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  1. njiruk

    acoustic resistor to upshift an electret microphone maximum SPL

    @amanuensis You should take into account the acoustics of the small capsule, it will act as a compliance C so that its impedance Z = P/U = P/jωX = 1/jωC explains that displacement is proportional to pressure. @IRstuff Indeed, that's what I meant with "the dynamic range will be the same as...
  2. njiruk

    acoustic resistor to upshift an electret microphone maximum SPL

    @GregLocock I should have used the standard term instead of "dynamic threshold" indeed. But yes, I mean maximum SPL. It is just strange that: -I don't seem to find cases of people who tried/are looking for the same... -It shouldn't be too complicated to manufacture such an electret so that an...
  3. njiruk

    acoustic resistor to upshift an electret microphone maximum SPL

    Hello, At the moment I'm using an (obviously expensive) B&K microphone with a dynamic threshold at 162dB, to be able to measure the acoustic pressure inside a clarinet mouthpiece. As I'm considering to move on to a commercial application I'm trying to find a way to do the same with a cheap...
  4. njiruk

    Common mode choke as a regular inductor (small signals), #inductance?

    Lossy doesn't necessarily mean low Q as for a RLC circuit for example: Q=sqrt(L/C)*1/R For an equal resonant frequency (f0=1/(2Pi LC), Q increases when L/C increases, because the losses increase more slowly (also see my previous post...) !{
  5. njiruk

    Common mode choke as a regular inductor (small signals), #inductance?

    OK, thanks, I guess benta's answer is the most meaningful... I'll post again if I find out the contrary!{
  6. njiruk

    Common mode choke as a regular inductor (small signals), #inductance?

    Hi, For a specific audio application (see my previous thread http://www.eng-tips.com/viewthread.cfm?qid=341157), I'm considering to use a common mode choke as a regular inductor (this one: http://uk.farnell.com/multicomp/mct25x15x15c-502nu/choke-common-mode-5mh-6a/dp/1864501) as a single...
  7. njiruk

    0.2-2uF cap with lowest ESR, concrete ESR values?

    @Comcokid : Initially I said a RLC oscillator, to keep things simple, but given the development of the post, I explained the purpose into more detail in my previous post... It is not really the Q of a single RLC, but the "modal Q-factors", so the ESR and the inductor's DCR becomes independent...
  8. njiruk

    0.2-2uF cap with lowest ESR, concrete ESR values?

    @BrianG: that's right, as in a simple RLC-circuit R=ESR+DCR... However, I'm actually building a "discrete audio transmission line", where various frequencies will travel through, here the resistive part of the capacitor becomes important, especially at high frequencies.
  9. njiruk

    0.2-2uF cap with lowest ESR, concrete ESR values?

    That sounds great! They even appear to be not that expensive... ESL is still high enough indeed. I didn't find ESR information though. Generally the dissipation factor @ 120Hz is specified. Logically I can presume ESR = tan(d)/(2*pi*120*C), right? Strange, when I compare ESR at 120Hz and the...
  10. njiruk

    0.2-2uF cap with lowest ESR, concrete ESR values?

    The piezo-electric effect, I see... Well, I guess that's not a big concern as it's a test that I can perform in silent and "hissless" conditions... I'd think paralleling caps gives the same results as taking a similar type of twice the capacity, no? But, should I opt for MLCC's rather then...
  11. njiruk

    0.2-2uF cap with lowest ESR, concrete ESR values?

    @ScottyUK: Your question makes sense... -size is not of importance. -voltage rating and current handling neither, as I can use the oscillator at any amplitude. -I'd like not to surpass 3€/piece @itsmoked: the sanyo os-con's look interesting indeed, but I'm curious about the specs of ceramic...
  12. njiruk

    0.2-2uF cap with lowest ESR, concrete ESR values?

    Hi, I'm looking for a capacitor between 0.2 and 2 uF with ESR as low as possible. Electrolytic polymer capacitor's are not available for such low capacities, and I found several sources stating that ceramic's would have lower ESR. This page...
  13. njiruk

    Quest for an electrovalve acting at audible frequencies

    Thanks for your responses! @MikeHalloran The air supply is fed to the exterior of the tube, however, I think the problem is similar to the inverse case, so the remarks you gave about the inverse case also apply here. It should be mentioned that the proposed construction is meant for a...
  14. njiruk

    Quest for an electrovalve acting at audible frequencies

    For a musical acoustic application we would need a very fast linear proportional 2/2 way air electrovalve that acts at audible frequencies with a minimal phase lag. The valve capacity should be at least: 5 l/min, the response time should be smaller than 0.5 ms and hysteresis should be smaller...

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