» MAKE: NOISE — Discuss this article

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• got ours working!
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  Whew! With some very timely help from the author of the article, we got ours working. Yay.
  
  Here's what's wrong with the diagrams in the article.
  
  1. The diode is backwards.
  2. There is a 3rd wire coming from the potentiometer (new diagram he sent shows the left-most pot wire going to the 1uf capacitor, middle wire going to the left 3rd-down pin on the LM386, and the right-most wire going to the 2nd-down pin on the LM386.
  3. No capacitor polarities shown on the diagram. In all cases, the positive side is on the left.
  
  After making these corrections, our stuff worked great.
  
  Also we were told that the speaker is a little weak and we would end up blowing it in just a few hours so we might want to upgrade.
  
  Finally, here is the link to a kit with the parts(maybe cut down on a little soldering!): http://www.web-tronics.com/kit-17.html
  
  (not sure if I'm allowed to link to this, but it seemed like a good option)
  

  Posted by MeganConklin on December 31, 2005 at 14:07:46 Pacific Time

• got ours working!
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  Glad to hear it's working...
  
  Somewhere along the way in the ever-mysterious publishing process, the diode and trimpot connections got reversed in the published schematic. I've posted the proper schematic here:
  http://www.onefreeminute.net/images/Make_revised_schematic.jpg
  
  Hope you all enjoy your anonymous speech!
  
  Daniel

  Posted by danielj on December 31, 2005 at 14:19:29 Pacific Time

• Thanks!
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  Thanks all for your help in finding the error and providing the revised schematic! I've posted it on our site and linked to it from an Errata you'll see on this page above.
  
  Cheers,
  t
  

  Posted by terrie on January 03, 2006 at 10:11:45 Pacific Time

• has anyone built this?
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  We just finished building this tonight and sadly, it doesn't work at all. We're in the midst of troubleshooting it right now but it doesn't look good. I was hoping to use this as a project for my university students in January, but maybe not. :(
  
  We tested all connections and they are good. One thing that seems weird is that the IC and the diode get really, really hot. Is this normal?

  Posted by MeganConklin on December 28, 2005 at 19:00:17 Pacific Time

• has anyone built this?
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  I haven't built this one yet, but I was planning on it. I think there may be a mistake or two in the picture on page 130.
  
  I was wondering if they have the diode backwards. Additionally the potentiometer looks to be wired wrong. My experience is somewhat limited, but I always thought you needed to use the center lead in-order to vary resistance.

  Posted by airampoa on December 31, 2005 at 05:46:40 Pacific Time

• has anyone built this?
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  Well, you are much smarter than I am in the electronics department, that's for sure! :) pretty much everything you've suggested turned out to be the actual problems as reported by the author to us! (see my posting above) I sure learned a few things working on this though.

  Posted by MeganConklin on December 31, 2005 at 14:10:50 Pacific Time