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Topic: curious battery problem (Read 571 times) previous topic - next topic

cxl2253

i used arduino to control one toy motor with L298N,  the motor  only want 3-5V voltage . I just have a  AC/DC adaptor which can output 9v 1A ,So i used it to supply the arduino and L298N. because the motor is small ,i used a 78L05 to get 5v  for L298n Pin4 and connect the adaptor output directly to arduino external powerin .  but the arduino seem not to work and blink and the outpin (should high) have no result. After five or later minutes, it work and not blink.  i think maybe the adaptor not provide enough current for arduino,but the adaptor output is 1A and 9v , is not enough to driver a small motor and arduino??

Oracle

Quote
i used arduino to control one toy motor with L298N,  the motor  only want 3-5V voltage . I just have a  AC/DC adaptor which can output 9v 1A ,So i used it to supply the arduino and L298N. because the motor is small ,i used a 78L05 to get 5v  for L298n Pin4 and connect the adaptor output directly to arduino external powerin .  but the arduino seem not to work and blink and the outpin (should high) have no result. After five or later minutes, it work and not blink.  i think maybe the adaptor not provide enough current for arduino,but the adaptor output is 1A and 9v , is not enough to driver a small motor and arduino??


Check the specs on your motor.  Those cheap low voltage motors take 2 amps easily.  Your 1A power supply doesn't come close.

Also, 298N has a minimum motor voltage of 5V (and up to 46V).  It doesn't play well with low voltage motors.

cxl2253

#2
Jul 21, 2008, 05:37 am Last Edit: Jul 21, 2008, 08:41 am by cxl2253 Reason: 1
when i used USB supply for Arduino, It work well.I Want to know when arduino use external supply ,what is its working voltage and working current? if i use the usb power , i have two power source, it is nonsense. anybody can shed a light ?

Oracle

If you mean the USB supply for Arduino and the 9V adaptor for the motors, what's happening to you makes sense.  The motor is putting a huge load and a lot of noise on the power power supply.  The supply can not keep a stable 9V at such a high current, so the voltage drops down.  When it drops too
far, it causes a brownout on the Arduino and the Arduino resets.

Even if you got a 2 amp supply, you'd probably have the same problem because of noise.  You can try putting a decoupling capacitor across the power supply near the ATMEGA chip on the Arduino and maybe a second one across the power input to the Arduino board.

cxl2253

thanks ,oracle, do you mean i should put two capacitor, one across the  two wires of motor and one for power supply between Arduino. in fact i have put one 104 capacitor across the two wires  of motor,but it still not work . should i put anotor between power supply. i will try it. thanks again.

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