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accurate 4.194304Mhz source

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roykyn

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4.194304 crystal+clock

i need very accurate 4.194304 Mhz source...i am using crystal for that.....now i dont know the exact value of the parallel(shunt) capacitors for stabilization.
is there any other method....cos i dont want to use tcxo....
AND i am using pic16f72...wat is the best suited configuration bit XT or HS (for 4.194304Mhz)
can any one tell me wat hapns when i select XT or HS





sorry for tat i mean too many QQQQQS
 

crystal oscillator 4.194304

If you need exact and stable frequency generator you can use off-the-shelf 4.194304 crystal and HA7210 low power crystal oscillator ..
This IC (see its data sheet at: http://www.ife.tugraz.at/datashts/Harris/ha7210.pdf) allows you to fine tune frequency .. see picture below ..

Regards,
IanP
 

4.194304

WOW!!!!! tat was amazing....but it looks like the same ckt the one inside the microcontroller....only the balancing method and the values will help.....any way its a hard to get ic but i ll promise to find one....
SO ANY OTHER METHODS.....
 

Can you clarify "very accurate" and other special requirements you may have such as tempco, cost, size, and power consumption?

Maybe you could use an oscillator instead of a crystal. You may need to buy one that's custom cut to your required frequency, or use a programmable oscillator (beware higher phase noise).
 

i have built a frequency counter using microcontroller...it uses 4.194304Mhz crystal....
i did check the freq using oscilloscope....the last 3 digits will vary.....sometimes it use to become 4.195 or 4.193....as u can see it is a low cost..app..i cant use an oven controlled crystal for this(toooooooooooo costly toooooooooooo).....
 

Your crystal oscillator is probably more accurate and less jittery than the oscilloscope's frequency measurement. Check your oscilloscope owner's manual.

How much accuracy do you need? The DigiKey catalog (USA parts dealer) shows an Abracon oscillator with 30ppm stability for under two dollars US. The frequency is 4.00 MHz, but maybe you could adjust your software to compensate.

Many years ago, I discovered that I had a very good frequency reference already sitting in my room. When I tune my television set to a major network channel, the set's color reference oscillator (3.57954545 MHz NTSC or 4.43361875 MHz PAL) phase-locks to the network's atomic standard. (If you start poking around inside your TV, please don't electrocute yourself!)
 

can i use a phase lock system for this...if so then how ....and how will it improve the accuracy of the system.......
(i dont know how the one in ur tv works...but its a very good concept.....all i know is that pll use rc network...the temperature effects rc network resulting in large freq sway....than the one i am experiencing)....
 

In a PLL frequency synthesizer, the RC network controls loop response, not frequency accuracy. The PLL synthesizes a new frequency based upon the input reference frequency, so the output frequency has the same accuracy as the reference frequency. However, the input and output will usually have different amounts of jitter.

By the way, low-cost programmable clock oscillator chips usually contain a crystal oscillator (fixed reference frequency) plus a PLL synthesizer that generates the desired output frequency.
 

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