Anyone built a little LM386 circuit battery amp?

Discussion in 'Shock Brother's DIY Amps' started by Robster, Jan 11, 2014.

  1. Robster

    Robster Tele-Afflicted

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    I want to build one of these in the smallest container possible. Would like it to be pocket sized. I would like to use it as a headphone amp and would be nice if it had a speaker in it too.. to as a test amp. I find lots of guitars and pedals at flea markets, etc and most times they do not have power there or they are missing an amp or cable to test with. I do have some bigger battery amps (vox da5, Microcube) that I could use for this but I would leave them in the car rather than carry them with me. It could be a 1/2 mile walk to back to the car so something I could stick in a pocket would be best. The least amount of distortion would be best for what I want. I see schematics for Ruby, Little Gem, etc but all the demos just show how much it distorts...
    Thanks
     
  2. BruceF

    BruceF Tele-Meister

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  3. printer2

    printer2 Poster Extraordinaire

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    The distortion is a function of the volume you are trying to get out of it. Driving headphones you would blow your ears out before it distorts. You have to remember the chip was designed as an audio amp for consumer goods, its clean is cleaner than any guitar amp. You should be fine with it as long as you realize how loud it will play clean is more related to the speaker. Since it is small you are not going to get a lot out of it.

    I built one into palm sized amp with a small speaker twenty years ago to be used as a portable practice amp. Gave one to a buddy who used it for years as a busking amp. Since then lot of mini amps came out.
     
  4. nofrets

    nofrets Tele-Meister

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    I built a Ruby from runoffgroove. Did the 'bassman' mod, sounds great clean. There's also a mod on that page that lets you pre-set the gain ceiling with a trimmer - keeps the distortion under control, plus eliminates a knob from the enclosure. Mine's driving a 4" full-range driver which is a bit heavy, and doesn't have the same freq response characteristics as a guitar speaker, but for the purposes you describe, a salvaged speaker out of a radio would be light and small.

    Here's a pretty good demo showing the range of tones on tap:



    HTH,
    Patrick
     
  5. luckett

    luckett Banned

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    The LM386 will do reasonable clean into a 2"x4" speaker at 9V. Even better at 18V. To get a decent clean volume level out of a speaker small enough to fit in a pocket, you'll need more power than the LM386 can provide. That will require more batteries and a speaker that has high efficiency and can handle the power without breakup from the speaker.
     
  6. nofrets

    nofrets Tele-Meister

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  7. LongLiveRock54

    LongLiveRock54 Tele-Holic

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    I built this one using spare parts I had in the shop. Speakers were from an old boom box that didn't work. Other parts were from an old karaoke machine.
    If I remember correctly, it was based on the Lil Smokey amp.
     

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  8. andyfromdenver

    andyfromdenver Friend of Leo's

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    I built one for a customer's super sneaky magic trick....I've said too much lol.

    It was my first paid job I kept the receipt for nostalgia :)

    Yes, I work cheap...
     

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  9. Lindsay

    Lindsay TDPRI Member

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  10. Robster

    Robster Tele-Afflicted

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    I should have looked in my parts box first...

    I kept thinking I had something like this. Checked the parts box and sure enough I turned up a pocketsize mini amp from Radio Shack. It has a LM386 and a schematic pasted on the inside. Will need to add a 1/4 jack on the side and see what I need to change on the schematic to match a Ruby or something. That will be easy. It has a 1/8 output if I want to bypass the speaker too. Would still like to build one from scratch too. Thanks!
     

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    Last edited: Jan 11, 2014
  11. LongLiveRock54

    LongLiveRock54 Tele-Holic

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    Cool. If I had that I would build my own cabinet with a decent aftermarket speaker and install that circuit.
     
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