Current amplifier

[Bri4n]

Is it possible to use an amplifier between the driver board and motor? I was curious to see if I could take a board with a 2.5a output and boost it to around 4a without screwing up the signal to the motor.

[bharbour]

It is not technically impossible to do, but I think that you would have to build your own from scratch. It would be simpler, less expensive, and quicker to just buy a driver with the current capacity that you need.

If you want to build a motor driver board, there are several threads over in the Open Source Hardware forum describing home built step motor drives.

Good Luck,
BobH

[Bri4n]

Thanks, I was hoping it was as easy as adding a mosfet but should have known better.

[bharbour]

Originally Posted by Bri4n Thanks, I was hoping it was as easy as adding a mosfet but should have known better.

If the original driver had discrete transistors (compared to all on one chip), you could probably replace them with heavier transistors and make sure the heat sinking was up to the new requirements. Then you would have to change out the current sense resistor(s) to re-scale the current sense path. You might need to swap out any protection diodes for higher current capacity ones (if the drive uses them) and when you are done, it would probably be a fragile thing that is a pain to repair.

If the original driver was done with a chip like an L298 or something similar, it would be more complex, because you would have to add your own gate drivers and do a curent divider to scale how much of the phase current is seen by the current sense for the IC driver in addition to adding your own FETs and diodes.

If the point of the project was to extend the power of an existing driver, yes it could be done. If the point was to have heavy enough drivers to run your CNC machine that you want to work every time you go out to the shop to use it, it seems less desireable to me.

Good Luck,
BobH