Slow Flashing LED Module Needed

Discussion in 'The Projects Forum' started by rainycity1, Jan 6, 2014.

  1. rainycity1

    Thread Starter New Member

    Jan 6, 2014
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    I have a 4 ft landscape lighthouse that I would like to light using an 18 SMD LED 12v tail light bulb. I substituted these bulbs into all of my yards lights and they work great. Now I want to put one in my lighthouse and have it flash on and off every 3 to 5 seconds. I have seen a "breathing module" but it still flashes too fast. Any ideas?
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Perfectly doable with a 555 timer circuit and a MOSFET driver transistor.
     
  3. elec_mech

    Senior Member

    Nov 12, 2008
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    Welcome to AAC.

    Do you want a true flash or a fading effect?

    A true flash will be like turning on a flashlight on then off - full brightness or completely off.

    A fading effect acts more like a dimmer switch being turned slowly from off to full brightness then back down to off.

    True flash - look at for an astable 555 circuit such as this.

    For fading, look at Bill's blog, specifically Section 12 entitled Special LED Effects - Throbbing LEDs.

    For either type of circuit, I'm guessing you'll need more current than the 555 can provide, so take a look at Chapter 10: Transistor Drivers from Bill's blog.

    Can you post a link to the bulb you're using, specifically the specs?
     
  4. inwo

    Well-Known Member

    Nov 7, 2013
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    absf likes this.
  5. rainycity1

    Thread Starter New Member

    Jan 6, 2014
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    Thanks for all of the answers to my post. As requested here is a link to the type of bulb I plan to use: http://www.superbrightleds.com/more...d-bulb-single-intensity-18-smd-led-tower/163/.
    I was hoping to find someone on here that would be willing to build the module for me. I am pretty handy with electricity, wiring and mechanical things but electronics are a little over my head. As for the effect I am looking for, I guess it doesn't matter if it blinking on and off or throbs. Whichever is the simplest. I can build a waterproof box to house the module and mount it inside the lighthouse. Thanks again for all of your replies. Rick
     
  6. inwo

    Well-Known Member

    Nov 7, 2013
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  7. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Throbbing might be a problem, AC & hi V DC input, sounds like a bridge rectifier input with something like a buck regulator controlling V or constant current. On-Off might be only option without hacking bulb, or build a new bulb.
    Is that a red bulb, why not a white or yellow or a mixture?
     
    Last edited: Jan 8, 2014
  8. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    I can build a 555 module if you want that, but I have a couple of questions. 1. When you replaced the incandescent bulbs with the LED towers, was it strictly a simple process of removing the incandescent and plugging in the LEDs, or was it necessary to add a resistor? 2. You say you want the light to go on and off in 3-5 seconds. Does that mean you want it to complete a cycle of on and off in 3-5 seconds or you want it to come on for 3-5 seconds and then go off for 3-5 seconds? Please state more precisely what you would like.
     
  9. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Have you tried operating with lower voltages to see if lamp dims?
    I'd say it is a direct replacement.Total cycle time 3-5 sec.
     
  10. rainycity1

    Thread Starter New Member

    Jan 6, 2014
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    Hey you guys are awesome. First to Inwo: that cyclic timer looks like just the thing I am looking for. One question, it says 12v DC power supply. I run all of my yard lights off a 100 Watt transformer that says 12v AC output. Not sure I understand that because the original bulbs were 18 watt bayonet bulbs just like an automotive tail light. The LEDs that I replaced them with were just a straight replacement, no resistors or any modifications made. If I posted a "red" LED that was inadvertant. I will be using bright white. I want the light to flash on 3 to 5 sec and off 3 to 5 sec, just like a real light house. You guys are great. I am a retired appliance repairman so if you have any range, oven, dishwasher, water heater questions I would be glad to assist if I can. Thanks, Rick
     
  11. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    LEDs light with DC voltage; my guess is that yours are actually flashing on and off at 60Hz because of your AC power supply. That's not really a problem if they are as bright as you want. If I am correct, and you were to power them with 12VDC, they would be twice as bright.

    However, the AC will have to be rectified and smoothed in order to power the timer. In addition, the timer uses a relay, which will work fine for a while, but will eventually wear out from being cycled on and off 6 or so times per minute. (It will also produce a small click each time it switches.) If the timer is a 555 circuit, you could simply do away with the relay and power the LED straight from the 555. Finally, the LED may be brighter than you want if you power it from 12VDC. In that case, the relay has the advantage of being able to switch AC as well as DC.

    Choices, choices.
     
    Last edited: Jan 8, 2014
  12. inwo

    Well-Known Member

    Nov 7, 2013
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    It may be available in other voltages including 120vac.
    I'll look again and edit with a link.
     
  13. inwo

    Well-Known Member

    Nov 7, 2013
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