Woo hoo. First post!
Getting to the point,
I have some parts I am recycling into a microphone ...
-Old steel Mic body (with XLR jack output)
-Electret Capsule from old cassette recorder (nice tone)
-SPST push-button switch
-Blue LED diode (1.5-2v drop at 80mah)
-box of various cap's and resistors
Goal ...
-A very simple, low parts count vocal microphone.
-All the components must fit inside mic body (hence low part #)
-When SPST switch is thrown, phantom power runs both the
capsule and LED (which indicates 'power on').
-No clipping with power up/down of switch!
Where I am at?
Well, after playing rubix cube with the parts I have got, I have arrived at something I don't understand at all (*cough* newb here *cough*)... The diagram below provides me with clear quality audio, with absolutely no clip when shorting/switching the SPST.
Any clues how this supply's good audio with no connection to ground?
Would it be possible to add the LED in somewhere (have tried a few different routes only to also add the 'clip' - which must be avoided)?
Layout your harshest critiques ... That is what I came here for!
Thanks.
Getting to the point,
I have some parts I am recycling into a microphone ...
-Old steel Mic body (with XLR jack output)
-Electret Capsule from old cassette recorder (nice tone)
-SPST push-button switch
-Blue LED diode (1.5-2v drop at 80mah)
-box of various cap's and resistors
Goal ...
-A very simple, low parts count vocal microphone.
-All the components must fit inside mic body (hence low part #)
-When SPST switch is thrown, phantom power runs both the
capsule and LED (which indicates 'power on').
-No clipping with power up/down of switch!
Where I am at?
Well, after playing rubix cube with the parts I have got, I have arrived at something I don't understand at all (*cough* newb here *cough*)... The diagram below provides me with clear quality audio, with absolutely no clip when shorting/switching the SPST.
Any clues how this supply's good audio with no connection to ground?
Would it be possible to add the LED in somewhere (have tried a few different routes only to also add the 'clip' - which must be avoided)?
An externally hosted image should be here but it was not working when we last tested it.
Layout your harshest critiques ... That is what I came here for!
Thanks.
Well. a small addition.
I can power the LED with this circuit above with no 'pop'.
Yet the switch still only activates the mic, and the LED is on constant (as long as phantom is supplied).
right way to go?
(also, moderator - if there is a better forum for this post glad to have it moved)
An externally hosted image should be here but it was not working when we last tested it.
I can power the LED with this circuit above with no 'pop'.
Yet the switch still only activates the mic, and the LED is on constant (as long as phantom is supplied).
right way to go?
(also, moderator - if there is a better forum for this post glad to have it moved)
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Why don't you look up "phantom power" for microphones. It is a well defined method of powering mics that need it.
How can this work with no connection to ground? But there IS a connection to ground - pin 1 of the microphone. And +48v is applied equally to pins 2 and 3. SO there is no voltage between 2 and 3, but they both have voltage with respect to ground. Shorting pins 2 and 3 kills the signal, and doesn't bother that "common mode" 48v on them.
How can this work with no connection to ground? But there IS a connection to ground - pin 1 of the microphone. And +48v is applied equally to pins 2 and 3. SO there is no voltage between 2 and 3, but they both have voltage with respect to ground. Shorting pins 2 and 3 kills the signal, and doesn't bother that "common mode" 48v on them.
But due to the way the phantom voltage is fed to the circuit, closing the switch doesn;t change that voltage.
SInce this is one stand alone thing, consider using a switch with an extra pole just for the LED. ANything connected to the signal lines and causing a step change in current is likely to pop. Keeping it off the signal lines reduces that risk. A small battery could power the LED for complete separation.
80ma sounds extremely high for the LED current. LEDs are still easily visible at much lower currents than their max. "80mah" I am not familiar with with respect to LEDs. mah sounds like milliamp-hours, some sort of small battery rating. Of course it wouldn;t be the first thing I hadn;t heard of that everyone else knows.
SInce this is one stand alone thing, consider using a switch with an extra pole just for the LED. ANything connected to the signal lines and causing a step change in current is likely to pop. Keeping it off the signal lines reduces that risk. A small battery could power the LED for complete separation.
80ma sounds extremely high for the LED current. LEDs are still easily visible at much lower currents than their max. "80mah" I am not familiar with with respect to LEDs. mah sounds like milliamp-hours, some sort of small battery rating. Of course it wouldn;t be the first thing I hadn;t heard of that everyone else knows.
Enzo,
That was a typo.
It is Ma, and actually the led was running 80 (max) and I have ran it as low as 3 with some dim output.
The application calls for a medium amount of light, but not bright at all.
Is there any way to create an unbalanced voltage between pins 2 and 3 so as to provide a path for the led across? Like a significantly bigger resistance on one over the other creating a voltage path (without unbalancing the overall output) ?
I might be stepping on thin ice here with all this in respect to the mixer and its on-board power.
No luck on the battery inside the microphone... not for lack of room, but for lack of anything but this spst switch.
Is there any way to branch diodes off the switch making a separate circuit, while still being controlled(if so, the battery idea might work)?
"...it wouldn;t be the first thing I hadn;t heard of that everyone else knows..."
Much of the plot line to my life man. Your not alone.
Thanks.
That was a typo.
It is Ma, and actually the led was running 80 (max) and I have ran it as low as 3 with some dim output.
The application calls for a medium amount of light, but not bright at all.
Is there any way to create an unbalanced voltage between pins 2 and 3 so as to provide a path for the led across? Like a significantly bigger resistance on one over the other creating a voltage path (without unbalancing the overall output) ?
I might be stepping on thin ice here with all this in respect to the mixer and its on-board power.
No luck on the battery inside the microphone... not for lack of room, but for lack of anything but this spst switch.
Is there any way to branch diodes off the switch making a separate circuit, while still being controlled(if so, the battery idea might work)?
"...it wouldn;t be the first thing I hadn;t heard of that everyone else knows..."
Much of the plot line to my life man. Your not alone.
Thanks.
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It appears you're re-hashing this thread from last August.
http://www.diyaudio.com/forums/parts/194283-power-led-48-volt-phantom-power.html
G²
whoa my friend.
hash or no hash, I felt this project was not the same as that posting.
While that thread has been a huge reference in learning how to go about this - it seemed right to seek knowledge on the differences in goals.
If it really is a bother to have this posting here - I implore the moderator(s) to remove it with no dread from me.
I should be more thorough in the future I suppose.
Thanks.
hash or no hash, I felt this project was not the same as that posting.
While that thread has been a huge reference in learning how to go about this - it seemed right to seek knowledge on the differences in goals.
If it really is a bother to have this posting here - I implore the moderator(s) to remove it with no dread from me.
I should be more thorough in the future I suppose.
Thanks.
I didn't mean to imply you were doing something 'bad'. I thought you might not be aware of it and quite a bit of it is in the same vein.
G²
so I have a couple of old pots, and managed to Frankenstein the back plate of one to the turn plate of the other, resulting in a variable resistor that goes from 0(short)-50k (immediately after short) - full open.
Basically like a really slowly opening manual switch.
Im wondering if this might be a way of solving my problem.
The drawing might better depict what Ive got going...
above is how the pot. is wired
What kinda circuit would might work for powering up the led and mic with pot?
I suppose the high initial resistance would minimize the 'pop'.
A sort of analog voltage ramp?
Basically like a really slowly opening manual switch.
Im wondering if this might be a way of solving my problem.
The drawing might better depict what Ive got going...
An externally hosted image should be here but it was not working when we last tested it.
above is how the pot. is wired
What kinda circuit would might work for powering up the led and mic with pot?
I suppose the high initial resistance would minimize the 'pop'.
A sort of analog voltage ramp?
after reviewing the thread mentioned pretty thoroughly
http://www.diyaudio.com/forums/parts/194283-power-led-48-volt-phantom-power-3.html
(to the point where I am starting to learn some of its content)
I have come to terms with the having to be a slight 'pop'.
Also tossed aside the the variable switch as well. Way to far off target.
I will take some photos this week and get a photo.
Just for sake.
Nothing special of course - just some parts recycling.
cheers.
http://www.diyaudio.com/forums/parts/194283-power-led-48-volt-phantom-power-3.html
(to the point where I am starting to learn some of its content)
I have come to terms with the having to be a slight 'pop'.
Also tossed aside the the variable switch as well. Way to far off target.
I will take some photos this week and get a photo.
Just for sake.
Nothing special of course - just some parts recycling.
cheers.
variable switch was a bad way of saying variable resistor/potentiometer with a built in power switch.
Ended up going simple instead, DPDT.
This was the quietest 'thud' with the limited components on hand.
works with or without phantom. good.
My friend is happy.
Thanks for all who shared their experience and previous topics.
cheers.
An externally hosted image should be here but it was not working when we last tested it.
Ended up going simple instead, DPDT.
This was the quietest 'thud' with the limited components on hand.
works with or without phantom. good.
My friend is happy.
Thanks for all who shared their experience and previous topics.
cheers.
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