Saturday, September 02, 2006

 

XY Axes Controller Board Schematic...

I've got KiCad going and have just finished a draft schematic of the board layout.

Have a look. Any comments and criticisms will be very welcome.

Comments:
You only have X/Y limit detectors in one direction?

I was thinking I'd need two; how do you determine both the minimum and the maximum? Software?

I was thinking of putting in two limits per axis, and having the software automatically calculate the working space (I.E, the same board would work for a 10cm axis, and for a 50cm axis.)
 
I was thinking I'd need two; how do you determine both the minimum and the maximum?

That was the traditional way of thinking about it. Indeed, if you put them on fixed places on the axis and then wait for the bit that moves to come to those sensors you will need two.

If, on the other hand, you put the sensor on the bit that moves and have it look for scribed marks on the axis you only need one.
 
Ah, I get it. I was planning on only having one line into the processor for the limits (I.E, the 'traditional' approach would be tied into an OR configuration for the input line.) So, it would be equivilant to this. I was planning on using a metalic contact sensor, rather than an optical solution; with this kind of configuration, it seems that two limit detectors would be easier, since the axis can 'crash' into the contact rather than having to slide past it.
 
I was planning on using a metalic contact sensor, rather than an optical solution...

I suspect that if you compare prices you'll find that the Hamamatsu limits detector is actually cheaper than a microswitch.
 
Oh, I wasn't thinking of a microswitch. I was thinking much more low tech than that.

Rubber bands and copper wires was more towards what I was leaning towards. Easy to make, easy to put together, and should work most of the time. :)
 
BTW, I should have mentioned this before.. the schematics look pretty good. You might consider adding some diodes to the motors, though, you might want to wait and see how I solved this - I'm just finishing up my schematics that I'm working towards on the Z8. I'll post them when I've finished.
 
You might consider adding some diodes to the motors.

I used Schottky diodes with the Frankenmotor board. I may use them on this one eventually, too, though it seems like a bit of overkill for such small motors.

I'll post them when I've finished.

I'm looking forward to that. :-)
 
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