to collect and display ECG. It uses two electrodes which are attached to body (on chest) and signal si transmitted through op-amps to Arduino ACD-pin.
Yes, and no.As others have pointed out, the Arduino runs from 5V.However, if you are not using batteries, then leakage from the powerline becomes an issue. An ungrounded power supply may be floating at 1/2 of the AC line voltage. And your circuits specifically strive to make a low resistance connection to your body.I've been shocked before on dry skin by a floating switch mode power supply that had a missing ground pin on the power plug. I was touching actual ground, and case ground, and got a bit of a tickle with dry skin. High impedance voltage measurement was about 60Vac (120Vac powerline), and short circuit current was around 25mA.I'd run it from a battery.
But I need connection to PC becase I'm sending there data. Is there any way I can send data and not power Arduino from PC?
Is it safe for both human and Arduino board to be connected this way? Should I make some safety pracautions and if so, which?
You should not be relying on advice from forum members who probably have no in-depth professional knowledge of electrical safety (that includes me!).With electrodes connected close to the heart, you obviously need to be especially careful about safety. In this situation, don't even rely on the advice of a qualified electrician.
The dual supply voltages were generated by inductive coupling charge pump circuits that used magnetic coupling to create an electrical isolation barrier. On the input side was all the circuitry that ran off the ac wall power. On the patient side (all the ekg electrode monitoring circuitry) was 100% electrically isolated from the the AC input side by the magnetically coupled charge pump power supply circuits.