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Author Topic: 12v dc motor control with pot and lm324  (Read 1889 times)
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Hi,
Does anyone or has anyone done a dc motor control with a potentiometer
and a lm324 op ic? Is it possible? Looking for basic speed and direction
control with the direction of pot and increase of pot sweep. I know there
are h-bridges out there and motor shields, I am currently not interested
in those. Just would like to know if it's possible and if anyone has schematics
and schetch. Something to get my feet wet. If not the I will be purchasing
a SN754410 H-bridge.
Thank you for any help
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LM324 is good for +/-20 to 30mA of current source/sink.
Are you driving really small motors from split power supply (+/-5V, +/-12V)?
http://www.ti.com/lit/ds/symlink/lm324.pdf

If not, then use a real motor driver chip such as the SN754410 you wrote, or an L293 or L298.
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I will be driving a 12v motor at 1A. Appreciate the reply any idea on wiring this thing up? Saw plenty of post for the sn754410 but am finding nothing for the lm324.
Best regards
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You could have the op amp make a square wave
http://www.facstaff.bucknell.edu/mastascu/elessonshtml/UsefulCircuits/SqWaveGenerator.htm
and drive the 744410 with that as speed control on input 2.
Use a 2nd op amp as inverter to drive input 7. That will get you motor speed.
Use a 2nd pair of op amps to control which output is enabled, for direction.
I think the L293 datasheet shows the control relationships more clearly.

Pin 2 pulsing with 7 low is motor spin one direction. Pin 7 pulsing with 2 low is motor spin the other direction.
The wider the on-time of the pulses compared to low, the more the motor is on, with full speed when the output is just high.
Both 2 and 7 low or both high and the motor does not spin.
http://www.ti.com/lit/ds/symlink/l293d.pdf

http://www.ti.com/lit/ds/symlink/sn754410.pdf
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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