Here is a design for a full-featured motor shield that will be able to power many simple to medium-complexity projects.4 H-Bridges: L293D chipset provides 0.6A per bridge (1.2A peak) with thermal shutdown protection, internal kickback protection diodes. Can run motors on 4.5VDC to 25VDC.Up to 4 bi-directional DC motors with individual 8-bit speed selection (so, about 0.5% resolution)Up to 2 stepper motors (unipolar or bipolar) with single coil, double coil or interleaved stepping.Pull down resistors keep motors disabled during power-upBig terminal block connectors to easily hook up wires (18-26AWG) and powerArduino reset button brought up top2-pin terminal block and jumper to connect external power, for separate logic/motor suppliesTested compatible with Arduino Mega 1280 & 2560, Diecimila, Duemilanove, and UNOL293D motor shield, the input voltage DC4.5-25V600mA OUTPUT CURRENT CAPABILITY PER CHANNEL1.2A PEAK OUTPUT CURRENT (non repetitive)PER CHANNELENABLE FACILITYOVERTEMPERATURE PROTECTIONLOGICAL "0" INPUT VOLTAGE UP TO 1.5 V(HIGH NOISE IMMUNITY)INTERNAL CLAMP DIODESThe Device is a mnolithic integrated high voltage,high current four channel driver designed to accept standard DTL or TTL logic levels and drive inductive loads (such as relays solenoides, DCand stepping motors) and switching power transistors .To simplify use as two bridges each pair of channels is equipped with an enable input. A separate supply input is provided for the logic, allowing operation at a lower voltage and internal clamp diodes are included. This device is suitable for use in switching applications at frequencies up to 5 kHz.