(Topic ID: 209049)

Guidance on rectifying voltage for an LED strip

By arolden

6 years ago



Topic Stats

  • 6 posts
  • 4 Pinsiders participating
  • Latest reply 6 years ago by arolden
  • Topic is favorited by 2 Pinsiders

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    #1 6 years ago

    Hi all,

    I am trying to wire up an LED strip for my Judge Dredd topper. Appreciate some assistance with this.

    I've installed a 6V DC LED strip across the top of the backbox to light up the topper. As the strip is DC, there is a noticeable strobe effect as I have hooked into the 6V AC voltage going to the backbox general illumination. I'd like to eliminate the strobe effect.

    Can anyone please explain how I would go about this? I'd prefer to buy a discrete bridge rectifier instead of messing around with individual diodes, so what are the specifications required for it? The circuit is 5A, and the voltage is at 6V (actually, it is slightly above 7V according to my meter), so is any rectifier OK as long as its specifications exceed these figures? I've got plenty of old 35A, 200V rectifiers from power driver boards lying around - are these OK?

    Second question - how exactly should the rectifier be wired? I am assuming the LED strip is connected to the + and - terminals of the rectifier, and the other legs of the rectifier connect to the lamp socket. Is that correct?

    Thanks for any advice.

    #2 6 years ago
    Quoted from arolden:

    is any rectifier OK as long as its specifications exceed these figures

    Yes

    Quoted from arolden:

    I am assuming the LED strip is connected to the + and - terminals of the rectifier, and the other legs of the rectifier connect to the lamp socket. Is that correct?

    Yes

    Now, before you go hooking it all up, hook just the AC to the GI, and check the DC with a meter. The output DC voltage isn't exactly the same as the input AC voltage. Usually a bit higher. Make sure you're still safely within the operating voltage range of your leds.

    Even then, you might have problems. All a rectifier really does is invert the negative half of the AC wave, you'll still have a wave, so your LEDs may still flash (just not nearly as much as before). You may need a capacitor too to smooth it out. Probably 100uF would be fine? (There's no 'bad' value here, just what works better or not as well, so feel free to play around if it's necessary)

    #3 6 years ago
    #4 6 years ago

    When you rectify the 6vac and then smooth it with a cap, you are going to get an increase in voltage (possibly as much as 8VDC. Can your Led strip handle higher voltage? If not, you will fry it.

    #5 6 years ago

    At this stage I'm not installing a smoothing cap. Will see how it looks first.

    As for the increased voltage, how big a resistor would I need to lower it?

    #6 6 years ago

    I have just checked the voltage and there is only 3.5V coming out of the bridge. This is lower than I'd like but it actually looks pretty good. No strobing at all. I think I will leave it at that.

    Thanks for the help.

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