This is a simple circuit that can be used for charging (mengisi) car battery. In this circuit there is facility for monitoring the charging current and voltage.
Circuit of charging battery Mobil is based on the IC MC78T12ABT . The IC is nothing but a 7812 in TO-3 package with 3A capacity. The transformer T1 steps the mains voltage to 15V AC and diodes D1&D2 does the job of rectification. Capacitor C1 does the filtering and C2 acts as a decoupling capacitor. The ground terminal of IC1 is lifted to 2.1V using the diodes D3 , D4 and D5 . So the output from the IC1 will be a regulated 14.1V (12+2.1). Battery is charged via diode D6. The D6 blocks reverse flow of current from battery to charging circuit when the mains power is not available. Meter M1 shows the charging current and M2 shows the charging voltage.
Spesifikasi IC MC78T12ABT
This family of fixed voltage regulators are monolithic integrated circuits capable of driving loads in excess of 3.0 A. These three–terminal regulators employ internal current limiting, thermal shutdown, and safe–area compensation. Devices are available with improved specifications, including a 2% output voltage tolerance, on AC–suffix 5.0, 12 and 15 V device types. Although designed primarily as a fixed voltage regulator, these devices can be used with external components to obtain adjustable voltages and currents. This series of devices can be used with a series–pass transistor to supply up to 15 A at the nominal output voltage.
Feature IC MC78T12ABT
• Output Current in Excess of 3.0 A
• Power Dissipation: 25 W
• No External Components Required
• Output Voltage Offered in 2% and 4% Tolerance*
• Thermal Regulation is Specified
• Internal Thermal Overload Protection
• Internal Short Circuit Current Limiting
• Output Transistor Safe–Area Compensation