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Tinker

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Joined: 07/11/2007
Location: Australia
Posts: 1904

Posted: 10:16pm 26 Nov 2015

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I have a requirement for a 7 segment display that shows 0-15 from a binary input.

The 74LS47 chip does 0-9 and I have been trying to use two 74LS47 chips & 2x 7 seg display to show a higher binary input than 1001, no luck.

Trolling through many posted articles & circuits on google only made this idea more confusing, is it at all possible to cascade 74LS47 chips without using many more IC's?

Any advise is welcome.

Klaus

VK2MCT
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Joined: 30/03/2012
Location: Australia
Posts: 120

Posted: 06:23pm 27 Nov 2015

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Have a look at a 74ls185 or equivalent to convert binary to BCD.
John.

Tinker

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Joined: 07/11/2007
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Posts: 1904

Posted: 12:45am 28 Nov 2015

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VK2MCT said Have a look at a 74ls185 or equivalent to convert binary to BCD.
John.

Thanks John, that would do the trick.

However, it seems its no longer available, even the TI website does not offer it for sale.
Did you buy one recently, if so, where?

Thanks

Klaus

VK2MCT
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Location: Australia
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Posted: 01:08pm 28 Nov 2015

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Never bought one.
Have you thought about using a micro.
Something like a Micromite maybe a one chip solution ?
John.

Tinker

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Posted: 01:56am 29 Nov 2015

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Thanks again John.
I know a micromite would work but as my circuit already gets the binary data from a picaxe chip that is also busy doing other things I do not want to complicate things with another microprocessor.

After trawling through the literally hundreds of relevant circuits that google brings up I found this:
http://forum.allaboutcircuits.com/data/photos/o/0/230-1233754129-0b80d412c3f18d255daa9df5b288785c.jpg

Which actually might work, it certainly looks simple enough and full adder chips are available here in Perth.

Klaus

VK2MCT
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Joined: 30/03/2012
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Posted: 02:42pm 29 Nov 2015

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Why not output data from the picaxe as BCD rather than binary ?

John

Tinker

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Joined: 07/11/2007
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Posted: 06:56pm 29 Nov 2015

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VK2MCT said Why not output data from the picaxe as BCD rather than binary ?

John

John, as mentioned above, the picaxe chip does other things which is easiest to do with binary data.
Just in case you wonder what I'm doing, I am presently converting my stand alone battery system from 24V to 48V.
With 24V I used the binary data to connect to 1 of the 8 cells at a time and sample & log the voltage at it. A single 7 segment display showed which cell was monitored with the corresponding cell voltage displayed on a DPM.

With 48V there are 16 cells so 2 x 7 segment displays are required. The common decoder/ driver chips for a 7 segment display do not allow cascading them, they show funny characters above binary 1001 inputs.

Klaus

VK2MCT
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Posts: 120

Posted: 01:22am 30 Nov 2015

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Maybe then two 'banks of 8 cells".
3 bits LSBs count from 0 to 7 (8cells) 0000 0001.. 0111 then sets MSB
1 bit (1000) selects 1 then LSBs cycle 0-7.

enough,
John.

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