[pminmo]

Konstatin,
The 600 DPI is the scale. Depending on graphics application software you have to print it true size, don't check any boxes that say fit to page or similar.

Phil

[pminmo]

Ok,
I think I figured out a true acrobat (pdf) file for toner transfer. Please double check image for size and orientation. Thanks, Phil
1 axis:
http://webpages.charter.net/pminmo/1axisttcopper.pdf
tach's 3 axis:
http://webpages.charter.net/pminmo/3axisttcopper.pdf

[tachus42]

They both look good printing with page scaling off.
I lined the 3 axis layout up with the print direct from eagle and it was spot on.
The horzontal rulers are spot on but the vertial is a bit off - 1/32 on the 3 axis board but I think this is just my printer as the print is exactly the same size as the one from eagle. Most printers aren't to acurate in this direction anyway as the paper can slip slightly and rollers change diameter with tempreture age and humidity etc.
If i zoom right in I can't see any jaggies so I assume you exported postscript from eagle and the converted it into a pdf? Done this way the scale should be spot on.

[pminmo]

Yea I bought an inexpensive product - deskpdf couple of months ago, really like it. It uses gostscript and looks like a selectable printer. Much easier than doing the process manually. You can print a pdf document straight from eagle.

Phil

[slp_prlzys]

for the chopper converter current setting resistors,
the total resistance should be equal to .82ohms if I
wanted to have 1.5A right?
Is there such a calculator likethis that do more than 2 resistors?

thanks

[pminmo]

Use a spreadsheet - 1/Rtotal = 1/R1+1/R2+1/R3+1/R4 and so on. For example 2, 5, 10, and 20 ohms in parallel = 1/2 +1/5 +1/10 +1/20 so .5+.2+.1+.05 = 1/.85 = 1.176 ohms. Remember the total parallel resistance will always be less than the smallest resistor value.

Phil

[slp_prlzys]

thanks, I knew I should have taken an electronic
course rather than desktop publishing (maybe, because it's free)

[slp_prlzys]

oh, I forgot.
the calculator I posted does the computation in reverse tho.

[tachus42]

I'll draw up a proper table of currents and combinations of resistors to use later. The resistors don't dissipate much power as there is current flowing in them for a short time in each chopper cycle. So you can use just four if it makes it easier to get the value you need. The resistor value is approx 1.1/Total Current (both phases)
Slp if you want 1.5 A per phase- 1.1/3 = 0.37 0.37*5=1.85 so use 5 1.8 Ohm resistors (1 watt).

[pminmo]

Updated the webpage and cleaned it up a bit. Added a printable sheet for Digikey and Newark part numbers. Tach, do you have a pic of your populated 3 axis board and chopper adapter?

Phil

[slp_prlzys]

thanks tachus42,
just getting ready to purchase components
'want to make sure I get all the parts,
I hate it when I want to build something and
I can't find a particular component, I got no ride
so I have to get complete parts at one time, if
my brother is in the mood to give me a lift.

pminmo: nice job on the pages I like what you did
with the part list.

[tachus42]

New zip file text file with current limit resistor values, also a small change to the board - added a spot for a optional supply cap to use if power suplly connections are long.

[pminmo]

Tach,
I's like to look at the spice displays closer. Can you zip them so they are'nt resized?

Thanks,
Phil

[mvaughn]

I hate to ask you guys, you've already done so much for everyone here.

Is there any hope of a 4-axis controller?

[pminmo]

You can use 4 of the single axis boards. The one thing about a modular approach is the ease of switching driver boards to trouble shoot a problem.

Tach, do you think you could fit a 4th axis on a single board? I guess the other possibility would be to put some hocks in the 3 axis board to piggyback a fourth axis.

Phil

[mvaughn]

I like the modular approach as well. How hard is to to build a 4-axis break out board?

The reason I ask is because I eventually would like to build a foam cutter.

[pminmo]

4 Axis compatable with the modular boards attached.

Phil

[tachus42]

4 Axises on a single board might be posible but it's probably better just to use a 3 axis plus a single or a partaily filled 3 axis board if you dont mind wasting a bit of pcb would fit right onto the "stack".
I'm toying with the idea of a simple boost converter to get more volts out of a pc power supply. There is a prelimliary design attached but I'm not sure how well it will work at high power levels. The peak currents on the 5 volt rail especially are huge. Still if it works it could be cheaper than building or buying a 200w power supply.
Comments?

[pminmo]

Interesting thought as old PC supplies are a dime a dozen.

Phil

[tachus42]

After some thought it won't work as drawn(discontinous mode), the ripple current would kill the pc power supply but if it's operated in continous mode it can be made to work. I'll need to do some simulation.