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Topic: DC Motor speed control (Read 7123 times) previous topic - next topic

FFTMaster

no diode is okay...i tried plus-diode-motor-minus..and motor does not work...i turn diode around and it works

dc42


Yeah.. thx a lot
Sadly it didnt fix the problem...somehow no voltage is going to the drain(collector)


The voltage on the drain should be very close to zero when the mosfet it turned on (i.e. +9v applied to the gate), and the same as the battery voltage when the mosfet is turned off (because the drain is connected to the +ve terminal of the battery through the motor).


no diode is okay...i tried plus-diode-motor-minus..and motor does not work...i turn diode around and it works


In your photo, the diode is the right way round (the diode in parallel with the motor, and the end with the stripe connected to the +ve terminal of the battery), unless you've acquired a diode that is incorrectly marked. If you turn the diode the other way round, it will bypass the motor and that will make the battery go flat very quickly.
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FFTMaster

#32
May 19, 2012, 05:50 pm Last Edit: May 19, 2012, 06:09 pm by FFTMaster Reason: 1

In your photo, the diode is the right way round (the diode in parallel with the motor, and the end with the stripe connected to the +ve terminal of the battery), unless you've acquired a diode that is incorrectly marked. If you turn the diode the other way round, it will bypass the motor and that will make the battery go flat very quickly.

I just thought maybe diode is dead, but no it is okay, i did test where i connected battery + to diode and at the other side of diode i placed motor and to the other side of motor minus of battery....this test showed that diode was okay, it allowed current to pass only in one direction.
About voltage being near zero at the drain when mosfet is working.... yes it is near zero... then i have to check wether current goes out of emitter somehow...maybe not enough for motor or something....
I just did some tests with mosfet..and it allowed current to go through when nothing was placed on the gate...
I also tested 2n2222 a bit and discovered that motor works when i take out resistor between battery and base, battery i used was 3v and even 100oom was too much...

FFTMaster

omg....now it does not care what i put on the gate..it just works

FFTMaster

Now it works with 5from arduino...the mosfet.... but it does not from pwm and digital output                                                                                         

FFTMaster

Hi guys!
i have a lot of improvements... everything works...It seems problem was in the board...
First i will explain the situation and then i will tell u  what i want to achieve...
Right now with the help of MOSFETs i supply motors. Its done by taking 220 V out of power supply and transforming it into 9V 3A. So now i need to supply arduino and motors separately...i want to supply arduino from same 9V. How can i do that... what parts do i need to do that...

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