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I’m trying to understand the biasing of a 2-terminal electret condenser microphone. The inner workings of a 2-terminal electret microphone are always drawn without a resistor at the JFET source. ...
#2: Post edited
by
Nick Alexeev
·
2024-10-25T15:44:17Z (4 months ago)
new tags added
- I’m trying to understand the biasing of a 2-terminal electret condenser microphone. The inner workings of a 2-terminal electret microphone are always drawn without a resistor at the JFET source. Is it supposed to be biased like a JFET in a self-bias configuration? If so, how would that work without a source resistor? Or, is there a source resistor and it’s omitted from diagrams for brevity?
-  (from [here](https://diymics.com/how-to-use-electret-condenser-microphones/#the-basic-ecm-operating-circuit) )
 (adapted from [here](https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Semiconductor_Devices_-_Theory_and_Application_(Fiore)/10%3A_Junction_Field_Effect_Transistors_(JFETs)/10.4%3A_JFET_Biasing), same in [pdf](https://batch.libretexts.org/print/url=https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Semiconductor_Devices_-_Theory_and_Application_(Fiore)/10%3A_Junction_Field_Effect_Transistors_(JFETs)/10.4%3A_JFET_Biasing.pdf))For context, the microphone which I’d like to use is Knowles EK-23133-C36. It’s a 3-terminal electret mic. I’d like to wire it in a 2-terminal (common-source) configuration, because I read that 2-terminal configuration is more sensitive at low sound pressure level.- (table on page 9 [here](https://media.digikey.com/pdf/Data%20Sheets/Knowles%20Acoustics%20PDFs/Acoustic%20Design%20Guide%202010.pdf#page=9) )
- I’m trying to understand the biasing of a 2-terminal electret condenser microphone. The inner workings of a 2-terminal electret microphone are always drawn without a resistor at the JFET source. Is it supposed to be biased like a JFET in a self-bias configuration? If so, how would that work without a source resistor? Or, is there a source resistor and it’s omitted from diagrams for brevity?
-  (from [here](https://diymics.com/how-to-use-electret-condenser-microphones/#the-basic-ecm-operating-circuit) )
- general scheme for a JFET in a self-biased configuration (adapted from [here](https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Semiconductor_Devices_-_Theory_and_Application_(Fiore)/10%3A_Junction_Field_Effect_Transistors_(JFETs)/10.4%3A_JFET_Biasing), same in [pdf](https://batch.libretexts.org/print/url=https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Semiconductor_Devices_-_Theory_and_Application_(Fiore)/10%3A_Junction_Field_Effect_Transistors_(JFETs)/10.4%3A_JFET_Biasing.pdf)):
- 
- For context, the microphone which I’d like to use is Knowles EK-23133-C36. It’s a 3-terminal electret mic. I’d like to wire it in a 2-terminal (common-source) configuration, because I've read that 2-terminal configuration is more sensitive at low sound pressure level.
- (table on page 9 [here](https://media.digikey.com/pdf/Data%20Sheets/Knowles%20Acoustics%20PDFs/Acoustic%20Design%20Guide%202010.pdf#page=9) )
#1: Initial revision
by
misk94555
·
2024-10-24T19:29:36Z (4 months ago)
How does JFET biasing work in a 2-terminal electret condenser microphone?
I’m trying to understand the biasing of a 2-terminal electret condenser microphone. The inner workings of a 2-terminal electret microphone are always drawn without a resistor at the JFET source. Is it supposed to be biased like a JFET in a self-bias configuration? If so, how would that work without a source resistor? Or, is there a source resistor and it’s omitted from diagrams for brevity?  (from [here](https://diymics.com/how-to-use-electret-condenser-microphones/#the-basic-ecm-operating-circuit) )  (adapted from [here](https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Semiconductor_Devices_-_Theory_and_Application_(Fiore)/10%3A_Junction_Field_Effect_Transistors_(JFETs)/10.4%3A_JFET_Biasing), same in [pdf](https://batch.libretexts.org/print/url=https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Semiconductor_Devices_-_Theory_and_Application_(Fiore)/10%3A_Junction_Field_Effect_Transistors_(JFETs)/10.4%3A_JFET_Biasing.pdf)) For context, the microphone which I’d like to use is Knowles EK-23133-C36. It’s a 3-terminal electret mic. I’d like to wire it in a 2-terminal (common-source) configuration, because I read that 2-terminal configuration is more sensitive at low sound pressure level. (table on page 9 [here](https://media.digikey.com/pdf/Data%20Sheets/Knowles%20Acoustics%20PDFs/Acoustic%20Design%20Guide%202010.pdf#page=9) )