2Mhz clock from 4Mhz crystal

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simonm
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2Mhz clock from 4Mhz crystal

Post by simonm » Sun Jun 02, 2019 12:41 pm

Hi folks, I've got an electronics question that Google hasn't been able to help me with, and I know wizards live here.

Are there any clever tricks to get a 2Mhz clock signal out of a 4Mhz crystal?

I have a project where I want to drive two chips - one at 4Mhz and one at 2Mhz but I only have 4Mhz crystals.

I'm getting the idea I need a counter chip probably (4060 maybe) but perhaps theres other options?

TIA!

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hoglet
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Re: 2Mhz clock from 4Mhz crystal

Post by hoglet » Sun Jun 02, 2019 12:46 pm

All you need is a single D-type FF:
counter-cou1.gif
counter-cou1.gif (9.12 KiB) Viewed 284 times
(https://www.electronics-tutorials.ws/co ... unt_1.html)

Dave
Last edited by hoglet on Sun Jun 02, 2019 12:46 pm, edited 1 time in total.

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simonm
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Re: 2Mhz clock from 4Mhz crystal

Post by simonm » Sun Jun 02, 2019 1:15 pm

Fantastic thanks! This looks perfect. Will an SN74LS74AN do the trick?

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oss003
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Re: 2Mhz clock from 4Mhz crystal

Post by oss003 » Sun Jun 02, 2019 1:20 pm

Just look at the Atom schematic, the CPU clock has a 4mHz crystal and an 393 to generate 1 mHz. Another output of the 393 is 2 mHz.

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Kees

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1024MAK
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Re: 2Mhz clock from 4Mhz crystal

Post by 1024MAK » Sun Jun 02, 2019 3:23 pm

simonm wrote:
Sun Jun 02, 2019 1:15 pm
Fantastic thanks! This looks perfect. Will an SN74LS74AN do the trick?
Yes, half a 74LS74, 74HC74 or 74HCT74 will do the job.

Mark

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Re: 2Mhz clock from 4Mhz crystal

Post by bprosman » Sun Jun 02, 2019 9:30 pm

The MPF-1B is one of the designs that uses this.
Clock in on pin 3, Clock/2 out on pin 6.
ClockDiv.JPG

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