Turn a battery powered Cmoy into a DC powered one... - Head-Fi: Covering Headphones, Earphones and Portable Audio

twilightrevenant · #1 (**permalink**) 09-23-2004, 02:23 AM

How do I go about doing this? I didnt make the cmoy but I know how to solder a little. The cmoy is in a mint tin can, currently powered by two 9v batteries. I know I have to get a power supply, the question is which and how. Thanks a bunch.

Juergen · #2 (**permalink**) 09-23-2004, 03:10 AM

All you would need is a 9V DC wall wart type power supply from Radio Shack for instance. Then get a DC jack that matches the power supply plug (also from Radio Shack). Take the + and - wires that went to the 9V battery and connect them to the 2 contacts on the jack. Be sure to check the polarity of the power supply plug. That's all there is to it. If you want both battery and wall power that gets a little more complicated. Hope this helps.

Earwax · #3 (**permalink**) 09-23-2004, 04:13 AM

If you're using a metal case such as a mint tin, you also need to woory about isolating the DC jack from the case. The easiest way around that is to use a 9V snap to DC pigtail. there's a picture of how to do that in jboehl's post http://www6.head-fi.org/forums/showthread.php?t=85681

Megaptera · #4 (**permalink**) 09-23-2004, 01:32 PM

For what it's worth, if you know the maximum working voltage of the caps and opamp, you can go with an adapter higher than 9V. Depending on the opamp you've got in there, that may be a really worthy thing to do.

Juergen · #5 (**permalink**) 09-23-2004, 01:50 PM

Quote:

Originally Posted by Earwax

...use a 9V snap to DC pigtail. there's a picture of how to do that in jboehl's post http://www6.head-fi.org/forums/showthread.php?t=85681

I love that solution! This way you don't have to modify the cmoy in any way and you can switch back to battery any time you want.

MrJoshua · #6 (**permalink**) 01-23-2005, 10:57 PM

Quote:

Originally Posted by Earwax

If you're using a metal case such as a mint tin, you also need to woory about isolating the DC jack from the case. The easiest way around that is to use a 9V snap to DC pigtail. there's a picture of how to do that in jboehl's post http://www6.head-fi.org/forums/showthread.php?t=85681

I have a problem with my cMoy...

I have just fitted a 2.5mm Switching Power socket to my tin and when I plug the power in, the sound stops (but the LED stays on)...

If I take the socket out of the tin (letting it dangle in free air) it works fine, just not when it's in contact with the tin...

HELP!!!

Do I need to insulate the socket from the tin? If so, why?

Magsy · #7 (**permalink**) 01-23-2005, 11:49 PM

If its like the Pimeta then the output jack is virtual ground and the casework is connecting that to dc ground through the jack - not good

I am assuming your output jack is metal, nonisulated and in contact with the tin also..

MrJoshua · #8 (**permalink**) 01-24-2005, 06:57 AM

Yes, you're correct.

I have "worked around" this by wrapping the DC socket in loads of electrical tape and making the hole in the tin slightly larger... But it doesn't look pretty

aeriyn · #9 (**permalink**) 01-24-2005, 08:41 AM

If you don't insulate a metal case from the power jack, it'll collapse the virtual ground and it won't work on a circuit that uses 2 resistors to form a VG. On amps that use the TLE2426 rail splitter, it'll fry your TLE. -.-'

MrJoshua · #10 (**permalink**) 01-24-2005, 11:03 PM

EvilFire are replacing my cMoy as I originally asked for a power socket but they accidentally missed it off my order...

NOW IS THAT CUSTOMER SERVICE OR WHAT!!!