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Little Amp build

Discussion in 'DIY Amp Forum' started by Otisblove, Jul 12, 2017.

  1. Otisblove

    Otisblove Strat-O-Master Strat-Talk Supporter

    Age:
    42
    544
    May 20, 2016
    Chicago
    So I've got my heart set on building a 5e3 amp. In the meantime I'm reading all I can and watching as many tutorials as I can. I found this little amp build in a book. I've got all the parts.
    What do I do with the negative lead from the 9v connector? IMG_0254.JPG
     

  2. johnnymg

    johnnymg Senior Stratmaster Strat-Talk Supporter

    Sep 5, 2015
    Central Coast Ca
    By 9V connector.................. do you mean from the 9V power source? If so, it connects to the GND.

    Note: Check the specs on the hybrid amp. It probably needs to be mounted on a heatsink.
     
    Last edited: Jul 12, 2017

  3. Otisblove

    Otisblove Strat-O-Master Strat-Talk Supporter

    Age:
    42
    544
    May 20, 2016
    Chicago
    I see nothing about a heat sink. My understanding of schematics is remedial at best. I like to think I can color by numbers, but
    More pictures.
    IMG_0255.JPG IMG_0257.JPG IMG_0258.JPG IMG_0256.JPG
     

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  5. Otisblove

    Otisblove Strat-O-Master Strat-Talk Supporter

    Age:
    42
    544
    May 20, 2016
    Chicago
    This is the 9v battery connector I'm talking about.
    IMG_0259.JPG
     

  6. johnnymg

    johnnymg Senior Stratmaster Strat-Talk Supporter

    Sep 5, 2015
    Central Coast Ca
    Yes, connect the black lead from the battery to the ground rail.

    Check this out: http://www.ti.com/lit/ds/symlink/lm386.pdf

    On page 6 (see figure 7) you can find the internal dissipation curves. At 9V DC the internal dissipation can be >0.5W. That's actually a lot of power for an IC that isn't connected to some sort of heatsink. Heatshinks for this type of chip are very inexpensive.

    At the VERY least make the 3/4 connection to ground/chassis a big fat wire. That may pull away enough heat to keep the chip from frying.
     
    Last edited: Jul 12, 2017
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  7. Otisblove

    Otisblove Strat-O-Master Strat-Talk Supporter

    Age:
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    544
    May 20, 2016
    Chicago
    How big of a wire are we talking for connecting to ground/chassis?
     

  8. johnnymg

    johnnymg Senior Stratmaster Strat-Talk Supporter

    Sep 5, 2015
    Central Coast Ca
    Maybe a couple 18 AWG wires. If I was going to use this chip I'd mount a heat sink to the top if it. Even better would be to 'deadbug' the 386 to an aluminum chassis box. That's probably overkill................ unless you plan on pushing this amp into heavy distortion.
     

  9. Otisblove

    Otisblove Strat-O-Master Strat-Talk Supporter

    Age:
    42
    544
    May 20, 2016
    Chicago
    I just want to see if I can make a simple amp work and with any luck, understand how and why. Thank you for your help. I appreciate it.
     
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  10. stratman in va

    stratman in va Most Honored Senior Member Strat-Talk Supporter

    Age:
    47
    Jul 27, 2012
    Virginia
    There are some other easy projects out there. Velleman has some small amp circuits in kit form. Building one of those will give you some more assembly experience. I built a simple fuzz device called the Electra distortion pedal. There should be a link somewhere to that project as well.
     
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  11. stratman in va

    stratman in va Most Honored Senior Member Strat-Talk Supporter

    Age:
    47
    Jul 27, 2012
    Virginia

  12. Otisblove

    Otisblove Strat-O-Master Strat-Talk Supporter

    Age:
    42
    544
    May 20, 2016
    Chicago
    I believe it is an idiot's guide to electricity and electronics.