Whenever I'm in the car listening to my favourite CD, it always happens; my batteries go dead. To solve that problem, I built this extremely simple regulator circuit. It steps down the 12V from the lighter socket to 9V which is used by the CD player. Different CD players (I have a Sony Discman) may require different voltages, so just use the correct regulator. All the 78xx series regulators have the same pin out, so the circuit is universal. CD Player Adapter For Car Circuit Diagram Part Total Qty. Description C1 1 1000uF 25V Electrolytic Capacitor C2 ...