ECG project circuit osciliiscope only show mains frequency.

[fanshenren]

HI I am doing a school ECG project, I used the circuit design in the AD620 Datasheet. How come when I implenmented the design, I still get 50 Hz mains frequency?
When I ground the body, I dont get anything displayed on the osciliscope.
Any one can help me?
thanks

 

[chuckey]

1. have you checked the DC condition? - this will point you to where you have made a wiring error.
2. Body? , if you ground the live input you expect to see nothing on your oscilloscope.
Frank

 

[Einar M]

Just about all biometric measurements require a differential amp. The ground connection is made to the ankle or wrist. ( I've forgotten what ECG stands for; Cardio? )

 

[fanshenren]

Thanks guys I have got it working now. I will try to eliminate some high frequency noises.

 

[andre_luis]

There is need to implement some filters at ECG circuits :

HighPass 2Hz > Base-line reduction
BandRegection 35-50Hz > Muscle interference
BandRegection n*2*50Hz > Sampling rate following this rule eliminates AC main

Remember to shield PCI with grounded plate bellow.
ECG signals have a range of ~1mV and hardware care must be take.

+++