Trying to work with 2 DC motors Need Advice

Archiver

Hello Everyone. I'm new here and this is my first Microcontroller
project. I bought the "What's a Microcontroller" kit and that's what
I'm working with. I'm in the middle of building a mini robo sumo from
scratch (not using a kit) I have everything figured out except how to
power the motors. The stamp will source 20mA and sink 25mA if the
documentation I have is correct. The motors I have require about 52mA
free running and as much as 600mA stalled. I'd like to run them at 9
volts but I'm not sure how to interface them with the stamp. I looked
around the internet for a driver circuit that I could build but
didn't have much luck.

Can someone provide some insights? I would be very grateful.
Unfortunately cost is VERY Much and issue so I was hoping to do it on
the cheap. I can build just about any circuit you can show me and I
already have plenty of components but not many IC's.

Thanks
Bill

Archiver

--- In basicstamps@yahoogroups.com, "billdoser2003"
<billdoser2003@y...> wrote:
> Hello Everyone. I'm new here and this is my first Microcontroller
> project. I bought the "What's a Microcontroller" kit and that's
what
> I'm working with. I'm in the middle of building a mini robo sumo
from
> scratch (not using a kit) I have everything figured out except how
to
> power the motors. The stamp will source 20mA and sink 25mA if the
> documentation I have is correct. The motors I have require about
52mA
> free running and as much as 600mA stalled. I'd like to run them at
9
> volts but I'm not sure how to interface them with the stamp. I
looked
> around the internet for a driver circuit that I could build but
> didn't have much luck.
>
> Can someone provide some insights? I would be very grateful.
> Unfortunately cost is VERY Much and issue so I was hoping to do it
on
> the cheap. I can build just about any circuit you can show me and I
> already have plenty of components but not many IC's.
>
> Thanks
> Bill


Hi Bill,

Very common question on here.

To power an external device, you can use a transistor. A 2n2222 will
handle up to about 60 volts and between 500 and 600mA depending on
manuufacturer.

The unit can be driven (switched) with a 5 volt output from the stamp.

You can use a multi-pack or IC style version called the ULN2803 with
8 channels in a simple package, and that too handles up to about
500mA per channel.

A TIP122 or similar will handle about 5 amps, and this is the big
brother to the 2222 for our switching purposes.

From there, move into MODFETS. You can get a MOSFET rated for about
27 amps and 600 volts, so these have a pretty high limit.

Anyway, back to your needs.

Google H-bridge and pick a circuit you like.

Since you are looking to keep the costs down, Glitchbuster.com offers
all the above.

IIRC, a dozen 2222's are 99 cents
a UNL2803 is 39 or 79 cents or something.
A TIP120 is 39 cents
and a MOSEFET with a high amp rating is about 79 cents.
P channel will be more across the board.

Now, before you get too excited, you will need more than a few to
make an H-Bridge. the 2222 can drive the MOSFETS so a mix and match
will keep prices low.

Also if you want to make a charge pump, you can use all N-channel
parts. The trade off is more complexity and more parts that cost
less.

Dave

Archiver

--- In basicstamps@yahoogroups.com, "Dave Mucha" <davemucha@j...>
wrote:
> --- In basicstamps@yahoogroups.com, "billdoser2003"
> <billdoser2003@y...> wrote:
> > Hello Everyone. I'm new here and this is my first Microcontroller
> > project. I bought the "What's a Microcontroller" kit and that's
> what
> > I'm working with. I'm in the middle of building a mini robo sumo
> from
> > scratch (not using a kit) I have everything figured out except
how
> to
> > power the motors. The stamp will source 20mA and sink 25mA if the
> > documentation I have is correct. The motors I have require about
> 52mA
> > free running and as much as 600mA stalled. I'd like to run them
at
> 9
> > volts but I'm not sure how to interface them with the stamp. I
> looked
> > around the internet for a driver circuit that I could build but
> > didn't have much luck.
> >
> > Can someone provide some insights? I would be very grateful.
> > Unfortunately cost is VERY Much and issue so I was hoping to do
it
> on
> > the cheap. I can build just about any circuit you can show me and
I
> > already have plenty of components but not many IC's.
> >
> > Thanks
> > Bill
>
>
> Hi Bill,
>
> Very common question on here.
>
> To power an external device, you can use a transistor. A 2n2222
will
> handle up to about 60 volts and between 500 and 600mA depending on
> manuufacturer.
>
> The unit can be driven (switched) with a 5 volt output from the
stamp.
>
> You can use a multi-pack or IC style version called the ULN2803
with
> 8 channels in a simple package, and that too handles up to about
> 500mA per channel.
>
> A TIP122 or similar will handle about 5 amps, and this is the big
> brother to the 2222 for our switching purposes.
>
> From there, move into MODFETS. You can get a MOSFET rated for
about
> 27 amps and 600 volts, so these have a pretty high limit.
>
> Anyway, back to your needs.
>
> Google H-bridge and pick a circuit you like.
>
> Since you are looking to keep the costs down, Glitchbuster.com
offers
> all the above.
>
> IIRC, a dozen 2222's are 99 cents
> a UNL2803 is 39 or 79 cents or something.
> A TIP120 is 39 cents
> and a MOSEFET with a high amp rating is about 79 cents.
> P channel will be more across the board.
>
> Now, before you get too excited, you will need more than a few to
> make an H-Bridge. the 2222 can drive the MOSFETS so a mix and
match
> will keep prices low.
>
> Also if you want to make a charge pump, you can use all N-channel
> parts. The trade off is more complexity and more parts that cost
> less.
>
> Dave

Thanks for the reply Dave. I tried to use a 2n3904 transistor. I
connected the base of the transistor to one of the pins on the stamp
and i connected the collector to my motor through Vdd. I connected
the emmiter to Vss. I was able to get an LED to blink this way but no
reaction from the motor.

Archiver

> Thanks for the reply Dave. I tried to use a 2n3904 transistor. I
> connected the base of the transistor to one of the pins on the
stamp
> and i connected the collector to my motor through Vdd. I connected
> the emmiter to Vss. I was able to get an LED to blink this way but
no
> reaction from the motor.


I'm assuming you missed something in your post ? it sounds like you
have the NPC transistor connected to Vcc and Vss and nothing in-
between ?


The motor would connect to Vss, then the 3904 collector.

The 3904 would connect to the motor on the collector and Vss on the
emiter.

The Stamp would connect to the Base of the 3904 with a 220 or 330 ohm
resistor.

The 3904 would connect to the resistor to the base.


The motor can be connected to your higher voltage as only the
collector and emitter see that higher voltage.

And, power ground and logic ground need to be tied together. ie:
emitter and Vss of the Stamp.

Is this what you tried ?

just as a thought, I expect your motor spins when connected directly
to power ? I mentioned that on the off-chance it is a stepper. : )

Dave

Archiver

--- In basicstamps@yahoogroups.com, "Dave Mucha" <davemucha@j...>
wrote:
>
> > Thanks for the reply Dave. I tried to use a 2n3904 transistor. I
> > connected the base of the transistor to one of the pins on the
> stamp
> > and i connected the collector to my motor through Vdd. I
connected
> > the emmiter to Vss. I was able to get an LED to blink this way
but
> no
> > reaction from the motor.
>
>
> I'm assuming you missed something in your post ? it sounds like
you
> have the NPC transistor connected to Vcc and Vss and nothing in-
> between ?
>
>
> The motor would connect to Vss, then the 3904 collector.
>
> The 3904 would connect to the motor on the collector and Vss on the
> emiter.
>
> The Stamp would connect to the Base of the 3904 with a 220 or 330
ohm
> resistor.
>
> The 3904 would connect to the resistor to the base.
>
>
> The motor can be connected to your higher voltage as only the
> collector and emitter see that higher voltage.
>
> And, power ground and logic ground need to be tied together. ie:
> emitter and Vss of the Stamp.
>
> Is this what you tried ?
>
> just as a thought, I expect your motor spins when connected
directly
> to power ? I mentioned that on the off-chance it is a stepper. : )
>
> Dave


Ok. I'll try to be a little more clear. Yes the motor does spin when
connected to a battery. I used a nine volt. As for the circuit I
built.

I connected pin 8 of the stamp to the base of the transistor.
I connected one wire from the motor to Vdd. I connected the other
wire to the collector of the transistor.
I connected the emitter to Vss.

When I do this with an LED I can get it to flash. (I added about 50k
resistance)It will not work with the motor I was wondering if I did
something wrong. I did not use a resister from pin 8 to the base. The
schematic I have didn't show one. Is that a problem? Can you maybe
post a link or two to other driver circuits that have been known to
work for my situation. I tried building an H bridge that I found in
the book "Bug Bots, Junk Bots and Bots on Wheels" but didn't get any
results.

Thanks for the help.
Bill

Archiver

--- In basicstamps@yahoogroups.com, "billdoser2003"
<billdoser2003@y...> wrote:
> --- In basicstamps@yahoogroups.com, "Dave Mucha" <davemucha@j...>
> wrote:
> >
> > > Thanks for the reply Dave. I tried to use a 2n3904 transistor.
I
> > > connected the base of the transistor to one of the pins on the
> > stamp
> > > and i connected the collector to my motor through Vdd. I
> connected
> > > the emmiter to Vss. I was able to get an LED to blink this way
> but
> > no
> > > reaction from the motor.
> >
> >
> > I'm assuming you missed something in your post ? it sounds like
> you
> > have the NPC transistor connected to Vcc and Vss and nothing in-
> > between ?
> >
> >
> > The motor would connect to Vss, then the 3904 collector.
> >
> > The 3904 would connect to the motor on the collector and Vss on
the
> > emiter.
> >
> > The Stamp would connect to the Base of the 3904 with a 220 or 330
> ohm
> > resistor.
> >
> > The 3904 would connect to the resistor to the base.
> >
> >
> > The motor can be connected to your higher voltage as only the
> > collector and emitter see that higher voltage.
> >
> > And, power ground and logic ground need to be tied together. ie:
> > emitter and Vss of the Stamp.
> >
> > Is this what you tried ?
> >
> > just as a thought, I expect your motor spins when connected
> directly
> > to power ? I mentioned that on the off-chance it is a
stepper. : )
> >
> > Dave
>
>
> Ok. I'll try to be a little more clear. Yes the motor does spin
when
> connected to a battery. I used a nine volt. As for the circuit I
> built.
>
> I connected pin 8 of the stamp to the base of the transistor.
> I connected one wire from the motor to Vdd. I connected the other
> wire to the collector of the transistor.
> I connected the emitter to Vss.
>
> When I do this with an LED I can get it to flash. (I added about
50k
> resistance)It will not work with the motor I was wondering if I did
> something wrong. I did not use a resister from pin 8 to the base.
The
> schematic I have didn't show one. Is that a problem? Can you maybe
> post a link or two to other driver circuits that have been known to
> work for my situation. I tried building an H bridge that I found in
> the book "Bug Bots, Junk Bots and Bots on Wheels" but didn't get
any
> results.
>
> Thanks for the help.
> Bill


What type of motor are you trying to run ? DC ? stepper ?

will it run directly on the 9 volt batt ?

Check the pin connections on the transistor. Make sure it is not
upside down. (been there, done that)

Does the motor draws more current than the transistor can deliver and
the motor is just not getting enough power ?


Can you post a shcematic of the h-bridge you are trying to use ?

Dave