I have put together the Chaney Sound Organ (http://www.electronickitsbychaneyelectronics.com/prodinfo.asp?number=C7025) and replaced the microphone input with a rca plug.

I tested this with a sansa audio player (battery operated) and it worked fine.

However, when I use a splitter with the audio player -- and have the other side of the splitter going to an amplifier, I trip the reset in the power strip that is powering both the amplifier and the sound organ. Is this some sort of ground loop, or some sort of feedback? And if so, do I isolate the two systems?

Thanks in advance

  • \$\begingroup\$ I'm going to take a wild guess, just looking at the photo on the included link. It has (what looks like) a polarized US AC plug soldered to a transformerless circuit. I'm thinking that you soldered the cord backwards so that the circuit's ground it actually connected to the AC hot. This is a very dangerous situation. In fact, I'd go so far as to say that this kit should not be sold! The fact that the web site warns that "knowledge of AC safety is required" is not sufficient; the notice doesn't know really what that means. \$\endgroup\$ – DoxyLover Nov 20 '14 at 5:58
  • \$\begingroup\$ The plug is polarized, and I've validated that the polarization is correct. This kit worked fine with the microphone and even worked with a battery operated music player \$\endgroup\$ – gec Nov 20 '14 at 6:19
  • \$\begingroup\$ Is there a schematic of the Sound Organ anywhere? I didn't see one on that web-site. I suspect that something in the organ isn't properly isolated from the mains, and connecting it up as you described is linking AC neutral with AC earth (ground). This will trip an RCD. \$\endgroup\$ – John Honniball Nov 20 '14 at 9:44

According to the linked page, it's designed to operate from its own microphone, thus providing isolation from the audio source via the air. Connecting it to anything else directly is potentially dangerous. (Even if the polarity is correct, it may connect "live" to your precious stereo should one of its components fail short-circuit...)

To connect it to any other device you need to provide isolation : the simplest way is via an audio isolating transformer. That one is fairly expensive, designed for professional audio, but its flying leads make it easy to connect up. This one is probably adequate for your needs if you can make a small PCB to connect it up.

  • \$\begingroup\$ Thank you. I am concerned about the 600 ohm impedance would prevent much of the mp3 player signal from getting through. Should I use one with a lower impedance instead? \$\endgroup\$ – gec Nov 27 '14 at 6:25
  • \$\begingroup\$ It should be fine. Indeed as it's replacing a microphone it may provide too much signal. \$\endgroup\$ – Brian Drummond Nov 27 '14 at 10:23
  • \$\begingroup\$ Thank you, I will find an equivalent part in the US and give it a shot! \$\endgroup\$ – gec Nov 27 '14 at 16:58

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