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Alarm Open Circuit

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5 Threads found on edaboard.com: Alarm Open Circuit
I have a 12v power supply and a flow switch which is closed when water is flowing through it and open when water isnt. I want to make a simple piezo alarm + LED light that tells me (comes on) when water STOPS flowing. How do I do this? That is, how do I take a normally closed switch and make it normally open? Simple is best for me and the (...)
I want to build a laser alarm circuit but some of the posts in the internet are not so clear for me.. Can anyone post here some schematics of that alarm that: * Keeps beeping until the tact switch is pushed and turns off. * Can adjust the beep for a certain time.. * And also have a pot that adjusts the sensitivity of the LDR.. (...)
Hello, Why don't you try using a window comparator circuit. Fire alarm circuits work as a "short" for alarm and an "open" is circuit trouble. Using a LM339 Quad comparator would allow you to build 2 complete comparator circuits. If the micro you are using has (...)
I have the need for an alarm when house power fails. I purchased a sump alarm which trips on high water. The sump alarm probe is normally (low water) open. When water rises it closes and the alarm goes off. I want to substitute a normally open ciruit when house power is applied which (...)
what is your request, i fact it is not easy to realize the VSWR alarm accurately! so you should provide more information for your request If you have 7 dB attenuate (including filter and cable loss) between amplifier and antenna, is impossible to see if antenna end is open, shorted or connected correctly if approve