Let's Make Robots!

L293/SN754410 h-bridge schmatic



I am a technology education teacher who teaches an industrial design course. This previous year we used the L293D chip to make a motor shield that works withe Arduino. The schematic that i was using works very well with the L293D chip but will not work with the L293 or the SN754410. Attached is a schematic of my motor shield with diode protection. i hope the diodes allow me to use the L293 and the SN754410. If any one is familiar with this sort of motor shield i would love to have my schematic looked over and any possible suggestions made. 

I did post this on the Arduino forum, but i thought it my be more usefully on here.

H-bridge_2_.jpg71.29 KB

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okay i refined the PCB. I added resistors and pins that work with the LDR ultra bright LED combo used for line following and sumo fighting.

If any one trust my electronics ability feel free to use my PCB.


Links are to the Eagle files

Hopefully they work








Built the PCB and tested it today works great. I will take some pictures of my students bots when they are done.


Thank you again for all the help.

I guess i can run Vcc1 back to the Arduino to get the 5 volts required or do i need to add a voltage regulator? the circut shown works well with the L293d with out the diodes but won't work with the sn754410, could Vcc1 be the problem?


Thank you for your input

Not sure if you know but you can skip the diodes if you use the SN754410 chip. You speak about it in the same breath as the diode-less L293. The SN754410 has diodes built in like the L293D does.

You have to connect Vcc1 to 5V regulated, now you have it connected to 6V through a 10k resistor.