New DIY Altoids Tin Amp - The Pocket Class A "Wintergreen Handwarmer" by xrk971

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  1. Hutnicks
    Hoo Yah. That is what I have been awaiting. Need to explore this big time.

    On insane clown mode. I have an almost irresistible urge to go old school with this design and do a point to point wired version. I will consult a therapist obviously before going there, but still....

    On heat dissipation. There are several great choices out there readily available at most large hardware retailers. Begining with aluminum paint available at Home depot, to hammertone copper, Krylon Silve and gold plate. A lot of the above mentioned were pioneered in the laptop trade as coatings to inhibit rf interference and somewhat alleviate the heat generated by high clocked cpu's in an enclosed space.
  2. xrk971
    Well this was almost hand made P2P for the serial number Zero:

  3. Hutnicks
    Hmm not seeing an image there.
  4. xrk971
    Ok I had to re upload as it was on DIYA server and you probably don't have an account there.

    Here it is...
  5. Hutnicks
    Actually I do, which is all the more puzzling.
  6. stellarelephant
    Raptorlightning kindly shared Gerbers for the two custom PCBs that enable his battery mod, as well as a BOM, schematics, and some instructions.

    For folks without a DIYA account, you can also grab them here:

    I ordered several of each board from OSH Park a few days ago. The two zipped folders within the main folder I've linked worked perfectly for me when I uploaded them for printing. If you order from OSH Park, as Raptor and I did, expect to get a warning that they can't do slot drills. According to Raptor, this is fine and just means you'll have to use wire cutters to trim the micro USB jack somehow. I assume this will make sense once I see the part and the board.

    To do the mod, you'll also need a MT3608 boost module and a 2600mAh 3.7V tablet battery that measures 7.8x52x51mm.
    Both items are all over eBay and AliExpress. They look like this:
    s-l1600.jpg $_12.JPG
    Anybody have tips for cutting PCB traces? X-acto knife?
    Last edited: Sep 4, 2017
  7. funch
    X-acto would be my weapon of choice.
  8. macky112
    May I know an estimate of the total cost to do this mod?
  9. stellarelephant
    Pretty cheap. The three boards can each be had for less than a dollar. Battery is like $10. I haven't made a Mouser/Digikey cart with the BOM yet, but I am hoping the assorted parts needed to populate the load sharing board and cap mx board will total $5 or so plus shipping. Ballpark $20, all shipped? About the same as buying some rechargeable 9V batteries and a charger.
  10. xrk971
    Hi StellarE, would you mind running a GB for us? I am in for 4 sets of boards. :)
  11. funch
  12. stellarelephant
    I'd love to, but man, I am covered up with work and house projects for the foreseeable future. I'll be lucky if I find time to get the mod done! With free shipping available for all the parts, I'm not sure it would really help much anyhow. Except maybe for folks outside the US.
  13. xrk971
    That's cool StellarE - we have all have been there, and totally know that family and "yes, Honey" duties always come first if one wants longevity with diy. :)
    Last edited: Sep 9, 2017
  14. stellarelephant
    Just filled up a Digi-Key cart with parts for the RaptorLightning mod. All the components for one mod add up to about $9.50 plus shipping (cheapest shipping option is $3.50). Adding in the battery and the 3 boards, I'm at about $26 total cost for the mod, not including the few cents worth of extra wire I'll need to connect all the boards together. X, can you recommend a certain wire gauge?

    I had to substitute a different 1uF cap and 47R resistor, as the ones on the BOM were not available.
    Also, here is the 47uF cap that Raptor used (this replaces the 100uF on the BOM):
    Other than those three parts, I'm ordering using the exact part numbers on the BOM Raptor provided.
    Last edited: Sep 14, 2017
  15. stellarelephant
    I soldered up my first cap MX but failed my first attempt at the USB load sharing board. Tiny pins under that micro USB jack... Must buy a fine solder tip and liquid flux!
    IMG_2892.JPG IMG_2894.JPG

    In the meantime...I bought some new planar Mayflower V1 cans. These are a T50RP v3 modded for accurate frequency response.


    I was worried that the Pocket Class A wouldn't have enough juice for them, but alas, it seems this amp fears no headphone. According to X, it helps that I'm running the amp at full 18V. It probably also helps that I boosted bias further with my resistor values. And thank goodness my x3 player puts out a generous 1.5v line out signal. First impressions tell me that I have headroom to spare (pot set at about 2:00 is loud) with good dynamics and more detail than I have ever gotten from a headphone before. :)
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