Blank PCB's available

[pminmo]

After numerious requests, I have procured a number of blank PCB's for a version of the single sided Allegro 3977SED board. It is very similar to the single sided SS3977 board on my website, but smaller to take advantage of a commercial manufacturer's capability (and to reduce your cost). These come from an ISO Certified PCB house and look really nice. I also did a version of the 4 axis interface board for those who want a cleaner wiring method. The difference from the 4 axis on my website, is the estop circuit has been removed and a second driver added, 5V regulator removed and a jumper setup to get it from an X axis driver, plus a simple method to jumper enables for one enable control. I've attached pictures. The boards are FR4, solder masked and silk screened. The 3977 boards will be $8 each, and the interface board $10 each. If you want to compare the total cost, a 3 axis system with the interface board and ALL the parts is around $85 depending on where you procure the parts. Than includes $6 each for the 3977SED's, four PCBs (3 drivers, 1 interface), 3 IDC cables, and discrete components. For those of you who don't know, this is the same stepper driver on the brand X board that goes for $145 assembled. To get a visual of the configuration take a look at the system electronics overview on my website: http://pminmo.com/ More information to come at http://pminmo.com/forsale/blankpcbs.htm

[ShayArnett]

So do you have the boards in hand now? and whats the final pricing? Also at the $85 price for building, where did you source your parts. I would like to make a single order with digi-key if the costs aren't dramatically different.

Will be depositing some money in my paypal account in the next couple weeks (I assume thats your method of payment )

[pminmo]

3977 boards are $8, 4 Axis is $10 $shipped US. Boards are in hand and going quickly. I buy most of my parts from www.mouser.com and www.futurlec.com. Some from Digikey. More info at:
http://pminmo.com/forsale/blankpcbs.htm

[robaz]

Could anyone help me work out what resistors I will need for the following motors using a PC 12v @ 8A PSU,
all of the motor are unipolar (6 wire)
Motor 1, 4volt 4.1ohm per phase ( there is no current rating on the label)
Motor 2, 4volt 7.6ohm per phase (" ")
Motor 3, 3volt 9.2ohm per phase (" ")
also if I upgrade to a 24v PSU would I double or half the resistance?
I have got my unit working but the motors get very hot quickly, so I cannot run it for long for testing don't want to burn the motors out, my driver boards can run at 35v @ 6A .
Your help with this matter would be fantastic.
Regards
Barry (robaz)

[pminmo]

Barry,
Two electronic rules. Ohm's Law I=E/R or R=E/I, and Kirchoff's law of sum of voltage's in a loop = 0. How to apply here to your question: With a 12V Power supply that means that the voltage developed across a resistor and the voltage across the coil will = 12V. On motor 1, the coil voltage for 4V means the voltage across the resistor will need to be 12V-4V = 8V. The coil current for the coil at 4V @ 4.1 Ohm = .975A (I=E/R) so the resistor will be (R=E/I) 8v/.975A = 8.2A The resistor power is E*I or 8*.975 = 7.8 Watts or greater (typical would be 10W). This is assuming you will be using two resistors, one in each center tap.

[ynneb]

Phil, I would love to have a bash at making up your board design. Though I dont have an immediate need, it will be fun to see how well your design works. I will even post a step by step diary of what I do.
Since I would consider myself as a 2 out of 10 in the electronics skills, I am hoping that I will be able to announce that if I can do it, then almost anyone elase can do it.

What paypal name do I use in order to pay you?

[ShayArnett]

Originally Posted by pminmo It is very similar to the single sided SS3977 board on my website, but smaller to take advantage of a commercial manufacturer's capability (and to reduce your cost).

Does this mean that the parts list for the SS3977 on your site is the same? I assumed it did, and that you only changed the layout to take advantage of paneling at the manufacturer. I'll shoot you an e-mail when I get the money in paypal, if you can hold on to a full 3 axis setup for a week or so for me.

[pminmo]

Hi Benny,
attached is the paypal address (Maybe this will help prevent the spam).

Shay,
The website http://pminmo.com/forsale/blankpcbs.htm has the board instructions which includes a parts list. It's basically the same but was able condense it, which allowed some smaller parts. I've set a full 3 axis aside for you. Phil

[ShayArnett]

I know these questions may sound stupid to you guys, but I want to make sure I don't screw up on the parts and end up frying my freebie 3977's

On the parts lists, alot of the stuff doesn't really give that specific of a name for what the item is, I know enough to tell that something is a cap or a resistor, etc but there are so many variations of each little thing that i want to make sure i get the right type, values aren't a problem those are labeled beautifully. Just wanting to make sure i get the right things.

all of the 50v 2.5mm caps on both parts lists, can those be monolithic ceramic caps?
do resistors really matter 1/8w vs 1/4w?

i think thats all i will bother you guys with for now

[edit]
ok so i lied....

is it ok to substitue a 51.1k metal film resistor in place of the 51k carbon film? all futurlec has is 56k carbon films

[edit again]

i should have waited till i got through with the parts list before i posted LOL

on the schematic and pictures for the driver it looks like there are 2 pots R10 and R16 with the same numbering in the pic. but the parts list only shows one R16. is R10 correct on the parts list and supposed to be a regular 4.7k resistor or is it supposed to be a 10k pot like R16?


[edit yet again]

looks like the only thing left on the parts list i'm not sure on if the things i have mentioned above seem ok is the 2w .2ohm smd resistors that futurlec doesn't have... i really don't wanna pay $5 shipping from mouser for em LOL
is there anything that futurlec does have that i could use?

[pminmo]

Shay I have extra of the smd resistors, remind me and you can get them from me with the boards. I think I payed .60 each.

Phil

[ShayArnett]

ok great... i'm double checking my list for futurlec right now

do the drivers need 2 of the 10k pots? the pictures and schematics both show them but the parts list shows 1

[pminmo]

Depends on wether you want to be able to adjust pfd. The board has provisions to satisfy pfd as a fixed value via two fixed 4.7K resistors, or vary pfd with a 10K trim pot. http://www.allegromicro.com/datafile/3977.pdf is the datasheet that explains pfd. Easiest and cheapest is to use the two 4.7K resistors.