How to bypass optocoupler in ECG circuit?

[vhha]

Hi there,

I am successfully using the attached ECG circuit to get ECG signal.

The problem is that this circuit needs two separate 9V DC batteries - one for the amplifier circuit & other for the isolation circuit (which has an optocoupler).

This safety feature is great when one is physically connected to a PC using a USB cable, etc.

In my case, I want to build a micro-controller application using this amplifier. As such, I want to supply the micro-controller and the amplifier with same single battery source using voltage regulators.

However, I am unable to use single battery for this amplifier. Because as soon as I start supplying its 2 circuits by the same battery using DC-DC voltage regulators, I lose the ECG signal.

I wan wondering could I just by-pass the optocoupler and get rid of the 2nd 9V battery? Is it as simple as connecting the 4 pins from the amplifier side to the corresponding 4 pins on the optocoupler side (without the optocoupler)? Also, then I could just leave the 9V supply pins disconnected?

Any help/ideas would be greatly appreciated!

Regards,

Vhha

 

[Audioguru]

It is simple to properly bias the inputs of opamps then they use only a single battery.
For isolation, the input opamps and input of the opto-isolator needs its own battery so that the remainder of the circuit can be connected to and powered from the PC.

 

[vhha]

Thanks so much for your reply, Audioguru!

However, what I gather from your post is that I still need 2 supplies: one from PC and one from battery?

I want a solution where a single battery does everything. In my case, the microcomputer cannot give out enough power. Moreover, I am supplying microcomputer from same battery source. So grounds are common.

Cheers,

Saif

 

[vhha]

Thanks so much for your reply, Audioguru!

However, what I gather from your post is that I still need 2 supplies: one from PC and one from battery?

I want a solution where a single battery does everything. In my case, the microcomputer cannot give out enough power. Moreover, I am supplying microcomputer from same battery source. So grounds are common.

Cheers,

Vhha