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Electronics => Electronics => Topic started by: emmannuel on July 27, 2008, 09:12:56 PM

Title: ~3V motor controller?
Post by: emmannuel on July 27, 2008, 09:12:56 PM
I've been using the TI SN754410 as my dual motor controller but I'm interested in on my next project using a circuit I'd like to keep at just 3.3V.  The SN75441 sadly is for 5V I know I can use stepup voltage regulator but I was wondering if anyone knows a simple part I could use that is similar to the SN754410 cause I had no luck.
Title: Re: ~3V motor controller?
Post by: Admin on July 30, 2008, 09:45:56 PM
Just to clarify . . .

You want your microcontroller at 3.3V? Why are you running the microcontroller at 3.3V?

And your battery is 4.8V or 3.6V?

And you want a motordriver that operates with these two requirements?

If you are using 3.3V just to save power, its not really worth it when you have motors draining 99% of the power . . . And motors don't work well under low voltages.
Title: Re: ~3V motor controller?
Post by: emmannuel on July 31, 2008, 12:33:15 PM
Well I haven't decided on the batteries yet but I decided the motor I am going to use is this worm gear motor

In its datasheet it mentioned nominal voltage range of 3V.

So I was thinking of making the controlling circuit in the 3.3V range since there seem to be quite a few devices that support it.

Closest thing to what I wanted so far seems not sure how hard a SOP pavkage is to solder :P

Right now though I'm probably just going to go with a 5V circuit.  Giving the motor controller a lower duty cycle to control the motor at to keep it around around 3V for the motor.  This way I have most of the pieces already.

The goal is to make an efficient system that would only turn on the motor for a few seconds every hour.
Title: Re: ~3V motor controller?
Post by: izua on July 31, 2008, 02:04:28 PM
You do know that you can control the motor at 5V in pwm, and get a lower voltage at a high efficiency, right?
Title: Re: ~3V motor controller?
Post by: bens on July 31, 2008, 06:15:24 PM
The Tamiya motors are intended for 3 V operation, but they definitely work at higher voltages.  The only down side is that using a higher voltage shortens their usable lifetime.  One customer of ours did a fairly detailed study to see how voltage affected the lifetime of the motor used in the Tamiya gearboxes.  You can find his results here:

Another thing worth noting is that many popular, inexpensive H-bridge ICs (e.g. the L298N ( have voltage drops between the input voltage and the output voltage, and the drops can be as large as 3 V at 1 A.  What this means is that if you use a 6 V power supply with something like the L298N motor driver, you would only have around 3 - 4 V on your motors.  Your best best might be to use something like four NiMH batteries as your power supply, which would give you a voltage of around 5.5 - 4.5 V as they go from fully charged to depleted.

Lastly, the Tamiya motors are very noisy (electrically), so make sure you solder caps across the motor terminals.

- Ben
Title: Re: ~3V motor controller?
Post by: Spoil9 on August 01, 2008, 02:09:02 PM
I am using Tamiya's motor gear box for a project as well. I've been told though that even though it's only 3v, they like to draw a lot of current, so I was recommended to buy this motor controller:
It works up to 7v, and can handle up to 5A per motor (2x motors) or up to 10A if set up for only one motor.
Although I have not been able to use it yet cause I'm still working on the programing, I do believe it will be worth the investment.
Hope this helps.
- Bill
Title: Re: ~3V motor controller?
Post by: bens on August 01, 2008, 02:18:29 PM
The LVDSMC (low voltage dual serial motor controller) is specifically designed for low-voltage toy motors such as those in the Tamiya gearboxes, so hopefully you will find it to be a good investment.  It's worth noting that another option when using the Tamiya gearboxes is to replace the motors with Solarbotics RM3 replacement motors (  These are higher voltage, lower current motors (800 mA stall at 6 V instead of around 4 A stall at 6 V for Tamiya's Mabuchi FA-130 motors ( that generate less electrical noise than the Tamiya motors, and they have the same form factor, allowing them to be used as direct replacements for FA-130s.

- Ben