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Electronics => Electronics => Topic started by: Canabots on January 28, 2009, 10:35:38 AM

Title: NPN Motor Driver Circuit
Post by: Canabots 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
Title: Re: NPN Motor Driver Circuit
Post by: Canabots 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

Title: Re: NPN Motor Driver Circuit
Post by: MaltiK on January 29, 2009, 07:20:50 AM
(http://www.neufeld.newton.ks.us/images/electronics/2006/03/08/motor-demo-transistor.png)

port B is obviously the output
Title: Re: NPN Motor Driver Circuit
Post by: Canabots 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!
Title: Re: NPN Motor Driver Circuit
Post by: fuzzyt 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

Title: Re: NPN Motor Driver Circuit
Post by: Canabots 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
Title: Re: NPN Motor Driver Circuit
Post by: paulstreats 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...
Title: Re: NPN Motor Driver Circuit
Post by: Canabots 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
Title: Re: NPN Motor Driver Circuit
Post by: Soeren on January 29, 2009, 02:21:30 PM
Hi,

Try this: http://That.Homepage.dk/PDF/H-bro_TO-92.pdf (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.
 
Title: Re: NPN Motor Driver Circuit
Post by: Admin on February 07, 2009, 07:36:22 AM
http://www.societyofrobots.com/schematics_h-bridgedes.shtml