Mic MUTE with Led/Phantom Power

[Buffalo Tom]

Here is what I'm trying to do. Its a mute switch (4PDT) that mutes a microphone and a piezo pickup. When muted LED should light up with power from the phantom supply. Its important that the pedal only draw power in MUTE mode. The difficult part is how to use the phantom power for the LED?. And without poping noice and other problems. This is my first idea. Haven't tried it yet. Am I on the right track? Its the phantom power part that worries me..

[PRR]

Looks like your input is shorted-out ALL the time.

Draw it out withOUT regard for how you will put it on terminal strip. Then "ooops" like this may be clearer.

There is no way you need a 3 Watt resistor in Phantom Power. Only 480mW is allowed, you can't possibly pull over 677mW and then it is all in the console resistors, not your stuff. The max power a Phantom device can actually use is 170mW.

You steal DC from Phantom by tapping *both* lines, 2 resistors.

[Buffalo Tom]

Looks like your input is shorted-out ALL the time.

Draw it out withOUT regard for how you will put it on terminal strip. Then "ooops" like this may be clearer.

There is no way you need a 3 Watt resistor in Phantom Power. Only 480mW is allowed, you can't possibly pull over 677mW and then it is all in the console resistors, not your stuff. The max power a Phantom device can actually use is 170mW.

You steal DC from Phantom by tapping *both* lines, 2 resistors.

Thanks! So I added a pair of 100K resistors for tapping the DC power. Will this work? Or is the input still shorted all the time? The other pair 300R is being used only for the audio mic mute circuit. They are not connected in this drawing but you see in my first post how I'm using them. How about wattage on the resistors? Can I use standard 1/4 watt? Need some help to calculate it. Im using this LED http://docs-europe.electrocomponents.com/webdocs/1386/0900766b81386f34.pdf

[PRR]

> 100K resistors
> How about wattage

You need to tap Phantom from the Output (the mixer), not the mike.

You should model Phantom as two 6.8K resistors from 48V.

You need to learn Ohm's Law.

You will need to pick an LED current. The 20-30mA numbers on the specsheet are not available on Phantom. However most modern LEDs will be very bright with much less. 2mA may be a fine number.

I'd draw; but I have cabinets coming this morning so it will be a while.

[Buffalo Tom]

You need to tap Phantom from the Output (the mixer), not the mike.

Oooups. That was a misstake.. Of course it should be on the mixer end.   

You need to learn Ohm's Law.

I know! Did a new schematic (just the power tap).. It looks like this now. If I got it right it should give me 3.6mA for the LED and the voltage will drop to around 36V when muted.

[PRR]

DC to light the LED will not go "through" that capacitor.

I'm not sure why the 2K is needed in this case.

Yes, 3.6mA may be fine for the purpose with that LED aimed at the user.

[Buffalo Tom]

DC to light the LED will not go "through" that capacitor.

Yes I saw that now.. Will be corrected. Time to wire up and try this now... Thanks for your help.

[mck]

No cap used in this drawing...
Does it seems ok to you ?

[PRR]

> Does it seems ok to you ?

That plan turns the microphone OFF (no power). When it comes ON again, does it come up smooth and quick? Or with a delayed pop? There are so many different ways to design phantom mikes, who knows? (It seems safe to Try It, but with loudspeakers turned-down to whisper.)

[ilcaccillo]

This seems like a better circuit to mute the mic.

Just need to add the led and taping resistors.

[ilcaccillo]

This is a similar circuit,
PPR do you think the supply for the LED could be tapped with 2 resistors but also have ramp up circuit in order to avoid clicks and pops when switching?

Thank you so much