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sammichSID Prototype


Wilba
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Just finished building mine. Had a minor problem which had me scratching my head. I got confused after misreading the manusl and fitted all of the 8 pin chips, I then realised the manual was telling me NOT to put them in so I took them all out again pre-MIOS. MIOS seemed to load OK, but I couldn't get the LCD message to work, or up load the hex. After lots of headscratching, and sleeping on it, plugged in IC2 all was resolved. :thumbsup:

I made a timelapse video over the 4 days, so I'll post that up as soon as it's done :)

I know this doesn't have anything to do with anything, but your avatar is killer. Boulder Dash is one of my all time favorite c64 games ever..

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I know this doesn't have anything to do with anything, but your avatar is killer. Boulder Dash is one of my all time favorite c64 games ever..

HEHE! Yeah, Boulder Dash is the primary reason for buying a C64 again. Chipmusic comes second :D

Question about cases (sorry if this has been asked), is it possible to get a spare/extra case? Just so I can make some wild modifications to my case, but still be able to put it back to stock if I ever take leave of my senses and want to sell it.

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I don't know if this is the best place to post - but here's my time-lapse video of the assembly :)

http://j.mp/db2m48

Just to confuse, the backing music was done on LSDJ

Enjoy! (unless you hate bouncy happy hardcore, in which case turn your volume down.....NOW!)

EPIC WIN

You win a free sammichSID keyring.

Email me your address.

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Just finished mine after a lil struggle with myself and that´s the f*** best lil synth i´ve ever owned.

What a great piece of gear!

Great job, TK, nILS and Wilba! That´s so much fun, i am totally hooked.

Edited by phunk
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I'm currently waiting for the next batch of kits to ship, so I can join the fun. This got me so excited, I had the idea to use different colors of LEDs on the different rows of the panel. More blang. :drool:

Thing is, if I understand correctly, the resistors that limit the current to the LEDs are on the columns of the matrix, not the rows. That means resistors of different colors need to run on the same resistors. I'm a bit worried about relative current specs vs. relative brightness of different colors, since I don't actually know how to calculate the max forward current, etc... :ermm: :huh:

Does anyone have specs for the LEDs to use? The proper method for calculating LEDs' specs? Or should I just keep it simple and go monochrome?

Thanks!

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I'm currently waiting for the next batch of kits to ship, so I can join the fun. This got me so excited, I had the idea to use different colors of LEDs on the different rows of the panel. More blang. :drool:

Thing is, if I understand correctly, the resistors that limit the current to the LEDs are on the columns of the matrix, not the rows. That means resistors of different colors need to run on the same resistors. I'm a bit worried about relative current specs vs. relative brightness of different colors, since I don't actually know how to calculate the max forward current, etc... :ermm: :huh:

Does anyone have specs for the LEDs to use? The proper method for calculating LEDs' specs? Or should I just keep it simple and go monochrome?

Thanks!

If you're already familiar with the concept of a LED matrix with common cathodes in "columns"... then I'll explain it briefly... there are six "columns" of eight LEDs, and the current limiting resistors are on the eight "rows", and the "rows" are arranged so the order is middle to extents... i.e. one "row" drives the six outermost LEDs. So if you wanted to make the outermost LEDs red and the next outermost yellow and the rest green (like a LED bar VU meter) that's easy, you just tweak the resistors.

For LED specs, I use Mouser parts 638-204GD and 638-204ID which are the right size and good brightness. Note the reds are high-efficiency meaning they're a great brightness for low current (which is what you get from a 74HC595)... don't be turned off by the low mcd values, these are bright enough even in a matrix at 1/8th duty cycle!.

It's easy to tweak resistor values to suit multiple LED colours, but obviously a lot easier to test this on breadboard first before soldering to the PCB.

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Hi, Wilba. About the Ponoko enclosure: Will you share the .svg file(s) with us?

Your work is inspiring, and I'd like to try to adapt the case to another DIY project (the Shruti-1: http://mutable-instruments.net/).

I have never worked in Inkscape before and your design would be extremely helpful in the learning process.

Thanks.

Regards,

-d

I forgot how to upload stuff to the wiki... so I'll just upload here for now with some info.

There are two versions of each file... one has no stroke width on cut lines, so that Inkscape will show width/height not including the stroke. The "ponoko" versions have 0.003mm blue stroke which is required for ordering from Ponoko.

The 0.9 files are the ones I use now, which uses "vector engraving" for the artwork. The 0.7 files use the "raster engraving" which didn't come out as nice, but if you are doing some other method of labels (i.e. printing), then you can choose to use these instead.

If you plan to order from Ponoko, let me check your file before you send it. Sometimes strange things happen when ordering with SVG files... such as a group of objects having it's own stroke/fill different to the grouped objects own stroke/fill which can lead to those objects not being engraved or cut. It is probably safest to ungroup everything in the final file before sending it to Ponoko.

In these design files I've made allowances for 0.2mm laser kerf - i.e. laser burns away 0.2mm of material, thus to make the LCD window cutout and the window fit exactly, each is offset by 0.1mm to allow for material burned away by the laser.

Download Inkscape and look at the files. Other apps can scale SVG files differently and the dimensions will be wrong. Confirm the dimensions by checking in Inkscape.

sammichSID case 0.9.zip

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If you're already familiar with the concept of a LED matrix with common cathodes in "columns"... then I'll explain it briefly... there are six "columns" of eight LEDs, and the current limiting resistors are on the eight "rows", and the "rows" are arranged so the order is middle to extents... i.e. one "row" drives the six outermost LEDs. So if you wanted to make the outermost LEDs red and the next outermost yellow and the rest green (like a LED bar VU meter) that's easy, you just tweak the resistors.

Ah, that what caused the confusion. I meant the rows on the panel, which are then the columns in the matrix. (right?) My idea was 16 red LEDs, 16 green, and 16 blue, using only primary colors to reminisce about the lo-res old computer graphics. That was why I was thinking about more than one color of LEDs running on the same resistor.

For LED specs, I use Mouser parts 638-204GD and 638-204ID which are the right size and good brightness. Note the reds are high-efficiency meaning they're a great brightness for low current (which is what you get from a 74HC595)... don't be turned off by the low mcd values, these are bright enough even in a matrix at 1/8th duty cycle!.

Wow, those are low. I guess that's fine, since they're diffuse, but I have trouble finding a 3mm blue LED that matches the red and green. Everlight doesn't make a diffuse blue like the red and green you linked. Mouser part 604-W7104MBC/K looks close electrically, but it's a clear LED with a low viewing angle, and it's the closest thing that's in stock. I guess I'll try DigiKey, or use all-clear LEDs... :unsure:

It's easy to tweak resistor values to suit multiple LED colours, but obviously a lot easier to test this on breadboard first before soldering to the PCB.

Good point, I have a few spare 595's from some things I tried out with an Arduino. I'll make sure things look good before soldering.

Thanks for your help!

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Good point, I have a few spare 595's from some things I tried out with an Arduino. I'll make sure things look good before soldering.

You won't need 74HC595 to test LEDs... just use 5V. It's not worth simulating a 1/8th duty cycle matrix either. If the LED looks good with a resistor and 5V, it should look good when in the matrix. The alternative is soldering LEDs first and testing resistor values by touching them on the pads on the PCB. Unfortunately the spacing of the LEDs doesn't match 100mil spacing machine pin strips, so I can't suggest making the resistors "socketable" :hmm:

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Hi, Wilba.

A question about your design: Did you add the 3mm "teeth" at the end of your design phase or did you create your case, including the teeth? In other words, let's say you had a 150mm X 100mm x 70mm case design: Would you have to make the dimensions 153 x 103 x 73?

Also, did you include the "bumps" on the teeth that Ponoko recommends for the interlocking method?

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I'm not sure I fully understand the question.

I started with the PCB size and added clearances and thickness of side panels to make the final outer size of the top panel.

i.e. if the PCB was 100x100mm then the "start" of the teeth are 0.5mm offset from this, then the "end" of the teeth another 3mm offset.

Then ALSO I shifted those offsets by 0.1mm outward to allow for laser burn. So the design would show final outer dimensions of 100+(2*3.1)=106.2mm

I didn't include "bumps" (nodes) on the teeth or added offsets to allow for laser burn, as the idea is not to make it a tight fit. Thus there are 0.2mm gaps between the teeth when they interlock. It is the top panel screws which apply pressure on the sides and hold it together. To achieve this, an extra 0.5mm gap is added between the top spacer and the top panel... i.e. the dimension between the "start" of the vertical teeth on the side panels should be the sum of the spacer/PCB/nut heights plus 0.5mm so that when the top panel is screwed down, the clamping effect happens on the sides and not against the top spacer.

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I'm not sure I fully understand the question.

I started with the PCB size and added clearances and thickness of side panels to make the final outer size of the top panel.

i.e. if the PCB was 100x100mm then the "start" of the teeth are 0.5mm offset from this, then the "end" of the teeth another 3mm offset.

Then ALSO I shifted those offsets by 0.1mm outward to allow for laser burn. So the design would show final outer dimensions of 100+(2*3.1)=106.2mm

I didn't include "bumps" (nodes) on the teeth or added offsets to allow for laser burn, as the idea is not to make it a tight fit. Thus there are 0.2mm gaps between the teeth when they interlock. It is the top panel screws which apply pressure on the sides and hold it together. To achieve this, an extra 0.5mm gap is added between the top spacer and the top panel... i.e. the dimension between the "start" of the vertical teeth on the side panels should be the sum of the spacer/PCB/nut heights plus 0.5mm so that when the top panel is screwed down, the clamping effect happens on the sides and not against the top spacer.

You answered it perfectly, thanks.

Now, you said that screws hold the sides together, but if the interlocking method was the only one I intended to use for one of the panels (for easy access; the others would be glued), should I add 0.1 or 0.2mm to that piece to allow for the laser burn-off? Do you think the fit would still be decent enough to hold with normal use?

(Come to think of it, your idea to use screws to apply pressure for the top panel sounds pretty good...)

I'm nearing completion; I'll PM you when I'm done, if you don't mind.

Thanks so much for your help.

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I just realised I added up incorrectly in my explanation... I didn't add the 0.5mm offset.

Basically from the edge of your PCB, add 0.5mm clearance, then another 0.1mm for laser burn. That's the start point of the "teeth". For the end point, from the edge of the PCB, add the 0.5mm clearance, then 3mm (panel thickness) then another 0.1mm for laser burn.

I can't really say what's best for an interlocked panel when there's nothing else holding it.

From experience, the LCD window on sammichSID is cut to be the same size as the panel cutout... i.e. given a size you want, add 0.1mm offset all around for the inner part (clear acrylic) and subtract 0.1mm offset from the outer part (panel cutout). Then both parts will be the same dimension and "snap fit" together. You should use rounded corners to make it easier to put in, and prevent cracking, and also apply the offsets to the corner radii.

So... you could do the same... offset the "teeth" edges on both parts by 0.1mm outward (i.e. make the teeth wider by 0.2mm thus also making the gaps narrower by 0.2mm). This makes both parts identical after cutting, and it should "snap in" without needing nodes etc. If you want to be fancy about it, you could make nodes of 0.1mm instead of widening the entire "tooth".

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I am ordering my lcd. I got red led's and I think a crystalfontz blue text on black might look nice. Anyone have any experience with blue lcd text I am worried about reading it in the dark and I might go with a brighter color text.

If I buy 2 lcd's and decided after testing them what legnth male lheader pins do I need for the lcd side of the connection?

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Since those headers are expensive, hard to cut without splitting them lengthwise, and more than you need for one sammichSID, I chop them up into 2x8 and 2x5 headers. The downside is if you want to replace your LCD, you need another header, so it's sort of easier/cheaper for me to send out replacement headers as required than force everyone to pay for more than half a 36x2 pin header that they're not likely to use.

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  • 3 weeks later...

arg I messed up and put one of the caps in the wrong spot and I had to cut it off. I could not find the cap at my local store and not having any luck finding it on mouser.

I need part number for the 100nF monolithic cap if possible. mouser prefered

Edited by kaleaf
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