Baby Orangutan B-328 Motor drive

I have a B-328, 120:1 Mini Plastic Gearmotor 90-Degree Output, and a Pololu Adjustable Boost Regulator 2.5-9.5V.
When I try to power the motor from pinouts M1A & M1B or M2A & M2B I don’t get any movement. I get a small wine from the motor… My guess is under power. So I powered it from the Pololu Adjustable Boost Regulator 2.5-9.5V. I bumped it up to 9. something volts. I still get the motor wine and no movement… There is nothing connected to the output shaft. I’m still just coding and using a breadboard.

I have also tried a 50:1 Micro Metal Gearmotor HP, and get the same results. I have also tried tuning the motors at different speeds. I only have one motor connected at a time… I’m sure that I’m doing something wrong.

thanks for the help,


What are you using to power your boost regulator? Can you post your code?

- Ben

I’m using the Orangutan USB Programmer’s power and ground. it’s giving me about 4.4 volts.

#include <pololu/orangutan.h>

unsigned long prevMillis = 0;

int main()
   //Beginning Custom code
    int motorSpeed = 100;  
    set_motors(motorSpeed, motorSpeed);
   // End Custom code

    int ledDelay = motorSpeed;
    if(ledDelay < 0)
      ledDelay = -ledDelay;  // make the delay a non-negative number
    ledDelay = 256-ledDelay; // the delay should be short when the speed is high

    red_led(1);       // turn red LED on

    red_led(0);       // turn red LED off

This really sounds like a power issue to me. USB power is generally not suitable for powering motors, and you’re making things worse by boosting the voltage. By doubling the USB voltage, you’re only making half the USB current available to your motors while simultaneously causing your motors to try to draw more current. You should definitely switch to a power source capable of delivering the power you need (i.e. at least the stall current of your motor at whatever voltage you’ll be running it at) and see if that fixes your problem.

- Ben

Awesome Ben, your a magic man… I’ll try this tonight.

Ben, another quick question… The 67:1 Metal Gearmotor 20Dx45L mm. How would I figure out the minimum battery power to use? I’m reading up on AA and AAA batteries and they talk about mAh… Is there a way to see mA or mAh with a multimeter?

I have some big 14.4volt 90WH batteries that I would like to use too. I was hoping that the Pololu Adjustable Boost Regulator 4-25V to regulate this.

My goal is to make my project flexible in the way of choosing battery systems.

Thanks for the help Ben, I’m really just learning all of this.


Amp-hours (Ah) is a unit of capacity. A 1000 mAh (or 1 Ah) battery can deliver roughly 1 A for one hour or 100 mA for ten hours (or 6 A for ten minutes). Capacity also gives you an idea of how much current you can draw from the battery before the voltage drops unreasonably. A general rule of thumb is that you want a battery with a capacity that is at least a tenth of the maximum current you anticipate needing to deliver. For example, if you have a motor with a 10A stall current, you should choose a battery with a capacity of at least 1000 mAh.

I definitely would not recommend using the 20D metal gearmotors with the Baby Orangutan. The stall current at 6V is already more than the peak current the motor drivers on the Baby Orangutan can deliver and significantly more than the boost regulator can handle. For these motors I would recommend one of our higher power motor drivers or our new Orangutan SVP, and I would advise against having the boost regulator in the power circuit.

The boost regulator can only boost voltage, so you will not be able to use it to decrease the voltage of your batteries. Using it with your batteries will also severely limit the power you can get out of them. Also, you should not use those batteries with your Baby Orangutan as they exceed the maximum supply voltage for that device.

Why do you want to have such flexibility in choosing a battery system? That kind a flexibility might ultimately make your life easier in some ways, but it greatly complicates your overall system and might not be worth it. Powering large loads off of a regulated voltage can be complicated and expensive. Unless your project has constraints I’m not aware of, you are probably better off just getting a suitable battery pack and using that as your power source.

- Ben

Hey Ben, When I test my 210:1 Micro Metal Gearmotor HP out it stalls when I try to turn it at round 83 and below… The problem with that is that they need to be accurate with the movement. I’m wanting to turn the load as slow as possible.

I’m not sure but I think I got a 1600mA version of the 210:1 Micro Metal Gearmotor HP… If I got 298:1 Micro Metal Gearmotor HP @ 1600mA, do you think this would help me with this kind of issue… or get me closer? Or do I need to look into another type of motor controller and a heavier motor?

thanks for the help ben

Is your motor free-running or under load?

- Ben

under load. I’m not concern about high rpms. It only has to make about 1/4 of a turn to reach the end of allowed rotation… in both directions

My power source is 2x aaa batteries getting a volt but with a Pololu Adjustable Boost Regulator 2.5-9.5V to about 9 volt… That is the only power source that I have at this time. I’m hoping to make my first project work off of the 2x aaa… But I understand if I can’t. I can have a 7 volt 5200mA battery system later today… if you think it would help…

It might be worth trying with your other battery system. I also recommend you try lowering your boost voltage to something around 6 V since that will make more current available for your motor and will cause your motor to draw less current under load. Of course it will also make your system more apt to brown-out (reset due to under-voltage) if you try to draw too much current from the regulator and the output voltage drops.

In general, it’s difficult to get a motor to spin slowly, especially when it’s under load. For applications that require precise speed control (and driving a motor very slowly is typically such an application), using feedback really helps. When the feedback tells you your motor has stopped turning, you can apply more power, and when it says you’re turning too fast, you can decrease the power. Right now it’s like you’re trying to drive a car blindfolded. You might know what pedal position generally corresponds to 5 mph, but if you’re going up a hill you’re going to need to push the pedal further down to maintain your speed and if you’re going down a hill you’re going to need to let up on the gas. Without being able to see (i.e. without the feedback), you don’t know when to make these adjustments.

The other alternative is just to use a motor with a very high gear ratio. It’s top speed will still be slow because of how geared down it is, and it will have so much torque that it probably won’t be affected much by the load you put on it. The only drawback is that it might also have enough torque to break something if you don’t take proper precautions.

You might also want to check out this thread:

Russmc wanted to make a model train drive as slowly as possible, and he managed to accomplish this using current-sense feedback to tell if he the motor was turning. If not, he would apply more power, otherwise he would decrease the power again.

- Ben

I am having the same probelm of wining motor eventhoug I am using 9 V battery as my supply. I am using 210:1 micro gear motor and baby orangtan.



The sound from your motor is probably just the PWM frequency, and it does not indicate a problem. However, a 9V battery is not a very good choice for powering motors, so you might not be able to run it well or at all. By the way, we sell two different motors with a 210:1 gear ratio, so you should specify which product you are using if you continue to have trouble.