Posted on Feb 4, 2014

After testing the motors I found current draw as high as 1. 3Amps. So I stuck 2 of the SN754410 H-Bridges on top of each other, and then built a heat sink from an aluminum can. Should be OK for 2Amps or more. The heat sink is just the aluminum can bent into fins with some heat transfer paste and a spot of silicon glue at each end to hold it on. Dod

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gy but it might work. I dropped the diodes from the previous circuit, and put more standard resistors instead. Also went for the standard pull down resistor to enable. This robot is going to draw plenty of power keeping the Android screen on, so having the SN754410 enabled isn`t going to make much difference anyhow. I`ve tested the motor driver circuit shown on the previous post by plugging it into a breadboard. I wasn`t confident on using the diodes to pull the enable pin high, but it seems to have worked. I still need to check the current draw using the pin for both enable and also to activate each motor. Show in the pictures is a simple test using an Android phone hooked up to an IOIO board which goes to the SN754410 motor driver chip. The IOIO is an amazing piece of kit that provides a voltage regulator with 5V and 3V3 outputs to power your project. In this case I`ve created 5 buttons to test each of the motors in forward and reverse. Download the full source code in Basic for Android if you want to take a look. The IOIO connection method is particularly useful. On my Chicken Gate circuit I had diodes everywhere to stop back current from the motors. I`ve done a bit more research and I believe the internal diodes in the SN754410 and L293D (interchangeable parts) will do the job. Having external diodes will reduce the heat produced, but for my chassis I have 2 x 170mA motor stall on each side of the motor driver, so a...

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