Can I add an LED to the Schoeps/Alice circuit ?

[smikofficial]

Hi,guys !
I am studying about microphones.
Thank you for learning a lot from this amazing site.
I'm asking you a question because I have a question recently.

Usually, DIY microphones don't seem to have LEDs on them.

Can putting LEDs on the microphone have a bad effect on the sound quality?

Also, if you can put an LED in the Alice circuit, I want to know which part of the circuit you can add.

Thank you for reading it.

 

[Khron]

... But why?

 

[smikofficial]

... But why?

I posted the question with the thought of checking the microphone operation in the dark and thinking, "Wouldn't you be able to make a great microphone with LED?"

 

[Lampie519]

This can be done very easy here. You could replace the zener with a smaller value zener like 9v and add a led in series with this zener ( until you have reached the 12V again of the original zener value). As different color led have different voltage drop you would have to experinent a little here but 1V difference will not cause any issues.

 

[smikofficial]

This can be done very easy here. You could replace the zener with a smaller value zener like 9v and add a led in series with this zener ( until you have reached the 12V again of the original zener value). As different color led have different voltage drop you would have to experinent a little here but 1V difference will not cause any issues.

If I connect it in series with the 9V zenor, is there no need to connect additional resistance? Normally, I knew that the driving voltage of the LED was 3V. I wonder if the voltage overload of the LED occurs when 9V is applied.

 

[Lampie519]

As the zener will drop the 9V and the LED about 3v all will be fine. The resistor is already in place (6.8k).

 

[Khron]

This can be done very easy here. You could replace the zener with a smaller value zener like 9v and add a led in series with this zener ( until you have reached the 12V again of the original zener value). As different color led have different voltage drop you would have to experinent a little here but 1V difference will not cause any issues.

I was thinking of the same method actually, but without bothering changing the zener. Yes, most leds have a 2-3v voltage drop, but that's at the "usual" 20mA. At lower currents, that'll be somewhat lower (worst case 2.5v for a blue or white led), but the circuit won't mind being supplied with 14v instead of 12.

 

[smikofficial]

@Lampie519 @Khron
I would like to thank both of you for your answers. When connecting led and zenor in series, is it okay to connect
'+ LED - --- l<l zenor --- GND'?

 

[Khron]

Yes, assuming that by the "+" of the led you mean its anode.

 

[Екатерина]

This is very simple. LED can be added to all power supply lines. It can work well only by connecting appropriate resistors in series. Of course, this will also bring a certain amount of noise, which is insignificant

 

[Lampie519]

There will be no noise added in this case as it will be series with the zener (a zener is much noisier then any LED), probably will be even less noisy if you would replace the zener with only LED's until you have the voltage you like.

 

[smikofficial]

@Екатерина @Lampie519 @Khron
Thank you for your reply.

I'm using EasyEDA for simulation, so can I connect the LEDs in parallel?
When designing a PCB, I would like to design it with the pin of the LED as an option.


-Parallel


-Series

 

[Khron]

In series.

 

[Lampie519]

You can use a jumper in case no LED is populated on the board (or an other diode to get a similar voltage drop).
Placing diodes in parallel is never a good idea as one will always dissipate all the current as the other will be doing nothing (unless you use ballancing resistors).

 

[RuudNL]

If I would have a microphone with a LED inside, I would cut it out!

 

[smikofficial]

If I would have a microphone with a LED inside, I would cut it out!

really ? May I know why you think so, and why?
I'm thinking of placing the LED itself on the outside of the microphone.

 

[RuudNL]

A LED on a microphone makes it look like a cheap Chinese toy!

 

[Екатерина]

@Екатерина @Lampie519 @Khron
Thank you for your reply.

I'm using EasyEDA for simulation, so can I connect the LEDs in parallel?
When designing a PCB, I would like to design it with the pin of the LED as an option.


-Parallel
View attachment 106340

-Series

View attachment 106341

Both of them should work normally. I prefer parallel connection. The noise caused by series connection will be greater. More filter capacitors should be added nearby. I don't like to use Zener diodes here. Do you want to try resistance partial voltage here, and don't forget LED current-limiting resistors

 

[smikofficial]

Both of them should work normally. I prefer parallel connection. The noise caused by series connection will be greater. More filter capacitors should be added nearby. I don't like to use Zener diodes here. Do you want to try resistance partial voltage here, and don't forget LED current-limiting resistors

capacitor and resistor ?
@Екатерина thanks for reply.
Example.. schematic

series resistor (current -limit)and parallel capacitor (filter)?
but I'm guessing that the current in that part is very low (below 10mA). If you connect the resistance, wouldn't there be less current?

 

[Екатерина]

capacitor and resistor ?
@Екатерина thanks for reply.
Example.. schematic

series resistor (current -limit)and parallel capacitor (filter)?
but I'm guessing that the current in that part is very low (below 10mA). If you connect the resistance, wouldn't there be less current?

The common power supply parameter is 48V30ma, but now most of them are only about 20ma. In order to work stably, the current consumed by led cannot be greater than 5ma