• renkforce mp2000 power measurements and mini review

    11/15/2017 at 23:17 • 0 comments

    wattage test of the renkforce mp-2000

    it is rated for 100wrms / 4ohm load at one channel driven.

    i decided to test if that is true.

    my results:
    no load volt: 18AC on terminal
    1ch 4R7 dummy load volt: 17.9AC (68W)
    1ch 3R8 dummy load volt: 17.7AC (82W)

    not the rated watts, but still rather good.
    especially given these facts:
    only costs around 90€ msrp (conrad store)
    is using discrete class a/b amplifier IC's
    has a toroid transformer, something my ht receiver worth over $1k doesn't have!
    is passively cooled (no noise, though don't play it loud for too long)

    extra notes:
    all tests with max input voltage, lightly clipping, 50hz test tone
    i don't have enough resistors to test 2 channels at the same time ^^;
    i first thought the transformer was 120VA 23v, but it turns out it's close to 160VA, 23v

    improvements needed:
    with 18volts peak AC (aka 36VDC) and the caps being rated at 35V 4700UF, i might have to upgrade those soon to improve lifespan.
    i won't recommend this amp for lower than 6ohm speakers if you want to play loud. (possible overheating problem)
    the heatsink design isn't very effective when the amp is on it's feet, giving higher thermals, hence why i don't recommend 4ohm loads.
    a power led would be useful, as well as a secondary input.
    i prefer this amplifier without those mounting tabs (or at least i prefer them removable) so it fits better with my desk and saves some width.
    the internals are semi modular, so one can make a unique case for it. (good for a DIY receiver or something)
    to save power, one can also swap the transformer for a 18V 160VA one.
    a speaker protection relay isn't included, so be carefull with clipping.

    conclusion:
    pros:
    rather good value for the money
    gets close to it's rated watts
    good for modding

    cons:
    barely any protection circuitry
    can get hot on < 6ohm loads
    coupler caps have a supertight voltage rating

    ......well, it seems i wrote a review instead of a test, anyhow, sharing my knowledge about this amp with hackaday! :

  • guidelines for beginners in wearable development

    07/21/2016 at 21:29 • 0 comments

    things to condsider in small embedded wearable applications



    space usage
    - microsd or flash
    - bga or lqfp or other packages
    - how many sensors
    - are there sensors with multiple functions in one package
    - communication with other devices
    - battery placement and size
    - how do-able will it be pcb wise



    power
    - usb or custom charging
    - how long will it run on a single charge



    programming
    - how will one program the project
    - will it support over the air updates
    - can users modify the software
    - how will you use low power modes
    - how hard will it be to code it



    misc
    - how much will it cost (parts cost * 2,5)
    - do others want it for the said price above
    - how much of an interest is there
    - is a kickstarter needed




    at all times: think realistic!


    so thinking you can fit an arduino zero/m0, oled, 500mah lipo, bluetooth, buttons, accelerometer, rtc and what not in just 40*40*10mm?
    then you're wrong.



    i just put this up for your reference.
    i made quite the mistakes in the past without these own made guidelines