Maker Pro
Maker Pro

Crystal Oscillator

eptheta

Dec 20, 2009
188
Joined
Dec 20, 2009
Messages
188
I found this diagram off the net for a generic oscillator IC.
ipaAF

I'm using the 4060 and i have a crystal of 2.4576MHz.
I tried with Rf=15Mohm, R1=330k, C1=39pF, C2=10pF , (trying to make it work like the 32.768kHz one--which worked by the way), but they don't work with the 2.4576Mhz crystal.

I can't find any references for the right values. Could you point me to equations or tell me what values for the resistors and capacitors I should use ?

Thank you.
 

Resqueline

Jul 31, 2009
2,848
Joined
Jul 31, 2009
Messages
2,848
For starters, a 39pF cap has an impedance of 1661 ohms at 2.4576MHz so clearly R1 must be lower than this in order to retain the gain factor needed to sustain oscillation.
C2 should also usually be larger (22-39pF). The value is something the xtal manuf. specifies. It can be made adjustable around this value for fine frequency adjustments.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
This contains lots of handy hints.
 
Top