any ideas? i mean such a +12V coin meter/counter being plugged or not...

Posted on 2004-04-18 21:06:18 by dion
Im not sure what your asking for, but to detect a load all you need to do is monitor the series current out to the load's port.

Placing a high wattage, but low resistance resisotr in series and through OpAmp instrumentation, you can determine the voltage difference, which based on the resisters resistance, can determing the amount of current being drawn. From here, multiply this value by the voltage sourced and you have the amount of power being supplied to the load.

Posted on 2004-04-18 23:40:30 by NaN
I take it you want to know if customers are unplugging and plugging the machine in again. You could count the number of times and with a battery and some additional programming you could pin point the time and date. You need a VPP circuit for the flash or if seperate memory (not a PIC) you can use Intel smart voltage flash to record each time to unit has initialized (turned on) and a battery to quickly run the processor an additional few seconds to write when unplugged then continue to shut it's self off.
Posted on 2004-04-20 14:40:28 by mrgone
thanks all
and i think that op-amp idea is make sense, NaN.
but, i just think that i have to output or drive the load meanwhile i could sense the current too, but how?
Posted on 2004-04-23 21:23:12 by dion