Bipolar stepper drives

I am using a Xylotex board which I purchased from

HTH

Anthony Remove eight from email to reply.

I've got the Xylotex boards (XYZ board + A board) which will do 2.5A and

35V maximum, and can do whole/half/quarter/eighth steps. These are chopper stabilised and the current limit is easily adjustable.

Thanks, I have ordered the 3 axis board from Simplycnc, The guy there was very helpful on the phone and said NOT to exceed the 35V and allow for the back EMF from the motors. What are you using as a power supply and what voltage are you running at? I plan to use a 24V 8A transformer (actually 25.5VAC) which when rectified and filtered gives 34.1VDC. Should I add a few diodes to the output of this to drop the voltage? Should these go before or after the filter cap? I think if I put them before, the cap will help soak up the back EMF. The motors I am using are approx. 4V 2A/phase.

Indeed - the flyback from the inductance in the motors is dumped straight back into the power supply. A nice bit of power recycling which makes these boards very efficient, but the periodic spikes will limit your PSU voltage to quite a bit less than 35V to allow for the back EMF.

Currently I'm using a 13.8V/20A power supply from one of my transmitters to bench test the whole thing. This will be replaced by a pair of cheap

13.8V/3A stabilised supplies in series adjusted up slightly to give me 30V DC @ 3A.

Jeff at xylotex has put a drawing up showing a typical linear supply like the type you plan to use:

The drawing says not to exceed 30V output (this gives you enough margin to cater for flyback).

I wouldn't be keen on the diode dropper route, simply because the PSU will become even more sensitive to mains voltage variations. For sailing close to the edge, a stabilised supply @ 30V is only route I would be happy to pursue. To be honest, the stabilised supplies are only £46 brand new for the pair, and I don't want to smoke £140 worth of controller boards because of a power surge ;-)

Failing that, you might want to try a smaller transformer such as 18V or

20V which will give you enough margin for back EMF and mains voltage variations.

Re: capacitors for controlling back EMF, the ideal place to put them is fairly close to the blue power connectors on the board.

My own boards are temporarily out of service while they get put into a proper controller box, but I'll put some pictures up on the website as it comes together over the next few days.

Paul Warrender at Alzanti is a pretty busy bloke. I have bought quite a bit of kit from him over the last few years and have often had to wait for an email reply. You just have to keep chasing unfortunately. For the record all of his kit is excellent quality and very conservatively rated.

JB

In message , JB writes

I finally bought the Xylotex board from Simplycnc, very helpful on the phone, quick and easy transaction, arrived in a couple of days. Still no reply from Alzanti. I even phoned several times a day for over a week, no answer, not even an answerphone.

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