What kind of motor? You're probably talking about a DC motor. If so, what voltage and current? Pololu makes lots of different nice DC motor controllers. Parallax has their HB-25 which can handle large motors (up to 0.5 HP). You'd need one for each motor. Some of the Pololu controllers handle two motors, but at lower currents than the HB-25.
Most likely 12. Our power supply will be running both motors about 4 sonar and about 4 IR transmitter/receivers, a watchdog timer and respond to a remote deadman switch. We can adjust batteries or build a divider to lower volts or amps if needed.
The motor controller choices depend on the voltage and maximum (stall) current of the motors. Like I said, I'd look at Pololu's on-line catalog and Parallax's offerings ... the HB-25 and the Pololu controllers they carry. A "divider" won't help you with the motor's voltage or current requirements. The controller has to handle the voltage the motor needs (sounds like 12V in your case) and the maximum current drawn by the motor (under worst case conditions)
A quick rundown of components gives us a peak amp rating of 1.8 amps. So assuming we spike over saftey limits we would be pulling 2 amps and frying things. All components are less than 12 volts. A 4 phase DC motor is included with these figures.
Motor controller is not included in those figures and we may need to bump up the power of the motor to around 250 - 300 watts.
Mike I will private message you on more details rather than clog the forum.
It's much more polite (IMO) to ask in the forum so the time Mike and others spend answering questions can help others with similar projects. It's not clogging the forum; we all want to hear the juicy details of volts and amps.
Speaking of which (similar projects), here's one of my latest multiple motor Propeller controlled projects. I'm using some inexpensive motor controllers I purchased off ebay.
We are building the prop board to make the components fit. Both directions are needed for motor control. The motors haven't been finalized because the controller and the motors need to go hand in hand. The motors will be moving between 15 - 20 lbs between the two of them and may need to do so rapidly for 3 minutes at a time.
It would appear that you are having a couple of decisions to make at the same time.
It seems as though you are building a robotic platform.
Do you know how fast your platform needs to run at maximum speed?
Sizing the motors, wheels and gear ratios needed can be a vary large decision.
While I'm using the automotive Scrapyard windshield motor path, I'm not sure it's the best decision.
The pre engineered motor and gearbox seems to be the best path.
I'm planning on using HB25 motor controller in my current under development platform.
The only thing that I was concerned about when developing my current, under development platform was that the gearing of the
Parallax platform motor and gearbox combination appeared to be too tall for running my platform at about 12" per second.
I went the Automotive scrapyard path and purchased Two 98 Chevy Tahoe wiper motors that run at about 40RPM on the slow speed
unregulated from a 12V power supply drawing about 1.3 amps.
The problem with the path I chose is that building a coupling that will attach the wheels to my windshield wiper motors
was a major project using only aluminum bar stock and my low tech drill press.
Also, I will need to see how long the bearings or bushings used in the wiper motors will last.
No matter which path you wish to follow, I think that deciding on a motor/gearbox combination that will give you the correct nominal average
speed and then chosing a controller that fits the motor gearbox will be the best path towards success.
Thanks for the input. I am seeing some re-occuring themes come up here and with those I speak with as my personal resources.
For the sake of the forums understanding I am putting in some more details -
As indicated we are making our own Propeller platform based on the Hydra gaming system, Prop demo board and the DIP kit. I took the specs sheets from when they were purchased, looked at what was available, talked with a few electronics techs and laid out a board for our needs.
The motors are going to be moving 15-20 pounds for up to 3 minutes but will be working intermittantly and may need to go from a dead stop to full speed immediatly. Ability to get moving quickly is very important. We will be using a RC receiver for a dead man switch along with a watch dog timer to make sure the motors shut off.
I use the l6205 it can drive ~6 to ~12 amps if you wire the bridge in parallel. Basically you would want to use one chip per motor then wire the two bridges in the chip in parallel, the data sheet shows how to wire it. It really is a nice chip it can switch up to 100khz, it has over current and over heating protection, along with built in flyback diodes. STMicro makes the l6205, you can sign up at there site for free samples if your on the fence about it. It only requires a few caps/resistors and two signaling diodes to hook up, and comes in a dip package if thats what you like.
Comments
Motor controller is not included in those figures and we may need to bump up the power of the motor to around 250 - 300 watts.
http://www.robotpower.com/catalog/
http://www.vantec.com/
It's much more polite (IMO) to ask in the forum so the time Mike and others spend answering questions can help others with similar projects. It's not clogging the forum; we all want to hear the juicy details of volts and amps.
Speaking of which (similar projects), here's one of my latest multiple motor Propeller controlled projects. I'm using some inexpensive motor controllers I purchased off ebay.
Do you need both direction or just on/off?
What Propeller board will you be using?
It seems as though you are building a robotic platform.
Do you know how fast your platform needs to run at maximum speed?
Sizing the motors, wheels and gear ratios needed can be a vary large decision.
While I'm using the automotive Scrapyard windshield motor path, I'm not sure it's the best decision.
Might I suggest that you look at something like the Motor Mount and Wheel Kit offered by Parallax?
http://www.parallax.com/Store/Accessories/MotorServos/tabid/163/CategoryID/57/List/0/SortField/0/Level/a/ProductID/507/Default.aspx
The above line should link you to the proper place in the store to review this product.
The pre engineered motor and gearbox seems to be the best path.
I'm planning on using HB25 motor controller in my current under development platform.
The only thing that I was concerned about when developing my current, under development platform was that the gearing of the
Parallax platform motor and gearbox combination appeared to be too tall for running my platform at about 12" per second.
I went the Automotive scrapyard path and purchased Two 98 Chevy Tahoe wiper motors that run at about 40RPM on the slow speed
unregulated from a 12V power supply drawing about 1.3 amps.
The problem with the path I chose is that building a coupling that will attach the wheels to my windshield wiper motors
was a major project using only aluminum bar stock and my low tech drill press.
Also, I will need to see how long the bearings or bushings used in the wiper motors will last.
No matter which path you wish to follow, I think that deciding on a motor/gearbox combination that will give you the correct nominal average
speed and then chosing a controller that fits the motor gearbox will be the best path towards success.
I wish you luck in your endevour.
For a robot with 12 v battery and two DC motors (max 2,5 Amp each) a use a Pololu Trex JR motor controller.
Connecting 2 pins of the Propeller with 4,7 K resistors to the TTL connectors of the Pololu card.
Sending commands with Fullduplexserial.Tx .
I agree with Mike : it works fine .
Have also used this card with a RC model receiver.
http://www.pololu.com/catalog/product/767
Jean Paul
For the sake of the forums understanding I am putting in some more details -
As indicated we are making our own Propeller platform based on the Hydra gaming system, Prop demo board and the DIP kit. I took the specs sheets from when they were purchased, looked at what was available, talked with a few electronics techs and laid out a board for our needs.
The motors are going to be moving 15-20 pounds for up to 3 minutes but will be working intermittantly and may need to go from a dead stop to full speed immediatly. Ability to get moving quickly is very important. We will be using a RC receiver for a dead man switch along with a watch dog timer to make sure the motors shut off.
They have a more powefull Pololu DMC01 , perhaps it may work.
So why not source the dual h-bridge of your choice then?
http://www.ti.com/paramsearch/docs/parametricsearch.tsp?family=analog&familyId=2007&uiTemplateId=NODE_STRY_PGE_T
P.S most quad drivers can be paralleled to drive 2 motors at double the rated amp.
Put large copper area around it on boths sides, may have to attach smt heatsinks too.