Robotics Products by Noetic Design, Inc.
Robotics Products



FlexDrive Dual Motor H-Bridge Board No longer in production, sorry....

Assembled Circuit Board
Assembled FlexDrive Circuit Board (click for larger image)
Demonstration Robot Using FlexDrive (click for larger image)

  • up to 1.1 A per brushed DC motor at up to 36 volts
  • flexible control of motor speed, direction, and braking
  • can be controlled with as little as 1 I/O line for simple on/off control, or use 3 I/Os per motor for complete control!
  • small size for small but powerful robots

View Schematic

View Board Layout


Rev 1.00 of the prototype board requires a small jumper wire connecting between R1 nearest pin 2 of U2, and pin 2 of U2 itself. Without this wire, R1 does not pull down the PWM input for Motor 1, so a floating or disconnected PWM input might result in unwanted motor activity.

Rework Diagram


Bill of Materials

Count   Component Type    Module Type      Component Reference
-----  ----------------  ---------------  ---------------------
 6     47K               RC05             R1 though R6
 1     470uF 40v         CK15-S           C1       
 1     0.1uF             CM5-390          C2       
 1     SN754410          16DIP300         U1       
 2     74HCT00           14DIP300         U2 & U3       
 2     CONN02            2HDR-100         J1, J2, J5 & J6; JP1-JP3
 1     CONN04            4HDR-100         J3 & J4       


You can omit JP1-JP3 if you will always provide full control of the motors. You can also omit R1-R6 if you will always connect all 6 control lines to a microcontroller. However, they are still recommended due to the fact that many microcontrollers float their I/O lines after reset until they are explicitly set as outputs by your firmware. The resistors prevent unwanted motor motion during the setup portion of your programs.

The value of C1 should be in the neighborhood of 470 uF, but the voltage rating is flexible -- it all depends on what voltage your motors run at. If you are using 12 volt motors, then a 25 volt radial electrolytic capacitor would be fine.

The value of R1-R6 can be anything from 10K to 47K.

The value of U2 and U3 can also be 74HC00.

On rev 1.00 of the board, the holes for J1-J6 and JP1-JP3 are too small for square pin headers. Round pin headers can be substituted, or you can directly wire to the board without connectors. DO NOT drill out the holes to make them bigger, as this will break the vias and potentially disconnect some of the signals running though those holes.

Apply liberal solder to pins 4, 5, 12, and 13 of the SN754410 motor driver chip, as this will help conduct heat away from the chip during operation. Just be sure you don't create solder bridges to the adjacent pins!

Contact Pete Skeggs, plskeggs -at= noeticdesign d0t com, for support.


Last Updated May 27, 2005