dc motor activate with out shield?

I had an part of an idea for activating a 6 volt dc motor with just using an Arduino uno board, a 3 volt dc motor and a switch that will some how be pushed by the 3 volt dc motor. once button is activated the serrate power supply to the 6 volt dc motor will be activated. the sketch would be the same as the pin mode sketch. project is making a rc car that moved to a location by gps coordinates that are transmitted form cell phones app or vehicle gps system.

You cannot drive a motor direct from a microcontroller, you must use a motor driver or shield.

Logic pins cannot provide anything like enough current and they are fried by inductive kickback.

I figured that out after I read up on it but you can control a little 4 volt dc motor with just the Arduino board. So using the 4 volt dc motor the board activate the motor. The motor may be activating a push button switch on a separate circuit that has the capability of power up a 6 volt dc motor. Which would possibly make the Arduino motor shield not necessary

No. As already said ANY motor, even a "little 4 volt dc motor" will take much more current than an Arduino pin can safely deliver. Of course you don't have to believe this you can try it your way...then buy a new Arduino when you've ruined the one you have now.

If you only want a 6V motor to turn in one direction at one speed then a relay would work. If you want to control the speed then a single MOSFET and a couple of resistors would do it. You only need a motor driver or shield to run the motor forward and reverse and you'll also get speed control.

Steve

Repeat after us: "Motors takes LOADS of current and are inductive - they cannot be driven direct from logic chips" :slight_smile:

Of course if you don't mind your circuit suddenly dying at random, do whatever you like, but don't expect
reliable operation of a chip when abused.

The smallest motor I have is 5mm x 6mm and it still uses more current than an Arduino pin can handle.

A small motor is like a short piece of copper wire wound round an armature, its resistance is a few ohms
to a few tens of ohms.

It be 2 different circuit. The Arduino one using the pinmode to power the 4volt dc motor. The 2nd circuit would be designed to power the 6volt dc motors with a button to control the 6volt dc motors. The Arduino circuit propose would be just to push the button in the complete separate circuit not wired to the Arduino circuit In any way at all.

O.k. so you didn't want advice. You just wanted someone to say that your stupid idea isn't really a stupid idea. That's not going to happen!

Steve

The Arduino one using the pinmode to power the 4volt dc motor.

Feel free to try. Arduino.cc will be happy to sell you another if it doesn't work out.