What is the name and purpose of the following component?

It's a white rectangle with a S shaped thick trace on it.

enter image description here

Is it a resistor? It came from this teardown (microphone). Unfortunately, there is no information on it.

  • \$\begingroup\$ Precision current sense resistor. \$\endgroup\$ – winny Jan 22 '18 at 21:45
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    \$\begingroup\$ Which is then bodges onto the circuit removing all benefits of "precision" \$\endgroup\$ – JonRB Jan 22 '18 at 22:09

It's a very high value resistor (maybe hundreds of M to G\$\Omega\$), used to bias the capacitor microphone element.

This kind of capacitor (aka "condenser") microphone will have low frequency rolloff limited by the RC time constant of the bias resistor and the capacitance of the element.

\$fc = \frac{1}{2\pi R C}\$

See, for example, this website:

enter image description here

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    \$\begingroup\$ It seems a very un-torturous and wide path for a GΩ resistor though. What would have such low conductivity, I wonder? \$\endgroup\$ – Transistor Jan 22 '18 at 22:31
  • \$\begingroup\$ @Transistor some kind of thick film part. Actually it looks to me like it was designed to stand up to high voltage rather than the 48V of a condenser mike. Maybe what they could buy easily in low quantity with leads. You could make those in a basement with a silk screen and an oven. \$\endgroup\$ – Spehro Pefhany Jan 22 '18 at 22:34
  • \$\begingroup\$ But where is the 48V? It's a USB mic \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 22 '18 at 22:54
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    \$\begingroup\$ @TonyStewart.EEsince'75 48V is the standard condenser mic phantom power supply voltage. Unit likely contains a 5 to 48V boost converter. \$\endgroup\$ – vofa Jan 23 '18 at 0:04
  • \$\begingroup\$ 48V phantom power doesn't imply the capsule bias is 48V, sometimes it's stepped up to 60V in the mic. (When I couldn't find a Gohm resistor to make one, I found a sliver of CrO2 videotape worked nicely.) \$\endgroup\$ – Brian Drummond Jan 23 '18 at 10:26

It looks like an amateur rework job.

The part is a power resistor over ceramic substrate rated for a few watts.
Locating the specs from the OEM, Samson, it appears to be a 5V USB powered condenser mic with a headphone jack. Since many headphones are 8 ohms and this is rated for 16 ohms, I would suspect they added a series R to the mono audio driver output to prevent overheating of the audio driver. It is intended for zero latency monitoring.

enter image description here

  • 1
    \$\begingroup\$ Does not appear to be work. All images of the inside of this mic show the same (shoddy) workmanship. \$\endgroup\$ – vofa Jan 22 '18 at 23:55

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