Different case materials=different sound...ummm...explain.

[ronc]

Well SY without testing its hard to say. But looking at it from a strictly mechanical point of view if the fins are vibrating and transfering the vibrations to the chip and the chip vibrates and causes distortion then its likely(<---keyword) that vibrations of the chip causes distortion.It dosent distort when i dont finger it (hehehe) so at the moment all i have is the cause and effect to base anything on.
Having been in QC for the majority of my life i am not stating that it is the only possible answer to the question.I have learned (the hard way) that only extensive testing trying to re-create the actual in use conditions with a scientific approach to data collection is the best method.But even then there could be some factor that wasent considered.
ron

 

[ronc]

Ok yall in another chip amp forum it as brought up that a possible cause of the ringing could be the caps attached to the chip (P2P remember).
As i can state that vibrations can cause effects on caps this could be an answer.
ron
Told ya guys i was an ME type and not an EE type.LOL

 

[IanHarvey]

Well SY without testing its hard to say.

...and possibly dangerous to hypothesise too deeply.

Vibrations of a component causing gross distortion sound to me like a bad connection. Eliminating this possibility completely would be a useful first step.

Cheers
IH

 

[SY]

As things to look at, consider integrity of connections and inducing oscillations by injecting noise and stray reactances in a train of pulses. Or a bad chip. The behavior you describe is quite atypical.

EDIT: I see Ian had the same idea that I did but managed to hit the "reply" button a little faster!🙂

 

[purplepeople]

I ordered some isolated 3886's from NatSemi for first ever GC. Still haven't arrived but will report when I have results.

🙂ensen

Note to self. Start projects and finish within lifetime. 🙂

 

[ThorstenL]

Re: Re: Re: Re: What about Piezoresistive Sensors

Konnichiwa,

Have you measured/demonstrated microphonic effects in semiconductors, and if so, what's the test setup?

I did some experiments, but nothing sufficiently structured and complete. Anyway, one we get to 10ppm or lower audio measurements become an expensive game.

Does anybody make strain gauges out of semiconductors?

AFAIK - Yes.

If this works reliably, why do people still make 'traditional' ones out of basically resistance wire? I ask merely for information.

It works relaible but not neccesarily with too great accurcay. It's a question of application.

Sayonara

 

[ronc]

Actually the most common type strain gages are not even electrical.They are a one shot deal where you glue the gage onto the test object , put the load on then measure the gaps under a microscope.Dosent really work for a dynamic test though.
ron

 

[vic2]

From my days of measuring fluorescence from earthworm giant axons (yes you did read this correctly), I learned about the sensitivity of electrical components to mechanical stresses. Just bending cables would change the resistance enough to affect my data. Of course the currents I was measuring were extremely small.

Vic

 

[purplepeople]

Would the change in resistance occur only during the application of mechanical stress and then settle back down or would the change be permanent?

🙂ensen.

 

[vic2]

The resistance would settle back down. I can't say that it came back to exactly the same level. Bending any cable will cause microscopic cracks in the copper that are detectable on electron microscopy. This could affect the conductance.

It was through these experiments that I actually learned the importance of good cable construction.