Mosquito Noise Maker

Thread Starter

Razor Concepts

Joined Oct 7, 2008
214
Hi, I want to build this:
http://www.instructables.com/id/The-Raven-high-pitched-torture/

Here is the schematic:


The 4194304hz crystal, located on pins 2 and 3, is also connected to two 18pf capacitors. I looked up the details on the crystal and found that it had a load capacitance of 18pf. Is that why he chose to use the two 18pf capacitors?

I want to use a 49152941hz crystal, but in the specs all it says for load capacitance is "series".
 

SgtWookie

Joined Jul 17, 2007
22,230
Radio Shack sells an assortment of ceramic caps for around $2. It used to be that you'd get a wide variety of caps, from 1pF to 1nF. Nowadays, most of them are 1pF to 10pF.

If you picked up one of those assortments, you'd practically have a lifetime supply of 10pF caps, which would match up pretty well with your 7pF caps. The numbers printed on the caps nowadays are pretty accurate.

I think one of the RS 10pF caps with one of your 7pF caps would be a better match than two pairs of 7pF caps. The latter may be too much stress on the xtal.
 
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