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Lighthouse project, flasher relay

Discussion in 'Microcontrollers, Programming and IoT' started by hotrodjohn71, Sep 25, 2019.

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  1. hotrodjohn71


    Jul 22, 2017
    If "microcontroller' is the incorrect forum for this question, please advise and I will repost in the correct forum.

    I have a pond which I built a wood cover for the float level mechanism which governs the water fill. On the cover I have a garden lighthouse about 3 feet tall. I have a box.of old yard solar lights like the kind you find at 99 cent store or harbor freight. Each light has either a AAA or AA battery making about 1.5vdc.
    My idea is to cluster 8 of the solar panels together in series to make 12v and run that to one 12v bulb in the top of my Lighthouse. I would also like the light to flash. Is there a flasher relay that would work on such low current, then the.issue of timing the light flash to faster or slower. What do you think?,Thanks
  2. Nanren888


    Nov 8, 2015
    A real electromagnetic relay might not be the best choice. A solid state solution might be lower power and not mind a large number of switch cycles.
    Also, LEDs are likely more efficient than a real "bulb".

    I googled [lighthouse flasher] and [solar lighthouse flasher] and found a few people who did similar.
    For the timing, some use a 555 timer, or digital gates.
    Most use a(n) FET for the switching element, but some use a bipolar transistor.
    Have a look at a few circuits.
    Not sure whether you are looking for anything working or cheap or the fun of making.
    I also saw adverts for cheap 12volt motocycle flasher units, but probably not low power for running off tiny solar cells.
  3. dave9


    Mar 5, 2017
    1) Those old solar lights probably use solar panels with a short lifespan, are not something I would design a new project around. If you want that type of panel I would at least buy new ones.

    2) Those lights use a boost circuit to get that 1.5V up to the forward voltage of the (presumably) white LED, so just run the LED without the boost circuit and there is no reason to target 1.5V per light, closer to 3.2V might be better but with current limiting.

    3) Lighthouses spin their light instead of blinking it. You can use a simple geared motor to achieve this. Whether it is easier to spin a powered LED with brush contacts, or keep the LED stationary and spin mirror(s), I don't know given the variables in supplies and construction skills, but it would look a lot more neat/realistic to have spinning light. It would need nothing more than the motor with a flat plate mirror in its output shaft and the LED pointed at the center, but of course you would replicate the lighthouse light throw better with a collimating lens on it.

    4) 12V incandescent bulbs are horribly inefficient. I don't recall the numbers but wild guess is LED is 10X more efficient. With LED, I'd use a very warm color temperature to get closer to the old lighthouse lantern color temp. I wouldn't go any higher than 2700K.

    If you really want to just flash a 12V incan bulb, I would go the simple route of using an automotive (turn signal) relay flasher and accept the rate it gives. The rate will go up with a higher current bulb and down with lower current, but the current will be high enough that a few solar light panels won't cut it.

    Go LED. This will also greatly reduce the battery needed to store the solar power. However if you have a float level mechanism, does it have live power to it, is a power switch rather than a logic switch? If so you might be able to tap power from that for an LED driver and not need solar cells or batteries at all.
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