[time-nuts] Microphonic Inductor?

[Joseph M Gwinn]

Said,


time-nuts-bounces at febo.com wrote on 04/13/2010 12:49:05 PM:

> From:
> 
> SAIDJACK at aol.com
> 
> To:
> 
> time-nuts at febo.com
> 
> Date:
> 
> 04/13/2010 12:54 PM
> 
> Subject:
> 
> Re: [time-nuts] Microphonic Inductor?
> 
> Sent by:
> 
> time-nuts-bounces at febo.com
> 
> Hi there,
> 
> I do have space on the PCB, but I am worried that the ceramic 
> as well as ferrite cores both are sensitive to vibration.
> 
> I will try Joe's idea of using a doorbell buzzer to introduce 
> vibration. 
> It's not easy to generate 1KHz vibration without professional 
> (and heavy) equipment :)
> 
> Another suggestion was to put the part on a scope, and lightly 
> tap it, to see any variations in voltage.
> 
> It's time to experiment.
> 
> If anyone knows a good inductor-series (leaded or smt) that is 
> known-insensitive to vibration please let us know!

Air wound coil potted in wax.  Or soft epoxy.  You can make your own, if 
it comes to that.


Joe

 
> Thanks,
> Said
> 
> 
> In a message dated 4/13/2010 06:34:53 Pacific Daylight Time, 
> wpxs472 at gmail.com writes:
> 
> Said,
> I assume you are using something like the Coilcraft 0603 LS  series 
which
> seem to have ferrite cores. You might want to try a 0805 size  part 
since
> that inductance is available in the CS series which are ceramic  only. I
> don't know if size constraints prohibit using an 0805 but you 
> can  try one 
> to
> see if the inductor is the problem.If you must use a 0603, you might try
> massaging the filter impedance so you can use a 390 nH which isavailable 

> in
> 0603 size with a ceramic core. Then, you will either have to 
> put up with a
> mismatch or include some impedance matching components. I use 
> the LS series
> 0603s a lot and they are somewhat temperature sensitive if 
> that could be an
> issue. The ceramic cored CS series don't seem to be 
> temperature sensitive.
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