motor control problem

[bananasiong]

The 2N3904 is an American transistor with its pins EBC. European transistors like the BC547 have their pins the opposite: CBE. If the E and C pins are swapped in the circuit then the transistor has very low gain and won't saturate.

yes.. i know the pin of 2N3904... but what is the maximum voltage can it drive? 12V?

 

[Nigel Goodwin]

The 2N3904 is an American transistor with its pins EBC. European transistors like the BC547 have their pins the opposite: CBE. If the E and C pins are swapped in the circuit then the transistor has very low gain and won't saturate.

yes.. i know the pin of 2N3904... but what is the maximum voltage can it drive? 12V?

More than that, I doubt you can find a transistor that low?.

 

[audioguru]

Why don't you look at its datasheet?

 

[bananasiong]

i have seen this.. but.. last time i tried to make a h bridge using this 2N3904 in 12V, it produced heat.. it was very heat...

 

[Nigel Goodwin]

i have seen this.. but.. last time i tried to make a h bridge using this 2N3904 in 12V, it produced heat.. it was very heat...

It's only rated at 200mA, were you driving a motor with it?.

 

[bananasiong]

i have seen this.. but.. last time i tried to make a h bridge using this 2N3904 in 12V, it produced heat.. it was very heat...

It's only rated at 200mA, were you driving a motor with it?.

yes.. i drive a DC motor..

 

[Nigel Goodwin]

yes.. i drive a DC motor..

Not with a 2N3904 you don't!.

 

[bananasiong]

yes.. i drive a DC motor..

Not with a 2N3904 you don't!.

oh!! can't i do this? why?
then what transistor should i use?
and how about the stepper motor?

 

[hyedenny]

Hi,
Well, you CAN use a '3904, but definitely not in the capacity youre thinking of! Heres a good link to a common circuit, and how the '3904 can be used...
http://www.armory.com/~rstevew/Public/Motors/H-Bridges/Blanchard/nch-brdg.htm
PS - DO SOME HOMEWORK!!!

 

[bananasiong]

no.. i not talking about the h bridge.. i need to control a stepper motor.
just look at figure shown below.

 

[Nigel Goodwin]

no.. i not talking about the h bridge.. i need to control a stepper motor.
just look at figure shown below.

You've never mentioned a stepper motor before?, you've been talking about a DC motor - COMPLETELY different things!.

You simply need four NPN transistors that will handle the current, and make sure they are turned hard ON.

Have a look at for an example, the transistors are rated at 800mA, and were fine for the stepper I used, which came from an old 5.25 inch floppy drive, and which I simply fed from 5V.

 

[bananasiong]

no.. i not talking about the h bridge.. i need to control a stepper motor.
just look at figure shown below.

You've never mentioned a stepper motor before?, you've been talking about a DC motor - COMPLETELY different things!.

You simply need four NPN transistors that will handle the current, and make sure they are turned hard ON.

Have a look at for an example, the transistors are rated at 800mA, and were fine for the stepper I used, which came from an old 5.25 inch floppy drive, and which I simply fed from 5V.

sorry.. i thought they are the same.. no wonder i can't run it.. must i use BC337 and IN4148? can i use a BC327 coupled with IN4001?? coz only these conponents are available in my college lab. thanks for answering me.

 

[Nigel Goodwin]

sorry.. i thought they are the same.. no wonder i can't run it.. must i use BC337 and IN4148? can i use a BC327 coupled with IN4001?? coz only these conponents are available in my college lab. thanks for answering me.

A BC327 is PNP, not NPN, so you would need to redesign the circuit, as it stands you can run the stepper off more than 5V, with PNP's you would need extra circuits to do so. IN4001's would be fine, but you don't need a diode that big - but it's fine.

I presume you're driving the stepper with the correct sequence of pulses?, I'm somewhat concerned as you don't know the difference between a DC motor and a stepper!.

 

[bananasiong]

I presume you're driving the stepper with the correct sequence of pulses?, I'm somewhat concerned as you don't know the difference between a DC motor and a stepper!.

yea.. i was doing it correctly with the right phase and pins, i can drive the stepper using 5V, but i did it straight from the output of my microcontroller without using the BJT as switch... and.. i know the difference between the DC and the stepper.. i just thought that i can use the same method as switch..

so, besides the BC337, is there any other suitable NPN transistor which can be used in the same circuit design?

 

[Nigel Goodwin]

so, besides the BC337, is there any other suitable NPN transistor which can be used in the same circuit design?

Anything you can get that will handle the current required - I only used BC337's because they were available to me. Obviously they must have enough gain to switch correctly, but there are many small 1A transistors available.

 

[bananasiong]

Anything you can get that will handle the current required - I only used BC337's because they were available to me. Obviously they must have enough gain to switch correctly, but there are many small 1A transistors available.

i thought BC337 is 500mA npn?? so, u mean as long as i can get the 1A npn, i can drive the circuit, am i right?

 

[Nigel Goodwin]

Anything you can get that will handle the current required - I only used BC337's because they were available to me. Obviously they must have enough gain to switch correctly, but there are many small 1A transistors available.

i thought BC337 is 500mA npn?? so, u mean as long as i can get the 1A npn, i can drive the circuit, am i right?

BC337 is 800mA, so any NPN around 0.8A-1A should be fine.

 

[bananasiong]

BC337 is 800mA, so any NPN around 0.8A-1A should be fine.

okay !!! thanks for helping ya!!

 

[bananasiong]

thanks!! it works with very high torque.