Gadgets3D, Pololu style A4988 Drivers complete soldered with mounted heatsinks - tested before shipping, just plug and play. Original Allegro A4988 inside. Professional design and manufacture ensure stable operation of our driver - it contains double copper PCB for better heat dissipation and all the parts are from brands such as TDK, Murata, etc. - sense resistors are true sense resistors and all capacitors are Class 2 selected to work properly up to 25V!
This is a new innovative stepper motor driver for your 3D printer or any task involving stepper motors! It is a new generation as replacement for Pololu/StepStick it is fully compatible with Pololu and StepStick.
So why is it better and innovative ?
Using the original design Pololu A4988 drivers in combination with some types of stepper motor there is a problem where the driver cannot output the low current parts of the cycle properly at low speeds so it outputs higher current than it should. This can cause vibration / shaking stepper motors and frame when stepper motors are moving slowly(most noticeable on Z stage). These drivers solve this problem by using an additional 30k trimpot instead of a fixed value resistor allowing you to select the decay mode option you want. Is it complicated to use? No, you only need to turn the second trimpot (OSC) fully counterclokwise and that's all - you can enjoy smoother and quieter stepper motors operation and no more lost motor steps because of non-optimal off-time settings. The trade off is that this mode creates more ripple on the supply current and is less efficient. Set the trimmer to about 1/3 and it is identical to the standard Pololu operation.
For the full details and schematics of this driver refer to: http://reprap.org/wiki/G3D_driver