Thanks, this really sound like the perfect solution to my problem. /Ake -----Ursprungligt meddelande----- Fr=E5n: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]F=F6r M. Adam Davis Skickat: den 3 maj 2004 16:30 Till: PICLIST@MITVMA.MIT.EDU =C4mne: Re: [EE:] Smartest binary way to detect current or no current in = a cable Several years ago a practical electronics article was written up for just this type of project. The author wanted to know when his pipe heating cables were on (the cables have temperature sensors built in) so he could just check every so often and take action if they seemed to be off for too long. He wrapped several (many?) layers of wire around one conductor, then hooked the coil to an LED and resister. Since the current didn't vary when it was on then the voltage on the coil is known and he didn't need any voltage limiting circutry. If your current varies then you may want, at least, a zener diode and a regular diode (to prevent reverse overvoltage from breaking the LED). You can replace the LED with any optocoupler, and most optocouplers will have a higher reverse breakdown voltage rating so you wouldn't need the additional diode. Since you can get an optocoupler with many kinds of output it's easy to interface to practically any other project. A simple transister opto and resistor can be used to connect to a microcontroller pin. You could also skip the optocoupler and simply rectify and filter the output of the coil and measure that. There have also been many projects in the days of yore which switch AC loads based on whether another circuit was turned on. Typically used to power printers, monitors, etc when the computer switches on. The idea is the same, so if you can find one then examine the current sensing circuit for more ideas. -Adam Ake Hedman wrote: >What is the smartest and lowest cost method to detect if there is a >current flowing in a 110/220 V cable, preferably without doing any thing >else with the wire then to attach something outside of the cable. > >/Ake > > --- >Ake Hedman (YAP - Yet Another Programmer) >eurosource, Brattbergavdgen 17, 820 50 LOS, Sweden >Phone: 46 657 413430 Cellular: 46 730 533146 >Company home: http://www.eurosource.se Kryddor/Te/Kaffe: >http://www.brattberg.com >Personal homepage: http://www.eurosource.se/akhe > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.