Question about ULN2803

kenwtn · 2008-08-14 14:14

Hi All,

···· My question is the stepping motors I have require 1.2 Amps per phase can the ULN2803 handle this amount of current?

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_{When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !}

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Mike Green · 2008-08-14 14:27

Each transistor of the 8 in the ULN2803 can handle 1/2A, but they can be paralleled. You'd need to connect 3 inputs and 3 outputs in parallel for your stepping motor phases. You can do it this way, but I'd recommend using just an ordinary Darlington power transistor per phase, something like the TIP120 which you can get from RadioShack as well as other sources. The collector would be connected to your stepper coil. The emitter would be connected to ground and the base would be connected to a 330 Ohm resistor the other end of which would be connected to a Stamp I/O pin. There are examples of this in the Nuts and Volts Column #6 downloadable from Parallax's website.

kenwtn · 2008-08-14 14:33

Thanks, Mike I will look into it.

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_{When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !}

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kenwtn · 2008-08-14 15:45

· I have 3 stepping motors and at 1.2 amps per phase on each seems like alot of power. Would a power supply from a old Desktop computer supply the power I would need? Forgive me but I know little about electronics and I am still lerning.

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_{When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !}

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Mike Green · 2008-08-14 15:57

You don't need highly regulated power supplies for most motors. Each motor only uses one phase at a time, so your maximum drain is 3 x 1.2A or roughly 4A. What voltage do the stepper motors use?

kenwtn · 2008-08-14 16:12

They use 4 volts. I guess I thought I need more power

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_{When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !}

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kenwtn · 2008-08-14 16:16

I have 9 Volt Wall Plug supply power to the Board of Eduction but that does not seem to supply the current I need. Can you help me figure this out Mike

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_{When you spend 10 times what it cost to build it yourself - That's when it becomes a HOBBY !}

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Question about ULN2803

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