MakerBot PCB adaption and electronics parts

I'm just about done with the mechanical construction of my Mendel and now I'm working on the electronics. I have pre assembled boards from MakerBot and I'm trying to figure out what I need to adapt them to the RepRap style using the instructions on the wiki here [reprap.org]

My problem is finding all the right components. I can't find a list anywhere and all the parts in the assembly data sheet seem to be for the MakerBot setup. It also doesn't list the parts for the USB board and power adapter. Since I'm an electronics newbie, some of these things aren't really obvious to me. I spent some time trying to grok everything and come up with a list for Mouser. Here's what I have so far, I'd really appreciate it if someone could look this over and let me know if it's correct and I'll add it to the wiki:

[spreadsheets.google.com]

Also, I'm kind of confused why the design uses the XLR connector for power? Since you can get a 12V 5A power supply brick pretty cheaply like this one [www.amazon.com] why not use a normal power brick type connector?

---

--
Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects

There's lots of ways to do it - those mods are setup to get rid of the ATX power supply. I can get ATX power supplies for $10 used, so I just bolted one on to the side of my Mendel. I put the upper circuit board on the same side as the stepper circuit boards so all the power connections would reach.

Here's a photo:
[gallery.me.com]

I think the XLR connector was just what Adrian had handy. Anything will do, really, as long as it can handle the current. Not sure that 5A supply will do it though - my Mendel is capable of about 2 A per stepper, and I've got 4 steppers, plus the heater coil, which is another 2 A. I usually run the steppers around 1 A each, but even that would be 6 A at 12 V, neglecting efficiency losses.

Wade

My original plan was to just use an ATX power supply, but I really like how neat everything is without it. Do people typically just use ATX power supplies?

That is interesting, I see it mentioned twice on the wiki that Mendel requires 12V 5A. Theres another discussion about this confusion here: [forums.reprap.org] and they decided 60W should be sufficient. Also the highest cheap power brick type supply I can find is this 12V 6A: [www.amazon.com] For some reason all the power bricks on Mouser cost a fortune and I was kind of hoping to get everything at one place.

It would be nice if I could just plug the power brick in and not have to splice in the XLR connector. I can't figure out what I'd need, I think it's called a coaxial power connector? I can't find anything on Mouser.

---

--
Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects

I think this would be the kind of jack I'd want instead of an XLR socket? [mouser.com]

---

--
Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects

The power adapter you linked to says it is a "72-Watt 12V 6A AC Power Adapter".

It is unclear whether the "AC" in that description refers to its input, or its output! If it really does output 12V 6A AC, then it is not what you need for as Reprap, which needs 12V DC. However, trying to read the image of its label, there does seem to be an indication that the output is center positive... which means the output *is* DC. So it may be the right thing after all.

Since the Amazon page doesn't seem to specify the low voltage output connector at all, it is hard to know whether the jack you linked to would be the right size. It *might* need the smaller part 502-722A instead, for example. How did you decide on the 502-712A part -- by eye from the picture?

It might be wise to confirm with the supplier (a) that its output is 12V DC, and (b) what size the output connector is, before ordering it. (Or maybe I'm just paranoid??)

Jonathan

I assume it's DC lol, never really thought of that. It's hard to find specs since it's so generic. I did email the company selling it, Computer Geeks to ask about the connector size, but never got a response. See: [www.geeks.com]

I decided to just order the socket and try to get it working with one of the 12V 5A adapters I have laying around since I know what size they are and I couldn't find a socket rated for 6A either. I'll be trying it all out later this week.

---

--
Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects

I think I've organized everything I need and I'm almost done with the modifications, however I can't seem to find anywhere to buy ribbon cable! You need about 10' of ribbon cable according the plans at [reprap.org] This would be the best you can do at Mouser: [www.mouser.com] However, mouser is sold out and doesn't expect a shipment until July 2nd and every US supplier also seems to be sold out. (at least sold out of long lengths which would be needed to wire a Mendel cleanly) Does anyone know of another place I might be able to get long lengths of ribbon cable?

---

--
Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects

A quick check at Digikey found http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=MB10R-100-ND in stock. Do check that it is really what you want -- it is relatively expensive, and is clearly far more of it than you want, but it does at least seem to be in stock Even if their cost/meter is higher, a local Radio Shack or similar might be considerably cheaper, if they have such cable available at all, since you only want 10 feet, not 100 feet!

---

---

Jonathan

I forgot to post an update, I found this 10' long offer for $2.33 on DigiKey, is that a good price? [search.digikey.com] It says 0 in stock, but it turns out that Value Added Item means I guess they cut it on demand. So I ordered it this afternoon and it shipped today. I know you only need about 10' but all Mouser sold was either 1' or 100' and nothing in between.

---

--
Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects

gr0k: Great catch on the "Value Added Item" strangeness; it means all the sane ways to get that cable do not appear if you check "In stock"... which, of course, I did almost by instinct!

Yes, that looks like exactly the right thing to me, at a decent price.

---

---

Jonathan

Quick update, the Coax power connector from [mouser.com] I think will make for a good alternative to using an XLR connector. I also created this OpenSCAD script to generate an XLR or Coax style power bracket model: [www.thingiverse.com]

---

--
Tony Buser http://tonybuser.com * http://reprap.org/wiki/User:Tbuser#Projects