This circuit consists of two separate 20W bridged power amplifiers (one for each channel) based on four TDA2003 monolithic Integrated Circuits to deliver more than 40W of music power into a pair of 4 Ohm speakers. Running on 12V DC, this stereo amplifier is ideal for use in the car to boost the audio power or to power additional speakers. Supply voltage: 12 - 18VDC / 3 - 4A.