Just wondering if there is anything available that could sense a voltage change and close a momentary switch circuit? Thanks.

Aaron

 

How much of a voltage change are we talking? You can use a comparator with a set reference for this, but it would help if you could provide more specifics.

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How big of a change, how fast of a change, which direction is the change, do you need to know the direction of change ....

A window comparator will set a low and high level for the voltage and if it moves outside that range, will trip the comparator. But if you want the thing to stay "tripped" and not reset back to normal on a quick transition, you'll have to follow up the comparator with another circuit (e.g., an RS flip flop) that will retain the trip.

Dean

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Dean Huster, Electronics Curmudgeon
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I am trying to find something to trigger a momentary switch (normally-open) when voltage goes from 24vac to 27vac on something. Can't find a relay in this range. Thanks.

Aaron

 

hi Aaron,
You will not source an 'ac' relay that will be sensitive enough to differentiate between 24Vac and 27Vac,

Is this project the same as the other thread, reference when a switch is opened.?

IMO to get a reliable circuit that will detect that 3Vac change will require some electronics circuitry.

Whats the application and your budget.?

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