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I want to make a microphone myself with the Arduino (capsule=microphone):

enter image description here

I have bought the following as microphone:

As is in the datasheet the microphone operating voltage is between 1.5 and 10 volts. The problem is how do I calculate what resistor do I use to get that voltage? I can't use it as a voltage divider (the resistor with the microphone) right?

P.S. I have resistors laying around between 10 \$ \Omega \$ until 10 M\$ \Omega \$ so that won't be a problem.

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Page 1 hints at the value - it says output impedance is 2k2 and, given that the internal transistor is a JFET and, JFETs tend to have output impedances in the 10k+ range, it can be assumed that the 2k2 is the value of the resistor needed to power the circuit.

It'll be no problem with 2k2 but, don't forget to apply a very clean supply to the device - if you use 5V then filter it with a 1kohm and 10uF RC filter before connecting the mike via the 2k2.

Of note is the microphone current specified at a maximum value of 0.5mA - this is a guarantee that the microphone won't consume anything greater than 0.5 mA under quiescent conditions.

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  • \$\begingroup\$ Good point about the RC filter! SO the 2.2k can be used as the resistor and then for example I can do 5=10*((2200)/(2200+x)) and with some rewriting x becomes 8800 ohm? The 5 is the voltage that I want to be on the microphone and 10 is the input V+. Is this 8800 correct. This is apart from the filter, but just to make it easier for myself to understand right now \$\endgroup\$ – user3892683 Oct 30 '15 at 9:12
  • \$\begingroup\$ Sorry I'm not understanding what x is or what the "10" is? I'm guess the 5 means 5 volts but why the calculation at all? \$\endgroup\$ – Andy aka Oct 30 '15 at 9:13
  • \$\begingroup\$ Sorry I wanted to make a new alinea, but that made the message go online already \$\endgroup\$ – user3892683 Oct 30 '15 at 9:14
  • \$\begingroup\$ The calculation is there, because part of the voltage drops over the resistor and part of it goes over the microphone. So I need to calculate the resistor to make sure that the voltage over the microphone is in between the 1.5 and 10 volts. Is this correct? \$\endgroup\$ – user3892683 Oct 30 '15 at 9:17
  • \$\begingroup\$ No that's incorrect. the microphone will always consume a bit less than 0.5mA in all situations when the voltage applied to the 2k2 is between 1.5 volts and 10V. Microphone specs tend to be unclear on this and your spec is just a one sheet document and is particularly bad at conveying this information!! \$\endgroup\$ – Andy aka Oct 30 '15 at 9:21

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