33 posts in this topic

A number of people claimed interest in a Eurorack variant of my TPD, so I sat down and tried to modify the parts layout to somewhat better accommodate the Eurorack width. Here is a screenshot of the PCB.

large.EuroTPD.jpg.4c138746caf66d7b53b1d4

It is essentially built on altitude's advice on Eurorack dimensions, which I know nothing about... is this 14HP? So, the PCB is 100mm x 69mm (height x width), and the parts list is identical to the regular standard TPD. Also, the UI has the exact same layout, so you can use the template in the Wiki for your front panel. The mounting holes are different, though.

Depending on interest, I might get a run of boards made after an initial testing of the prototype which will probably go to altitude.

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hi illmenator,
so in the end you see it's not such a bad idea to eurorack the thing =)
I advice you to stick to 16 HP, maybe a little wider but better for rack integration, stays a 2^X form.
Could update my order with this one ?
Bests,
Jerome

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I think if you want a wider frontpanel you could also stick with the original PCB?

I am not sure when it will be available to the general public, it might take another two months or so.

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I say no wider than it needs to be.  14HP is just fine IMHO

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just to be sure, are you using SMT components? when i see 74hc595 footprints i wonder?
I'm not sure then about the order... Moreover that i can obtain same result with modulbox-ng expanders in the end.
Sorry about that.
Bests,
Jerome

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42 minutes ago, Altitude said:

I say no wider than it needs to be.  14HP is just fine IMHO

Depends on your usual rack alignments.
By my side i try to stick to 2^X form width factors as much as possible because of symmetry and not having only one row in cases. Moreover i'm maniac with alignments. Ex graphic designer... Like things not in mess.
But you might want save as much place as possible and not caring about global alignments because having just one row in your rack =)
14HP is 2HP multiple but not 2^X form - 16 is .
Bests,
Jerome

Edited by Psykhaze

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6 hours ago, Psykhaze said:

just to be sure, are you using SMT components? when i see 74hc595 footprints i wonder?
I'm not sure then about the order... Moreover that i can obtain same result with modulbox-ng expanders in the end.
 

I am not exactly sure what you are talking about? You want to obtain the same results using some non-TPD??

 

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Nothing wrong with SMD, most of my upcoming modules will have some SOIC/1206. It's better to learn sooner or later.

Edit: nothing stopping @Psykhaze adding 2HP to his front panel.

TPD looks cool, but shouldn't the decoupling caps be nearer to pin 16?

Without trying to spread FUD, I wonder about lots of blinkenlights in a Euro case when potentially combined with analogue modules. Do you have any data on power supply recovery when everything's humming? It could be okay with the PSU driven from the SEQ or at least isolated from the Euro rails. 

For my latest work, I include a 3-pin 100mil/2.54mm Molex header with the centre pin 0V/ground and +5V on the right when the polarity tab is at the bottom of the connector. The left pin is NC. Could we consider a standard perhaps?

Edited by latigid on
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Just now, latigid on said:

Nothing wrong with SMD, most of my upcoming modules will have some SOIC/1206. It's better to learn sooner or later.

Edit: nothing stopping @Psykhaze adding 2HP to his front panel.

TPD looks cool, but shouldn't the decoupling caps be nearer to pin 16?

 

Decoupling caps are highly overrated. If really paranoid you could still fly a through-hole capacitor across the IC...

Quote

Without trying to spread FUD, I wonder about lots of blinkenlights in a Euro case when potentially combined with analogue modules. Do you have any data on power supply recovery when everything's humming? It could be okay with the PSU driven from the SEQ or at least isolated from the Euro rails. 

For my latest work, I include a 3-pin 100mil/2.54mm Molex header with the centre pin 0V/ground and +5V on the right when the polarity tab is at the bottom of the connector. The left pin is NC. Could we consider a standard perhaps?

You need a SEQ somewhere anyway, so power will be taken from there. Adding a power supply connector just creates false hopes, I think.

I am not sure about a TPD in a Eurorack either, but there was a request so I checked what I could come up with. Personally, I will try to avoid the moneypit Eurorack.

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Decoupling caps are highly overrated. If really paranoid you could still fly a through-hole capacitor across the IC...

I don't agree; I've read about cases where decoupling caps were the difference between a chain of serial shift registers working or not. A fly-wired cap would be just as effective as your current layout -- the closer to the power pins the better.

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You need a SEQ somewhere anyway, so power will be taken from there. Adding a power supply connector just creates false hopes, I think.

 

If the current consumption is "high" then it makes sense to wire the power lines in parallel  EDIT: I should say "star wired." This sends the return current back to the source rather than influencing other modules in the chain. I only asked because I was wondering about the 2-pin connector at the top on the rear side. Flexibility, even if it's "over designed," can extend the device beyond its original purpose.

Edited by latigid on

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Well you have a point in that. The 2-pin connector has the exact same purpose as on the original TPD, it disconnects the encoder switch.

Can you send me a link to the Molex connector you are using?

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Just now, latigid on said:

I don't agree; I've read about cases where decoupling caps were the difference between a chain of serial shift registers working or not. A fly-wired cap would be just as effective as your current layout -- the closer to the power pins the better.

From experience (my own and many other TPD users) I can say that what we have now is close enough :happy:.

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All good, here is the part:
http://www.mouser.de/ProductDetail/Molex/22-23-2031/

Also available for next to nothing at Tayda:
http://www.taydaelectronics.com/connectors-sockets/wafer-housing-crimp-terminal/serie-2500-2-54mm.html

578b4c55c4208_Molex100mil.thumb.PNG.0938

 

Pin 3 NC
Pin 2 0V/ground
Pin 1 +5V

Lots of edits today: it's of course possible to use an ordinary 100mil breakaway header in place of the Molex part.

 

Best,
Andy

Edited by latigid on

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11 minutes ago, latigid on said:

Pin 3 NC
Pin 2 0V/ground
Pin 1 +5V

Are you sure you got the numbering right? All my Kicad libraries (also for Molex parts, though I don't have this exact part number) start counting pin numbers from the left when the tab is at the bottom, so your pin 3 would be my pin 1!?

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The EAGLE library part has pin 1 on the right as referenced to the schematic:

578b620cc03f1_SchemMolex.thumb.PNG.a3db8

 

I can't say how this would relate to KiCAD, but it would be great to standardise the power connector on the right relative to the polarity tab on the bottom edge.

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Defining standards is almost useful for everybody. I totally agree with some "standard" Power connector concept . We should define some common design rules to follow in upcoming designs.
For example @latigid on , @ilmenator , @Altitude, following your experience on PCB design, we should define some list about design rules/issues in PCB making in wiki ( Having ground plane, Decoupling caps etc....)

Eurorack size format is also about following some standards . It's maybe some "fashion" , you may not like it but I mean no "common" real size-format has been taken in consideration before in MBHP to me.
(maybe excepted mb-6582 and pactec case?) Most of MBHP PCB designed were having arbitrary size and designed to fit in standalone boxes. Trying to have some common base in different works should lead to homogenic MBHP things.Defining standards is for example what made the web grow. Eurocard specs is for sure good point

Most of musicians are used to rack hardware things, in 19" or Euro now. That was also a point for me about sticking to 2^X HP-width . Just notice that even on modulbox-ng i made some compromise by having some panels 24 HP. but 24 = 3x8 , so it fit for symmetry. @ilmenator Also really sorry about that , but the thing about re thinking my TPD order is also that i won't have the full V4 Seq but only V4L. Then TPD makes really less sense.

Regarding SMD components, to me it should be avoided as much as possible. Most peoples aren't  dealing easy with SMD soldering, and I'm the first. i know sometimes component size is an issue and the choice of having SMD components is also related to the fact it's sometimes not available DIP/PDIP package. But in order to keep PCB assembly accessible to most of us , if DIP could be choosen, i think it should be better.
Imagine some noob buying some pcb+kit and missing his SMT solderings, ending in hating this precise way of handling. Just my thoughts.

I hope many Full V4 Seq owners will find interest in this great TPD expander re-sized. Really nice about rethinking it 

Bests,
Jerome

Edited by Psykhaze

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We're all coming from different backgrounds, with different time commitments and so on. The number one priority is that the board should work, and that's the responsibility of the designer. Many other choices come down to personal preference or experience, which is totally cool seeing as we aren't under contract to provide a specific service. E.g. I will always put decoupling caps near the power pins, and if you don't believe in them (:-P) it's your choice not to populate those components.

The direction towards a casing standard is quite smart, because that's often the limiting factor in builds and can contribute majorly to the cost. @Rowan actually suggested that as a direction a little while ago, and it's very doable simply by limiting the PCB height to ~100mm. I don't agree that panel sizes should be equal to a power of two, though there is a loose idea to keep the HP values as even numbers.

It's very rational to use SMT, not just because of size and certain availability, but it allows for easier trace routing, double sided placement, closer clearance (look at the registers placed under the dot matrices above), less drill hits etc. And you'll actually find that it's easier than through hole assembly as you don't have to clip leads. Can be much cheaper for components too. Avoid SMT on parts that experience mechanical stress like pots, switches, sockets etc. Personally I stick to through hole design when I can.

Sorry for the off-topic discussion, feel free to split if needed.

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31 minutes ago, Psykhaze said:

..
Regarding SMD components, to me it should be avoided as much as possible. Most peoples aren't  dealing easy with SMD soldering, and I'm the first. i know sometimes component size is an issue and the choice of having SMD components is also related to the fact it's sometimes not available DIP/PDIP package. But in order to keep PCB assembly accessible to most of us , if DIP could be choosen, i think it should be better.
Imagine some noob buying some pcb+kit and missing his SMT solderings, ending in hating this precise way of handling. Just my thoughts.
..

Couldn't disagree more.  The sooner people move away from THT, the better.  There is a whole thread worth of people at muffs that never held a soldering iron before that made up Mutable DIY modules successfully which are 0603 and have all sorts of fine pitch parts.  If those people can do it, anyone can.  SMD parts are available with better specs, more packing options, and there are many more parts to choose from.  THT resistors/ICs/capacitors are going away, every year manufactures are dropping lines and there is less and less to choose from.  Besides, I much prefer to buy a reel of 5000 resistors that will probably last me for the rest of my life for $10 than having to restock parts every couple of weeks with THT.

More and more module makers are offering SMD kits and no one is really complaining.

There used to be a standard PCB size for midibox projects which was governed by the maximum board size in the free version of eagle but obviously things have progressed since then.

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Just now, Altitude said:

Couldn't disagree more.  The sooner people move away from THT, the better.  There is a whole thread worth of people at muffs that never held a soldering iron before that made up Mutable DIY modules successfully which are 0603 and have all sorts of fine pitch parts.  If those people can do it, anyone can.  

Maybe. By my side I prefer THT but i'd say that's some taste. The fact is just smd soldering is harder than through hole. Tried to think in a end user way .

Just now, Altitude said:

SMD parts are available with better specs, more packing options, and there are many more parts to choose from.  THT resistors/ICs/capacitors are going away, every year manufactures are dropping lines and there is less and less to choose from.  Besides, I much prefer to buy a reel of 5000 resistors that will probably last me for the rest of my life for $10 than having to restock parts every couple of weeks with THT.

Once again, i feel like it's a question of taste . For sure choosing SMD is rationnal about some technical issues and soldering-doable.
But i feel like you're thinking "Designer Side" and taking as admitted that SMD is a future that everyone should be ok with ?

Just now, Altitude said:

More and more module makers are offering SMD kits and no one is really complaining.

There used to be a standard PCB size for midibox projects which was governed by the maximum board size in the free version of eagle but obviously things have progressed since then.

just having 100mm height +2HP multiple width constraints is almost a simple design rule. Now kiCAD is a correct alternative to Eagle, things have moved.
As latigid said , we are coming from different backgrounds and may have some different advices on technical issues ,as well as different tastes. It is good to see different alternatives solutions to a same problem.

We are quite off-topic so then let's re focus discussion on eurorack TPD =)
Bests,
JK

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Here are the dimensions for the mounting holes. Altitude is testing the prototype, I have PCBs available if anyone is interested.

 

EuroTPD_dimensions.jpg

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Testing successful! All good.  I'll post some pics and video shortly.  Ilmenator brought up the point that the 4 buttons and LEDs dont have an official function yet so this might be a good time to discuss that..

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I think one button should be a preset for the "Magic BPM" ;)

 

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ill take 2 of the pcbs -  thx.

Edited by Phatline

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....

 

 

 

 

Edited by Altitude

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