Potentiometer Row Mounting/Ideas

[gophert]

I've always wanted to try to build something myself, but never could come up with anything useful yet also suitable for a complete novice.

Most of us don't come up with anything useful either - but we build our projects anyways.

 

[Visitor]

Great first effort at laying out a circuit board!

Did you use EasyEDA?

As was suggested, making the bottom side a ground plane will work really well (not that there is any extra charge from the Chinese fans for removing over a certain amount of copper). Be sure to set the isolate distance (clearance between ground plane and other tracks and pads) to something reasonable – say 0.01" at least.

Also, be aware that 0.1" single row IDC connectors almost don't exist in the real world. I've seen them installed on some stuff I've purchased surplus, but I've never been able to find them at any of my suppliers.

 

[KeepItSimpleStupid]

Also, be aware that 0.1" single row IDC connectors

They won't exist. IDC is Inter Digitated Contacts which by definition is two rows between each other.

 

[Visitor]

They won't exist. IDC is Inter Digitated Contacts which by definition is two rows between each other.

Sorry. No. IDC = Insulation Displacement Contact and I have a bunch of character LCDs with 1×16 IDC connectors. They have existed, but they may not any more.

Insulation Displacement Connector

So how can 0.05" pitch ribbon cable work with a 0.1" pitch connector? Every other conductor is used, or maybe they are paired up. At any rate, they do or at least have existed.

 

[gophert]

Sorry. No. IDC = Insulation Displacement Contact and I have a bunch of character LCDs with 1×16 IDC connectors. They have existed, but they may not any more.

Insulation Displacement Connector

So how can 0.05" pitch ribbon cable work with a 0.1" pitch connector? Every other conductor is used, or maybe they are paired up. At any rate, they do or at least have existed.

yes, I had some that I recovered from an older Sony 5.1 Amplifier receiver. 22 gauge wires with a thin film between them To keep 0.1" offset. I've never seen anything like it since. The OP can easily make a 2x5 array Of male headers for a 10-conductor ribbon 2x5 w/0.1" spacing (using 0.05" spaced ribbon). Alternatively a DB-9 connector with IDC "D" connector W row of 4 and row of 5. The D connector allows an easy screw type positive lock.

Also, there is a trace missing on the LEDs unless it is connected to the back plane.

 

[rjenkinsgb]

Also, be aware that 0.1" single row IDC connectors almost don't exist in the real world.

Molex style pins and sockets are simplest for small projects, if you want a SIL connector design.
eg.

22-27-2101 | Molex KK 254 Series Straight Through Hole Pin Header, 10 Contact(s), 2.54mm Pitch, 1 Row(s), Unshrouded | RS

uk.rs-online.com

22-01-3107 | Molex, KK 254 Female Connector Housing, 2.54mm Pitch, 10 Way, 1 Row | RS

uk.rs-online.com

08-50-0032 | Molex KK 4809 Crimp Terminal Contact, Female, 0.05mm² to 0.35mm², 30AWG to 22AWG, Tin Plating | RS

uk.rs-online.com

IDC types are readily available, but usually need very expensive special tooling to insert the wires properly, so not very practical unless you are mass producing gear.

4-640441-2 | TE Connectivity 12-Way IDC Connector Socket for Cable Mount, 1-Row | RS

uk.rs-online.com

 

[gophert]

IDC types are readily available, but usually need very expensive special tooling to insert the wires properly, so not very practical unless you are mass producing gear.

4-640441-2 | TE Connectivity 12-Way IDC Connector Socket for Cable Mount, 1-Row | RS

uk.rs-online.com

the 0.05" idc connectors are installed with a simple vice and the MTA100 connectors (0.1" header option) needs a $35 crimp tool ("very" is a relative term). The Tool is only necessary if you are not handy with a flat bladed screwdriver.

 

[ChrisP58]

You mentioned that you were using multiplexers to expand the number of analog inputs (pots) that you could read.

I expect that you're probably using a multiplexer board. You might consider moving the multiplexer chip onto the pot board. That will simplify wiring as there will only be one analog wire from the pot board directly to the Arduino. You will need three pot select wires plus one board enable wire. The three select wires are from three GPIO pins and are shared with all of your pot boards. You probably have those same signals for your multiplexer boards.

And, since you're adding LEDs, and assuming that you want to light the LED adjacent to the selected pot, you can use the same select and enable signals with a digital decoder to drive the LEDs.

Analog multiplexer CD74HC4051E
Digital decoder SN74HC138AN

 

[KeepItSimpleStupid]

I give up: https://en.wikipedia.org/wiki/Insulation-displacement_connector

 

[Visitor]

When I mentioned that single-row IDC connectors are hard to come by, I was specifically referring to Gophert's post #12. Dual-row IDC are easy to assemble, but not so useful for connecting to an Arduino or other dev boards.

 

[jonnojonno]

Hello Everybody,
I had a bit of a honey-do Saturday, but I'm glad to have some more input on the next step of this process: connector selection. There's so many different connectors in different configurations, I can say, it's a bit like stepping up to a full Grainger catalog after shopping at the corner hardware store. Sometimes a beginner like me just wants to walk up to the counter and say "I'd like a couple of screws, please." and yet these supply houses have hundreds of options to choose from, from row count, pin pitch, angles, etc!

Here's the next iteration of my PCB.

I've added the ground plane, as suggested, and also moved the power to a 2 pin connector, also so I can daisy-chain the boards together. I'm quite impressed with how intuitive EasyEDA is, even for a total novice like me. It sort of bodes well for the democratization of STEM fields for folks younger than me wanting to get into electronics earlier than I did. As always, I'm happy to hear a better way of doing things!

Here's what my research has yielded so far, and since this is likely the only project I'm going to do for at least a little while, I'm not adverse simply buying pre-terminated cabling, markup be damned.

I can see the Samtec HCSS line seems to be a single-row IDC board header, along with the ZSS ribbon. Mouser has these in stock, and I'm considering them.

HCSS - IDC Socket and Terminal Cable Assemblies, 0.100" Pitch | Samtec

HCSS - The HCSS series is a range of classic pre-terminated IDC cable assemblies. Featuring single row socket connectors, the HCSS is available in custom lengths from 2 inches, and can be supplied in single- or double-ended variations.

www.samtec.com

https://www.samtec.com/products/zss

I also have been looking at the XH style connector from JLC, especially for my 2 pin power leads.

B8B-XH-A(LF)(SN) JST Sales America Inc. | Connectors, Interconnects | DigiKey

Order today, ships today. B8B-XH-A(LF)(SN) – Connector Header Through Hole 8 position 0.098" (2.50mm) from JST Sales America Inc.. Pricing and Availability on millions of electronic components from Digi-Key Electronics.

www.digikey.com

And the pigtails seems to be extremely plentiful from even retail vendors like amazon.

Thank you for sharing the Molex KK style, I knew there were some that fell under that style, but searching for molex connectors seemed to always return connectors I associate with computer power supplies.

A note to share about the project overall: I've been trying to get this all to fit in a cigar box, so I've had to split the circuitry into two halves: The inputs in the lid, and the rest, including the multiplexing in the bottom. The functionality is sort of split into smallish perfboards spread out across the bottom. Here's a pic of my multiplexing perfboard, it's utilizing screw terminals, because that seemed the most logical choice at the time.


The decision tree I'm at right now is: Do I want to redo the muxing board? If not, I should likely go with a connector that crimps individual wires, and terminate the mux-end with the screw terminals, otherwise I should likely look for the most universal 2 Row IDC model and get used to working with it, because I'd likely design my next project around them from conception.

I'm leaning towards the Molex KK or the JLC XH, especially for the 2 pin power, and also just to reuse as much out of the bottom as I can. It's all essentially working, but the previously posted rat's nest in the lid is the source of all my woes.

 

[rjenkinsgb]

I'm leaning towards the Molex KK or the JLC XH

I'd suggest using the common two-row headers and 0.050" pitch IDC cable, with one row grounded and the other row used for the signal connections.
They are likely cheaper and are very easily available from most electronics suppliers, plus no special tools needed.

 

[KeepItSimpleStupid]

Be careful putting power on IDC type connectors.

 

[jonnojonno]

Hello Everyone!
Apologies for necroposting, but I thought I'd update you on my progress, and give a final thanks for your input.

Here it is working now:
Project Imgurl Gallery


This was my first foray into electronics, and I'm expecting I'll do things a lot neater with my next project. This version had a lot of iterative try-and-fail mistakes built into its DNA, so has character, but not winning beauty contests.

If anyone wants a copy of the source, I'll give you a link to the github once I've cleaned it up.

 

[throbscottle]

That's a nice build. I was going to say I was surpised those little green pots didn't fit the perf board as the pins should be the same spacing, and you just need enlarge a couple of holes for the tabs. But anyway, I see you are well past that now. Well done!