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James Newton[JMN-EFP-786] Published and replied to post 39987.6168865741 by goahead
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goahead@gmx.ch asks:
Hello
Thanks a lot for this very nice project. I've built a linistep but used BD667s which have very similar characteristics as TIP122 except for a slightly lower maximum current. As diodes 1N4001s were used which i thought should be fast enough for the frequencies used here.
The stepper used is a Shinano Kenshi STH-39D213 with 200steps/5.2Ohm and is operated at 12V.
The correct wires were identified with a multimeter and the correct sequence with applying a small voltage at the 4 wires until the stepping sequence was correct.
The linistep does work so far but nowhere near optimal.At around 200 rev/min the stepper stops. I measured the current which the motor takes and it starts at about 0.3A at low speed and sinks below 60mA as the speed is increased.
The linistep is triggered by a NE555 circuit which generates impulses with near 50% duty cycle and up to 150kHz.
Does anyone see a problem with my setup? Any suggestions how to improve the performance?
I looked at the signals on pins 6 through 9 of the PIC. It was a square with 50% duty cycle on each of them. I would have thought that in 200 step mode each of the darlingtons should be switched on for 25% of the time, so the signals should have a duty cycle of 75% and not 50%. Is that correct?
Thanks a lot.
Metin
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