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Help me with bipolar stepper motor..

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bashok001

New Member
I am devising a knock lock for which i used a bipolar stepper motor using a mosfet driver..I have four terminals coming out of motors! I connected them all with four mosfets...Now it doesn't move...so I did a small research on internet on bipolar stepper motor drivers and i got these circuit diagrams in which they connected the motor with MC driver as I did but the coils are also coonected to 12 v from their middle...
From where should this connection be made..??? We have four terminals coming out of motor which are all already engaged completely... So how will this 12v battery connection to motor made?
 

duffy

Well-Known Member
The tap in the middle is there so you can also use those kinds of motors with either unipolar drive OR bipolar drive. What you have is correct for bipolar drive, just make sure you have them connected correctly - hook a coil pair to +12V and ground while holding the shaft of the motor, see if you can feel it "jump".
 
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bashok001

New Member
So u r telling me that I need not change anything except to check whether my motor is working....There will be no connection needed to make it to 12v or something
 

BrownOut

Banned
No! 4 wired motor is definitely a bipolar stepper motor and i even confirmed that with datasheets!

You're right. That's why I removed my post. I'm glad you asked, because that make me go look up this circuit. I plan on using it to test some surplus steppers I bought. The reason I like this circuit is because it helps me to understand the logic of driving the motors. It also shows how the leads connect to the h-bridges. If you suspect you're motors aren't working, you can quickly breadboard the ckt and try it. Inputs "Direction" and "Step" can just come from switches, and the "Enable" signal, along with Q10 and Q5 aren't really needed.
 

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bashok001

New Member
I am really confused on what part of my circuit is not working...I had this whole circuit made on breadboard in front of me but not the motor is running....Two LEDs i connected to Microcontroller to show the right inputs glow when I power up the circuit without microphone and amplifier ..with them, one of the leds puts off all by itself...Dont know why but it is a symbol of false hit made for the lock in the program..then even the motor is not running..I had motor powered up by mosfets. Shall I provide u with schematic?
 
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BrownOut

Banned
A schematic might help, but if you're using a microcontroller, we might need the code too.

You know, I think there is an error with the circuit I posted in the way that the J-K flip flops are connected to the XOR gates. Can anyone verify?
 
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duffy

Well-Known Member
Get the motor turning first, worry about the microphone later. Send a slow quadrature signal to the mosfets and see if the motor turns.
 

MikeMl

Well-Known Member
Most Helpful Member
If you have a data sheet for the motor, it shows the correct phase progression to get the motor to step. Some motors will function with unipolar drive where current only flows in one direction through the active windings (connect 12V to the common, and then ground one or two windings at a time). The drive transistors only switch to ground.

Other motors require bipolar drive, where current flows alternately one direction, not at all, or the other direction. Bipolar motors require push-pull drive transistors.
 
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