Problems with motor generating electrical noise.

josephsouter

New Member
I have recently built a chicken house door opener using a picaxe 08M2 and various other components including an L9110H motor driver driving a simple gearbox motor to open the door depending on light levels etc. The system has worked flawlessly for about a month until today when I checked on it and the motor had not activated and was just making a pulsing clicking noise while stationary. I have a capacitor across the motor terminal as it would created too much noise otherwise. I just wondered if anyone could help as I am stuck as to why motor has suddenly stopped working. Is it creating noise that is going back to the picaxe and disturbing it? Is there any way to easily combat noise or it it best to find a new motor. When I disconnected the motor, the output was fine and ibtested it with an led and multimeter but with the motor connected the led just pulsated and the meter didn't register any DC voltage. Thanks
 

The bear

Senior Member
Hi, Is your power supply OK?
On current draw, you cannot compare a led to a motor.
Try a known good power supply.
Good luck, bear..
 

premelec

Senior Member
Welcome to this forum - Sometimes power supply issues from motor current pulses will cause PICAXE to reset [start program again] to check if this is happening put an LED circuit in and a turn on LED for one second at the beginning of program - if then you see the LED going on and off it means you are having power supply issues...
 

AllyCat

Senior Member
Hi,

today when I checked on it and the motor had not activated and was just making a pulsing clicking noise
Was it the opening cycle in the (early) morning? It might be due to falling temperatures as Winter approaches.

At lower temperatures, lubricants will thicken and the motor coil (copper) resistance falls, so the motor current demand may rise. Conversely, many batteries lose some capacity at lower temperatures, etc..

The general solution to interaction between motor and the PICaxe is to increase their isolation. First use separate capacitors for the motor (driver) and the PICaxe, with perhaps a small resistor or inductor between their supply rails. Ultimately, it might be necessary to try separate power supply sources (or add a regulator for the PICaxe), but not forgetting to maintain a connection between their earth rails!

Cheers, Alan.
 

techElder

Well-known member
Joseph, the basics of troubleshooting:

First, go "out" to the observed problem and try to independently make that work. Power the motor with a separate supply.

If that works, try to operate it with the internal supply.

Then, perhaps having found that to work, go to the next level; the part that drives the motor.

See if you can independently make that part operate the motor.

Keep going back towards the PICAXE until you find what is NOT working.

Methodically test each separate system.
 

inglewoodpete

Senior Member
From my experience, you don't need separate power supplies for the motor and microcontroller.

The first rule to observe when you have microcontroller resets occurring when driving a motor is: use separate ground (0v) feeds from the power supply. So, on the 0v point of the power source, run two wires: one to the microcontroller circuit and one to the motor control circuit. That way, the electrical noise from the motor will have very little influence of the current being fed to the microcontroller.

As others have said, use separate capacitors across the microcontroller power supply and power pins and the motor driver. Mount them as close as possible to the driver and microcontroller chips.
Logic Earth2.jpg

You may notice that I have used the word "microcontroller" rather then PICAXE. The problem is related to good (or bad :() circuit design/layout for any type of microcontroller.
 

rq3

Senior Member
I have recently built a chicken house door opener using a picaxe 08M2 and various other components including an L9110H motor driver driving a simple gearbox motor to open the door depending on light levels etc. The system has worked flawlessly for about a month until today when I checked on it and the motor had not activated and was just making a pulsing clicking noise while stationary. I have a capacitor across the motor terminal as it would created too much noise otherwise. I just wondered if anyone could help as I am stuck as to why motor has suddenly stopped working. Is it creating noise that is going back to the picaxe and disturbing it? Is there any way to easily combat noise or it it best to find a new motor. When I disconnected the motor, the output was fine and ibtested it with an led and multimeter but with the motor connected the led just pulsated and the meter didn't register any DC voltage. Thanks
"pulsing clicking noise". Since the whole thing has been working flawlessly for a month, I'll wager the motor is actually turning, but the gears in the gear motor are stripped.
 
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