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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 (...)
Hobby Circuits and Small Projects Problems :: 01-09-2013 03:12 :: peters.carl :: Replies: 4 :: Views: 2660
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.. (...)
Hobby Circuits and Small Projects Problems :: 09-29-2011 23:29 :: joemnice :: Replies: 1 :: Views: 1329
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 (...)
Microcontrollers :: 05-08-2010 21:34 :: BobK :: Replies: 1 :: Views: 1465
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 (...)
Analog Circuit Design :: 10-03-2009 19:44 :: 1geo :: Replies: 3 :: Views: 1638
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
RF, Microwave, Antennas and Optics :: 08-06-2005 05:52 :: xxargs :: Replies: 2 :: Views: 827