Electronics > Electronics

L298N motor driver

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jim:
hi.. I want to clarify something. I recently made this circuit in the below link. http://www.instructables.com/file/FT8ERG4GYVDJSP8

unfortunately it is not working and i guess something is wrong.. i have a doubt regarding the two pins 9 and 4.. i think it has been interchanged in the circuit... because the datasheet of L298 says that pin 4 is for supply and pin 9 for logic. Also the Vc +5V is being connected to the ground in this link.. I guess this is the mistake why the circuit is not working. Could anyone please tell me whether I am correct or wrong..?? thank you

jkerns:
Something is wrong with your schematic and the VS  connection - you show your Vc+5v connected directly to ground and a capacitor in series with the supply which will block the current to your chip.

Edit - re-reading, I see you asked about this.

It will not work as drawn. The voltage source needs to be on the other side of the capacitor - directly to pin 4.

As far as pins being mixed up - pin 9 should be the same 5V as your chip. Pin 4 should be the motor supply voltage - does the label on the drawing Vc+5v mean that it is at 5V or that it is 5V more than Vcc?

jkerns:
Also, you don't need the 22 ohm resistors unless you plan on measuring the current. Those pins can be connected directly to ground. Putting the 22 ohms in series with your motor supply will reduce the performance.

And, are 'Vmotor" and "Vcc+5" the same voltage source? They should be.

Duane Degn:
That schematic sure has some problems.

Pin 9 is the logic power supply. This is usually 5V. 4.5V to 7V is the allowed range for the logic supply. (The datasheet calls this Vss which can be confusing since Vss is often ground.)

Pin 4 is the motor power supply. This needs to be at least 2.5V higher than the logic power supply (so at least 7.5V if using 5V for the logic power supply). 12V seems to be a common motor power supply value. It can be as high as 46V.

There are lots of cheap L298 boards on ebay. I have a bunch from this seller.

http://www.ebay.com/itm/L298N-DC-Stepper-Motor-Dual-H-Bridge-Drive-Controller-Board-Module-for-Arduino-/140895190441

I have had to resolder some of the connectors but in general these cheap boards seem to work well.

jim:
thanx.. i made a few changes. im not using those sense resistors as your advice..well i am using arduino and i powering it with 9 V battery. my motors are 5V.. im using a voltage regulator (7806) to supply the 6v to the motors. my question is pin 4 being connected to the REGULATED voltage (6V) is correct or wrong?

Also i read in one the SOR tutorials that a capacitor being connected to the two terminals of each of the motors  will increase their lifetime.. So what capacitor should I use? I guess it is an electrolytic capacitor..Please tell me the most suitable  value for it..

thank you..

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