Tiny Phantom Power Tester
https://tcfurlong.com/tiny-phantom-power-tester/

The title says it all. I’d like to power an led using phantom power

LEDs drop about 1.5 – 3.5 volts, depending on the type, colour, size, brightness etc. Most modern LEDs will glow quite brightly at only about 5 mA. The math is easy to calculate the value of the required series dropper resistor:

R dropper = ( Vsupply – Vled ) / Iled

eg. 48 volts phantom supply, Led drops 2 volts approx., go for 5 mA ( = 0.005 Amps)

Therefore dropping resistor = ( 48 – 2 ) / 0.005 = 9,200 Ohms.

Go for the nearest 5% preferred value, 10K Ohms, or 8.2K Ohms

The current can be easily calculated for a given resistor:

Iled = ( Vsupply – Vled ) / Rdropper

eg. ( 48 – 2 ) / 8200 = 0.0056 Amps = 5.6 mA.

You should also calculate the power dissipated in the resistor:

Power = ( Vsupply – Vled) * Iled = ( 48 – 2 ) / 0.0056 = 0.2576 Watts

So you should use a 0.5 W rated resistor for long term reliability.

QED.

What are the dangers and solution to using phantom power?

How does phantom power work? What happens when sending phantom from more than one console to a mic? What happens sending phantom down an unbalanced mic cable? Can phantom power destroy a mic?

00:00 What is phantom power?
01:57 Phantom power is high voltage, low current
02:59 Phantom measurement setup
04:21 Measuring phantom power output
04:56 Phantom power wiring
06:15 How phantom powers a condenser mic
08:43 Plug in a condenser mic an measure phantom
10:40 Dynamic mic wiring
12:23 Phantom to a dynamic mic
12:36 Dangers of phantom on dynamic mics
14:56 Phantom from two consoles wiring description
15:37 Impact on phantom when second console is connected
17:03 Test and measure phantom sent from two consoles to the same mic
18:48 Parallel vs series
20:32 Phantom and isolation transformers
21:15 Summary

48 volt phantom power that is common in pro audio can kill the sound card in your laptop or computer. Here is a quick and easy test to make sure you do not accidentally damage your valuable computer.

00:00 Intro and setup
02:14 100 meter (3 28 feet) test Shure SM58, AKG C414 and Neumann U89
04:24 800 meter (1/2 mile) test Shure SM58, AKG C414 and Neumann U89
06:57 1600 meter (1 mile) test Shure SM58, AKG C414 and Neumann U89
09:22 2400 meter (1.5 mile) test Shure SM58, AKG C414 and Neumann U89
11:46 4800 meter (3 mile) test Shure SM58, AKG C414 and Neumann U89
14:21 6400 meter (6 mile) test Shure SM58 and Neumann U89 ( I tested the C414 as well and it worked without issues, I skipped it as it performed the same as the U89)
16:21 Outro