17.xx. The simple electronic devices.

    17.88  Solar powered 'Rodent Pest Repeller', after one year.

  Interesting story. Years ago I bought this "Yard Solar Power LED Mouse Mice Mole Gopher Rodent Pest Repeller Chaser". 

  Of course, first of all, I disassembled it. The expectation that in the middle there will be something special was wrong. But everything looked good, except that 6 Volt solar panel was wrong for this application.

  A conventional multi vibrator on bipolar transistors, turns ON vibrator (hidden in the base), for 5 sec., every 40 seconds. The resonance frequency of this "earth shaker" is 250 hertz.

  The schematic diagram would be nice... As usual, it's easier to draw a schematic than to infinity look on the Internet (the manufacturer web site will be happy to share:))). Here it is.

  If you repeat the circuit, please note that:
 a. The original polarity of capacitors C1 & C2 is not correct. You need to change the plus and minus;
 b. This 6V 50mA solar panel over kills the circuit. The solar panel 2,4V/3,2V 100mA will be more than enough;
 c. White LEDs D2* should be added. It shows when the device is turned ON and protects transistor Q1* from hi-voltage spikes.

  An 'electromechanical' device that produces vibration is shown in the photo below. Interestingly, it produces an absolutely accurate frequency of 250Hz.

  After assembling everything together, I installed it in the backyard. I had a feeling that the result did not take long-long.

  Now, after one year (one winter), it stopped working. Not that I would be very surprised. Probably the opposite. To my surprise, all that could go wrong - did it. The killer was a water, which was everywhere.

  Thin film solar panel suffered first. Corrosion started in a place where leftovers of soldering flux was not cleared.

  The same reason killed the main board and some components.

  By some reason, the water gathered below, where the speaker is located. It is not sealed, of course, and was killed by rust.

  Replacing the solar panel, rebuilding the main board, applying 'Conformal Coating'‎ to everything, and charging the battery - is a matter of hours. Since the water will be collected below in any case, nothing better than to make an additional breathing tube I did not come up with. *The LED is connected by two additional wires. It looks like.

  It's time to give a second chance to this "ground shaker". I will test it and install in a few days.

  Just wondering. How long this will work at this time?

28.05.2017  SKootS



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