Hey, I'm Daniel and new in the forum!


I'm trying to build a circuit to preform ECG with DRL for a school project. I'm having problems with amplification and simulation.

In the circuit I'm using the Wilson Central (Right Arm + Left Arm + Left Leg), one high pass filter (0.5 Hz), one low pass filter (150 Hz) and one band pass (50 Hz). I'm still learning about circuits but I think the calculus for the amplification and filters are ok, correct me if I'm wrong please, all feedback is welcome.

I'm getting a signal of pV on the Vout, with the gain of the circuit should be V. (Desired Gain is 1kV/V)

I attach the circuit and some pics. I do the simulations in multisim because in LTSpice I can't get the right components.
If you need more info let me know.

Thanks in advance!


Daniel.

 

Your simulation has U8 with a gain of only 1 instead of a gain of 200.

 

True thanks! I changed the R15 to 25 Ω to put a gain of 200 (5000/25=200). Now I get a signal of nV. Still don't know why I'm making the signal smaller. Here are some pics of th change:


The Rg of the INA333 for a gain of 5 should be 25kΩ if I'm not wrong, the formula of the datasheet is: G = 1 + (100kΩ / Rg). If i put the Rg to 25kΩ I get even a smaller signal.

Edit --> I used a 5kΩ for the R15 and 1MΩ for R16 wich gives the same Gain