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I am trying to control a 12V door lock using this solid state relay. In my switchboard, I picked the power from the common power line to power up my SSR at 5V using an adapter, The power line is also connected to an electric fan through a dimmer. The problem here is that whenever I turn my fan switch On/Off really fast or rotate the dimmer in either direction my SSR trips and the door lock unlocks for a moment (100ms maybe) even if I have left corresponding input channel in my SSR disconnected. I am not sure the reason behind it and how to prevent it.

Also, I put my 12V adapter input through SSR to turn on adapter instead of putting it's output through SSR to save power, Would it save any power?

Any help would be appreciated. Thanks in advance.

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  • \$\begingroup\$ Huh? What are those "adapter" things? Power supplies, maybe? I don't see where the SSR input is switched. It looks like 5V is always applied to the "f" input, whatever that is. Draw a real diagram, and use real electrical engineering words. \$\endgroup\$ – Olin Lathrop Jun 3 '17 at 11:26
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    \$\begingroup\$ The adapter things are power supplies. The connection appearing as 'f' was myself drawing an '+' symbol. The SSR is supposed to turn the 12V power supply ON when I supply ground at CH1 input but I left that out because it trips even if I don't connect anything at that point just by switching fan ON/OFF or rotating dimmer. I tried to draw it as much elaborate I could. \$\endgroup\$ – anonR Jun 3 '17 at 11:31
  • \$\begingroup\$ So, ultimately, what device controls the door lock and if you think this question is irrelevant to being able to answer your question think again. \$\endgroup\$ – Andy aka Jun 3 '17 at 11:38
  • \$\begingroup\$ The door lock is controlled by 12V power supply. The input to the 12V power supply runs through the relay and the relay is supposed to give power to 12V power supply and open the lock when I connect the ground to CH1 Input. But even when I leave the CH1 input disconnected and rotate the dimmer the relay trips and for a moment powers the 12V adapter and hence opens the door lock for a very short amount of time (100ms maybe) \$\endgroup\$ – anonR Jun 3 '17 at 11:42
  • \$\begingroup\$ Looks like your fan interferes with the 12V PSU somehow. Perhaps it creates voltage spikes/dips on startup. Can you measure that? \$\endgroup\$ – Dmitry Grigoryev Jun 7 '17 at 9:47
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You are probably getting switching spikes (transients) through your 5 volt or 12 volt adapter. Dimmers are often a source of spikes.

I would suggest trying, on the low voltage side of each adapter, adding a 0.1 uF disc capacitor in parallel with a 220 uF electrolytic capacitor. You can experiment a bit with the value of the electrolytic capacitor based on what you have available.

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  • \$\begingroup\$ Thanks. I am going to try that and will post the results of that here. \$\endgroup\$ – anonR Jun 3 '17 at 11:31
  • \$\begingroup\$ Also keep your low voltage switching away from the power lines. \$\endgroup\$ – Glenn W9IQ Jun 3 '17 at 11:47

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