Rectifying a sinusoidal signal which has dc offset

[xeratule]

Hi all,
I want to rectify my current sensor output to dc. When I power up the current sensor it outputs 2.5V dc value. When it senses current flown through it, output becomes a 50hz sinusoidal signal which has an offset of 2.5V. I want the sensor output to be at a dc level, so want to rectify that output. When I try to rectify it like doing AC signal using diode bridge, it does half wave rectification below 2.5V level. What I want it is to rectify it as fullwave and above 2.5V dc. How can I do that? Thanks in advance.

Regards
Erhan

 

[kak111]

You cant use only diode rectifier with signals lower than +/- 2.5V.
Every diode in series with signal takes 0.7V voltage drop.

I think , there is two ways:

1)- use active precision rectifier op-amp circuit with compensating offset setting
or dc-blocking capacitor. ( see pict. , these circuits needs dual supply )
( google other circuits as "op-amp rectifier" )

2)- if MCU is used , then continous reading of sensor signal and taking max. values as measured signal.



One more possible solution is , power supply desing so that sensor zero voltage supply level is 2.5V lower than measuring circuit.

What is the sensor you use.

 

[xeratule]

What is the sensor you use.

Thanks kak111,
I use LEM's CAS15n-p current transformer. I have a noisy output from the sensor that's why I needed to have DC output instead of taking max value of the signal. However I'm gonna try it. Using active rectifier seems a little bit complicated for now. I thought there should be an easy way to handle this issue.

Regards,
Erhan