??? 11/07/04 17:17 Read: times |
#80610 - RE: The perfect design.. Responding to: ???'s previous message |
Hi Steve, Thanks for your reply,
why he needs to do a precision rectifier anyway, when its appears that direct conversion will yield a higher precsion result. This all seems to be straining at gnats. I said I am using PCF8591 ADC which is a unipolar input ADC and can't handle negative potential signals. And for measuring current of the order of several hundred Ampere I am using CT which when terminated with a burden resistor produces potential in propotion to current flowing. This signal thus generated has identical waveform to the current flowing and this sinusoidal signal is going well below zero and thus can't feed directly to unipolar ADC and thus I need to rectify it so that the -ve half cycles are rectified to +ve side. Since an ordinary rectifier will show the diode drops which is not tolerable thus I need a precision rectifier. Fine,in a 14bit plus accurate system, but for 7 bits ? You are very right steve, for 7 bit precision that is my present requirement all these grounding and other techniques are certainly an over engineering, but as I have already said soon I will be using 12 bit ADC AD574 in my product I am preparing my self for that. Regards, Prahlad Purohit |