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I found some 3 volt switching power supply @ 5 amps I need some circuit help — Parallax Forums

I found some 3 volt switching power supply @ 5 amps I need some circuit help

sam_sam_samsam_sam_sam Posts: 2,286
edited 2011-04-04 19:13 in General Discussion
Controlling them with a Basic Stamp
I want build a Supper Bright LED Light

I am thinking about using about 200 LED running at 15 milliamps at 3/4 power

What would way be the best way to do this

http://www.mpja.com/prodinfo.asp?number=18557+PS

18557.jpg "MFG: AULT"
"P/N: MW125RA0303B01
Input: 100-240VAC 50-60Hz
Output: 3VDC @ 5A
Specifications/Features:
Wall mount switching supply. Non-polarized 2 blade input, 6ft. ZIP cord with 10mm long X 5.5/2.5mm coaxial power plug Center +. ULus/canada/TUV/CE listed.
L: 3-7/8" W: 2-1/2" T: 1-5/8" WT: .78"


A while back I tryed a UN2803 with a 3.3 voltage regulator But this did not work the way I want I know I could use a relay but I am not really liking this idea to much

http://forums.parallax.com/showthread.php?117491-Using-a-3-Volt-power-supply-to-power-LEDs-with-a-2N3904-will-this-work-lower-do

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-04 16:27
    What LEDs?
    [ 3V leaves out Blues and Whites (their V_f > 3V), from my P-O-V. ]
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2011-04-04 16:33
    I want to use White ones

    What about switch the incoming power to the power supply with a soild state relay

    Do you think would work
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-04-04 16:39
    If it's not a regulated supply, chances are the voltage output will be much higher than 3V without a load, decreasing to 3V as the load approaches 5A. Your plans are for a 3A load, so you may yet have enough headroom for the white LEDs. OTOH, if it's a regulated output, you're probably out of luck driving white LEDs, as PJ pointed out. Your other challenge will be load-sharing that many LEDs since, at that low voltage, they will have to be wired in parallel, each with it's own series resistor.

    -Phil
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2011-04-04 16:55
    So I should use a relay to do this project

    Has any one found a way to change the output voltage on these switching power supply

    I have open a few switching power supply and they do not have any part # on these IC chips that are used

    IF yes please share thanks
  • tonyp12tonyp12 Posts: 1,951
    edited 2011-04-04 17:00
    That is not how you drive 200 leds.

    You instead start with 12-24v and put LEDs in series
    Final step is a LED driver that controlls the current so they last years.

    TPS61195
    http://www.ti.com/lit/gpn/tps61195

    if you need individual control of each led
    http://focus.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=tlc59116&fileType=pdf
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2011-04-04 17:59
    Dose any one have a working code for the TLC59116 chip or TPS61195 chip with a Basic Stamp

    I am not sure which one I want to use
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-04 18:01
    What a guy ought to do...
    Around here? If only.

    Anyway, Sam, I hope you didn't buy many.
    You could do a super-red or super-green or some combination,
    but you'll need to buy some resistors and transistors.
  • kwinnkwinn Posts: 8,697
    edited 2011-04-04 18:16
    sam_sam_sam, tonyp12 has a point about using a higher voltage and putting as many leds as possible in series. This will increase the efficiency and reduce the complexity quite a bit. With 200 leds you could have 4 strings of 50 leds or 5 strings of 40 leds and run them from the 120V line.

    If you do this you must BE VERY CAREFUL. Working with line voltage can be hazardous.
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2011-04-04 18:21
    kwinn wrote: »
    With 200 leds you could have 4 strings of 50 leds or 5 strings of 40 leds and run them from the 120V line.

    If you do this you must BE VERY CAREFUL. Working with line voltage can be hazardous.

    I thought about doing it that way BUT Working with line voltage can be hazardous this the killer part of it that is why I do not want to that way
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2011-04-04 18:28
    PJ Allen wrote: »
    What a guy ought to do...
    Around here? If only.

    Yea If only I had allot of money Then I could really play with some real toys but that another story

    Anyway, Sam, I hope you didn't buy many.

    I only bought 3 of them
    You could do a super-red or super-green or some combination,
    but you'll need to buy some resistors and transistors.

    If I used red one then who know what warning displays I could come up with

    I might use some orange ones with these power supplys

    I have some orange LED board that have three LEDs on them I would have to rework them to work that way
  • tonyp12tonyp12 Posts: 1,951
    edited 2011-04-04 18:48
    You did not say what you are building.
    Do you need to have indivdual on/off controll of each led?
    Do you need them to be on a long string (buy led christmas lights)
    Or as a panel buy this.
    http://www.amazon.com/WHITE-LED-Aquarium-Light-2501WH/dp/tech-data/B001NDU9XG
  • sam_sam_samsam_sam_sam Posts: 2,286
    edited 2011-04-04 19:07
    I not sure what I builting but I want all of the LEDs on one board and close together I was hoping to have all LEDs wired in parallel <...........BUT maybe not I will have to think about this some more
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-04-04 19:13
    You simply cannot connect LEDs in parallel without current-balancing resistors. The LED forward voltages will always vary a little, and those with the lowest forward voltages will draw the most current at the expense of the others. Tonyp12 is right: a series (or series/parallel) configuration is what you want.

    -Phil
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