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Mahmood Elnasser
02/14/06 10:42
Read: 481 times

Msg Score: +1
 +1 Good Answer/Helpful
#109965 - an Idea
Responding to: Per Guldmann's previous message
Per Guldmann said:
Hey Forum.

I am doing a monitoring aplication: If mains power is cut off, an alarm of some sort is needed. Verry simple - a few resistors and an optocoupler, and here we go.

The problem is, that if I want - say 10 mA - through my optodevice, then ill have a power disipation of about 2,3W (mains voltage is 230V AC). With aprox. 20 circuits to monitor, ill have some 46W to get rid of.

So, is there any body out there having an idea, how to monitor mains power with low loss?

For safety reasons ill prefer isolation!


Why not use normally closed realy contacts for the alarm and have the coil 220VAC, as long as the mains is on the relay is energized making the alarm open circuit, if the mains goes off, the battery operated alarm starts wining.
You can solve your problems and add simplicity to the design.

List of 34 messages in thread
monitoring mains voltage      Per Guldmann      02/13/06 04:38      
   Opto with capacitor      Oliver Sedlacek      02/13/06 06:33      
      re opto with cap      Per Guldmann      02/13/06 07:09      
         Some protective components required      Oliver Sedlacek      02/13/06 09:56      
            Fire risk      Kai Klaas      02/14/06 07:14      
   Transformer        Andy Neil      02/13/06 07:49      
      thats the best chioce      Abhishek Singh      02/13/06 07:51      
      There's nothing wrong      Per Guldmann      02/13/06 08:40      
         Space      Andy Neil      02/13/06 09:32      
   please do not go aargh      Erik Malund      02/13/06 08:48      
      Opto isolator = LDR + Neon?      Andy Neil      02/13/06 09:20      
      10mA?      Oliver Sedlacek      02/13/06 09:53      
         Hmmm      Per Guldmann      02/13/06 10:12      
            Why not...      Steve M. Taylor      02/13/06 17:03      
               Neon + Photodiode      Andy Neil      02/14/06 00:31      
                  Loosing brightness      Kai Klaas      02/14/06 06:05      
   Transformer isolation is needed!      Kai Klaas      02/13/06 19:42      
      Previously, on      Andy Neil      02/14/06 00:29      
         Safety first      Per Guldmann      02/14/06 03:11      
            Transformer      Kai Klaas      02/14/06 05:58      
               Sorry      Kai Klaas      02/14/06 07:18      
                  two places to look      Erik Malund      02/14/06 07:26      
                  Annoying, isn't it?!      Andy Neil      02/14/06 08:23      
                     Thanx!      Per Guldmann      02/14/06 08:35      
                        maybe Amveco 6200 series?      Erik Malund      02/14/06 08:37      
                        Transformers      Anders Sandström      02/14/06 11:01      
                     Could also be used      Kai Klaas      02/14/06 10:05      
   an Idea        Mahmood Elnasser      02/14/06 10:42      
      The simplest ideas are the best      Jez Smith      02/14/06 14:58      
         Poor dads      Mahmood Elnasser      02/14/06 23:12      
            Tainted food      Kai Klaas      02/15/06 08:25      
      Yes, but...      Kai Klaas      02/14/06 20:01      
         Low current      Mahmood Elnasser      02/14/06 22:50      
            Exactly!      Kai Klaas      02/15/06 08:40      

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