Scott Fraser <> wrote:
>
> <<Yep, the 48 V phantom power scheme is actually a huge waste of
> energy. Assuming that the 48 V phantom power voltage provided by the
> recorder is regulated down to 5 V inside the microphone,>>
>
> Can we actually make that assumption overall?
Sure, there might be microphones that use higher internal voltages.
> << then only about 10 % of the provided energy is actually used to
> power the microphone. The other 90% is just converted into heat...>>
>
> Voltage alone is not an indicator of the amount of energy available
> for consumption in a circuit. Voltage has an inverse relationship with =
> current. Thus, if current needs are kept low, a circuit can run on a
> high voltage without drawing any more available power from the supply =
> source.
Note that the power (which determines how fast your batteries will be disch=
arged) is defined as follows:
P =3D U * I
So, the overall power consumption can be increased either (or both) by incr=
easing the current OR the voltage.
Imagine the microphone circuit draws a current of 2 mA and it's internally =
regulated supply voltage is 5 V. So, the microphone itself would consume 1=
0 mW. The current that supplies the microphone must however also pass the s=
eries resistors of the recorder and the microphone output, which means that=
the current that flows through these series resistors will cause a voltage=
drop of 48V - 5V =3D 43V. The "wasted" power is therefore 43V * 2mA =3D 86=
mW. It's just ohms law...
Regards,
Raimund
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