small electric motor question

[mhein68]

hi all,
     Going through my learning curve here with my prop1. I have been working with LED lights through the out connections with great success. Today I am experimenting with small motors from a radio controlled car. (not servos but small electric kind). They have two wires from them. I tried to feed power from P0.R and P0.W to turn them on and off...nothing. Now if you connect them from P0.r and P0.B they run continuously. Where am I going wrong here? I am having great fun with the Prop1 and am trying work with it to learn as much as I can... Thanks for the help.

[menehune]

What voltage is the motor?  How much current does it draw?

Motors typically need to be buffered from the processor by the ULN chip since the processor pins cannot supply enough current to rotate the motor.  If the motor is 12 volts, have you tried connecting it to the OUTx screw terminals on the Prop?

On the three pin servo connector, the Red wires are V+, the Black wire is ground, and the White wire is Signal.  White is typically very fast alternating pules used to control servo positions.

Did you try connecting the motor between White and Black?  White is a switched lead controlled by the processor, the ground is needed to complete the circuit.  Connecting the motor to between the red (power) and black (ground) pins has it run all the time.  To switch the motor  off, you would need to interrupt the power.

The OUTx terminals switch the ground lead so you would connect one wire from the motor to the "V+" screw and the other wire to the "GND" screw.  Turn on or off the output by the prop and your motor should spin.

This forum page helps to explain the difference between the WRB pins and the OUT pins.
http://www.efx-tek.com/php/smf/index.php?topic=265.0
This page explains how much current the OUTx can switch
http://www.efx-tek.com/php/smf/index.php?topic=526.0

[mhein68]

What voltage is the motor?  How much current does it draw?

Motors typically need to be buffered from the processor by the ULN chip since the processor pins cannot supply enough current to rotate the motor.  If the motor is 12 volts, have you tried connecting it to the OUTx screw terminals on the Prop?

On the three pin servo connector, the Red wires are V+, the Black wire is ground, and the White wire is Signal.  White is typically very fast alternating pules used to control servo positions.

Did you try connecting the motor between White and Black?  White is a switched lead controlled by the processor, the ground is needed to complete the circuit.  Connecting the motor to between the red (power) and black (ground) pins has it run all the time.  To switch the motor  off, you would need to interrupt the power.

This forum page helps to explain the difference between the WRB pins and the OUT pins.
http://www.efx-tek.com/php/smf/index.php?topic=265.0

Thanks for the reply...I am very new to this! I found the RC car at a yard sale (for free) and it took a 4.9v pack so I assumed it could take 5v from the Prop1.. I only have at this time a two prong servo cable (came from Cowlacious board) that I am using to connect. This is all just to experiment with the Prop1 and learn how control differnt things.. I am going to find a local hobby shop and find a cheap servo to practice with..

[mhein68]

I did what you told me.. I put one wire in the v and the other in the ground... That didnt do anything... Iguess this is a little harder to figure out then I had thought... I will keep playing around till I figure it out..  :-\   :'(

[JonnyMac]

The Key is NOT to connect motors or other inductive (things with coils) devices to the Px.W pins -- these have a near direct connection to the processor I/O pins and you could damage your Prop-1 severely.  If the current spec on your motor falls in the range of the ULN then you can use that.  You could use an external 6v battery with your setup: connect your motor to OUTx, the other side of the motor to the positive side of the external battery, the ground side of the battery to the GND terminal.  Don't connect anything to V+.

Now... to be candid, motors are a little way up the chain as far as ease-of-use, and you may want to give yourself a bit more time before tackling them.

[mhein68]

Thank you Jon... I will start a little less ambitious...  ;D  I am enjoying working with the prop1 .. maybe I'm  biting off more then I can chew right off the bat! Thanks for the help!

[menehune]

If it is a RC car, the motor probably requires much more current than the prop can handle.

Was the battery pack small like a cell phone battery or as large as a TV remote control?  Typically the bigger the pack, the larger the current demand from the motor.  If the motor is larger in diameter than a pencil, the prop probably will not be able to drive it directly.  You will probably need to switch a relay connected between the OUTx terminal which will apply power from an external battery pack or power supply.  I have a remote control car that draws around 30A at full power and the motor is as large as a "D" cell battery.  That will never run from a prop without a motor controller in between the two.

Does the RC car have any servos inside?  You could modify a servo for continuous rotation or purchase one already modified to simulate a larger motor while you are learning, or just have a LED turn on or off.

Hopefully, the output pin the motor was connected to did not sustain damage.

Remember, you must learn to crawl before you can run a marathon!

It can be frustratingly slow to follow the lessons in the lesson plans (I started with a BOE BOT and a BS2 before I got a prop1), but the lessons build on top one another so they slowly teach you the required skills and how to build interfaces for higher powered equipment.

[mhein68]

Thanks! I am going to stick with LED's and If I can find a cheap servo then work with that... I am learning new things everyday I work with the prop1...