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BUCK CONVERTORS drive LEDs and charge batteries.

Discussion in 'Power Electronics' started by morphingstar, May 2, 2013.

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  1. morphingstar


    Mar 1, 2012
    BUCK CONVERTORS drive LEDs and charge batteries.

    The relation of my 2 threads listed below lies in controlling voltage (for incandescent lights and other voltage senistive loads in an RV, and 12 VDC LED strip control, with a current control option). The 3rd contains simply useful information on LED.

    Forum internal addresses:
    the 3 are somewhat related (mine) (mine) (other)

    LED's die early when they receive too much current (by too much voltage, e.g. in cars) and loose Lumen (brightness) when getting insufficient current (by too little voltage.
    LEDs without integral series resistor (single diode) need a controlled current limiter controlling the current independent of voltage.
    LEDs with integral resistor need a controlled voltage to work at their specified lumen output. (e.g. LED strips for 12 vdc)

    I found a solution for both for environments that do not rely on 115/230 vac sources, all in one device.
    The input voltage range can be less or more than 12 vdc, the output will be 12 vdc, adjustable.
    As an extra gift, the same device will charge a battery with constant current to the voltage level set at the device.
    There is more - Keyword: Rotating Light. I will not go into this application right now.

    The device is called a Buck Convertor. The name is probably derived fom the specific circuitry and behavior of this electronic stabilizer. Here I call it Buck for short. A description of such a device (mine) can be found as a PDF attachment to this message.

    I want to give you some experience , maybe tips in how to use it. I am new to Buck Convertors myself. You should do your own thinking. Please correct me where applicable.

    Let us assume we need stable 12 vdc. The device provides a potentiometer to adjust the voltage. DO adjust vdc without load.
    Let us assume we want a maximum of 2 amps. The adjustment is done easiest with a short circuit. BEWARE: The device will get all the heat from 12*2=24 watts, dissipate it like like a soldering iron, just a much shorter time, seconds. This is my experience with the particular Buck. There may be other models behaving different.
    To set the current to 2 adc the output voltage must be reduced. The data sheet of the Buck recommends 5 volts. The delivered Buck was factory set to 4.5 vdc. Hence: Set the voltage at no load to 5, then short circuit the output using a suitable ammeter (10 adc range is fine for our model) and set the current to 2 ampère, or whatever you need. Disconnect the short circuit and adjust the voltage to the needed value (12 vdc for this example).

    I checked the temperature of the semiconductor (chip) and the high frequency transformer with an infrared thermometer. I trying to keep the hotter one below 100°C in free air. I have not yet worked with enclosures and heat sinks affecting the Buck. The data in the spec' sheet seems to me on the high side, I rather not draw 100% current unless a fan delivers cool air.

    That's it for today. Please add experience informattion as you see fit. As for BUCK sources go to online stores you find suitable for your location and needs.
    The file is not accepted. Please obtain the info from here, whle it still exists.
    Last edited by a moderator: May 3, 2013
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    You're damn lucky you have 15 posts. If not, your post would have been deleted as spam and you would have been banned.

    This reads pretty much exactly like spamvertising, but maybe you're just really unaware of how commonplace switchmode regulators are in general more specifically how common switchmode LED drivers are.

    Your post contains a lot of msinformation (probably just due to misunderstanding).

    I recommend that you go to the tutorial section above and read the LED tutorial again. Remember it's all about current, not voltage. Toward the very end, there is some mention (I think) of switchmode constant current sources.

    edit: yeah, they're useful devices, but I'm not sure the link you provided is an especially good price. If you want 1 or 2, they're all over eBay as well.
    Last edited: May 3, 2013
  3. morphingstar


    Mar 1, 2012
    STEVE: Please delete my post

    Hi Steve,
    please remove my BUCK post.
    Last edited: May 3, 2013
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