XTAL oscillator with a XOR gate
			 
			 
			
		
		
		
			
			[Slightly off-topic request] 
 
Hi. 
As of the other post of mine, another part of my weekend was spent 
trying to get a XOR gate to oscillate with a XTAL. 
 
I have a working 74HC14 oscillator: 
"One gate of a 74HC14. 470ohm resistor from gate output to the parallel 
of 1Mohm//XTAL. 10pF and 33pF (from the junkbox) capacitors to ground on 
each side of the XTAL." 
 
Since my project calls for a frequency doubler, which I want to 
implement with a XOR gate, I wanted to use one XOR gate of a 74HC86 as 
oscillator. Remaining gates would work as buffer, delay line, digital mixer. 
 
(I have Googled newsgroups and found an interesting discussion about XOR 
frequency doublers, so I am aware of its limitations.) 
 
So I moved the oscillator circuitry (R; C; R, XTAL; C) from the 74HC14 
to the 74HC86, pulling the other input of the XOR gate to "1", so that I 
would produce an inverter. 
 
Nothing happens. I used a 10.0 MHz XTAL. 
 
I understand that the 74HC14 has Schmitt trigger inputs and that a 
74HC86 might have higher propagation delays. Still, is it possible to 
use a XOR gate as an inverter and oscillator? Do I overlook something? 
 
In the end I recovered the 74HC14 oscillator, but this adds one 
component to the final circuit I have in mind that wastes energy, space 
and is underutilized. 
 
Looking forward to your always helpful replies! 
Paolo IK1ZYW 
 
		 
		
		
		
		
		
		
		
		
	
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