I'm making ECG device and for that I need a dual power supply.
I decided to use 3 x 9V batteries and below there is my scheme:
unfortunately I encountered a problem. I created that power supply using that scheme but after connecting to the output small computer fan, the RPM (and voltage) gradually decreased and finally stopped rotating. construction was hot but after a couple of sec it started to work again but with the same result. where is the problem ? virtual ground ? maybe I should make scheme with 4x 9V batteries ? like this :