Hypothetical 1 axis 3977 board

[pminmo]

Part of my goal with my open source work is 3977 boards that the complete DIY'er can do. I believe we have accomplished that with the single sided version of the board. The other part of that is a professionally manufactured board that the hobbiest can build, repair, and is low enough in cost, it makes sense for the hobbiest. My original DS board, while I have made a bunch of, didn't really meet my goals for cost and repairability. BUT, I'm close to sending a design off for proto manufacture that I believe meets my objectives. This is my debate question, and what has me held up.

As is, it is not opto isolated. It is isolated to a PC's active pins by 10K ohms of resistance. If there is a failure of the 3977, 10K through the 74HC14 should be a failsafe protection for the PC. The ultimate protection though is opto isolation. But opto isolation has it's downsides as well. Extra power supply, not compatable with all parallel ports....., increased component cost.

Ultimately I hope to have a blank DS, solder masked, silk screen pcb that I could offer for sale to those who want the 3977, want to build their own electronics, but don't want to fool with etching or milling their own. My intent is not to profit, but not to loose money either. The cost goal for the blank pcb is $7 +/-.

This board would use the 3977SED (larger) part.

So which should I do, non opto or opto? Or not do it at all?

Phil

[MrBean]

I say do it, but non opto. People can use a breakout board that has opto if they require more protection.

That's my view.

Regards Terry.....

[TinkerDJ]

Yeah i agree with bean, if they want an opto isolated system they can use an isolated break out board.

Do it for sure, and i agree with what your saying Phil, you've put alot of time and effort into these boards, you deserve some compensation. All the commercially produced boards are priced way to far out of alot of peoples reach and thats what drives us to the diy stuff. Since if you are going to have boards made that is coming out of your pocket. Priced accordingly a diy board like these would be greatly appreciated.

[pminmo]

Much of my compensation is the personal satisfaction of helping. I did receive the otherday a "care package" from another zone member, IC's, motors, couplers... Completely blew me away!!! I must say, I never thought about it, but now realize it was a huge gift in several methods. Two new motor types that will allow me to test the boards with, some 3977's that will allow me to further test limits. His "care package" will ultimately help other zone members as it helps me continue my "Open source" work. Another zone member made me some prototypes of a nother board in development, again a huge help. Too both members - Thank you, Thank you, Thank you. If there are others out there that have some left over 3977SED samples, or stepper motor, or stuff you would like to donate to the cause, PM or email me.

Again thanks for all your support.

Phil

[tekno]

I feel that your idea is sound. I had help with my board that most dont have and as such I would bet that there would be more DYI'er if the hard part (board) was avalible. All the other parts can be ordered easily. As for the chip would you set it up so that the DYI'er could use a socket or just solder to the board?


Tek

[pminmo]

It's actually easier to solder the chip than solder the socket! The difference in the new board primarily is it uses the bottom side for the 3977 and just a few other components. Much easier access if the 3977 fails, it can be replaced without having to desolder half the board.

Phil

[pminmo]

Next question, how imprtant to the DIY'er is silk screened for component placement. It adds roughly $1.50 a board. Same for solder mask. Although on the 3977 board you really need the solder mask, but an single sided interface board wouldn't.

Phil

[tekno]

Originally Posted by pminmo Next question, how imprtant to the DIY'er is silk screened for component placement. It adds roughly $1.50 a board. Same for solder mask. Although on the 3977 board you really need the solder mask, but an single sided interface board wouldn't. Phil

I would be willing to pay the extra as it would make it easier to put together.

[TinkerDJ]

I think the savings on the board will be more helpful then the silk screen for component placement would be. If you include a good overlay in the documentation then i can't see it being a very big issue.

The option currently is to build the board from scratch and thats what i think discurages alot of people from trying to build the driver boards, or even starting a router project in the first place.

Having the option to buy the boards as cheaply as possible, and then get the parts will see more people getting into building cnc routers.

[miljnor]

I would say whats the overall Nut(price) on just the pcb when done with all the bells and whistles (ie silskring and solder mask)?

The option currently is to build the board from scratch and thats what i think discurages alot of people from trying to build the driver boards, or even starting a router project in the first place. TinkerDJ

while I believe this to be very true. I think just having them available at all (no matter the price, as long as your resonable) will bring more people into it. I doubt if the high side price is all that much different than the lowside.

But I don't think the price is as relevent to the buyer, (do to the probably low cost), as much as it is to the seller (because Paul has to buy all the boards with his own money) so realy its up to you paul wether you think you'll be able to sell them at the higher or lower price...right?

I have never allowed a 1.50 to be the deciding factor in a purchase, even when I was poor! Allthough a $1.65 thats going to far!

[pminmo]

It really depends on how much of a risk taker I am. $9 or $10 for a single axis 3977SED board. Double sided, solder mask. $6 or $7 for a ultra simple 4 axis interface board. Single sided no mask or silk screen.
Probably could do 3 single axis driver boards and a simple 4 axis interface board as a package for $33 to $35. If I am in a risk taking mood and order a bunch, price could go to less than $30 for the 4 boards.

Component costs for the interface board would cost a person roughly $5 depending on source. Component cost per driver board would run around $17/board including the 3977. So total cost for a 3 single axis boards and an interface would run around $90. USD For those that had access to 3977SED's aproximately $72.

Or hardwire the DB25 to the 3 single axis boards and skip the interface board. $1 for a DB25 and a dozen or so wires.

A 3 axis assembled and tested Xylotex is $152 shipped.

Phil

[miljnor]

whats the difference between the zylotex and the 3977 boards. Because sometimes its not neccessarily the price of the parts that stear someone one way or the other.

I personaly have alot of parts/components or boards that I could rob of parts. so the pcb and the actual chip are way more important than the ancillary parts are. I don't know about everyone else, but these are usually the factors I look at. And I bet more people are the same.