Associated with this FM transmitter: ereo-to / dp / B005IPW2E4 / ref = cm_cr-mr-title which requires very little consumption, this adapter 220v / 12v 0.1A (which does not heat and indicates his good connection by a red LED on one of its sides), becomes indispensable at home.
Do not do anything that feed more than a small device such as a GPS or mobile phone, otherwise it will make the soul.
