Malfunctioning solar motion lights

Discussion in 'General Electronics Chat' started by tab a, Feb 2, 2015.

  1. tab a

    Thread Starter New Member

    Jan 14, 2015
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    I've got 3 Naturelites that haven't worked for a long time, so thought I ought to either toss them or try to repair. They were nice when they worked, but none lasted for long. (Bad design vs bad execution?) Since their failures are similar I'm hopeful the problem may be similar on all 3.

    When in the 'test' position, the relay buzzes maybe every second or so, and the light sometimes will come on for a second or so. In the 'on' position --when it's dark, and NO motion--similar buzzing but much less frequent.

    I've checked the transistor, electrolytic caps, diodes and supply voltages to the chips, but am unsure what to look at next.

    The schematic I've drawn isn't very pretty but I've drawn it more than several times and it's far better than the original. :) Red lines indicate changes on what I presume was the most recent version. Thanks for any suggestions!

    motion light pcb251.jpg
     
  2. wayneh

    Expert

    Sep 9, 2010
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    I see you checked voltages, but how certain are you that the battery is still good? Maybe it doesn't have enough juice anymore to energize the relay.
     
  3. tab a

    Thread Starter New Member

    Jan 14, 2015
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    I wondered about that. The original batteries are long gone. I used another rechargeable, and a dry cell, 6.34v and 6.25v. Not fully charged but I thought probably adequate? Thanks.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Can you check the voltage under load? You could also try activating the relay with direct connection to the battery. (The relay may be labeled with a rating that confirms it can be activated with the voltage of your battery.) If the battery and relay are good, you can look at what the output of the 555 looks like, to check that transistor that controls the coil current.
     
  5. tab a

    Thread Starter New Member

    Jan 14, 2015
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    Hmmmm... 2.6v and 4.5v, directly driving a single halogen lamp. Will get better supply. Thanks.
     
  6. Rocket.Man

    New Member

    Jan 1, 2012
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    We have a lot of thunder storms in Tennessee I often loose at lease 1 motion detector light during each lightning storm. TV weather man says, we have 300 days of rain every year. I have given up on replacing my motion detector lights even though they only cost a few $s when they are on sale I have about 30 motion detector lights that dont work in a box in the garage I saved them for parts the circuit is molded in a block of black plastic.
     
  7. tab a

    Thread Starter New Member

    Jan 14, 2015
    10
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    Quick tests of two of the units seemed to work correctly, using a 6v deep cycle golf cart battery. :D Will order some new 4Ah batteries and see how they do. Will be REALLY irritating if they've been on the shelf for a decade just because of marginal batteries. :(

    While I wait on batteries, another question: Is the length of time the light stays on, simply the pulse width of the 555 output, determined by C10 and R23?

    Thanks again.
     
  8. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    The lamps are definitely under control of the output pin #3 of the 555. I haven't studied the schematic enough to know how the 555 is operating, but your guess is a good one.
     
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