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Author Topic: NPN Motor Driver Circuit  (Read 4182 times)

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Offline CanabotsTopic starter

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NPN Motor Driver Circuit
« on: January 28, 2009, 10:35:38 AM »
Hey,

Can someone here recommend me a basic bi-direction motor driver circuit that only uses NPN transistors such as 2N3904 or 2N2222 or other compatible versions?

This is for 2 small motors (tiny, infact) operating around 2.4 volts. I plan on receiving the output from a microcontroller. The motors run off a battery of 2.4V at 70mAh.

I've tried a few, but none of them have worked so far.

Thanks in advance!

PS: Incase you're curious, these are from a ZipZaps car
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Offline CanabotsTopic starter

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Re: NPN Motor Driver Circuit
« Reply #1 on: January 29, 2009, 06:31:34 AM »
Arg, I worded that a little wrong.

I want is a reccomendation for a really simple motor driver circuit, and it ca use PNP/NPN transistors.

I can only control it using a positive voltage output.

Thanks

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Offline MaltiK

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Re: NPN Motor Driver Circuit
« Reply #2 on: January 29, 2009, 07:20:50 AM »


port B is obviously the output
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Offline CanabotsTopic starter

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Re: NPN Motor Driver Circuit
« Reply #3 on: January 29, 2009, 08:35:09 AM »
I've already used motor drivers like that, but unfortunately, it's only a single directional motor driver. The project I'm doing requires a bi-directional motor driver, unfortunately, of which I've tried a few, but without luck :(

Thanks anyhow!
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Offline fuzzyt

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Re: NPN Motor Driver Circuit
« Reply #4 on: January 29, 2009, 10:36:24 AM »
If you can use both NPN and PNP, have you looked at a standard h-bridge?

http://www.robotroom.com/BipolarHBridge.html


Offline CanabotsTopic starter

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Re: NPN Motor Driver Circuit
« Reply #5 on: January 29, 2009, 10:51:16 AM »
The issue with that one, though, is that it requires being connected to GND, but I need to control it through a microcontroller output. Unless there was some was we could connect it to GND...

Would it be possible to place another NPN transistor there and have it connect the PNP to GND once a signal is sent to it? I think I'll try that out.

Canabots
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Offline paulstreats

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Re: NPN Motor Driver Circuit
« Reply #6 on: January 29, 2009, 11:09:53 AM »
Whatever you use will need a connection to a common gnd or the signal from the mcu wont work...

Offline CanabotsTopic starter

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Re: NPN Motor Driver Circuit
« Reply #7 on: January 29, 2009, 11:30:57 AM »
Hmmm,
I just threw together this schematic, to demostrate my idea.

It is attached to this post. I sort of threw it together quickly, so I now I'm missing resistors and such, but I just wanted a general idea.

So would it work?

Canabots
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Offline Soeren

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Re: NPN Motor Driver Circuit
« Reply #8 on: January 29, 2009, 02:21:30 PM »
Hi,

Try this: http://That.Homepage.dk/PDF/H-bro_TO-92.pdf
With such low voltage, I'd suggest transistors from Zetex, since they have some with very low U_CE. Another solution would be to up the voltage a bit, just enough to counter the drop in the transistors.
 
Regards,
Søren

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