Thanks, but I'm not trying to make a pitch for my drives. Any good switching type bipolar drive, ours or someone else's, will outperform these R/L drives by a very wide margin.
Sadly, it is a law of nature that there is no free lunch. Switching type drives are far more complex than L/R drives and thus cost more.
Things to look for when you see a deal that seems to be too good:
1) If there is a picture, count the power transistors. Anything that has only 4 power transistors will be a unipolar drive. Count the motor wires going to the drive, a bipolar drive needs only 4.
2) Look at the heatsink size. If you see those little clip-on heatsinks or none at all, then you know very little power is involved and little will be delivered to the motor. This applies to the dongle-looking drive. It's small and it is plastic. Where is the heat going to go?
3) High current ratings without high voltage ratings means low power. Power is voltage times current.
4) Use a figure of merit to get a rough idea of a drive's value. Multiply the rated per phase current times the rated supply voltage and divide the result by the price of the drive. Compare that against other drives' figure of merit.
5) If everything else is equal, pick a microstepping drive over a full or half step drive. The microstepper will always run much more smoothly at low speeds.
Mariss  |