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first cmoy built, working good but have some questions and need help!

post #1 of 5
7/20/10 at 5:54pm
Thread Starter 

I built a cmoy amp to use while metal detecting. i have a few cheap pair, a pair of mid range headphones and a high end pair. Here is where it gets confusing....

 

some metal detectors are set up mono and others are set up stereo?? but what gets me is ALL of my headphones work on both types but my high dollar pair there is a switch to change it if using one or the other.. for example one machine the switch has to be flipped up on the headphones, another machine it has to be switched down... first question is... why does my high dollar ones have a switch and my others dont but still work on both types of machines?

 

so here is the 2nd question... the amp works with both types of machines with different headphones BUT my headphones with the switch will not work with the amp on the machine that is mono?  I think (if possible) I need to be able to make the amp switch from stereo to mono, not even sure if I can do it but if anyone can give some ideas or clear all this up for me It would greatly be appreciated.

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post #2 of 5
7/21/10 at 9:24am

There is no real necessity, in my eyes, to make the amp any differently, if it is a mono source it will just bridge the contacts and output will be the same on both channels. 

I assume that the high end headphones have a switch to make sure that a proper connection is made between channels... dependant on the jack used (on the machine itself)  the headphones may not bridge both contacts and sound may only come out of one ear. 

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post #3 of 5
7/23/10 at 8:10am
Thread Starter 

thanks for the reply and info... your absolutely right... I had my output jack wired incorrectly and was messing with me... sounds great and works right with all my headphones now.

 

another question... since I am using it with my metal detectors would anyone know how to add a limiter switch to it to stop loud bursts from shallow, big targets?

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post #4 of 5
7/23/10 at 8:15am
Thread Starter 

DSC08824.jpg

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post #5 of 5
7/23/10 at 6:20pm

As a limiter for bursts use a simple diode limiter

 

http://coefs2.njit.edu/labmanuals/ece291/images/291-9-3.gif

 

you'll need 4 diodes, 2 for each channel, it works very well

 

cheers

FRED

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