Stepper motor driver PCB's, anyone interested?

[bojan]

Recently, I designed 3 types of PCB's....
Two of them are Stepper motor driver interfaces, to be used with Mel Bartel's software (or equivalent). One can handle 3A, 12-24V, the second one 200mA, 6~12V (for smaller steppers). Both have field rotator driver implemented, the 3A model has keep-alive timer with relay (not to overheat the motors when software is not active, which cam happen in certain configuration).
The third PCB can be used for any type of small equatorial mount (even barn door), as it is designed to drive one stepper for tracking, and another stepper is for declination axis manual movement (with command handpad). The processor used for this one is Motorola 705KJ, I have couple of OTP's and I would be prepared to tailor the firmware for the specific mount (the rotational speed can be different for each mount design) and to program them. Power handling for this third board is also 200mA, 6-12V.
Since the setup cost for one prototype is quite high (~400AU$ for A4 size panel), I was wandering if anyone might be interested in something like this, so we can share the cost. Or, perhaps somebody on the forum can manufacture the PCB's from Protel files? Personally, I am interested only in PCB's...
I am willing to share all the technical details (schematics, dimensions, parts lists etc) if there is a wider interest for something like this on the forum.
I am also open to suggestions and change the design, if the new proposal is acceptable.
Cheers,
Bojan

[radu5er]

Sounds like something I might be interested in if there is enough interest to bring the cost down a bit. Maybe available for breadboarding in smaller quantities?

Keep me in mind if things progress.

[bojan]

Originally Posted by radu5er

Sounds like something I might be interested in if there is enough interest to bring the cost down a bit. Maybe available for breadboarding in smaller quantities?

Keep me in mind if things progress.

Hi Rick,
If I solve the manufacturing cost problem, the PCB's (and documentation) will be available. I already made the breadboard prototypes, they work, but I wanted those boards to look better, hence this post..
I will certainly let you know if there is any progress..

[Omaroo (Chris Malikoff)]

Very interesting Bojan - I'm looking at a Mel Bartels system for my to-be-re-engineered EQ5. I was just about to start constructing the PCB for the following stepper controller: http://www.bbastrodesigns.com/steppercircuit.html

What's this plan of yours in monetary terms?

Cheers
Chris

[bojan]

Originally Posted by Omaroo

Very interesting Bojan - I'm looking at a Mel Bartels system for my to-be-re-engineered EQ5. I was just about to start constructing the PCB for the following stepper controller: http://www.bbastrodesigns.com/steppercircuit.html

What's this plan of yours in monetary terms?

Cheers
Chris

Hi Chris,
one of the boards I designed (in Protel) is based on the very schematic you are looking at, I only added the stepper driver for field rotator driver and keep alive circuit (with relay). Also, the connectors for motors are different (2x3 headers, the motors can be reversed by reversing the connection), and the size is euro-card (100x160mm). The smaller board is ~60x70mm, it is designed to be directly plugged into LPT port (with separate power supply, of course)
In monetary terms.... I am pretty sure that there is no significant enough production volume & money in it (considering the size of that market and the fact that the design is pretty mature) so at this stage, I would just like to offset somehow the cost of manufacturing for my own set of PCB's.
I think I can fit 3~4 of each boards on the A4 panel.
At later stage, we shall see..

[Omaroo (Chris Malikoff)]

Originally Posted by bojan

In monetary terms.... I am pretty sure that there is no significant enough production volume & money in it (considering the size of that market and the fact that the design is pretty mature) so at this stage, I would just like to offset somehow the cost of manufacturing for my own set of PCB's.

By what I asked, this is what I meant. Not interested in manufacturing - just making it worthwhile for us to construct our own rather than buying ready-made from the USA.

I'm certainly happy to share the cost if you could suggest a base line.

Cheers
Chris

[bojan]

This will depend on how many people are interested...
There is always a setup cost for the first panel, and it is higher (it includes phototools, silk screen et cetera plus material and workmanship), for any subsequent panel there is only material and work, which are significantly lower. I will be trying to find out the exact pricing and will let you know when I know more...

[Omaroo (Chris Malikoff)]

I've been using the photocopy iron-on transfer / acid bath method here for some time, and it's relatively cheap. Is the silkscreen method that much better to justify the additional cost?

Cheers
Chris

[bojan]

I was using all sorts of methods in the past, the best one (homebrew) was pen plotter on tracing paper or plastic foil and the photopositive resist spray on copper cladded fiberglass boards (or boards with photoresist), but the photopositive resist spray is not available any more - in Dick Smith the staff even does not know what it is, and it was pretty expensive when available).
But, that was in DOS days...
Today, Protel pen-plotter drivers (read: microsoft windows) are terrible (they produce unuseable plots), and on the other hand laser printers sometimes have problem with the paper transport (rubber wheels... so the longitudinal length of the printout is not well controlled and this creates difficulties in case of two-layer boards....
Proper PCB manufacturing process that I would like to use here produces professional results (printing, plated though holes, solder resist).
But, if you want to use the heat-transfer technology or anything else, I am willing to share my design, by all means. PM me the email address...

[Omaroo (Chris Malikoff)]

Originally Posted by bojan

laser printers sometimes have problem with the paper transport (rubber wheels... so the longitudinal length of the printout is not well controlled and this creates difficulties in case of two-layer boards....

Agreed - my printer does this reasonably well - but it is a $50K proofing device.

Originally Posted by bojan

Proper PCB manufacturing process that I would like to use here produces professional results (printing, plated though holes, solder resist).

No - I think that the plated-through holes have sold me. I'm with you on using your preferred method.

Cheers
Chris

[netwolf]

I am also interested in getting one of these.