[time-nuts] Small quantity custom crystals

Mark Sims holrum at hotmail.com
Fri Oct 1 21:18:47 UTC 2010


This type of circuit is NOT a free running oscillator.  It is a type of blocking oscillator that generates a short,  high powered ping every second or two.  It is designed to be able to extract every bit of power out of the battery.  It can run for over a month off of a couple of button cells,  yet generate a signal detectable over a mile away while it is laying flat on the ground.  The allowable frequency bands are at 216, 217, and 219 Mhz.  Each unit must be on its own freq,  hence the need for one-off custom crystals.

Yes, it is a weird circuit and depends upon all sorts of unspecified parameters.  The components have to be hand selected and matched.  This is the price one has to pay for this sort of operation.

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-Build a free running Colpitts oscillator and get it tuned to the frequency you want.  Then, insert the crystal in series with theemitter.  		 	   		  


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