best part is it has all the chips on board as well. Uses four 74HC164 and the information manual contains all the instructions and even some code (though it is in C). But the HC164 chips are very straightforward. Only uses two lines to clock in the data. So this could even run of an 08M.
 
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