sleemanj: Thanks, taht explains why they suggest using trailing edge dimmers with these bulbs. (That fact was originally the starting point of my investigation).
T3sl4co1l: Microphony, linearity and all sorts of that things were in the cr*p word in my description. I needed to build and test an SMD circuit very fast... but I changed my mind and tommorow I'm going to buy tantalum cap. Size A (EIA3216) fits exacly the 1206 pads I left on the board yesterday, for the 1 mike 50 volt ceramic.
And yea, the smaller the swing accross the cap, the smaller the capacity change. Cap was calculated for the cuttof to be round about 8 Hz, so the voltage acrross cap in the passband should be small enough.
I admit I have never got caught by ceramic cap microphony phenomenon. For THT, I use foil/ellytic automaticaly as needed, but I haven't done much audio stuff in surface mount. Maybe I will make an experiment. What do you suggest to use as a cercap and PCB configuration, to magnify the the phenomenon? Would be interesting and educative, to make and SMD cap microphone...
I think mechanical stress make the capacity change, so I should use some thin PCB substrate for that.. (and apply some DC bias to get the result)
Thx for replies
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