High Amp H-Bridge ?
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I have a 12v atv winch motor that measures .4 ohms
across the leads. I would like to be able to control
the speed and direction of this motor using a bs2.
My question is... Can I just use multiple transistors
in parallel to handle the high amperage requirements?
Sorry for the kindergarden question. I figured I
would ask before wasting a bunch of transistors
experimenting.
across the leads. I would like to be able to control
the speed and direction of this motor using a bs2.
My question is... Can I just use multiple transistors
in parallel to handle the high amperage requirements?
Sorry for the kindergarden question. I figured I
would ask before wasting a bunch of transistors
experimenting.
Comments
would spend a fortune on solid-state devices to control it.
Original Message
> I have a 12v atv winch motor that measures .4 ohms
> across the leads. I would like to be able to control
> the speed and direction of this motor using a bs2.
>
> My question is... Can I just use multiple transistors
> in parallel to handle the high amperage requirements?
>
> Sorry for the kindergarden question. I figured I
> would ask before wasting a bunch of transistors
> experimenting.
think it has some interesting applications..
http://www.capable.on.ca/rcstuff/esc.htm
regards,
Leroy
EL-JEFE@P... wrote:
>
> I have a 12v atv winch motor that measures .4 ohms
> across the leads. I would like to be able to control
> the speed and direction of this motor using a bs2.
>
> My question is... Can I just use multiple transistors
> in parallel to handle the high amperage requirements?
>
> Sorry for the kindergarden question. I figured I
> would ask before wasting a bunch of transistors
> experimenting.
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and Body
of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
multiple transistors in parallel without the great risk of sending up smoke
signals. Consider using a DPDT Relay with contacts that will carry your
inrush surge current for controlling the motor reversal function.
Original Message
From: <EL-JEFE@P...>
To: <basicstamps@yahoogroups.com>
Sent: Sunday, January 20, 2002 5:08 PM
Subject: [noparse][[/noparse]basicstamps] High Amp H-Bridge ?
> I have a 12v atv winch motor that measures .4 ohms
> across the leads. I would like to be able to control
> the speed and direction of this motor using a bs2.
>
> My question is... Can I just use multiple transistors
> in parallel to handle the high amperage requirements?
>
> Sorry for the kindergarden question. I figured I
> would ask before wasting a bunch of transistors
> experimenting.
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
http://www.irf.com/product-info/datasheets/data/irc540.pdf
Check out http://www.irf.com for the latest high power Mosfets, and such.
I ran several in parallel as I was flying high performance electric RC and
you needed to handle 28-36 nicad's in series with upwards of 100 amps or so
surge, at start time, and hand launching. The good low resistance Mosfets
can provide 100 amps and run so cool, they don't need heat sinks, which was
a plus in a RC model with barely any room for a radio much less 36 nicads. A
good example of high power ESC's is the ones Astro Flite makes is
http://www2.towerhobbies.com/cgi-bin/wti0001p.pgm?Q=1&I=LXTF93&P=7, it uses
only four IRFZ48's. The Nokav Atom
http://www2.towerhobbies.com/cgi-bin/wti0001p.pgm?Q=1&I=LXBJ57&P=7 uses four
mosfets with a on reistance of .0013 ohms, and can run up to 240 amps, and
it doesn't even get warm without any heatsinks. The newer Cyclone C2 has
mosfets with a on resistance of almost zero at .00049 ohms. I wonder if
anyone knows what the part numbers are for those Mosfets?
http://www.irf.com/product-info/datasheets/data/fa38sa50lc.pdf (500v 38
amp's .13 ohms on)
http://www.irf.com/product-info/datasheets/data/fb180sa10.pdf (this one's
juicy, 100v, 180 amps, .0065 ohms)
You can goto www.digikey.com and run a search on "Hexfet" or "mosfet" and
you should get some good hits to check out.
It's easy to modify the circuit below from the URL
http://www.capable.on.ca/rcstuff/esc.htm
that Leroy told you about. But they now have controller IC's and current
limiting IC's that you can use along with the Mosfets, to build some truly
spectacular motor controllers.
You could even take a controller chip like the LM298 chip and add mosfets on
the output to boost it's power too.
Relays are OK, but the new Mosfets or Hexfets or whatever they call them
now, have no moving parts, and less resistance than the contacts on the
relays. It's pretty spectacular when you burn out the contacts when you try
to turn off the circuit, and the contacts arc over like a arc welder.
Especially, at a 100 amps or so. The current doesn't want to stop as the
contacts open (it's one of the reasons they used to put capacitors across
relay contacts, in order to try and prevent that). You get an effect where
you go "oops", hit the off switch, and the motor keeps on running. Then you
start looking for the axe to cut the cable, no time for a wrench.
Original Message
From: Leroy Hall [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=xPWIJiobLvfAdJxhOxdMOHEPhN8qmaZBOBFKtdK46TN0te3TT19JcGS-Pj5vtX2H3HxAI9It]leroy@f...[/url
Sent: Sunday, January 20, 2002 9:57 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] High Amp H-Bridge ?
Would the following link be of any assistant? I like the circuit and
think it has some interesting applications..
http://www.capable.on.ca/rcstuff/esc.htm
regards,
Leroy
EL-JEFE@P... wrote:
>
> I have a 12v atv winch motor that measures .4 ohms
> across the leads. I would like to be able to control
> the speed and direction of this motor using a bs2.
>
> My question is... Can I just use multiple transistors
> in parallel to handle the high amperage requirements?
>
> Sorry for the kindergarden question. I figured I
> would ask before wasting a bunch of transistors
> experimenting.
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
simplest way.
A pair of relays will allow you to run forward or reverse with full
power, and if you want to run a speed control, one speed control can
work through the relays. Heck a third could by-pass the speed
control for full power.
just my 2 cents.
--- In basicstamps@y..., Rodent <daweasel@s...> wrote:
> I would use a relay / contactor -- those motors draw *alot* of
power and you
> would spend a fortune on solid-state devices to control it.
>
>
Original Message
>
> > I have a 12v atv winch motor that measures .4 ohms
> > across the leads. I would like to be able to control
> > the speed and direction of this motor using a bs2.
> >
> > My question is... Can I just use multiple transistors
> > in parallel to handle the high amperage requirements?
> >
> > Sorry for the kindergarden question. I figured I
> > would ask before wasting a bunch of transistors
> > experimenting.
>I have a 12v atv winch motor that measures .4 ohms
>across the leads. I would like to be able to control
>the speed and direction of this motor using a bs2.
Why do you want to control a winch with a stamp anyway?
Perhaps you have a load sensor that detects the load
and does something with the info right? Maybe you're
just using the motor for say, a scooter or robot?
What you're doing is vitally important to the solution.
I would need more info before suggesting something.
Greg
resistance with a simple meter. can't be done...not
like that.
I haven't slept in a few day's so correct me if i'm
wrong here people.
The current draw of the motor varies with load,
always, it will try to maintain it's speed with added
load, and to do that, it will draw more current, which
induces a stronger magnetic field, giving you more
torque to raise the speed back up to where it was
before. (there's more than one type of motor but
...that's a whole course)
Guess what happens to the resistance when it starts to
draw more current and get more induced voltage? ohms
law.
The point a motor will draw the most juice is called
its stall current, (this is its starting current).
Therefore if you want a circuit to switch it on, for
whatever reason, you first need to start by finding
out it's stall current, connect it to some sort of
ammeter, start with low voltage and crank it up very
slowly as you watch the current rise, if you do this
right the motor won't be moving yet, when the motor
starts to turn, you'll see the current drop suddenly.
That peak current is what you use to calculate it's
resistance by how much voltage you gave it by the way.
But the important part if the motor drew 10amps just
to turn it on, you need to build a circuit that can
deliver at least ten amps and not catch fire. say
15amps? Once you have that, you can get the stamp to
control "that circuit", which powers the motor.
and pulse width modulation is about the only way you'd
really want to do that if you need speed control of
any kind, but there's really no need for PWM if you
just need simple on/off.
One last thing, even if you have the motor's specs
stamped on it, it's good to test and find its actual
specs before you go building a circuit to power it,
save yourself some problems and money later on.
HOpe that's a start for ya.
Good luck
--- Greg Hensley <hensley1@l...> wrote:
> At 05:08 PM 1/20/2002 , you wrote:
> >I have a 12v atv winch motor that measures .4 ohms
> >across the leads. I would like to be able to
> control
> >the speed and direction of this motor using a bs2.
>
> Why do you want to control a winch with a stamp
> anyway?
> Perhaps you have a load sensor that detects the load
> and does something with the info right? Maybe you're
> just using the motor for say, a scooter or robot?
>
> What you're doing is vitally important to the
> solution.
> I would need more info before suggesting something.
>
> Greg
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
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Hbridge is one way to go, best off using mosfets ..or
paralled mosfets to really get full power to the
motors. With that and PWM you'll get what you are
after.
Relay network is far simpler to deliver full power to
the motors, you can get reverse out of something like
that but have fun getting speed control.
There's some great examples of parallel mosfet speed
controllers online if you do some searching.
Best of luck
--- Greg Hensley <hensley1@l...> wrote:
> At 05:08 PM 1/20/2002 , you wrote:
> >I have a 12v atv winch motor that measures .4 ohms
> >across the leads. I would like to be able to
> control
> >the speed and direction of this motor using a bs2.
>
> Why do you want to control a winch with a stamp
> anyway?
> Perhaps you have a load sensor that detects the load
> and does something with the info right? Maybe you're
> just using the motor for say, a scooter or robot?
>
> What you're doing is vitally important to the
> solution.
> I would need more info before suggesting something.
>
> Greg
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
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