Try using a resistor with higher value. Isaac Em 13/11/2011 07:35, Grant Tudor escreveu: > Isaac, > > Found an old PSU and pulled out the ferrite core. I set up a 60W light > globe as a test rig. With 5 turns I got about 3mV peak to peak. 25 turns > produced about 100mV peak to peak. A bit less than I expected but the > concept works. I think I need to get a bit more voltage though - will try > out a few more variations over the next few days. > > Grant > > On Sun, Nov 13, 2011 at 7:36 AM, Grant Tudor wrot= e: > >> Isaac, >> >> Thanks - I will give that idea a try. I have some old PSUs in the shed >> somewhere...... >> >> Grant >> >> >>> A current transformer is also very simple to implement and won't waste >>> any power. >>> You can build your own with a toroidal ferrite core found in computer >>> PSUs (around 1cm diameter), some insulated wire (around 28AWG) and an 1= k >>> resistor. >>> The main advantages are that it doesn't waste power and it provides >>> electrical isolation. >>> >>> Simply wrap four turns of wire in the toroidal core and connect its two >>> ends to the resistor. Insert one wire that goes to the heater in the >>> toroid's hole (just one leg, not the two wires). >>> When current passes through the heater a sinusoidal voltage will appear >>> between the two terminals of the resistor. It is easy to rectify and >>> filter it and feed to the MCU. >>> If the voltage is too low, simply use a resistor with higher value. >>> >>> >>> Best regards, >>> >>> Isaac >>> >>> >>> -- >>> http://www.piclist.com PIC/SX FAQ & list archive >>> View/change your membership options at >>> http://mailman.mit.edu/mailman/listinfo/piclist >>> >> --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .