Issue with command pump

Thread Starter

Fab6657

Joined Jan 9, 2009
5
Hello all's,

first sorry for the not so good english, this is not my mother langage.

I like to ask you help, i developping a command pump circuitry with microchip pic. This is a pwm command to slow down-up the speed of the pump and also reverse the fill-up and fill-down the fuel.

My problem is that sometime the relay is not activated when i reverse the rotation of the pump. I don't no if the relay is 'glued on' while current is passing, or if this is an effect of the dc-motor. The result is that the pump always run in the same direction. If no motor is attached, the reverse seams to run well !

I attach the part of the schema that are in use. If you have some idea, thanks' for help.

Fabrice
 

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JDT

Joined Feb 12, 2009
657
Your circuit looks OK. Do not reverse the motor without stopping it first or the relay contacts might weld.

Make sure the power supply to the PIC is well filtered. Noise from the motor might affect the PIC.
 

Thread Starter

Fab6657

Joined Jan 9, 2009
5
Hello,

yes i think also that the motor stop not enough.
The pic have a 100nF for decoupling the noise.

I will changing the code with a pause between
the rotation and try !

Thank's

Fabrice
 

Thread Starter

Fab6657

Joined Jan 9, 2009
5
Hello,

i complete underestimated the back electromagnetical flux from the dc motor. So i put a 1N4148 Diode in the circuit , and no problem anymore !

Fabrice
 

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