resistance values for LED's

Discussion in 'All Things Boats & Boating' started by Frosty, Apr 26, 2009.

  1. Fanie
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    Fanie Fanie

    Hi Billy,

    Sorry I was just giving you a hard time. See how it feels :D

    What is nice about using a uP is they can do all kinds of wonderfull things. You can fade the light in and out with on / off, have courtesy delays, automatic turn on when it gets dark and switch off when it gets light. If you don't like a feature you can change it. One light can tell another to switch on with it, or how bright to go on. The only limitation is one's own immagination.

    The nicest probably is that they are very easy to use. Most people run from them, but once you get to know a little and you have one or two successes, then they offer great possibilities. It's like anything, there was a time you couldn't drive, now you can and it's only due to a bit of exposure. Same with uP's and especially these stand alone ones like the Pic's and Atmel's are full house computers in a little package. The 'bigger' ones are extremely powerfull.

    It's never too late to take them up you know, really nothing to it.

    Not completely true. Mine agrees that I should give her the boat's money :D


    How old do you think I am Billy :D
     
  2. masalai
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    masalai masalai

    BillyDoc, I loved my Z80 machines used in the early Amstrad boxes from Blighty 512K of page mode RAM "paper white screen" 80 lines of partially WYSIWIG text and the OS and "Office" package loaded into 78K or ram each bloody magic stuff that is still faster and easier to use than anything MS has offered. and the dictionary Thesaurus worked in English...PRE 1980 - them was the days.... Latest model was the PCW9512... worthy of a Knighthood for the man who created it (Alan Sugar?)...
     
  3. Guest62110524

    Guest62110524 Previous Member

    by now you will know twas not my good mate Billy gave you neg, was me, at least it bought you two together, I could not sit here, say zilch, feel guilty
    Fanie I have given you plus and minus, and sorry for the minus, I was rattled because I know as you do now, this guy is brilliant and I know now that you are no duffer either,, I did not want to see you walk away from thread
    you will have to wait before I can make them up, sorry
    nice Rugby
     
  4. Fanie
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    Fanie Fanie

    If you get rattled that easy I'm not going on the water with you :D

    And what is Rugby :confused:
     
  5. Fanie
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    Fanie Fanie

    Since rugby became a paid sport here it sort of lost it's sparkle. Every idiot now wants to be the hero and pocket the score money and so result in poor team work. Too much politics in sport, and remember it is due to 'apartheid' that the rugby team is not just blacks. Nothing to do with any one's abilities.

    We now have to do a course if you want to use pepper spray as a form of self defence 4 5 c :( They are going to teach you how to use it so you won't discomfort the thief too much - probably after someone pushed the tin in where it really counted :D

    On a happier note Billy (and his guardian angel Woosh :D), it looks like I may be getting the LED PCB's by the morrow. I'll put up some pics.
     
  6. Fanie
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    Fanie Fanie

    I heard on the news tonight the All Blacks have a hooker :eek:
     
  7. Fanie
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    Fanie Fanie

    It seems Frosty's resistance value for LED's have evolved a bit :D

    The boards were delivered this morning.
    I forgot to order the spares I don't have, will get them tomorrow.

    Pic2 is how the LED's will sit on the board.
     

    Attached Files:

  8. masalai
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    masalai masalai

    What will you sell the assembled "lights" for ? - What voltage and other stuff do they need for boat installation?
     
  9. Fanie
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    Fanie Fanie

    I dunno what they will cost yet. The LED's are the expensive parts.

    I still have to make a housing for it, I was thinking of milling perspex so the PCB fits in the top of it, the LED's shining through the perspex. Seal it with conformal coating (I have about 60 liters of it) so the sea water cannot get to the electronics. I'll have a play with it to see what works best.

    To prevent the LED's from being irritating in one's eyes you can blacken the sides of the perspex but still maintain the widest angle of light. Depend how high overhead they are going to be installed. As they are they make light 180 deg to the horizontal and 360 deg all round.

    12/16V dc supply but they can handle up to 40V transcients and the LEDS have current protection built in. There is also a 35V transzorb on the board for protection, so the components always operate within a safe zone. Of course if the lightning hits YOU Masalai, I cannot guarantee the outcome :D

    I have designed these for my own boat (don't tell the wife, she thinks it's for customers :D), but I know some gimmic freaks who already ordered their's, so I have ordered enough PCB's.

    Dammit what's with wiemen that they always find fault with everything we do :( I see the radio amateur guys (hams) have the same troubles and I'm sure other hobbies suffer under the same feat.
     
  10. Fanie
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    Fanie Fanie

    Since 'rugby' was mentioned earlier on, I saw on the news the 'Wanna-be's' are playing the 'Springbok's' (who-ever they are :D)
     
  11. rxcomposite
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    rxcomposite Senior Member

    Most LED's will consume about 10 milliampere and drop about 1.2 volt. I say most because bigger LED's can handle about 15 ma. DC supply voltage is usually higher and needs to be dropped by inserting a resistor in series. This is common practice and is commonly termed a "dropping resistor". This resitor absorbs the excess voltage and regulates the current going to the LED.

    If you have a 12 volt supply, the resistor in series must drop 12-1.2volt or 10.8 volt and pass a current of 10ma. (0.01 amp.) The formula is R=E/I. then 10.8/.01= 1,080 ohms or about 1,000 ohms because resisters value are not that accurate. The resistor is absorbing 10.8 volts at 0.01 amps so the wattage rating is P equals E times I or 0.108 watts. So that the resistor will not heat up, the power is ususually multiplied by 2 so a 0.2 watt will do. Small resistors are available in 1/4, 1/2, 1, 2 watts value so a 1/4 watt resistor will suffice.

    To read a standard value resistor, we read the color bands. Color bands can be remembered by many Mnemonics. One is Big Boys Rush Our Young Girls (but) Veronica Goes Willingly for Silver (or) Gold or Black, Brown, Red, Orange, Yellow, Green, Violet, Gray, and White. Black is zero and White is nine.

    For a standard 4 band resistor, the first 3 band is the value, the fourth band is the number of Zeroes you will add to the first three number. The last band is either Silver (10%) or Gold (5%). That is the tolerance or the guarantee that the resistors value is within range.

    If you dont like to make a carreer out of it, there are several ways of doing it. search the internet for "resistor color coding", trust the salesperson that what he/she is giving you is the correct one, or buy a cheap digital volt/ohmeter.
     
  12. Fanie
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    Fanie Fanie

    I have a resistor here, it is 8 ohm and 15 Amp. What is the colour code of this thing :confused:
     
  13. masalai
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    masalai masalai

    long time away from that stuff but rectangular gray with rating stamped in black? but sooo long ago I am probably wrong... stuff that size (15A) we (poor hobbyists on valve electronice) would make with wire, wound on a ceramic former?
     
  14. rxcomposite
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    rxcomposite Senior Member

    That is a mighty big resistor you have there. As masalai has noted, it probably came from the days of vacuum valves. Resistor are rated by resistance and wattage. If what you are holding (I would say about the diameter of a cigar) says 15 amps, the voltage it can drop/handle is E=IxR or 15*8=120 volts. It will dissipate P=IxE or 15*120-1,800 watts. It's going to be pretty hot.

    Big resistors (usually after 2 watts) have their number stamped on it. There is no need for color code as there is none to read. The info is there. Only small resistors uses the color code as stamping it would be hard to read. But then again if you are color blind, better get the Digital Volt Ohm Meter. For the color coded resistors, wattage is something you have to learn by experience. A 1/4 watt is about 1/16" dia., a half watt about 1/8" and so forth.
     

  15. rxcomposite
    Joined: Jan 2005
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    Location: Philippines

    rxcomposite Senior Member

    Resistor Color Code

    Black, Black, Gray, Black

    Attached Resistor Color Code
     

    Attached Files:

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