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how to convert from Phantom power 48 to about 9v? Answered

Hi does anybody know how to convert from a phantom power supply +48 to 9v to power a single circuit of a microphone pre-amp
like this one "http://circuitdiagram.net/simple-audio-pre-amplifier.html " ?    it is for an electret microphone .... thanks

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user
Re-design (author)2011-12-08

You could use a resistor to get the voltage down below +40 then use an lm317 voltage regulator chip to regulate it to +9. Not the best way but certainly the cheapest and since the current demand will be small it should work.

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maguilar7 (author)Re-design2011-12-08

ok i found this what do you think

from this site:
Voltage Divider Calculator

calculations show that 2 simple resistors as shown will work.

input = 48v
R1 = 450ohm
R2 = 100ohm
output = 8.7v

and well what kind or value should the caps be ???

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thegeeke (author)Re-design2011-12-08

It would probably work, but it's possible that you will get extra noise with this setup. (Phantom is very specific in the way it works to keep noise out of the line.

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thegeeke (author)steveastrouk2011-12-08

Ya... that would help. I'm not used to using consumer equipment that uses 9v... so I've never really had this problem. :)

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