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woozle

I think I've done my homework...

38 posts in this topic

...but assuming has gotten me into trouble plenty of times in the past. Just wanted to confirm some thoughts and ask some questions.

I believe I'm going to build a Midibox64E. I started out thinking I'd build a Midibox64 but I've come to realize that I want some rotary encoders with momentary switches. It seems harder to dig up info on the design of a 64E. Please confirm that I have my facts straight.

1)The hardware implementation of a 64E in terms of modules, with the exception of the number of DIN and DOUT modules, is identical to a standard 64. \

2)One can have a total of 128 buttons or 64 encoders, or a mix of the two (ie 64 buttons and 32 encoders).

3)128 DOUTs, ie 128 LEDs are possible.

4)Banksticks and extra modules can be added at a later time up to the limits of the given project.

And a few questions:

5)Could someone point me towards some info on how to wire up a combination of buttons and encoders to DIN modules?

6)The controller I plan on building will be used for gigging. I need ruggedness. I'm thinking for starters that it would be wise to panel mount power and MIDI I/O jacks as opposed to mounting on the PCB. Any other tips on keeping a unit road ready?

7)This doesn't have anything to do with the MBHP necessarily and it's putting the cart slightly before the horse, but I'm looking for 20mm travel detented slider potentiometers. Has anyone run across these? I can find them without detents, but that wont do...

I'm sure I will have lots more questions along the way. Thanks to everyone in advance.

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Welcome aboard! :)

...but assuming has gotten me into trouble plenty of times in the past.

Wise!!

1) Well, the AINs are also (optionally) missing... Really the only thing they have in common is the core module and LCD... the rest is as-per your design.

2) correct

3) correct

4) correct

5) schematics on ucapps.de

6) what's your budget? I'd say use all milspec components, but you can prepare for an instant 10* pricetag if you do that.

7) not that I know of.... tried alps' and bourne's catalogues? How about google, first hit looks good:

http://www.google.com.au/search?hl=en&as_q=20mm+detent+slide+pot

SL20V2. 20mm Standard Type Single Unit Center Detent available

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I guess what I meant to ask was if there is a problem mixing on the same board (ie switches on j5 and encoders on j4), or on the same pins (ie switches and encoders on j5)

6) what's your budget? I'd say use all milspec components, but you can prepare for an instant 10* pricetag if you do that.

Probably want to cap things at around $400-500. Hopefully less.

7) not that I know of.... tried alps' and bourne's catalogues? How about google, first hit looks good:

http://www.google.com.au/search?hl=en&as_q=20mm+detent+slide+pot

I did google, but you got some different results than I did. Seems like any hits I'm getting are on big Asian distributors which I'm assuming have big minimum orders. Once again, instead of assuming I should just check. I was hoping to find someone who stocked them in single units. I had already perused the Bourne catalogue but the only thing I found fitting the description were pots with plastic posts and an LED. Doesn't seem to spell durability. I'll just keep looking.

Big thanks for the answers!

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I guess what I meant to ask was if there is a problem mixing on the same board (ie switches on j5 and encoders on j4), or on the same pins (ie switches and encoders on j5)

Nope :) Just keep the encoders first connection on even numbered pins and you're set (ie, pin 0+1 is good, pin 1+2 is bad). It's probably best practice to put all your encoders first, then your switches...

As for the other stuff, it's really up to you...

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Thanks!

First round of parts, tools, and samples ordered. How quickly the portion of the budget already expended gets into the triple digits!

Rather intimidating to think of the whole scope of what I'm taking on, much easier to think of it piecewise.

Will document my endeavors...

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it's all just small pieces.  understand each one and the whole thing becomes pretty clear.

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Nearly finished with a DIN, an AIN and a core. Everything went quite well until the last few joints. I managed to solder the DIL header on J5 lopsided all the way across before I noticed that I hadn't gotten it flush. First time I made this mistake as I was careful not to let it happen up until nearly the end! Tried my hardest to desolder it in one piece but to no avail. Destroyed the header and pulled the pins out one at a time, then finished desoldering. I initially thought the board had escaped unscathed, but upon closer examination it looks like i tore about half a pad off of the front of the pcb. I'm hoping that with good solder penetration on the new header this won't be a big deal, but I'm not sure. Please advise.

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check the pcb layout at ucapps to see where that pad connects to, and make sure there is continuity (ohm meter or continuity tester) from the bad pad to each other location it connects to.  follow the traces out to see where they go.  if you have a bad connection, solder in a small wire to the solder joints on the back.

i hope what i'm trying to say is clear.  ripping up a pad usually isn't game over.

for soldering headers, here's what i do:

put a small amount of solder on one of the pads.  line up the header to the holes and flip it over.  heat the solder and gently slide the header in.  make sure it's flush and let the solder solidify.  then you can solder the rest of them, and re-solder the first one once at least one other connection is in place.

and if you don't get them flush, but the solder joints are good and you can still get a cable attached, leave it.  although you just learned this one the hard way.  if you must desolder a header, take off the plastic piece first and desolder one pin at a time.

good luck.  don't worry about the pad, you can still midibox :)

ultra

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Will check the layout and see if my connection is good. Thanks for the info. It tempers my frustration towards myself somewhat.

What a dumb mistake. Prior to the one I botched I tacked each header down in a manner that achieved the same result as what you described. I think I just spent too much time working on it without a break. There's a tip for the newbies out there - take a breather once in awhile for sanity's sake!

Another thing that adds to the frustration is that I knew that I probably could have left it the way it was but the OCD in me demanded that I fix it properly. Oh well. I'll patch it up and move on.

Despite this little setback the progress I've made so far has been far less difficult and far quicker than I had expected. My solder joints were pretty decent from the beginning and only got better as I moved from the AIN to the DIN to the core. I think that is in large part due to the excellent construction of the PCBs coming from SmashTV's shop. If you exercise a little bit of patience and common sense, it's easy to make good looking joints and end up with a nice finished product.

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Good contact where I pulled the pad off. Whew, what a relief. I've got to reorder some pin headers, but I need more AIN and DIN modules anyway, so no big deal.

Another question. How do I wire up panel mount midi jacks? Not an easy thing to search for around here as "midi" turns up in every post.

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How do I wire up panel mount midi jacks? Not an easy thing to search for around here as "midi" turns up in every post.

True! The trick there, is to remember that the schematic pdfs are all on ucapps.de :)

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Good contact where I pulled the pad off. Whew, what a relief. I've got to reorder some pin headers, but I need more AIN and DIN modules anyway, so no big deal.

Don't beat yourself up not soldering that header flush - it happens to everybody.  It doesn't take long to get good at soldering, but it can take a long time to get good at desoldering.  Many projects I have created have little wires running all over the boards, as I've made modifications, changed my mind about things, or pulled off a pad when I tried to remove something.  You can almost always fix it - it just might not always be pretty.

Another question. How do I wire up panel mount midi jacks? Not an easy thing to search for around here as "midi" turns up in every post.

  Mount the jacks first.  Then you'll want to use stranded, insulated wire.  I like tinned copper, which shows a silvery colour once you strip off the insulation, but plain copper works as well.  You'll want anywhere from around 28 gauge to 22 gauge.  Strip about a centimetre off the wire, then push the stripped part through the eyelet of the terminal on the back of the jack. Then just wrap the rest of the bare wire around the terminal. Squeeze it a bit with needlenose pliers or tweezers if the wrap isn't nice and tight.

You'll want your iron to be hotter than you would normally use for circuit board work.  If you don't have a temperature control, allow the iron to get really hot by sitting by itself without much air movement around it for a minute or two.  Hold the tip of your soldering iron on of the flat sides of the terminal for a moment - remember that the mission is to quickly transfer heat from your iron to the terminal, so if your soldering tip has a flat edge, or is a "screwdriver" style tip, you want to use the flat part of your iron against the flattest part of the terminal.

Then apply your solder to the other side.  If it's hot enough, solder should immediately flow over the terminal.  Quickly remove your iron so that you don't melt any plastic parts of the jack. Let it get nice and hot again before working on the next terminal (if you don't have a high-powered iron, you just wicked away a lot of its heat with the relatively thick terminal, your wire, and the solder).

If you can still see the outline of the indivdual strands of your wire after you're done, you probably didn't use quite enough solder.  You want to use just enough to fill between the strands, making the joint appear smooth, or almost smooth.  You don't need any more than that.

BTW the exact same technique applies to almost any panel-mount part, including potentiometers.

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Thanks again for the help. Here comes a power supply question. I know 7-10V 500mA is recommended for LEDs and LCDs. I've found one for dirty cheap that's 600mA. Is this overly excessive? Which is more important for running lots of pots, leds and an LCD? Amperage, Voltage, or a combo?

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Voltage should _always_ be in 7-10V range. The current your PSU will need to supply will rise with parts count, so more Amps is better.

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600 mA is good. Anything 300+ mA is probably OK, with more being always better.

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Voltage should _always_ be in 7-10V range.

ASSUMING: this is to feed a 7805 regulator, depending on the brand of 7805 used, the minimum acceptable input voltage might be as high as 7.5 volts.

LyleHaze

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You'll want anywhere from around 28 gauge to 22 gauge. 

So using individual wires from a ribbon cable should be fine for hooking up the jacks themselves (ribbon cable is 28awg, right?).

What about power? I feel moderately confident assuming that 28 gauge wire is too small for power. I believe I read that somewhere in the forum but failed to find a recommended gauge.

I've got nearly everything ordered that I need. All that's left are detented pots and knobs. Both should be fairly inexpensive, thank goodness. I've spent a sum of money on tools and parts that I prefer not to tally right now. The nice thing is that I wont have to buy the tools again and I will have lots of leftover parts, enough for a smaller scale design if I choose to do so later on. I think I will be doing the enclosure out of plexi and wood. Hopefully I can get someone to do some CnCing for me on the front panel because I really don't want to cut all of these holes! That's still a little ways in the future, though. As soon as I get the LCD soldered up and the core powered, I'll start posting some pics. In the meantime, I'm sure more questions will follow.

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Wooooooooo!

My next batch of parts came from SmashTV's shop today. I replaced the DIL header that I goofed up and all seems well. I want everything to be as modular as possible, so instead of soldering my ribbon cable directly to the LCD, I used SIL headers:

n1641130258_231766_3617726.jpg

One thing I leaned very quickly is that soldering up SIL female connectors is a Royal PITA. They are more expensive than DIL connectors and take significantly more time to assemble. Yuck. I don't look forward to the rest that I have to prepare. Nonetheless, I'm glad I did it this way as I believe it allows for a more flexible configuration and provides a connection that is less likely to fail.

I also used a switching power supply. According to the documentation it should work with constant power draw ie that of a backlit LCD. Lets put it to the test...

4452_1097452170121_1641130258_231765_7254184_n.jpg

Success! Now lets see if I got everything else right. Put the PIC and optocoupler in and fire it up once more:

4452_1097452250123_1641130258_231767_4766728_n.jpg

Freaking awesome. At this stage I was prepared and almost expecting for something to not work so this was a pleasant surprise. I did get a bit ahead of myself as I had forgotten to wire up the MIDI ports at this point. I decided to pull the chips by hand and did a less than stellar job of it. I bent several pins pretty badly and had to gingerly correct my mistake. Looks like no harm, no foul.

Next is to order one more round of pots and finish drawing out the front panel and enclosure. I'm once again apprehensive about the work ahead of me, but very excited about having a working midibox sometime in the (hopefully) near future. Time for another question...

The dedicated pots for the LCD are on the core module. Are there or do there need to be any dedicated switches for working with the midibox directly, ie changing banks, channels, mapping etc? I know this can be done via the Desktop PC software, but how does one do it directly within the midibox?

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Nearly there!

Midi I/O works properly:

n1641130258_253835_3101098.jpg

And this is what the faceplate looks like with components mounted:

4450_1105648695029_1641130258_255406_4111716_n.jpg

It's designed to fit in a turntable flight case. I mapped out the faceplate design in Sketchup. Somehow, I overshot by a significant amount (over 10cm) when drawing it out on the PC so when it came time to lay everything out on the physical faceplate it was all on the fly and things got scrunched. This is, however, a prototype, so I will be changing it around some in the future. I didn't dedicate any buttons to menu navigation although I already wish I had. Maybe in the next iteration. No LEDs on this one- that's also for next time around.

Now for a couple more questions.

1)How I ensure that I'm not wiring up my encoders backwards, ie I turn my encoder clockwise and it sends a counterclockwise signal?

2)Do pots typically follow this diagram:

pots.jpg

so with the pins facing down one wires in the order of ground, ic, 5v?

With the exception of some minor desoldering and the shrinking faceplate I've had very few issues. I'd like to keep it that way and not have to do massive desoldering and rewiring. I think with the above two questions answered things should go smoothly.

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1)How I ensure that I'm not wiring up my encoders backwards, ie I turn my encoder clockwise and it sends a counterclockwise signal?

Check the datasheet and wire them correctly ;)

2)Do pots typically follow this diagram:...

so with the pins facing down one wires in the order of ground, ic, 5v?

Typically, yes - but if you get it wrong, you will fry things, so... see the answer to question #1 :)

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Good point. I'll see if I can find them. Sorry for the obvious questions, but being that this is my first time with this kind of stuff I just don't think of the simplest of answers.

I can't wait to get this thing running!

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Hehehe no need for apologies man. It's good to feel confident, and if we can help......

Can't wait to see it running  :)

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Yes it appears you have done your homework, and done a clean job, too.

Your display wiring is very neatly done. That improves project appearance, reliability, and makes troubleshooting easier, too.

Regarding your pots.. The +5 and GND terminals will always have the same resistance between them,  no matter where you turn the knob. The "wiper" is the moving part, and that's the terminal that goes to the AIN connection.

I will GUESS that the "max" setting would be the +5 volt end, but that's an assumption. I haven't built one yet.

Encoders: "Follow the documentation" is the correct answer. Or you could just try one and see which way it goes, then wire them all accordingly. That would be a sloppy, unprofessional, and way too easy way of dong it. :-)

I continue to be impressed with the quality of panel builds that we see around here.

Keep the pictures coming!

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