Hey, I have to do a PCB for the acquisition of the ECG signal and later I'll have to stack it on a PCB for a independent power supply (other than the digital lab). I wanted to know if someone can give me an ideia about how to do the power supply since I need a +5V and -5V and i'm especially intrigued about the -5V. I was wondering about doing one circuit that would involve a voltage regulator that needs 12,5V and gives 5V like the L7805, but it only works for the positive voltage. Sorry if you don't understand anything, english is not my main language, feel free to ask more things if you need. I'm really not sure what would be a good solution.

 

If your transformer fails you have the possibility of mains voltage on your ECG pick up electrodes. Isolation between your electrodes and the power supply is needed and that can get a little involved. Use batteries it's far safer.

 

If your transformer fails you have the possibility of mains voltage on your ECG pick up electrodes. Isolation between your electrodes and the power supply is needed and that can get a little involved. Use batteries it's far safer.

And with batteries how would i get exactly -5V?

 

Why do you need exactly 5V?

You can get either 4.5V or 4.8V depending on your battery type.

I'd use eight 1.2V NiMH Rechargeable AA batteries in series. Use the junction between the 4th and 5th battery for your 0V and that will give you +4.8V and -4.8V at either end of the chain.

 

And with batteries how would i get exactly -5V?

John