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It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit midwestaudiofest.com for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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Adding Custom USB Charging to the new Dayton Audio KAB-250v3 2x50W

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  • Adding Custom USB Charging to the new Dayton Audio KAB-250v3 2x50W

    I'm building a custom boombox for a customer and I need to add on a USB charging port. I DO NOT want to use the available interface expansion board, it will not work for my application. I'd like to use the "Future Expansion" terminal labeled # 14, as it seems to be the only output that is a) available to tap into, and b) switches off when you turn the main power switch off.

    Anyway, the Future Expansion terminal measures at 7.2 volts when amp is "on". The voltage regulator I am using for usb brings down the volts to a stable and quiet 5V 3A max. My questions is, do you think that the "Future Expansion" #14 terminal is capable of handling 3A? Again, the voltage regulator's output is "5V 3A Max". Once the voltage is brought to 5, I wiring in resistors to make it capable of charging Apple devices.

    A side note, if you purchase the new optional accessory panel, you cannot cleanly incorporate the interface expansion board. Weird quirk.

    Any thoughts welcomed

  • Hi-Fi Luggage
    replied
    I found a solution, although it wasn't ideal. I tapped into the battery extension board. There is a + and - terminal that measures 11.2v that was not being used so I tapped into that. It's not ideal because as long as batteries are mounted in the extension board, it stays "on", and does not switch off with the main power switch. I remedied this, by adding in a single SPST on/off switch right above the charging port, so when the customer wants to charge a device, they have to first turn on the switch. Not that inconvenient I suppose, and now they can use the charging port with the boombox OFF.

    Click image for larger version  Name:	kab-be_photo_4_1.jpg Views:	1 Size:	164.5 KB ID:	1396931

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