what about motor and reductor chosing?

For a small two-wheels first robot, which DC motor should I get?? The typical DC motor I've always seen is quite big and powerfull, and also takes 3V@330mA or 6@450mA which is a lot.

also, for reduction, how could I build myself one?
the ones they sell are quite expensive

thnks

Well i got a lego car moving whith one 80 mA motor at 7.5 volts.He was a quite heawy felow. I have a motor thet golps 2 A at 6 V!


Whith no reductor the thing wod go nice nad fast whith two 100 mA motors at 9V (Whith two 4.5 baterys)

What is your real problem? The weight of power supply? driver or the motor? Or you meant the total weight of your robot? Or you care about the dimensions?

My main aim is low power consumition, as the robot is small and light. But also cost. I know that servos maybe best solution, but they are expensive.

If you make it light enugh 100 mA motor at 3V shod do it.But i thing yul have to runit from button baterys.Beter rechargeble becose buton baterys can get dicrharged fast whith a motor.I have some Ni-HM buton baterys for this purpose 3.6V 250 mAh

Do you know a new Japanese battery? It's AA size, but it's so strong, only 3USD each.

If you use a 6V motor, you also can use 3 V supply, it still works. I cannot get the strongest torque of the motor, but I'm sure it will works. As you use PWM for 6V motor, at 50% duty cycle, that is, you seem to apply 3V to the motor. Yeah, there are some differences, but in a small light application (not a micro application) dont care muchie about it. It works.

If your application is a microbot, I think you have to use servo or RC motor. RC motor, in fact, it's used for remote controling, but if you use RC, it's so tiny.

Look for Cell phone vibrator motors. They are tiny.

https://www.allelectronics.com/ part number DCM-166 also might be what you're looking for.

Brent

thanks for the tips
I already thought about mobile vibration motor, it may be good idea for many applications.