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loss1234
Joined: Jul 24, 2007 Posts: 1536 Location: nyc
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wmonk
Joined: Sep 15, 2008 Posts: 528 Location: Enschede, the Netherlands
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Posted: Mon Sep 15, 2008 7:02 am Post subject:
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Hi!
I'm following this forum for about half a year or so, but didn't post yet.
You can divide by 12 with de 4040 (which is 12 bit ripple counter)
Same for 14 (4020) and the 4060, which is a 14 bit ripple counter with internal oscillator.
Cheers,
Woody |
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richardc64
Joined: Jun 01, 2006 Posts: 679 Location: NYC
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Posted: Mon Sep 15, 2008 10:13 am Post subject:
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Um...a 12 stage ripple counter doesn't divided by 12, it divides by 2 twelve times: 4096. _________________ Revenge is a dish best served with a fork... to the eye |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
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Posted: Mon Sep 15, 2008 11:26 am Post subject:
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richardc64 wrote: | It's quite OK to make music with tea spoons and rubber bands! |
Uh oh
Re. the Q.
I had a quick browse for an equivalent in CMOS but nothing showed up ... you can use two dividers though, one set to divide by three and another to divide by four. The 4017 would be suitable, you'd need two. For the 4017 you simply connect one of the outputs to its reset input, the output selected determines the division.
Other options would be the 4018 but that needs a bit of extra logic to make it divide by three. Or the 40103 could be used as well, for that one you set up a count on the jam inputs but it looks like it might need some logic to make it work properly. _________________ Jan
also .. could someone please turn down the thermostat a bit.
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robthefiddler
Joined: Nov 10, 2006 Posts: 16 Location: Dallas, Tx
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Mikmo
Joined: Dec 01, 2005 Posts: 150 Location: Copenhagen - Denmark
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Thu Oct 30, 2008 9:38 am Post subject:
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Does anyone know if the above 4027 divide by 3 circuit produces a 50% duty cycle output?
Also, in the divide by 3 counter diagram, there is an error. Pin 2 is shown as Q, but it should be Q-bar since it is an inverted output. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Thu Oct 30, 2008 2:02 pm Post subject:
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ScottG wrote: | Does anyone know if the above 4027 divide by 3 circuit produces a 50% duty cycle output? |
I haven't really checked it out, but I would propose that it would be impossible to divide by 3 using flip-flops and get a 50% duty cycle.
It will divide by 3 by counting to 3, so you could get 33% or 66% only. _________________ What makes a space ours, is what we put there, and what we do there. |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Thu Oct 30, 2008 2:22 pm Post subject:
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Now that you say that, it is impossible because the clocks to both flipflops are the same so the circuit cannot react except on one edge. I designed a 50% duty cycle divide by 3, but I manipulate the clock to one flop with logic to make that happen. My circuit uses 2 JK flops and an NOR gate. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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urbanscallywag
Joined: Nov 30, 2007 Posts: 317 Location: sometimes
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
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Posted: Fri Oct 31, 2008 4:07 pm Post subject:
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Great find Scallywag! _________________ What makes a space ours, is what we put there, and what we do there. |
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urbanscallywag
Joined: Nov 30, 2007 Posts: 317 Location: sometimes
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Posted: Fri Oct 31, 2008 4:47 pm Post subject:
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Thanks. I was looking into odd clock division for top octave dividers and remembered seeing divide by 3 with 50% duty cycle. The original application note I found might have been for programmable logic. |
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Mikmo
Joined: Dec 01, 2005 Posts: 150 Location: Copenhagen - Denmark
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Posted: Mon Nov 03, 2008 4:14 am Post subject:
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I just checked the Mims book that the schematics in my previuos post comes from, and it does not mention anything about the duty cycle. _________________ Stay Cool
Mikael
http://www.mikmo.dk |
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