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Author Topic: 'Clocking' a 4017 sequencer  (Read 6817 times)

phantompowers

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'Clocking' a 4017 sequencer
« on: May 05, 2010, 08:15:47 AM »

I've just built a variation on the 'Baby 10' sequencer, it's a 'Baby 4' actually, just 4 steps!
It works fine when I send it a clock signal from a 555 timer but what I'm having trouble with is syncing it to one of my keyboards.
I figured that if I ran a signal from the LED display on the keyboard, (the one that pulses for each beat of the bar), I could use that to clock the sequencer, so they'll both run in sync. But it doesn't work. Arggggh! The lights on my sequencer just flash seeming randomly and definitely not in sync. Can anyone figure out what I'm doing wrong?
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Gordonjcp

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Re: 'Clocking' a 4017 sequencer
« Reply #1 on: May 05, 2010, 09:05:11 AM »

There's a good chance that the LED is multiplexed, so it's actually getting several puilses every time.  One way round it would be to use a transistor to buffer the pulse from the LED and then a capacitor to filter out the multiplex pulses.  In many ways, what you're looking for is similar to a "debounce" circuit.
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phantompowers

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Re: 'Clocking' a 4017 sequencer
« Reply #2 on: May 05, 2010, 11:30:04 AM »

Cheers Gordon! I was hoping you'd understand and reply!
I'll do some more research now I've got something to go on.
Thanks again
Rob
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