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74LS90 act like 4017 counter

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Ald

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How can I configure a 74Ls90 to act like a 4017 decade counter. I don't want BCD out want one single pulse per clock, I only need to count to 4.
 
Hi Ald,

the SN74LS90 is a binary counter while the CD4017 is a decimal counter.

To count from zero to 4 the outputs of an LS90 are:
0000, 0001, 0010, 0011, 0100.

It's easier to make the CD4017 count to four by resetting it at count five. Connect Q4 (count five output) to pin15 (MR) of the counter to reset it to zero.

Boncuk
 
Hi
I am doing a simulation and I don't have a model for the 4017 only the ls90, so I'm trying to work around. I can't even get the LS90 to count in BCD at the moment
 
This is what I have at the moment.
 

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You should tie R0(1) pin3 and R9(1) pin6 to ground.

Boncuk
 
Hi,

Make the connections as follows...

Put your clock to input A.
Connect QA to input B.
Connect R0(1) to QA.
Connect R0(2) to QC.
Connect R9(1) to ground.
Connect R9(2) to ground.
Take your three outputs from QA, QB, and QC.
The count will go from 0 to 4 and then back to 0 again: 0,1,2,3,4,0,1,2,3,4,...etc.
 
Last edited:
Hi again,


Ok sure, and if it doesnt work then something else must be wrong.
 
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