Need help about 38khz Oscillator

[Waldo Pulanco]

Hi Im here again! can i ask about 38khz crystal oscillator.
what CMOS can i use to oscillate the 38khz crystal and the output is 38khz and 19khz?

CMOS 4060 is complicated because there is no divide by 1! bacause i need is 38khz and 19khz with 38khz crystal. if i use 4020 there is no divide by 1 but have divide by 2 so the out is 19khz below no 38khz output and there is no oscillator.

is there any cmos that have an oscillator to oscillate the 38khz crystal and the output is 38khz and 19khz?

thanks!!

 

[Waldo Pulanco]

i think it can be use to CMOS CD4060 with 38khz crystal! the output for 19khz is pin #7 how about the 38khz output can i use pin #9 or #10?

thanks!!

 

[ronsimpson]

Use the CD4060.
I can get crystals at 16.384mhz, 8.192mhz, 4.096mhz, and 2.048mhz.
All of which will work with the 74hc4060 (faster version) and by using Q4,5,6,7,8,9,10 you can get the two frequencies you need.
The CD4060 will not work well above 3mhz at 5 volts.

16.384mhz crystal use Q9 and Q10 divide by 512 and 1024

 

[Waldo Pulanco]

i think there is no available for 16.384mhz crystal in my location!!

 

[jpanhalt]

Hi Im here again! can i ask about 38khz crystal oscillator.
what CMOS can i use to oscillate the 38khz crystal and the output is 38khz and 19khz?

CMOS 4060 is complicated because there is no divide by 1! bacause i need is 38khz and 19khz with 38khz crystal. if i use 4020 there is no divide by 1 but have divide by 2 so the out is 19khz below no 38khz output and there is no oscillator.

is there any cmos that have an oscillator to oscillate the 38khz crystal and the output is 38khz and 19khz?

i think there is no available for 16.384mhz crystal in my location!!

Which is it, MHz or KHz? Divide by 2 is easily done in the KHz range.

John

 

[dr pepper]

Pilot and carrier frequencies for an fm stereo transmitter?

As mentioned the 4060 has a o/p for x1, os long as the loading on that pin is constant it'll work.

 

[Waldo Pulanco]

yes for fm stereo coder!! There are many cmos that can get 38khz but the problem is the crystal, in my location the crystal is limited!!

 

[Waldo Pulanco]

sorry double post!!

 

[dr pepper]

Watch crystals use 32.768 kc, you'll be able to pull one a little bit, but still might not get close enough.
1.2mc gets you 37.5 kc, with a little pull maybe closer
2.4576mc (uart xtal) gets you 38.4kc maybe even closer pulling it as much as you can, probably close enough for a pll receiver which most are these days.

 

[jpanhalt]

If you need the stability of a crystal, then you need a crystal. If you don't need that level of stability, then just use a relaxation oscillator. They can be made with a LM555/NE555, an inverter, or a Schmitt inverter.

Here's a good description of the latter two: https://www.fairchildsemi.com/an/AN/AN-118.pdf

John

 

[WTP Pepper]

If you have access to microprocessors then these tones can be easily generated by an on chip auto-preloaded timer interrupt by directing the output of a timer to an IO pin.
I have done similar with a SiLabs C8051F321. With it all being in hardware there is miniscule phase jitter.
Just choose your crystal ~ 8MHz and a suitable preload value.