perspective from a n00b just starting electronics build, some Qs too

I've ordered all the electronics parts have have built half the boards, but there are some errors I made I'd like to help others avoid. Some of the below contains statements that look like criticisms, but please note, they are not. Sometimes an outside view can be helpful as we new people have no assumed knowledge.

Firstly, I ordered based on the new generation electronics, Ardino, from Mouser, while the actual ordering process is a breeze, it's can be very confusing using the parts website, as every single option is there. So make sure you're ordering the components based on the boards from the 'new generation electronics' page, under how to build a reprap.
For those that live in Oz., Mouser is far cheaper than getting components locally, including international shipping. Suppliers here in Oz. only have 1/3 of the components each, and charge like wounded bulls. One supplier wanted $140 AUD/USD (!) for 1/3 of the components when mouser delivery them all for that price. They must think that $1 AUD still buys 60 USC.

My first mistake came about as the automated BOM orders electronics based on the stepper motor control board, I then made the mistake of ordering the universal control boards from RRRF, as it presented this in a way that made them look compatible (I think there were no stepper motor control boards in stock). IE "order these universal control boards and you can build them to be SMC boards", no mention that the electrons are different.

Other mistakes, I can't really explain how I made them
- ordered 2 PWM control boards.
- Ordered a power control board, but now it seems Ardino based electronics doesn't need it.
- I still can't figure out if the Ardino breakout board is required and how to use it, perhaps further in to the build this will become more apparent.
- It wasn't clear in my head that Ardino based electronics, required me to order an Ardino board, which I found cheaply locally (such a n00b).

Another point from an outsiders view, is it hardly made clear that the universal control boards have been replaced by the stepper motor control boards (as stated in the little sentence at the bottom of the stepper motor control board page).

Which leads me to my first question. The diodes in the 'new' stepper motor electronics are much bigger and different voltages from the smaller ones that the universal control board specifies. Can I use these instead? Specifically these are Mouser PN 512-SB360 (3A/60V Schottky rectifiers). Otherwise I'll have to order the other diodes '1N4005', which are used in the PWM controller board.

It's very hard to find the universal control board description page on the main website, I now think this is because they are not the current board. There also seems to be an error/difference either in the BOM page (parts page) and the how to build page, specifically the capacitor values are different.

Hope this is useful to someone, it'd be great if someone could help out with question about the electronics, namely, if I can just use the SMC board electronics in the universal control board.

EDIT, well now I see, the stupid universal controller board is for PIC BASED CONTROL ONLY. ARGHHHH. So do I have to order the SMC board, or can I use UC board somehow? What controls the extruder in the Ardino based electronics if not 2 UC boards?

Edited 2 time(s). Last edit at 05/05/2009 01:57AM by Jitsukablue.

Quote

ordered 2 PWM control boards.

I ordered a compleet pcb kit, so I know I have the right amount of each board. That would have been the easiest thing for you to do!

It also meant that there was no danger of me getting or using obsolete bits.

Quote

Ordered a power control board

I'm too lazy to look, but is this the same as a 'power comms' board? One of those was used in the dual-arduino setup (currently removed from the wiki, but visible in the history) and it seems highly likely that we'll move on to a dual arduino in the near future. SO it won't have been a wasted purchase.

Quote

What controls the extruder in the Ardino based electronics if not 2 UC boards?

A PWM board (for the heater and fan) and a DC motor board (for the extruder motor and a solenoid if you use one) drive the extruder. They are in turn driven by an arduino, which is attached to a PC running some suitable host software to drive the arduino.

Make sure you read [dev.www.reprap.org] as this tells you everything you need to know. [dev.www.reprap.org] this diagram shows you what is attached to what.

Quote

So do I have to order the SMC board, or can I use UC board somehow?

If you want to mix and match generations, you'll have to write the firmware yourself. I'm sure you can find a use of the UC board somewhere... there's nothing wrong with having useful toys lying about the place

Looking at the store and the wiki the information is there, but if you didn't find it I'm sure others will have the same problems.

I think part of the problem lies in that the page linked to, from the rrrf store, while giving a lot of information about the item doesn't actually say which generation it is for or if it is optional.

This information is available though on the wiki via 'Make your own Darwin' on the front page followed by 'skip straight to Generation 2 Electronics' in the electronics section:
[dev.www.reprap.org]

My thoughts for improvements are:

1. Adding to the component pages a header section on their use, e.g. '3 Used in Generation 1 electronics' along with a back link to the Generation 1/2 overview page would ensure it was clear which parts were used for what.

2. Add a couple of links in the information section of the store for 'What do I need for the generation X electronics' linking to
[dev.www.reprap.org] or
[dev.www.reprap.org]

3. Introduce sub-categories, to the PCBs and Kits sections, for Generation 1, 2, optional/experimental.


I always feel a bit odd posting tasks for others so, just to be clear, they are only suggestions; no-one dies if none of them are done.

1. I feel should be done and there are quite a few people who have write access to the wiki and so could do it.

2&3 involve changes to the store which I believe only Zach would be able to make at the moment. Zach already does a lot for reprap on top of running the store so I'm reluctant to add to his work list. At the same time I think it's best to list what could be done and let him decide what to do rather than try and guess myself.

Jitsukablue Wrote:
> Which leads me to my first question. The diodes
> in the 'new' stepper motor electronics are much
> bigger and different voltages from the smaller
> ones that the universal control board specifies.
> Can I use these instead? Specifically these are
> Mouser PN 512-SB360 (3A/60V Schottky rectifiers).
> Otherwise I'll have to order the other diodes
> '1N4005', which are used in the PWM controller
> board.

Sadly neither are quite right.

1N4005's are only rated for 1A and I think the audrio steppers draw more than that.

The SB360 doesn't have any recovery time information that I can find. The recovery time should be less than 200ns. The junction capacitance is listed so someone may be able to calculate the recovery time, but I can't ;-}> Not listing the recovery time means it is probably too high though.

Apparently Schottky diodes don't have a recovery time: [en.wikipedia.org] so that will be why it is not stated. I don't think you can calculate recovery time from junction capacitance for non Schottky diodes, they are separate effects.

---

[www.hydraraptor.blogspot.com]

I didn't think of it not being listed because it was too low ;-}>
Sorry for nearly leading you astray, thanks Nophead.

It looks like the Junction Capacitance determines the switching time, which I had confused recovery time. Given that wikipeadia page estimates the switching time at 100 ps to 10 ns depending on the diodes power handling it seems calculating how much faster than 200 ns it is would be a bit pointless.

Thank you for all your input, hopefully this info will be useful for someone. I'm going to order some motors and some more boards, and get on with generation 2 electronics.