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Homemade LED white light bulb cheap and easy going green

Konusu 'Genel Elektronik' forumundadır ve guclusat tarafından 22 Haziran 2014 başlatılmıştır.

  1. guclusat

    guclusat Tanınmış Üye Süper Moderatör

    14 Haziran 2009
    Ödül Puanları:
    Going green is fun and there is no need for it to be extreamly expensive ! you can DIY an LED white light bulb at a fraction of the cost
    compared to the ready made you see in the shops, actually at that cost they will payoff when seen over a decade or two..
    this project will payoff allready next week.

    First task is to test the LEDs and the mains supply direct drive is working
    I cheated and used a vario-transformator so I could turn up the "mains" voltage slowly, while checking and measure all is fine.
    this project will incase something is connected wrong potentially generate smoke and exploding parts
    maybe even fire and draw attention to your bad solder skils, so if this is your first DIY.. dont do it.. ask a friend with abit of skils.
    it is important to measure the DC voltage drop over the 220 ohm resistor and calculate the diode current
    I wanted to go for at least 5V drop but under 6V drop, so I know the LEDS are driven a bit under their specified current
    other diode types may be designed for more or less current, always check datasheet !!

    Plenty of light output at only 20-25mA, I tried first with 10 white leds only
    but the cheap types I found are a bit blueish, so I added 4 red leds in the chain to "warm" it a bit

    The schematic is quite simple, and is a LOSS FREE powersupply, only disadvantage is it's NOT isolated from the mains !!
    so take care when measuring voltage drop over the 220 ohm, do not touch anything while powered.
    the 100 ohm resistor protects for peak current at powerup - then you can use a tiny rectifier bridge
    the 400nF capacitor sets the energy level to be transfered, I needed to go up to 440nF when I added more leds, and also wanted a bit more curent
    be sure you use a voltage rating that is about double the AC voltage you have !! for 230 V AC input I use a 400 V type
    the 10uF capacitor is needed to make a perfect non blinking light source,
    its voltage rating must be double as what you measure on the capacitor while it is loaded, (NEWER power up this circuit with out LEDs connected)
    you may remember those cheap x-mas lights that blinks terrible ignoring ! remove the 10uF cap to get that effect :)
    the 220 ohm is for protection of diode current and linearisation, also it is a good point to measure voltage drop and calculate diode current
    In my case I have 5.6V over the 220 ohm = 25mA, and the supply voltage over the 10uF is 46V, so my power usage from mains is 1.17 Watt
    my AC power energy meter showed 1.1W so this proves it is an accurate methode and loss less supply, due to its capacitive voltage divider.

    To the left, an old defective light bulb, soon going to be smashed


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