# 7 Segment Display Help

Discussion in 'General Electronics Chat' started by syee10, Oct 10, 2010.

1. ### syee10 Thread Starter Member

Mar 26, 2010
59
0
Hi all,

I am designing a four digit 7 segment display just using IC 74LS90 decade counter and 74LS47 BCD to 7 segment driver. My question is how to link the 74LS90 decade counter together so that the four 7 segment display will show me the result?

Apr 5, 2008
19,907
4,138
Hello,

Did you have a look in both the datasheets?

You need to connect the A - D of the 7490 to the A - D of the 7447.
The 7 seg display must be connected at the a - f segment outputs of the 7447 with a 330 or 470 Ohms resistor in series to the respective segments of the display.

Bertus

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• ###### sn54ls47.pdf
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3. ### marshallf3 Well-Known Member

Jul 26, 2010
2,358
203
For 4 digits you're going to need 4 of each IC and the logic involved in driving the ICs such that the output will make any sense.

This is the basic building block for the display driver part:

later down is a question as to how to gang them.

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4. ### syee10 Thread Starter Member

Mar 26, 2010
59
0
Is the circuit in the attached Figure working? I want to get an electrical energy (kWh) output so i need a decade counter in the circuit. The input is the output frequency from VFC LM131, and i am using 74ls90 and 74ls47 and 7 segment display.

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5. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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Tht does not work tht way, seems to me it is a counter.

To measure KWH, u need a decade counter ?

Do u know what a decade counter is?

6. ### syee10 Thread Starter Member

Mar 26, 2010
59
0
I am just referring to an article that this connection is used to display the electrical energy. The input to the counter is an equivalent frequency coming out from the voltage to frequency converter VFC. I just want to know is this connection working to show the electrical energy and if yes how am i going to connect it...Thanks