In this simulator, crystals are modeled using
<a href="circuitjs.html?ctz=CQAgjCCsCmC0YTAJgHQAZJqWgzADmSQBYw8BOSKS6tAKAGMRi0nIA2JvPVjlslMgHYkcMERBp0aMLQA2nbknYgcODkt4SpSiQyZEWSYirzij4wyjxtBZO-Yd28oiJLTTaAJxVqeJs8osbChEtADu-kzG+AG84fqGxsx+dBHJ5uCC6sapkRlERIo5tEA">this equivalent circuit</a>.
<p>
To change the crystal parameters, you need to know the values of all
these components.  You can use the values below as a starting point
to get a crystal with a desired frequency.
<p>

<script>


function units(x) {
	 x = x.trim();
   if (x.match(/m$/)) {
       x = x.replace(/m$/, "");
  	return .001 * x;
   }
   if (x.match(/u$/)) {
       x = x.replace(/u$/, "");
       return 1e-6 * x;
   }
   if (x.match(/n$/)) {
       x = x.replace(/n$/, "");
       return 1e-9 * x;
   }
   if (x.match(/p$/)) {
       x = x.replace(/p$/, "");
       return 1e-12 * x;
   }
   
   return x;
}

function calc() {
   var cp = units(document.getElementById('cp').value);
   var cs = units(document.getElementById('cs').value);
   var L = units(document.getElementById('L').value);
   var r = units(document.getElementById('r').value);
   var fs = 1/(2*Math.PI*Math.sqrt(L*cs));
   //if (cl > 0)
   //  fs = Math.sqrt((cs+cp+cl)/(L*(cs*cp+cs*cl)))/(Math.PI*2);
   var fp = 1/(2*Math.PI*Math.sqrt(L*(cp*cs)/(cp+cs)));
   document.getElementById('result').innerHTML = "Series resonant frequency = " + Math.round(fs) +
     " Hz <br>Parallel resonant frequency = " + Math.round(fp) +
     " Hz <br>Q = " + Math.round(2*Math.PI*fp*L/r) +
     "<br><a href=\"circuitjs.html?cct=$+1+5e-11+12.050203812241895+55+5+50%0A412+112+144+192+144+1+0\\s" +
       cp + "\\s0+0\\s" + cs + "\\s0+0\\s" + L + "\\s0+0\\s" + r + "\" target=\"_blank\">crystal with these parameters</a>";
}

</script>
<form action="/action_page.php">
  Parallel Capacitor, F: <input type="text" id="cp" oninput="calc()" value="29p"><br>
  Series Capacitor, F: <input type="text" id="cs" oninput="calc()" value="0.1p"><br>
  Inductor, H: <input type="text" id="L" oninput="calc()" value="2.5m"><br>
  Resistor, &ohm;: <input type="text" id="r" oninput="calc()" value="6.4"><br>
</form>
<div id="result">

</div>

<script>calc(); </script>

</body></html>