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<p>Yes, it tracks vco frequency. No switchers. Power draw is low so
I don't think its the big electros. <br>
</p>
<p>btw microphonics can go both ways. It is caused by the dielectric
being piezoelectric, and that can both generate and absorb sound.</p>
<p>--tr<br>
</p>
<br>
<div class="moz-cite-prefix">On 1/22/2018 11:31 AM, Roman wrote:<br>
</div>
<blockquote type="cite"
cite="mid:1849fec8d39a42a3bf7d5b5512f112c9@grupawp.pl">Is whining
somehow related to VCO frequency?<br>
Do you have any DC/DC converter?<br>
My first guess would be the largest ceramic cap you have there.<br>
Or electrolytic capacitor run over maximum ripple specs.<br>
<br>
Roman<br>
<div><br>
</div>
<div class="nh_extra">
<p>Dnia 22 stycznia 2018 17:24 Tim Ressel <<a
href="mailto:timr@circuitabbey.com" moz-do-not-send="true">timr@circuitabbey.com</a>>
napisał(a):<br>
</p>
<blockquote class="nh_quote" style="border-left: 2px solid #999;
padding-left: 8px; margin: 0;">
<div id="gwp3b3c4a3d">
<div>Got a weird one...<br>
</div>
<div><br>
</div>
<div>An oscillator I designed is whining. Well, some units
do it. It is faint<br>
</div>
<div>and you have to have your ear right up against the
board to hear it. But<br>
</div>
<div>an end user complained so we had to investigate. Other
weirdness ensued<br>
</div>
<div>but we got the customer taken care of.<br>
</div>
<div><br>
</div>
<div>My question is: how to find where the whine is coming
from? I tried<br>
</div>
<div>using a microphone but could not pick anything up. This
is an ASM-1 type<br>
</div>
<div>VCO (saw core) so there is a pulse train present. That
could explain the<br>
</div>
<div>mic not picking it up. I tried putting my finger over
various components<br>
</div>
<div>on the board with no luck. I thought about using an
accelerometer but it<br>
</div>
<div>would have to be high sensitivity and low mass to work.<br>
</div>
<div><br>
</div>
<div>I am at a loss. Any thoughts?<br>
</div>
<div><br>
</div>
<div>--<br>
</div>
<div>--Tim Ressel<br>
</div>
<div>Circuit Abbey<br>
</div>
<div><a nh-compose-link=""
href="mailto:timr@circuitabbey.com"
moz-do-not-send="true">timr@circuitabbey.com</a><br>
</div>
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<br>
<pre class="moz-signature" cols="72">--
--Tim Ressel
Circuit Abbey
<a class="moz-txt-link-abbreviated" href="mailto:timr@circuitabbey.com">timr@circuitabbey.com</a></pre>
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