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Topic: Weird motor problem (Read 884 times) previous topic - next topic

vek11

Hi,
I have a 1.5-3v dc motor, and I am using a SN754410 to control them. The problem is that when I hook up 1 motor with a 3v power supply(2 AA batteries), the motor does not move but it makes a tiny noise when I put it near my ear. (I thought the motor no longer worked, but then I used 2 motors with a 6v power supply, and the motors ran at full speed.) Any help clearing this up for me? thanks.

dc42

Why oh why do people persist in using ancient bipolar H-bridge chips such as L293, L298 and SN754410? These chips have high voltage drop, which also means that they get hot and can't take much current. My advice is to forget bipolar motor driver chips and use modern mosfet-based chips instead. If you really want to use a bipolar chip, then read the datasheet to see how much voltage drop it has, and increase the power supply voltage over and above the motor voltage by that amount.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

Drew Davis

Hello!!!

The reason you'r hearing that noise is because your not giving the motor enough voltage. Due to the fact that your AA batteries probably are not really 1.5v more like 1.2v and because of the voltage drop due to The SN754410 your motors are not getting enough voltage. When you use the 6v your motors are getting plenty of voltage (probably to much). Keep in mind that voltage is not split up between the motors like amperage is. Each one is getting 6v. I would recommend using 3 AA batters. After voltage drop your motors should each get around 3V.

Best of luck,
Drew Davis

vek11

Thank you Drew Davis, that helps a lot.

Drew Davis

No problem!!!! Just out of curiosity what are you building?

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