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Author Topic: Problem to activate DC motor  (Read 2158 times)

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Offline roi_tauTopic starter

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Problem to activate DC motor
« on: November 27, 2008, 08:55:32 AM »
Hi Guys.

My Robot should activate little vibration motor.

The schema is attached

My battery is 3.6 volt (3 cells) Ni-MH

The base is connected strait to the uC with no resistor (It doesn't work with R>0.5K)

What do you think?

Is my values correct?

The circuit works but I want it to be correct.

Roi

Offline jamort

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Re: Problem to activate DC motor
« Reply #1 on: November 27, 2008, 09:02:15 AM »
you might want to make sure the motor works.... plug a battery into it with out it in the circuit.....
I think you said basically doesn't work from the get go because if it stopped working it could of been to much voltage
my english teacher once said, "dont talk about what you dont know in public...."

so I replied the truth, " Exactly why I dont ever talk about English."

Offline roi_tauTopic starter

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Re: Problem to activate DC motor
« Reply #2 on: November 27, 2008, 09:07:23 AM »
The motor works with and without the circuit


I just want to know if the way I connected it is right,(Wont damage the transistor in the long run)

Roi

Offline ArcMan

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Re: Problem to activate DC motor
« Reply #3 on: November 27, 2008, 10:22:07 AM »
That circuit is fine for such a small motor.  BTW, don't use the 30 ohm resistor unless you intend to measure the motor current.  That's what it's for.

Offline szhang

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Re: Problem to activate DC motor
« Reply #4 on: November 27, 2008, 12:30:07 PM »
make sure your transistor isn't flipped or something.

Offline ArcMan

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Re: Problem to activate DC motor
« Reply #5 on: November 27, 2008, 08:22:11 PM »
Ooh.  I just read your OP more thoroughly.  You must have a resistor between the uC and transistor base or you'll kill your transistor.  Take out that 30 ohm resistor on the emitter and use about a 500 ohm resistor on your base.  That arrangement will switch about 100 mA if the transistor hfe is 50 (which is typical for a bipolar switcher like a 2N2222).

Offline Admin

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Re: Problem to activate DC motor
« Reply #6 on: December 01, 2008, 03:18:52 AM »
The proper way would be to use a MOSFET and no resistor ;D

Offline roi_tauTopic starter

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Re: Problem to activate DC motor
« Reply #7 on: December 01, 2008, 04:14:20 AM »
You mean like the 2N7000?


Offline Admin

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Re: Problem to activate DC motor
« Reply #8 on: December 03, 2008, 06:50:57 AM »
Quote
You mean like the 2N7000?
yes, and any PWM optimized MOSFET ;D

Offline roi_tauTopic starter

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Re: Problem to activate DC motor
« Reply #9 on: December 03, 2008, 08:56:18 AM »
Hi Admin

I didnt understand your answer.


Roi

Offline Admin

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Re: Problem to activate DC motor
« Reply #10 on: December 04, 2008, 10:18:29 PM »
Quote
You mean like the 2N7000?
yes, just like the 2N7000.

Also, just like any MOSFET that is PWM optimized.

Offline roi_tauTopic starter

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Re: Problem to activate DC motor
« Reply #11 on: December 05, 2008, 04:11:04 AM »
I didnt understand the part of the PWM optimized.

What do you mean by that?

Roi

Offline Admin

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Re: Problem to activate DC motor
« Reply #12 on: December 05, 2008, 10:19:04 AM »
Optimized for PWM:
http://www.societyofrobots.com/member_tutorials/node/228

To operate a DC motor, you need to PWM your MOSFET. A PWM optimized MOSFET will give you a higher efficiency. You'll see 'PWM Optimized' typically on the very first page of the MOSFET datasheet.

And remember to google before asking questions :P

 


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