help with my first spiro

[milantheone]

Hi guys, how are you doing..
Recently i have done my first spirograph, and as i am total lama in building some circuits i have a little problem with my build..

I used socket adapter as a power supply which give me 3V and 1000mA.. it is enough to drive 3 small motors..
I have used 40-ohm potentiiometers, because it was everything i had..
I have connected everything like on my picture..
My problem is that it is probably paralel conection and if i turn one pot up and my motor stop, then other motor goes quickly.. simply everything is linked and i would like to know how separate each circuit...
I dont know how to describe it better..
I know if i will use 3V battery for each motor+potentiometer separately i will have succes, but how to do this if i want to use this pover supply???
Can anyone help???
Is there some trick, which can do that???

cheers

 

[lasersbee]

The problem is probably that your motors require more power than your supply
can put out...
What is the voltage rating of your Motors... :-? where are they from... :-?

Jerry

 

[milantheone]

The problem is probably that your motors require more power than your supply
can put out...
What is the voltage rating of your Motors... :-? where are they from... :-?

Jerry

well they comes from fan's like these http://www.dealextreme.com/details.dx/sku.11899

i have no problems to drive them with 4.5, 6, 9, or 12 Volts, as my adapter is variable..
first i had very weak one which gave me only 350mA and it was not enough for 3 motors..
now i have 1000mA and it is ok i think as it is running with all 3 motors at once...
i have also figured out, that if i move one potentiometer, it will affect an ohm's in all my circuit - build..

so what i am trying to figure out is how to separate each motor+potentiomet that it will not affect each other.. that each my motor with potentiometr will be like single simple circuit where i will have 40ohms for one motor.. because now everything is divided and have affect with each other.
i have really no idea how to do that..

 

[lasersbee]

Try testing the voltage at the Power Supply to see if the voltage changes
as you control the motors... At 1000mA there should not be a big difference
in output voltage...
Then do the same test again but this time test the current at the Power Supply
Don't forget to put your meter on Amps... The milliamps scale might blow the
fuse in your meter... The current should be well below 1000ma...

For the next test... disconnect your motor circuit from the Power Supply and
connect a 3 Ohm 5 watt resisistor to the output of the Power Supply..
Test the current of the output... it should be 1000mA or 1 Amp...

The last test.....
Take 2  "D" size batteries and connect them to your circuit instead of your
Power Supply... does this work better... :-?
If so... your power supply does not supply enough power...

Jerry

 

[ters]

@milan,

you need variable PWM driver for EACH motor...

 

[lasersbee]

@milan,

you need variable PWM driver for EACH motor...

If his Power Supply can't furnish enough current to run all 3 motors with a bit
to spare... PWM will make no difference...

Just knowing that the 2 other motor's speed changes as one motor's speed is
adjusted... points to that power problem conclusion... IMO

Jerry