crystal with 1mohm or not?

[skyrock]

i've seen both crystal works on schematic, but what's the difference with adding a 1 meg register in between?

 

[ericgibbs]

i've seen both crystal works on schematic, but what's the difference with adding a 1 meg register in between?

hi,
The resistor biasses the invertor input to its 'centre point' voltage and the invertor is then used an amplifier, to amplify the xtal osc.
Often PIC's etc have an inbuilt high value resistor, thats why you dont need to add one.

Is that what you mean.?

 

[skyrock]

yes, that's exactly what i mean. Thanks.