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MD23 - Dual 12Volt 3Amp H Bridge Motor Drive

md23b.jpg33.8 KB
Vendor's Description: 

Althou i just burned one, i think i could still share some info here :)

This is an advanced motor driver for 12V motors. It is usually coupled with EMG30 motors, but you can run it with any other 12V motor. It handles up to 3A per motor.

It is controlled with i2c and has some advanced features you usually don't find in other cheaper controller, for example:

  • Variable Speed: drive your motors with 255 different speed, from full backward to full forward and all middle values
  • Automatic Speed regulation: if your motors have encoders, the board is able to automatically adjust the power output to keep the speed costant even in case of different load or different ground (ie a small climb). This option can be enabled or disabled at will.
  • Acceleration rate regulation: you can choose how smoothly the motor pass from a certain speed to another. For example setting a low value you can avoid too sharp changing and have a smooth deceleration and turning.
  • Battery voltage reading: the board can tell you how many volts you are supplying (in decimals). Useful to check if the battery is getting low.
  • Motor current consumption reading: in any moment you can read how much current each motor is using (in decimals of A).
  • Motor speed reading: if your motors have encoders, the board can use them and tell you how fast they're spinning
  • 4 sets of GND and +5V pins that you can use for your own electronics (300mA continuous)
  • 4 sets of SDA and SCL pins, very useful for connecting many i2c devices without extra breadboard or custom PCB or wire hacks.


  • It's quite big (approx 7x6 cm).
  • Uses 6 way JST connectors, which fits perfectly with the EMG30 motors but can be a problem with other motors
  • It uses a connector with screws for main power input...

More info are avaiable here: http://www.robot-electronics.co.uk/htm/md23tech.htm


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You've put everything regular users would want to see at a glance, but also references for anyone who wants to drill deeper. Very useful. Note to self: here's a homebrew I2C speed controller (thanks, buhatkj).

yes that's very interesting! i'd like to know more about it :)

the only problem with homebrew board is that they're not compact and quite big..

I agree. I like to do as much as possible myself, though. The debate has happened in the past "where do you draw the line?" Do you mould all the plastic parts yourself? Perhaps you extrude your own copper wire?

No, seriously. My goal would be to build an array of I2C sensors and drivers, which we could all develop together. Then we'd sell them and raise money to feed Frits' family buy a new server for LMR. As we sell a few, we reinvest some of the cash into the production of custom SMD PCBs ( = small).

It may be a pipe dream, but it's my pipe dream.

well probably it's not impossible! i think i don't have the necessary knowledge of electronics to do it, but many others have it. I'm quite good at programming if it can help :) Probably you can do many of this i2c stuff by adding a pic controller to handle the i2c, just like buhatkj did. For example my IMU sensor has 4 analog outputs, probably it would be nice to have an i2c interface to select and read each single channel.

I think that, depending on quality and expecially on size, you could end up making something that has a market. Something like the L298 Compact Motor Driver Kit posted by fritsl (it doesn't look very professional, but it's still quite compact).

Maybe the problem is that a lot of this things already exists and it's hard to be competitive for price, i think.

What kind of sensor or driver would you start with ? :) 

I have the hardware designed and built for an I2C 40A 12V motor controller. I'm a bloody brilliant programmer and I can't, for the life of me, figure out how to use the native I2C interface on a PIC 16F818. I'm sure I'm doing something silly with the baud rate generator.

I'm not really interested in making a profit. I'm interested in developing modules which robot builders can build for themselves, out of easily obtainable parts, with only limited knowledge of electronics or software. If it turns a profit, that's a bonus.

I envisage a platform where you have a couple of sensors, a motor driver and a controller all hooked to the I2C bus. For example, I would make an I2C version of Frits' ultrasonic YDM scanner, a motor control board and another PIC (controller) to be the bus master, take the inputs, jiggle them and fire them back out the outputs.

Dong my own plastic moulding... now there's a thought.  As for the copper wire, any true DIY enthusiast would know that copper wire is drawn, not extruded.  :-)  :-)

But seriously, I've made my own PCBs (as I've shown on LMR)  and I have plans to do some electrolytic etching, too (of brass).  But it's quite possible to do vacuum forming of plastics at home, and to cast resin parts in silicone moulds (Mythbuster style).  I know that the old school model engineers used to make their own nuts and bolts, too.  As far as I'm concerned, I enjoy the "making" part of the process as much as any other.

Don't be silly. If it was "drawn" then it would be made from carbon (assuming you used a pencil) or ink (pen).

I make my own nuts and bolts.

I'd be interested in a home-made vacuum former. Seen anygood plans anywhere?

not much help right now as i'm about to throw my things in the car and head to daytona beach for a week so i cannot find you the EXACT issue and page number but makezine had an artical on vacuuming forming. basically made a wood frame + huge sheet of plastic+ object+ shop vac = cool formed plastics.. 

that's all i got right now =( sorry

the online subscription is WELL worth the money and you can look at every issue they have ever published.


Make has a few, apparently one described in Make 11 : http://makezine.com/11/vacuumformer/

As well as another link : http://blog.makezine.com/archive/2007/01/vacuum_thermoforming_in_y.html

and a link to another site : http://www.halloweenfear.com/vacuumformintro.html

And Instructables has several described, here's one :  http://www.instructables.com/id/Vacuum-Former/

Nice one,  Nicola! Really nice to have info in the future! Thanks.