Trying to make myself a simple stepper driver. - Page 1
Forum section: electronics / beginners

author: Refrigerator
author_rank: Super Contributor
timestamp: December 03, 2014, 09:30:11 pm
content: Hi.So i had a couple stepper motors laying around. I got them from a couple printers and i wanted to make a little discrete transistor stepper driver so i could hook my µcontroller to play around.I tried doing something on LTspice but couldn't get it to work ( it did do something though ).The motor i'm playing around with right now has four wires coming out of it but there is no common wire, it has a sticker on the side saying 7.5 deg/step and 7.0 ohms. I measured the wires and it seems like it does indeed have two coils with 7 ohms of resistance.I want to make a simple circuit with about 3 transistors driving each wire, i want the wire be grounded unless there is about 3-5V on the input side of the driver transistor array/thing.As i said i did try doing it on LTspice but i didn't get anything worth showing ( transistors dissipating terawatts, yeah...).I'd appreciate some if any help.

author: rob77
author_rank: Super Contributor
timestamp: December 03, 2014, 09:58:33 pm
content: 4 wires => bipolar stepperwhat you need is 2 H bridges to drive it.

author: jlmoon
author_rank: Unknown
timestamp: December 03, 2014, 10:24:27 pm
content: How about a STMicro L298 Hbridge in a chip. They work great!One of many examples on the web.http://www.pyroelectro.com/tutorials/l298_stepper/

author: Kappes Buur
author_rank: Regular Contributor
timestamp: December 04, 2014, 07:38:54 am
content: You could use something like this:http://www.dipmicro.com/store/L298N-MODThey are easily reverse-engineered, if need be.Or also:http://yourduino.com/sunshop2/index.php?l=product_detail&p=127

author: bance
author_rank: Contributor
timestamp: December 04, 2014, 09:12:44 am
content: You could also try Roman Blacks Linnistepper[ it's open source!http://www.piclist.com/techref/io/stepper/linistep/index.htm

author: Refrigerator
author_rank: Super Contributor
timestamp: December 04, 2014, 02:45:47 pm
content: Quote from: wilfred on December 04, 2014, 10:02:42 amThanks.As rob77 mentioned this is a bipolar stepper motor and it does not have a common wire. It would be much easier if it had a common wire, yet it doesn't so i'm kinda stuck with them right now.I did succeed at improving my driver thingy design ( only 10 mega watts of heat to dissipate!).I will order some of those super cheap stepper/driver board combos from eBay, those steppers have a common wire and the driver chip is nothing but a darlington array, they should be easy to set up.

author: rob77
author_rank: Super Contributor
timestamp: December 04, 2014, 07:13:39 pm
content: Quote from: Refrigerator on December 04, 2014, 02:45:47 pmthe darlington array drivers are usable only for unipolar steppers, you really need the two full H bridges for the bipolar motor (like the L298 is) or build yourself one (but it's a lot of components)

author: jlmoon
author_rank: Unknown
timestamp: December 04, 2014, 08:03:36 pm
content: the darlington array drivers are usable only for unipolar steppers, you really need the two full H bridges for the bipolar motor (like the L298 is) or build yourself one (but it's a lot of components)That's what I was thinking.. lots of parts and more parts...

author: Refrigerator
author_rank: Super Contributor
timestamp: December 04, 2014, 08:13:30 pm
content: What i'm making is a H-bridge circuit that would have the wire grounded unless it receives a signal from the µcontroller, i got it to work but i can't get it to ground the wire.

author: rob77
author_rank: Super Contributor
timestamp: December 04, 2014, 08:49:16 pm
content: Quote from: Refrigerator on December 04, 2014, 08:13:30 pmwhat you mean by wire grounded ? a H bridge is a H bridge - it's needed to change the direction of the current through the coil. actually a bipolar stepper is making the steps by changing the direction of the current in the coils (unlike the unipolar - which is simply progressively turning on and off the current in the coils - and therefore you can drive it with a set of Darlington low side switches.).

author: Richard Crowley
author_rank: Super Contributor
timestamp: December 04, 2014, 09:45:43 pm
content: Quote from: Refrigerator on December 04, 2014, 08:13:30 pmSo you have 4 wires coming out of the motor. i.e. each end of two separate windings.If you are saying that you will ground ALL FOUR motor leads until you need to connect one to power, then that is essentially the definition of a pair of H-bridges.If you think that you can hard-wire ANY of the four motor leads to ground, then you are mistaken.Because it has only four wires, you MUST be able to connect ANY of them independently to either power or ground.