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Audio panel to camcorder mic input

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dean.psiropoulos(at)veriz
Guest

Posted: Wed May 18, 2011 8:00 pm Post subject: Audio panel to camcorder mic input

Looking to connect a Sony camcorder to my PS engineering model 6000 audio

panel.  An electrical engineering collegue suggested a simple resistor

network that consists of a 10kilohm in series with the signal line coming

out of the audio panel followed by a 200 ohm resistor connected across the

signal line to signal ground which is then connected to the microphone input

of the camcorder.   I presented this to the support engineer at PS

engineering and he had no comment but instead suggested I talk to the folks

at edmo.com for a cable to make this connection.  After talking to edmo

today and looking at their website it became apparent that they have no

commercially available interconnect that can perform this function.



Edmo does have impedance matching cables to connect between civil aviation

audio panels and military headsets but I don't think these will work for my

application.  Any EEs out there who work in analog audio? Any suggestions on

making something that keeps the audio panel outputs from saturating the mic

input?  The camcorder input is stereo and so is the audio panel so hopefully

whatever design comes out of this exercise can be used in a stereo

application as well.  

Specs on the camcorder mic input are as follows:  Minijack, 0.388mV low

impedance with 2.5-3.0 volts DC, output impedance 6.8 kilohms, 3.5 mm stereo

type.



Specs on camcorder also show an audio/video (?line?) input as follows:  AV

Minijack, 1Vp-p, 75ohms, unbalanced 327mV, (at output impedance more than

47kilohms), output impedance with less than 2.2 kilohms/stereo minijack (3.5

mm), input impedance more than 47 kilohms.

Specs on the audio panel outputs are as follows: Headphone impedance- 150 to

1000ohms,  Headphone output - 45 mW each headset no clipping.  Audio

distortion less than 1% at 45 mW into 150 ohms, less than 10% THD at 70mW

into 150 ohms.



Any suggestions?  Anyone know of something I can purchase off-the-shelf that

will do this with no assembly required?  Thanks.



Dean Psiropoulos

RV-6A N197DM

Flying-3 years now!

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enginerdy(at)gmail.com
Guest

Posted: Wed May 18, 2011 8:58 pm Post subject: Audio panel to camcorder mic input

My calculation is:



To dissipate 45mW into 150 Ohms:

http://www.wolframalpha.com/input/?i=45mW+%2F+sqrt%2845mW%2F150Ohms%29

I get about 2.6V 'rms'.



apply an approximate conversion factor to get rms into peak to peak:

2.6V * (2/sqrt(2))

http://www.wolframalpha.com/input/?i=45mW+%2F+sqrt%2845mW%2F150Ohms%29+*+%282%2Fsqrt2%29

And I get 3.7V p-p



To get that to 1v p-p, you need to divide it by four... or five to leave some headroom.

So, unless somebody calls me on an error, I say 10k in series, 3.3k to ground, almost like your friend says.



This would be going into the Line-in jack, and you'd need a separate divider for left and right. Alternatively, you could just bring one channel off the intercom, do the two resistors, and split the outputs to left and right.

I'd say stay away from the mic jack if you can. It just adds problems.



You'll probably still need to experiment with the volume knob on the intercom to get what you're after.



--Daniel

On May 18, 2011, at 10:52 PM, DEAN PSIROPOULOS wrote:



 	  Quote: 	
		   

 

 

 Looking to connect a Sony camcorder to my PS engineering model 6000 audio

 panel.  An electrical engineering collegue suggested a simple resistor

 network that consists of a 10kilohm in series with the signal line coming

 out of the audio panel followed by a 200 ohm resistor connected across the

 signal line to signal ground which is then connected to the microphone input

 of the camcorder.   I presented this to the support engineer at PS

 engineering and he had no comment but instead suggested I talk to the folks

 at edmo.com for a cable to make this connection.  After talking to edmo

 today and looking at their website it became apparent that they have no

 commercially available interconnect that can perform this function.

 

 Edmo does have impedance matching cables to connect between civil aviation

 audio panels and military headsets but I don't think these will work for my

 application.  Any EEs out there who work in analog audio? Any suggestions on

 making something that keeps the audio panel outputs from saturating the mic

 input?  The camcorder input is stereo and so is the audio panel so hopefully

 whatever design comes out of this exercise can be used in a stereo

 application as well.  

 

 

 Specs on the camcorder mic input are as follows:  Minijack, 0.388mV low

 impedance with 2.5-3.0 volts DC, output impedance 6.8 kilohms, 3.5 mm stereo

 type.

 

 Specs on camcorder also show an audio/video (?line?) input as follows:  AV

 Minijack, 1Vp-p, 75ohms, unbalanced 327mV, (at output impedance more than

 47kilohms), output impedance with less than 2.2 kilohms/stereo minijack (3.5

 mm), input impedance more than 47 kilohms.

 

 

 Specs on the audio panel outputs are as follows: Headphone impedance- 150 to

 1000ohms,  Headphone output - 45 mW each headset no clipping.  Audio

 distortion less than 1% at 45 mW into 150 ohms, less than 10% THD at 70mW

 into 150 ohms.

 

 Any suggestions?  Anyone know of something I can purchase off-the-shelf that

 will do this with no assembly required?  Thanks.

 

 Dean Psiropoulos

 RV-6A N197DM

 Flying-3 years now!

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tshankland(at)sbcglobal.n
Guest

Posted: Thu May 19, 2011 4:49 am Post subject: Audio panel to camcorder mic input

Here is the simple way I used when making video from my airplane. This method is good for temporary connections. Just take an extra headset and put a microphone in the earpieces, put them together and tape the whole assembly together. No impedance problems to worry about. 

 

 Tim Shankland

 

 

 Daniel Hooper wrote: [quote]    	  Quote: 	
		  --> AeroElectric-List message posted by: Daniel Hooper <enginerdy(at)gmail.com> (enginerdy(at)gmail.com)



My calculation is:



To dissipate 45mW into 150 Ohms:

http://www.wolframalpha.com/input/?i=45mW+%2F+sqrt%2845mW%2F150Ohms%29

I get about 2.6V 'rms'.



apply an approximate conversion factor to get rms into peak to peak:

2.6V * (2/sqrt(2))

[url=http://www.wolframalpha.com/input/?i=45mW+%2F+sqrt%2845mW%2F150Ohms%29+*+%282%2Fsqrt2%29]http://www.wolframalpha.com/input/?i=45mW+%2F+sqrt%2845mW%2F150Ohms%29+*+%282%2Fsqrt2%29[/url]

And I get 3.7V p-p



To get that to 1v p-p, you need to divide it by four... or five to leave some headroom.

So, unless somebody calls me on an error, I say 10k in series, 3.3k to ground, almost like your friend says.



This would be going into the Line-in jack, and you'd need a separate divider for left and right. Alternatively, you could just bring one channel off the intercom, do the two resistors, and split the outputs to left and right.

I'd say stay away from the mic jack if you can. It just adds problems.



You'll probably still need to experiment with the volume knob on the intercom to get what you're after.



--Daniel

On May 18, 2011, at 10:52 PM, DEAN PSIROPOULOS wrote:



        	  Quote: 	
		  --> AeroElectric-List message posted by: "DEAN PSIROPOULOS" <dean.psiropoulos(at)verizon.net> (dean.psiropoulos(at)verizon.net)

Looking to connect a Sony camcorder to my PS engineering model 6000 audio

panel.  An electrical engineering collegue suggested a simple resistor

network that consists of a 10kilohm in series with the signal line coming

out of the audio panel followed by a 200 ohm resistor connected across the

signal line to signal ground which is then connected to the microphone input

of the camcorder.   I presented this to the support engineer at PS

engineering and he had no comment but instead suggested I talk to the folks

at edmo.com for a cable to make this connection.  After talking to edmo

today and looking at their website it became apparent that they have no

commercially available interconnect that can perform this function.



Edmo does have impedance matching cables to connect between civil aviation

audio panels and military headsets but I don't think these will work for my

application.  Any EEs out there who work in analog audio? Any suggestions on

making something that keeps the audio panel outputs from saturating the mic

input?  The camcorder input is stereo and so is the audio panel so hopefully

whatever design comes out of this exercise can be used in a stereo

application as well.  

Specs on the camcorder mic input are as follows:  Minijack, 0.388mV low

impedance with 2.5-3.0 volts DC, output impedance 6.8 kilohms, 3.5 mm stereo

type.



Specs on camcorder also show an audio/video (?line?) input as follows:  AV

Minijack, 1Vp-p, 75ohms, unbalanced 327mV, (at output impedance more than

47kilohms), output impedance with less than 2.2 kilohms/stereo minijack (3.5

mm), input impedance more than 47 kilohms.

Specs on the audio panel outputs are as follows: Headphone impedance- 150 to

1000ohms,  Headphone output - 45 mW each headset no clipping.  Audio

distortion less than 1% at 45 mW into 150 ohms, less than 10% THD at 70mW

into 150 ohms.



Any suggestions?  Anyone know of something I can purchase off-the-shelf that

will do this with no assembly required?  Thanks.



Dean Psiropoulos

RV-6A N197DM

Flying-3 years now!



    	
   

  	
 [b]

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rjquillin

Joined: 13 May 2007
Posts: 123
Location: KSEE

Posted: Thu May 19, 2011 8:38 am Post subject: Audio panel to camcorder mic input

On 5/18/2011 20:52, DEAN PSIROPOULOS wrote:

 	  Quote: 	
		   Looking to connect a Sony camcorder to my PS engineering model 6000 audio

 panel.

Is the camcorder going to be connected to ships power?
	


Consider seriously using a small transformer to match/couple between the 

two devices.



Roll your own or perhaps something like this...



http://www.bhphotovideo.com/c/product/750963-REG/Sescom_LN2MIC_ZMH4_MON_3_5mm_Line_to_Mic.html



Ron Q.

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Tim Olson

Joined: 25 Jan 2007
Posts: 2879

Posted: Thu May 19, 2011 12:55 pm Post subject: Audio panel to camcorder mic input

I had this problem recently when I tried to do the

same thing.  I built the simple resistor network

with one on the signal and then the one to ground

and such, as was the common solution.  I tested it

at home and while it did work, it induced noise

into the system with a portable intercom.  Not sure

exactly why.

But, as a fluke, I tested just attenuating it with

a resistor only on the signal wires Left and Right.

I used a 1.5Meg and also tried 2Meg resistors, just

in series with the signal wires, nothing on the

ground.  That actually worked out perfectly well.

It works pretty good with my PMA8000BT, which

I can't imagine would be different than the

PMA6000.  So you may want to give that a try...if

that works well enough, you'd be done real quick.

Tim Olson - RV-10 N104CD

On 5/19/2011 11:33 AM, Ron Quillin wrote:

 	  Quote: 	

 On 5/18/2011 20:52, DEAN PSIROPOULOS wrote:

> Looking to connect a Sony camcorder to my PS engineering model 6000 audio

> panel.

 Is the camcorder going to be connected to ships power?

 Consider seriously using a small transformer to match/couple between the

 two devices.

 Roll your own or perhaps something like this...

 http://www.bhphotovideo.com/c/product/750963-REG/Sescom_LN2MIC_ZMH4_MON_3_5mm_Line_to_Mic.html

 Ron Q.

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