Re: Help interfacing Current Transformers to ADC

Hello Jim,


CT -- load resistor -- active rectifier -- low pass filter -- 3pcs 8x1 mux -- MCU with ADC.

You can do it without the active filter. That's cheaper :-)))

Low-pass filer does not have to be active.
I did not think that I should state such trivial things...

Sorry, mea culpa. I meant to write active rectifier. If you really need linearity down to zero one can use an inverted transistor as a rectifier.

If the "burden" resistor is after the rectifier you don't need
"active" rectification.


True. But it adds a bit of risk in that the rectifier might croak. Probably not a huge risk if the diodes are nice and big. The inverted transistor wouldn't be a very "active" rectifier except that it needs a wee current into the base.

One issue to keep in mind with the "burden after diodes" approach is harmonics. Might need little ceramics across the diodes so no hum is modulated onto your favorite AM talk radio station :-)

BTW, did you get that power-on detect installed for the kitchen TV? An installation in our house is only considered "done" when the wife has approved...

--
Regards, Joerg

http://www.analogconsultants.com
.

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