Need Help with building a Stepper Motor

[shaneaust (Mick)]

Hey all:

I am trying to build a stepper motor to control the movement of my camera, so as to do astrophotography - in this instance, I am not using my telescope, just the camera.

I have built the mount for it and have thus far been manually tracking, which is real, real tedious!

I've got heaps of PC parts here, but I need help with this - if anyone has built their own stepper motor from PC parts (ie floppy disk drive motor, or printer motor, etc) can you PM me as I could use a bit of guidance. I'm currently using the FDD motor as a starting point.

Thanks in advance!

Mick

[ballaratdragons (Ken)]

Hi Mick.

I'm not very computer savvy so I don't know if you can use computer parts to run a stepper motor, but I know how to make a set-up using the proper parts.

For a smooth tracking system you will need a 1.8 degree motor, not the more common 7.5 degree motor. The 7.5 give more of a jerky motion.

You will also need a Stepper interface module. Jaycar sell them at a reasonable price at around $50.

Jaycar also has the software for free to drive the stepper interface and motor

At this page link you can see the link to the free software (AA-0352 Software.zip) at the bottom of the ad for the interface: http://www.jaycar.com.au/productView...Max=&SUBCATID=

[middy]

Hi Mick,

I used a 6 wire stepper motor from an old dot matrix printer.

I bought this stepper motor driver circuit from Oatley Electronics:

http://secure.oatleyelectronics.com/...6e682531781194

(K142D because I have a 6 wire motor)

I then cobbled together a basic timing circuit using a 555 timer chip to provide the timing pulses for the driver circuit. I use my benchtop power supply to provide the power.

Here are some photos:

Pic 1 shows the stepper motor mounted on the tracker. It is glued to the threaded rod and the two pieces of wood on either side prevent the motor from spinning.

Pic 2 shows the circuitry. The driver circuit is in the grey box. My timer circuit is on the breadboard. The power supply is in the background.

Pic 3 shows the connector (generic 9 pin serial connector) used to connect the stepper to the driver circuit.

I plan to put the timer circuit on its own board and mount it inside the box with the driver circuit, then it is all contained in one box. I have been planning to do this for 6 months now but I haven't got around to it yet.

It works really well. My only concern is that the motor draws a lot of current. I wind the voltage down to 4 V to keep the current at about 0.8 A then the motor only gets slightly hot instead of very hot.

I think I need to add a current limiting circuit which I will also get around to one day.

[shaneaust (Mick)]

Thanks to both you guys! I may seek your help when I get further into this project, IYDM.

TIA:

Mick

[Glenhuon (Bill)]

This is a circuit I used a few years ago to drive a 4 wire stepper salvaged from a very old disk drive.
You can probably add a couple more transistors to the 5th and 6th outputs and move the reset connection to the 7th for a 6 wire motor. Hope this of some help.