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Hi all, I previously posted a message here with regards to this problem but have been experimenting since and come up with some new results... I have designed and built a Unipolar chopper drive for an a lead Bifilar wound stepper (4Amp 0.85Ohm 1mH approx). I have had good success running smaller...

Hi all, I previously posted a message here with regards to this problem but have been experimenting since and come up with some new results... I have designed and built a Unipolar chopper drive for an a lead Bifilar wound stepper (4Amp 0.85Ohm 1mH approx). I have had good success running smaller...

Thanks Jon and Melone, Jon - I used the L298 with the L297 before I used this new drive. I kept blowing the L298 up! I now have the feeling that this is something to do with it. Melone - this delay is there on purpose and is set by the L297 so that the comparator ignores any transisents while...

Hi all, I have recently built a drive board for a stepper motor. This is a unipolar drive and simply has 4 mosfets, 4 fast recovery diodes and 4 1 ohm 3watt resistors (2 in parallel = 0.5 ohm sense resistors). All was going well until I encountered a problem using a different motor. The...

Hi all, I have recently built a drive board for a stepper motor. This is a unipolar drive and simply has 4 mosfets, 4 fast recovery diodes and 4 1 ohm 3watt resistors (2 in parallel = 0.5 ohm sense resistors). All was going well until I encountered a problem using a different motor. The...

Thanks guys, although the info you gave is useful the job has been called off. It is good to have this information anyway. Mark

Thanks for your reply Melone, I am using the mosfet to control the low side as you assumed. The mosfet is an SGS-Thompson Omnifet VNP10N07 and is a fully auto protected logic level FET. I like your idea about putting the sense resistor on the drain side but I fear that the voltage will rise...

Hi all, Thanks for a quick reply to my question, I feel I may have the answer. The circuit uses a sense resistor on the source pin of the mosfet. The voltage on the pin will rise with increasing current (2V for 4Amps) therefore is it possible that my 5V logic level input to the logic level...

Hi all, I have undertaken a project to build a 4 axis router type machine. I am attempting to build the stepper motor cicuits myself. I had already built one using the L297 + L298 chips from ST Semi but found that something was going wrong with the drive chip and it kept on blowing. I have now...

I have a job comming up that involves estimating the problems involved with moving different types of automated equipment from one country to another. I need advice on what types of things to consider when running a machine on a slightly lower voltage and higher frequency (from 240v 50Hz UK to...