clock crystals..
- Thread starter ShambleS1980
- Start date
- Replies 10
- Views 2672
.
The outputs merge to 1 point so i dont want the feed going back up through the crystal backwards..
So diodes to stop that. and i put the switch on the input so no feed atall to 1 crystal unless its switched on..
So diodes to stop that. and i put the switch on the input so no feed atall to 1 crystal unless its switched on..
Problem there, clock output is AC, so you'll end up half-way recitfying the output. A better idea might be switched at the input and a bandpass filter on the outputs.
for a brute force approach bebeks is certainly the implementation I would chose - having more time I would use a divisor and some jumpers.
Simply put both clocks with +5 / Ground and the output clock attach to a bipol switch - remember to keep wire lenfths short - and in this instance I would humbly suggest 28 - 30 AWG wire for the clock line.
Simply put both clocks with +5 / Ground and the output clock attach to a bipol switch - remember to keep wire lenfths short - and in this instance I would humbly suggest 28 - 30 AWG wire for the clock line.
May be helpfull to point out the clock crystal is more for a FSB application rather than a cpu only..
so the clock speed dictates the speed of everything, "ram cpu excetera" Dont think that will make a huge diference but probably worth mentioning.
So general thoughts are..
constant live supplied to both crystals. then a switch on the output going back to the board,
both crystals are always live and the switch dictates which gets used, This way both crystals are seperated from eachother and i dont need to worry about diodes...
Correct?
would i need to wire a cap or 2 inline for each clock to make sure there is no V droop..
or will they work as is.
so the clock speed dictates the speed of everything, "ram cpu excetera" Dont think that will make a huge diference but probably worth mentioning.
So general thoughts are..
constant live supplied to both crystals. then a switch on the output going back to the board,
both crystals are always live and the switch dictates which gets used, This way both crystals are seperated from eachother and i dont need to worry about diodes...
Correct?
would i need to wire a cap or 2 inline for each clock to make sure there is no V droop..
or will they work as is.
hmmm you may have problems with your implementation - especially if you are looking to feed a Front Side Bus, with Oscilators - everything thing you put in its path distorts the TICK - the worst to include is a jumper / switch, the second is any length of wire.
still its worth having a crack at - just remember it may not work simply because you would need another design approach.
the above description is apt enough to make a simple circuit - perhaps a 10pf capacitor for the feed of the clocks would also help - thats to say the output has a 10pf capacitor to the switch.
still its worth having a crack at - just remember it may not work simply because you would need another design approach.
the above description is apt enough to make a simple circuit - perhaps a 10pf capacitor for the feed of the clocks would also help - thats to say the output has a 10pf capacitor to the switch.
sounds like a cap should help then. any way thnx for the input. has ben pretty helpful, and i guess il find out if it works the old fashioned way lol.
Ok..
i think i may have encounterd 2 of my biggest hurdles.
1..
the tick rate of the crystal i wish to tamper with is 27.. Which to me implies that its also controlling the video output for pal format. but never mind thats not bothering me that much as the % increase i want to get takes me to 36 which If it is controlling the video signal happily happens to be VGA 800x600 (50hz) which pal should be compatable with any way. "i hope im understanding that correctly. i have a very basic knowlage of this stuff"
now the reall issue is the price of the things..
this cant be right can it?
http://www.ebay.co.uk/itm/ABRACON-A...al_Components_Supplies_ET&hash=item3cc2a855c4
any way thats what i need but im not paying that much for one.. Any one know where i can get similar for less?
and i dont understand the 18pf that they state in ebay..
if the one i have now is 5Nf. then isnt that 5000Pf..
is 18pf even possible??
maybe im not comprehending something prety simple right here lol.
i think i may have encounterd 2 of my biggest hurdles.
1..
the tick rate of the crystal i wish to tamper with is 27.. Which to me implies that its also controlling the video output for pal format. but never mind thats not bothering me that much as the % increase i want to get takes me to 36 which If it is controlling the video signal happily happens to be VGA 800x600 (50hz) which pal should be compatable with any way. "i hope im understanding that correctly. i have a very basic knowlage of this stuff"
now the reall issue is the price of the things..
this cant be right can it?
http://www.ebay.co.uk/itm/ABRACON-A...al_Components_Supplies_ET&hash=item3cc2a855c4
any way thats what i need but im not paying that much for one.. Any one know where i can get similar for less?
and i dont understand the 18pf that they state in ebay..
if the one i have now is 5Nf. then isnt that 5000Pf..
is 18pf even possible??
maybe im not comprehending something prety simple right here lol.