chopper question

[dertsap]

i have a stepper world fet3 controller , in order to go higher voltages i need power resistors of which i am getting quite the collection of , because i m trying new motors different power supplies etc, i ve been looking for an alternative to power resistors , now i know that a light dimmer is a chopper circuit ,now is it at all possible to use one of those as an alternative , or is there any other simple alternative , i m crash learning electronics lately and my knowledge is still pretty limited , so for me at this point of time is simplisity
thanks

curt

[H500]

The most effective solution is to return the drive and get a chopper. Non-current sensed PWM techniques won't work.

[pminmo]

Well actually you can add an external chopper to a board. On my website is a design by tachus42 that works in conjunction with the 3 axis discrete board. You sense the high side current and switch a P channel mosfet with a comparison circuit.

[dertsap]

the board is going nowhere its bought and paid for , plus most of the boards out there can t nearly handle the amperage this board can put out , 36amp / phase , im not running small motors and in the future i will be running far bigger, it just seems to me that if they can build a chop circuit into a tiny little chip , then why can t it be built outside of it , like i said i don t know much on electronics but logic tells me there has to be a way around using resistors

thanks alot for the link i took a quick peak and there is a lot of great usefull info , ill definitely be doing some more reading , i didn t find the external chopper circuit you mentioned but i ll dig around in your site some more and find it ,thanks dude

[H500]

The fet3 board is a very simple, low performance design. It has good marketing, but it's not a serious product. It won't handle anywhere close to 36 amps without using red-hot resistors the size of stove-top elements.

If you want to add a chopper as a learning experience, then it's a good project.
But it is nearly as much work as doing a complete driver from scratch. Even if it works, you won't have microstepping, so you might end up scrapping the whole thing anyways if your system end up with resonance.