[time-nuts] Microphonic Inductor?

SAIDJACK at aol.com SAIDJACK at aol.com
Tue Apr 13 12:49:05 EDT 2010


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!
 
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 is  available 
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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