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POWER OFF ON with delay

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Hi there
I have a system that is stop working for few times around the year (hang), and it only start working again when I power it off then on again. Is there any circuit that can be used to trigger the system power off then on. I will give it the pulse from a Microcontroller in the same system. So when the pulse is high, then the relay will be ON to switch the power OFF. Immediately the pulse will be low because the whole system is OFF which make the relay OFF to switch the power ON again after certain time.


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  • 3 weeks later...

Google "Watchdog Timers."  TI, Maxim, Analog Devices, and many other chip makers make devices with various levels of complexity and sophistication to restart a system if voltage levels drop below some threshold or if the watchdog input senses an absence of normal system activity or if it receives a reset pulse.  They come with preset or adjustable time delays of milliseconds to seconds.  They put out a delayed logic "0" or "1" that can be used for whatever you desire.

If you already have and are happy with a pulse from your system to command a reset you can use a TDR (Time Delay Relay)  They also come in all flavors of adjustability and functionality including delayed on, delayed off, one-shot, and many other programs.  Sounds like you may be seeking a one-shot function that will switch the contacts for a selectable time period from a fraction of a second to many hours upon receipt of a pulse or contact closure.

As I recall, Grainger's catalog offers a variety of TDRs and has a writeup explaining all the variations of programs available.


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