[quote author="PRR"]> TSB-160A http://jlielectronics.com/transsound/electrets/tsb-160a.htm
That part says it has the FET inside. Note the suggested schematic and the 0.5mA current requirement. That conflicts with Svart's description of a 470pFd cap and a 680M resistor, which sure suggests external FET. But note that Transsound's own page is self-conflicted: the schematic shows a 3-terminal capsule, but the mechanical drawing sure suggests a 2-terminal capsule? It is possible some idiot webmaster (I been one myself) cut-pasted generic info without knowing that this model is a special. And of course when Uli calls and orders a million, Transsound will be happy to do it his way, and even happier if they can use tooled-up case and terminals from an existing model. (What this may really mean: Uli can buy cheaper FETs than Transsound can....)
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It's a confusing diagram - the capsule is the part inside the dotted line, the rest is a suggestion.