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12V to 5V

Discussion in 'Boat Electronics' started by Floating Mind, Jun 16, 2006.

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  1. I have an MP3 player that requires 5VDC. I'd like to use this on my
    boat and adapt it to my 12VDC system. Any suggestions?
     
  2. Larry

    Larry Guest

    Or go by any Walmart and buy a 5V power supply that's built into a 12V
    ciggie plug. The 6V one will work fine, too!...(c;
     
  3. Larry

    Larry Guest

    (Floating Mind) wrote in @storefull-3113.bay.webtv.net:
    Go by any electronics store and get a 7805 IC regulator. Here's the
    simplest of power supplies:

    http://www.tkk.fi/Misc/Electronics/circuits/psu_5v.html

    You'll probably need to mount it on a little heat sink as it's an analog
    regulator. 14v-5v=9V across the IC at, say, 200ma current = 9V x .2A =
    1.8 watts of heat. You can try it without the heat sink, first, if you
    like. I don't know how much your MP3 player draws or what its battery
    charging adds to it. Run the batteries down, if they're rechargeable,
    first, then hook up the regulator and play MP3s while it charges to draw
    the most current. Hold your finger on the metal tab of the regulator.
    If it gets too hot to touch, immediately unplug it and add the heat sink
    to cool it. It depends on how much your player draws. Don't let the
    heat sink touch ground as I think it's gonna be at +12V. Radio Shack has
    heat sinks the just clip onto this TO-220 tab for a buck or two. They
    also have the 7805 regulator and the caps.

    Output is rock solid +5V with any input above 8V up to 18V, even noisier
    than hell. The IC even protects itself from overcurrent and shorts.

    It's easy to build. Just solder the components right to the little pins
    in a plastic pill bottle with the wires in the cap. Your kids and non-
    electronic friends will think you're some kind of genius scientist...(c;
     
  4. Thanks for the tips! I think I'm going to go with Larry's suggestion
    and build the one he posted. The 110V adapter that came with the unit
    states that it has a 2.4 amp output, but I'm sure that's only required
    during charging. Whenever I use this player on the boat it will already
    be charged. I'm still going to add the heat sink right off the bat
    though.

    I want to stay away from using an inverter, and the only DC to DC
    adapters I could find pre-made didn't have a 5V position, but thanks for
    all of your suggestions anyway.
     
  5. Larry

    Larry Guest

    (Floating Mind) wrote in @storefull-3115.bay.webtv.net:
    Ok, so let's use a bigger regulator...(c;

    http://www.linear.com/pc/downloadDocument.do?
    navId=H0,C1,C1003,C1042,C1033,P1005,D4236

    oops, sorry for wordwrap. This IC regulator won't even get warm at 5A
    load....it's a SWITCHER, which is what I always prefer...(c;

    Build this one and have 5V power to burn...er, ah, charge...(c;
     
  6. I built the first one you suggested Larry and mounted it to a CPU heat
    sink from an old junk computer I had. I hadn't checked back here to see
    the larger units that you fine folks suggested at the time. It got
    plenty warm. Not too hot to touch, but still plenty warm, so I took the
    12V fan that was mounted to the CPU heat sink and mounted it too. Put
    the set-up in an old small unamplified computer speaker enclosure with
    the grill from the other speaker mounted along a cutout I made on the
    backside for flow-thru ventilation. I even went for some bells and
    whistles. I mounted a 140° thermal switch with a light bulb to the
    heat sink.
    Everything works great! The air flowing out of the regulator enclosure
    is not noticeably warm at all. Cooler than the air flowing out of the
    inverter when I was using it for the same MP3 player. So I'd say I'm
    ahead efficiency wise.
    Even starting out with the MP3s battery fully charged it still must draw
    quite a bit of current. It's a old 20 gig player that has an actual
    hard drive as opposed to flash memory.
    I'm going to check the current draw the next time I use it just out of
    curiosity. The 140° indicator light hasn't came on yet.
    I kept notes on the sites you all posted for the larger regulators in
    case this one ever smokes. Thanks again for your help everyone.
     
  7. There in lies the problem with the 7805. 60% or more of the power goes up
    in heat. Considering that plus the time and effort to rig it up a simple
    $15 DC/DC buck converter is cheap.

    --
    Glenn Ashmore

    I'm building a 45' cutter in strip/composite. Watch my progress (or lack
    there of) at: http://www.rutuonline.com
    Shameless Commercial Division: http://www.spade-anchor-us.com

    I built the first one you suggested Larry and mounted it to a CPU heat
    sink from an old junk computer I had. I hadn't checked back here to see
    the larger units that you fine folks suggested at the time. It got
    plenty warm. Not too hot to touch, but still plenty warm, so I took the
    12V fan that was mounted to the CPU heat sink and mounted it too. Put
    the set-up in an old small unamplified computer speaker enclosure with
    the grill from the other speaker mounted along a cutout I made on the
    backside for flow-thru ventilation. I even went for some bells and
    whistles. I mounted a 140° thermal switch with a light bulb to the
    heat sink.
    Everything works great! The air flowing out of the regulator enclosure
    is not noticeably warm at all. Cooler than the air flowing out of the
    inverter when I was using it for the same MP3 player. So I'd say I'm
    ahead efficiency wise.
    Even starting out with the MP3s battery fully charged it still must draw
    quite a bit of current. It's a old 20 gig player that has an actual
    hard drive as opposed to flash memory.
    I'm going to check the current draw the next time I use it just out of
    curiosity. The 140° indicator light hasn't came on yet.
    I kept notes on the sites you all posted for the larger regulators in
    case this one ever smokes. Thanks again for your help everyone.
     
  8. Larry

    Larry Guest

    (Floating Mind) wrote in @storefull-3111.bay.webtv.net:
    Cool....the idea and story, not so much the heat sink...(c;

    People who hate switchers just don't understand them. They're waiting
    for their series pass transistors to short putting the 40VDC primary
    power unregulated to the electronics...(c;

    If you can touch the heat sink, the fan is overkill. Hell, I'm typing on
    a Gateway notebook with an AMD Turion 64-bit processor. Its fan comes on
    about the time the air coming out of the heatsink feels like a heat gun
    used for shrink tubing! Amazing what electronics (except electronics in
    American cars) can take.

    Glad you liked it. I have a rock solid 115VAC to 14V switcher I built
    years ago that runs the ham radio station, here. My 650W RF power amp is
    a Tentec Hercules II that was modified to take out the push-on connectors
    and other cheapness. At full power it only draws about 126 amps at 14VDC
    for its four parallel, push pull power amplifiers. The switcher was
    built for it because I didn't like the crap power supply Tentec offered
    that wouldn't run it anyway after the modifications. Using remote
    sensing for the switcher regulator right up inside the amp to the power
    distribution point inside the amp, output at that point only varies .2vdc
    from no load to 126 amps on a good antenna. Instead of weighing the same
    as a Humvee armored jeep, it weighs about 8 pounds and is quite small.
    Efficiency is around 95% so it only gets warm on data modes like old RTTY
    where it's keydown for many minutes at a time.

    Next thing you know you'll be dumping WebTV for a Athalon 64 on
    Broadband!....(c;
     
  9. Larry

    Larry Guest

  10. Hanz

    Hanz Guest

    I use it on my computer on the boat. It handles the spikes from the alt..

    I have a Via SP13000 in a Venus 668 cases..

    Hanz
     
  11. Larry

    Larry Guest

    If you have spikes from the alternator, your battery has an open cell.
    Across a good battery there are no spikes as the chemistry absorbs a lot.
     
  12. Hanz

    Hanz Guest

    Spikes: when the batteries goes from 11.75 up to 14.5 volts during
    normal charging. Maybe 'spikes' is a bad word. But the "buck/boost
    circuit" of the converter handle it.

    Hanz
     
  13. Larry

    Larry Guest

    I don't know of a single piece of marine electronics that won't run just
    fine on 16-18VDC. "Spikes" are 40V pulses that happen when a battery
    with a dead cell is charged with an alternator that happens each time the
    alternator's regulator, trying to figure out why the battery's voltage is
    only 9.8VDC and charging the hell out of it because it measures deep
    discharged, feeds full field current to the alternator.

    You can hear it in the stereo in a vehicle or boat as a loud, high
    pitched and varying with engine speed, whining in the speakers. You can
    also see it in any light as you rev the engine and the light gets MUCH
    brighter, the light bulb averaging out the pulses into an overvoltage
    condition as the spikes try to blow the filament.

    A charger will make the stereo speakers hum loudly, VERY loudly if a cell
    has died into high resistance. The charger's rectified pulses flowing
    through the dead cell's high resistance (higher than milliohms of a
    normal cell) create spikes on top of whatever DC voltage the battery
    actually is.

    If you're measuring the battery with a meter, the meter movement
    (mechanical) or a digital meter averaging out the spike during its
    measurment sampling cycle, don't give you any indication the voltage
    peaks are actually THAT high. In a cheap boat radio you can hear the
    spikes, your first indication of either a dead cell or corroded terminals
    in the charging circuit at the battery, which makes the same whining in
    the speakers.

    (42 lurkers have just found out why the stereo is whining every time they
    crank the beast...(c;)
     
  14. Larry, Since you suggest it I think I'll tie the fan into the 140°
    indicator circuit. 180° is meltdown so 140° should be way safe.

    As far as the WebTV vs. PC goes, well, I have 2 computers. One with
    '98, and the other with XP. I use them quite a bit for digital
    photography, storing & transferring audio to my MP3 players, and my
    other internet activities, but the WebTV is a better tool for these
    discussion groups.

    Glenn, I guess you didn't notice my original post. In it I neglected to
    tell everyone what the current draw was for this MP3 player, so Larry's
    original regulator would have been perfect without any modifications.
    As far as efficiency goes I'm still ahead of the inverter. Besides, I
    enjoyed the project, and sure couldn't find anything locally that'd do
    5V for anywhere near $15!
     
  15. Larry

    Larry Guest

    (Floating Mind) wrote in @storefull-3118.bay.webtv.net:
    I have 3 but have pretty much retired the old Win98SE machine only
    accessing it on an old LCD display I watched way too long when I'm
    looking for something old...(c;

    MP3 players - Digital Mind Xclef 500 had 100GB drive, not upgraded to
    120GB. The player has is NOT the one RIAA wanted you to have. Computers
    just treat everything on it as an external hard drive, no DCA funny
    business. Click and drag 800 MP3 files to it and it play them, even if
    they only have filename.MP3. Has FM Radio, woowoo!, but no commercial
    killer making it useless. Has direct-to-MP3 (your choice of speeds)
    audio recorder with virtually unlimited record time because of its
    massive hard drives. Runs 22 hours on a charge. Recharges in about 1.8
    hours from dead. www.digmind.com. Available in no drive, 20G, 40G, 80G,
    100G, but some configurations unavailable most of the time. They can't
    keep up with demand. Standard 2.5" notebook drives, standard Li-Ion
    battery packs, no proprietary crap like the RIAAiPod has...Nice leather
    case standard...

    Old one is a 20GB Archos Studio 20, also funny business free, that's been
    run so hard the pain all wore off exposing the aluminum case under it.
    It must have 30,000 hard hours on it banging around in my truck. V 1.0
    failed hard drive, Archos gave me this one, complete with new
    accessories, about 4 years ago with a VERY rugged Toshiba drive in it.
    Firmware in it is from a great bunch of hackers known as Rockbox, which
    is much better than factory w/lots more features/functions/controls.
    http://www.rockbox.org/ I haven't upgraded Rockbox in years and I see
    they got tons of new stuff for it. It's a simple, rugged
    MP3/wav/FLAC/wma player with a little LCD screen. I replaced the
    original 750ma Ni-MH AA cells in it (4) with 2300ma Ni-MH cells. It
    plays LOTS longer than you can stand to listen to it, now! Charging
    takes forever on huge cells, but it's got all night..(c;

    I also have a 400GB external Maxtor USB drive that plugs into the Gateway
    AMD Turion 64 notebook, which drives a port on my DJ soundboard into a
    QSC 1450W amp and 4 huge speaker boxes, 2 12", 2 15" bass horns.

    I've collected near 22,000,000 MP3 files from Edison's first cylinder to
    DJ music I see no point in. If you'd like to catalog your MP3
    collection, the finest MP3 (only) catalog program on the planet is from
    Russia, MP3 Catalog Pro. http://www.wizetech.com/amc/
    It will automatically catalog every MP3 file, extracting all fields from
    the MP3 ID3 data tags into an extremely fast database as fast as your
    hard drive can access them, an incredible feat. Once it has created its
    catalog, you can search for any field or filename, say searching for
    "Jimmy Buffett" songs over 4,000,000 songs on 6 hard drives. It will
    display a neatly listed file of Jimmy's music you have across the whole
    system in less than a second! Click and drag one or more or all the
    songs to any MP3 player, like Winamp's playlist and let Winamp play them
    in the sequence you want. If your collection is on CDR or DVDr, no
    problem. Feed the catalogger each disk and let it strip the songs on the
    disk. Name the disk, yourself, or just let the program feed you a disk
    ID number so you can mount it from your disk filing cabinet when it needs
    to play a song. The catalog now contains every MP3 stored on optical
    discs (or even floppy disks), labeled for callup and mounting. If the
    file you want to play isn't on hard drives or in a CDrom drive, the
    program asks you to mount disk 18372 and click OK. It then selects and
    feeds the song to your MP3 player program. Most efficient catalog
    program on the planet...the pro DJs use it. $30, lifetime upgrades and
    support.

    I'm one of those MP3 collectors you mother warned you about...(c;
     
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