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DC power drop alarm Answered

I need a very simple way to see if power is ever lost to load.  I am trying to run a long term test of at least 60 days.  I have a UPS that is powering a load and I need to be able to determine if the 12 - 15 V dc that the UPS is providing is ever lost. The UPS has a battery that will supply power if the AC input is lost.  The solution can be very simple and I really don't want the load to be reconnected if the current going to the load is ever lost. I need to know if the load is ever not powered, even for a brief instant.  I was hoping there might be some type of switch that would open if the current stopped flowing through it.  Sorry for the simplicity but I know very little about electronics.  Thanks for any help or advice.

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iceng

Best Answer 3 years ago

This relay will start when you press the red button and stay on until power is interrupted then it turns off and stays off...

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icengiceng

Answer 3 years ago

Or if you have a line coil relay then this circuit is easier to assemble... The red button activates the relay until a a power interruption or green button push.

Be sure you click the pictures to see the entire image...

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-max-brentatespicorpdotcom

Answer 3 years ago

That circuit can also be made using semiconductors pretty easily. A MOSFET (or BJTs if you prefer them) can be configured like

https://www.google.com/search?q=MOSFET+latch&espv=...

to make a really simple latching circuit that works exactly the same way in principle. The benefit of this is that it takes much less power because there are no coils to keep energized, but it is probably going to be better suited for lighter DC loads.

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icengbrentatespicorpdotcom

Answer 3 years ago

Your welcome, thanks for the BA.

BTW, you won't ever go wrong listening to Steve's advice.