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Light bar: intended for car battery, but....

Discussion in 'Power Electronics' started by mattfara, Jun 4, 2017.

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  1. mattfara

    mattfara

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    0
    Mar 16, 2017
    Hello. I'd like to plug THIS device into an U.S. wall wart. A car battery normally powers it. What can I do?
     
  2. Audioguru

    Audioguru

    3,142
    698
    Sep 24, 2016
    The wiring instructions do not say how much current the lights use so you cannot use a wall wart until you find out the current it must provide. A car battery is about 12V when it is dead to about 14.4V when it is charging and the engine is running.
     
  3. ChosunOne

    ChosunOne

    399
    110
    Jun 20, 2010
    There are 120VAC-to-12VDC wall warts out there ( I see several on eBay), but you need to know how much current (Amperes) your device draws. I don't see any mention of Amps in the literature you linked.

    My general rule of thumb, to be safe, is to use a power supply rated at 4 times the current draw of the device. That way, you won't burn the wall wart out.
     
  4. mattfara

    mattfara

    62
    0
    Mar 16, 2017
    These are the specs from their site:

    upload_2017-6-4_11-30-14.png
     
  5. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Sir Mattfara . . . .
    Easy peasy . . . . . with that all magical spec of 17.46 watts. Round that off on the upper side of 2 amps and use that current spec at 12 volts.
    OR go upwards to 3 or 4 amps if it is to be on for a length of time or you want a cooler running power supply.
    ( With a long time reliability boost.)
    Now in taking that sliding spec of 12------28 VDC is further telling us that the unit is having its own regulator or secondary power supply technology inside to create EXACTLY what is needed for supplying the units LED's.
    In that case it will ratiometrically be using less than 2 amps, when being fed at that highest violtage spec.

    It just so happens that another magical number of . . . 19Volts . . . falls within that spectrum.
    THAT was being the voltage output of myriads of laptop AC power adapter " power bricks" that were used during the 90's-----2000's. They typically had on up into the 3-4 amps at that voltage.
    (The light bar will ONLY pull out the minimum amount of power that it NEEDS.)

    This smells like . . . FREEBIE ! . . . . if you already have one available to you.
    Or a Goodwill-Thrift store-Computer repair shops junque box-Flea market-yard sale might score one for less than the full price having to be paid for a brand new supply out of its shiny new box . . . .ahhhhhhh . . . . . smell that fresh vinyl power cords aroma.

    The floor is now open for questions . . . .?
    Of course my first one is . . . . .What 'cha doin' to 'dat 'dere passed out dude ? . . . . a la . . . your Avatar.
    Exposing his bare back and super gluing a multitude of empty beer cans to it . . . . and then standing by for his sleep arousal time ?
    (Then its GREAT SHADES of a stegosaurus time ! )


    73's de Edd
     
    Last edited: Jun 4, 2017
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  6. mattfara

    mattfara

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    0
    Mar 16, 2017
    I'll start from the bottom. That's me. Getting "cupped." I lived in China for four years and this was one of many unusual experiences. But no dinosaurs, unfortunately....

    Just so I'm sure, let me summarize your recommendation: I'm looking for a laptop brick at 19V, 3 to 4 A. That would provide 19*3 up to 19*4 W, but the light bar will only pull about 17 W. 19V is OK given the range noted in the specs.

    Assuming I understand your explanation, how would I go about physically altering the brick to wire it to the bar? Never done such a thing.

    And thx for the humor. Needed it today

    Matt
     
  7. mattfara

    mattfara

    62
    0
    Mar 16, 2017
    Any final words from anyone? Still not quite sure how to do this.
     
  8. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Sir mattfara . . . . . .

    Why 'soitanly . . . .
    Those units typically used a plastic " Brick " housing and the majority of the units that I saw, had a plug in AC cord with a small 8 ball shape of AC power plug in.

    The DC output then had a length of wire with a connector on its end that was compatible with the DC power receptacle on the laptop.
    This was usually having just two wires carring the 19VDC , as the REAL regulation for the power supply was being done within the laptop proper.

    You just cut off the wire at the connector end leaving about 2-3 inches at the connertor end . . . in case you ever want to restore that connection.Then its just a metering of the stripped back -separated two wires to ascertain the polarity of each wire and a spot check on voltage .
    Then you figure the connection mode to the light bar by viewing its present connector types being already provided ( unless bare wires ) and mate up accordingly.

    This adapter is using about 1/2th the physical case size, of my units being seen, BUT its connectors being shown are spot on. Some of them even use a conventional IEC AC power cable.

    [​IMG]

    73's de Edd


    .
     
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  9. mattfara

    mattfara

    62
    0
    Mar 16, 2017
    I got my hands on a laptop power supply. Output is 19V, 4.74 A. Should do the trick?
     
  10. mattfara

    mattfara

    62
    0
    Mar 16, 2017
    A local computer repair man gave me a power source for free. I cut off the adapter head, stripped the wires, and hot-glued them to the leads of the light bar. Works! Thx
     
  11. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Now I ask you . . . . . doesn't that FREE taste good ?
    About he only use I see for those 1990-2000 old laptops is using them for poking up text on or makiing a digital juke box from them.

    ASIDE . . . . I still think the best use for empty beer cans , should you find a partaker all passed out , was to convert him to the stegosaurus that I suggested.

    The closest I came to cupping was around Tiger Balm Gardens in Hong Kong, but I thought that they were all using same sized "cups".

    73's de Edd
     
    Last edited: Jun 17, 2017
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  12. mattfara

    mattfara

    62
    0
    Mar 16, 2017
    I was wondering if you could help me troubleshoot a problem with the light bar. Sometimes when I plug it in, the bar will flash on but only for a split second. This will happen repeatedly if I leave it plugged in. I hear a soft clicking sound inside the power source when the light flashes back off. Sometimes, however, the light bar will stay on as expected.

    Hong Kong is fun, but Macao was better. They sell grapes near the casinos for the high rollers - good luck for the low price of $100....

    Matt F
     
  13. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Sir mattfara . . . . .


    All you need to do now is to differentiate as to the light bar or the now questionable conditioon of your free / gifted power supply.
    Disconnect the POSITIVE power lead from the light bar and get two test leads with clip connectors on both ends and move out to the olde automobile and lift up the hood and hook up to its battery.
    You are already familiar with the time elements and antics withuse of the light bar with the power supply.
    You now have a pure 12 VDC power source , with all of the current capability ever needed.
    If your problems clear up on battery power, then it looks as if the reality is, of the power brick having a problem.
    Imagine the havoc wreaked upon a laptop, by having short time loss of power like that.
    If that brick being at fault proves true, possibly the person might yet dig up another supply.
    With your new found hook up experience, you shoud be able to connect light bar wiring right to another power supply at the shop for its operational confirmation..

    73's de Edd
     
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  14. mattfara

    mattfara

    62
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    Mar 16, 2017
    Hi again, Ed. I was wondering what your take on this new power source is. I cut the adapter end off to find these three layers of wiring, each of which I have twisted to make the layers more manageable. Please see the pics. Would this work for the light bar? If so, please explain.
     

    Attached Files:

  15. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Sir mattfara . . . . .

    Tell ya’ what I’m gonna do . . . . . .

    I will just tack your connection explanation to the units schematic, just in case you . . .or any others . . . . are up against repairing one of these units.
    The HEAVY outer shield cable is the negative connection and the inner shielded line is the +19 VDC output.
    Just keep the inner white wire clipped off and possibly insulate its then small wire end from, any external contact.

    FYI . . . .
    It is being a Dallas ONE WIRE digital buss between this PS and a companion digital interfacing within the computer.
    Info is exchanged as well as a handshaking to have the computer showing a connection error being displayed, if this specific HP power supply is not being used with the computer.
    You can disregard all aspects of that . . . as you will get your +19, if being connected as I have shown.

    Is this a second supply that ‘ole computer guy gave you . . . . with profuse apologies for the first bad ? one, I presume, as you now seem to be his “test bed” .

    TECHNO SUPPORT INFO:

    [​IMG]


    Thassssit . . . .

    73’s de Ed
     
  16. mattfara

    mattfara

    62
    0
    Mar 16, 2017
    Actually, I picked this one up from a thrift store - $4

    The guy who gave me the first power source suggests that the first power source broke because it was not providing enough power. He claims that because of the variable voltage of the light bar, the power consumption can change. Here is his email:

    "
    Matt,

    Ok, the specifications you sent me are very vague. Having variable input power will change the total wattage needed. Let me explain.

    1.3 Amps @ 12 v = 15.6 Watts
    1.3 Amps @ 13 v = 16.9 Watts
    1.3 Amps @ 14 v = 18.2 Watts
    1.3 Amps @ 15 v = 19.5 Watts
    1.3 Amps @ 19.5 v = 25.35 Watts
    1.3 Amps @ 28 v = 36.4 Watts

    Now, the Specs also said 18 LEDs @ 3 Watts each. Making that 54 watts.

    @ 19.5V @ 54 Watts makes it 2.76 Amps.
    @ 12V @ 54 watts makes it 4.5 Amps
    @ 19.5V @ 99 Watts making it 5.07 Amps

    Now the specs would need to be way off, and the LEDs draw 5.5 watts each, making it 99 Watts and that would bring it around 5 Amps on the draw, and would explain the burned out power supply.

    There are so many options you can go with for a new power supply. Sorry it died on you.
    "

    This email confuses me because the specs of the light bar say that the power consumption is only a bit under 18W. Would power consumption change with voltage? The specs certainly don't suggest this, given that they allow for a range of voltage but only list a single value for power consumption.

    Is it more likely that the first power source was just faulty?

    As for the wiring you showed, the inner most wire is the digital bus, which I should clip/insulate, correct?

    Lastly, thank you very much for your ongoing guidance. Very encouraging for a new hobbyist.

    Matt
     
  17. mattfara

    mattfara

    62
    0
    Mar 16, 2017
    Jumped ahead and gave it a shot. Success! Hopefully this power source stays alive.

    Thanks again, Ed!
     
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