Recommended way to make a permanent one-off circuit

[rthorntn]

Hi,

I would appreciate some help figuring out the best way to make a permanent one-off circuit

Do I use one of these proto PCBs that you see everywhere (image attached) in a little enclosure?

I need DC voltage in terminals (2-way, 6-24v supported), meter input terminal (3-way) and a signal output terminal (1-way, or should I be taking ground out from the sensor as well, it's going to a Teensy MCU) between those three terminal blocks I need a voltage divider to get whatever DC voltage I choose down to 3.3v for the signal input to MCU, I'm not particularly clear in whether I need an external pull-up (can I use Teensy's internal pull-up and maybe the sensor could operate on 3.3v and I could do away with the divider?).  The sensor is the Honeywell 2SS52M.

For anyone interested why I'm doing it is here (tl;dr hall effect flow meter):

https://www.eevblog.com/forum/beginners/easiest-way-to-read-a-hall-effect-flow-meter/

Thanks.
Richard

[BillyO]

I rarely use perfboards any more unless I'm dealing with something that is just a one-off experiment to get results and not a permanent project or, rarely, in dealing with something that I know will need tweaking to get it to the stage it will stand the test of time.  Outside those cases I just have PCBWay or JLCPCB make up boards for me.  I think a lot depends on your available budget vs. the free time you have.  My free time is worth more than an order of 5 boards from one of those PCB houses.  So, if I'm even fairly certain of the outcome I just get them to make the boards.

[JustMeHere]

If your board is small, the best way is to get them done at a fab house for less than $5.

[rthorntn]

Thanks, I dont really want to be designing PCB's, I just want to put something together thats reasonably small and robust, I only need one and with the fab houses AU shipping is the killer anyway.

[james_s]

There is no best way, it depends on the complexity of the circuit, the package the parts are in and what skills you have. I like to build simple circuits on perfboard if they're low speed, or "Manhattan" style on copperclad if they involve high speed or RF. Occasionally I still etch my own PCB using toner transfer, and these days it's SO cheap to have boards made in China that it's worth doing that sometimes even for a one off, you can order just a few boards and the total cost with shipping is under $10 last time I did it.

If you don't know how to design a PCB with KiCad a simple project like this is a great tutorial.

[CatalinaWOW]

Part of this depends on what you mean by permanent.

In the right environment even one of those spring clip proto boards will last years or even decades.

One soldered up on perf board will make similar durations in much more stressful environments.

But that soldered up perf board can have problems with large thermal cycles, wet environments or exposure to fungus etc.

In all cases things other than the basic board technology often dominate the lifetime.  Connectors, cables, and sensors are often the weak points.

Some other questions about permanence also come up.  Will you remember what it did, how to repair it and have available parts for the planned lifetime of your gizmo.  A professional PWB can make some of these answers easier.

[themadhippy]

whilst the cheap pcb is a tempting route,for a one off you end up with 4 boards  gathering dust.My choice,unless its something special is veroboard,and for the total cost from even the cheapest pcb house you can get a decent chunk of board that will do sevral small projects.

[RoGeorge]

Many ways of PCB prototyping, from the list of W2AEW videos by topic:
https://silo.tips/download/w2aew-videos-by-topic

#122: Electronic Circuit Construction Techniques: review of some prototype circuit building methods


#123: Build a crystal oscillator from schematic thru prototype construction and testing - DIY


#129: How to cut circuit board PCB material - a couple of favorite methods I use...


#111: How to make a high performance oscilloscope probe socket



This one is from Leo's Bag of Tricks:
Techniques and Strategies for Building Electronic Circuits

[james_s]

whilst the cheap pcb is a tempting route,for a one off you end up with 4 boards  gathering dust.My choice,unless its something special is veroboard,and for the total cost from even the cheapest pcb house you can get a decent chunk of board that will do sevral small projects.

Throw them away, recycle them in e-waste or give them away to someone else that wants to make the same thing. With all the e-waste that gets produced, a few small hobby PCBs are hardly significant.

[John B]

PCBs have a time trade off. It takes to make the schematic and PCB layout, but then the construction is much faster.

Then there is a risk factor. I've created meticulous complicated perfboard designs that I accidentally blew up, wasting many hours of construction time. Was totally impractical to try and repair, and so the whole thing was a write-off. Should such a thing happen with a PCB, at least you have some spares and the construction time is much faster.

[shapirus]

Prototyping PCBs are the way to go only up to a certain level of complexity of the circuit. In fact, they are good only for fairly simple circuits. Wiring all the connections with individual wires quickly becomes a hell as the circuits get more complex.

On the other hand, they allow you to make and fix mistakes. There is much less tolerance for mistakes with designed PCBs. It may take more than one iteration of designing and ordering to get it right, meaning wasted time, even if it's cheap (which it is).

Homemade PCBs are in the middle, I guess. They take less time and (arguably) money to produce them and fix mistakes, but require effort to make them and some time for the trial and error to get the process right.

[tggzzz]

This is a common problem, and many solutions have been developed over the years. Some solutions are high-end professional, some low-end amateur, with all sorts of tradeoffs.

For a selection of examples and a discussion of the techniques, start at https://entertaininghacks.wordpress.com/2020/07/22/prototyping-circuits-easy-cheap-fast-reliable-techniques/

[Peabody]

You might consider having a supply of these on hand:

https://www.ebay.com/itm/292319384009

[BillyO]

Of course, if you can afford it, there is always wire wrap.

I used WW back in the late '70s and '80s.  It's great, but it has become a rich man's way to do things today.

[RoGeorge]

Poor man does wirewrap soldering instead of wrapping. 

[Terry Bites]

Nothing wrong with perfboard for a prototype. Clean it after soldering with IPA (no not the beer).
There's even a handy layout app.
https://www.electroschematics.com/veroboard-design-software/

Its not a good idea to share grounds between connectors it will make it harder to debug- amateur night!

[dietert1]

To study circuit ideas i have been using various methods, like the one shown above with a piece of copper plated board. The ground plane is nice for RF circuits.
For digital i mostly used protoboards with 0.3 mm transformer wire, removing isolation with the soldering iron. Recently i found that the same method can even be used for circuits where thermal EMF matters.
Image shows example. I built this under the stereo microscope within 2 or 3 hours. The circuit has a STM32H750 with a little display and GPIB buffers, so it can be a GPIB controller and sniffer with lots of spare pins and processing power.
To design the board in Eagle won't take much longer yet the board won't have the spare prototyping area which can be handy to extend the circuit into something useful.

Regards, Dieter

[rhb]

I have become a big fan of 'Manhattan' style using copper foil tape mixed with 'dead bug' for DIPs with wires to copper foil pads where needed  and daughter boards for SMD parts on single sided boards.  It's easy to create and modify and very durable because all the connections are soldered.  Just snip off a piece of tape, stick it down and solder.  Very nice for HF RF prototypes.

My experience with various proto boards was there was always a part that didn't fit.   I watched #122 by W2AEW which is an excellent overview of many options, but my favorite is 'Leo's  Bag of Tricks'. I saw that quite some time ago and it completely changed my build style.  I bought a 'laminate cutter' which cuts grooves really nicely.  And I now mix and match all the techniques as seems appropriate.

If that list of videos doesn't make it clear you should probably find another hobby.  They *REALLY* are that good.

Have Fun!
Reg

[tggzzz]

Of course, if you can afford it, there is always wire wrap.

I used WW back in the late '70s and '80s.  It's great, but it has become a rich man's way to do things today.

Wirewrap is useless with modern logic: ground connections and stubs wreck the signal integrity. (BTW in this context "modern" means mid 80s or later!)

IDC PCBs were better, but I doubt they are still made. Even more expensive than wirewrap too, since the entire board was populated with connectors.

[tggzzz]

I have become a big fan of 'Manhattan' style using copper foil tape mixed with 'dead bug' for DIPs with wires to copper foil pads where needed  and daughter boards for SMD parts on single sided boards.  It's easy to create and modify and very durable because all the connections are soldered. 
...
I bought a 'laminate cutter' which cuts grooves really nicely.  And I now mix and match all the techniques as seems appropriate.

Manhattan is good.

Dremel plus spherical dental bur is good for cutting lines in solid PCBs.

Mixing and matching techniques is sensible.

A couple of examples from https://entertaininghacks.wordpress.com/2020/07/22/prototyping-circuits-easy-cheap-fast-reliable-techniques/ See there for more examples and products

[Ground_Loop]

I use those boards all the time and they work just fine.  Below is a sampling with an another dozen or so that made their way into enclosures.   I have PCBs made occasionally, but the time spent developing the schematic and preparing a good layout is about the same as just building up the circuit on a perf board. The hole spacing is also convenient for SMDs.  And adaptor boards can be direct soldered to the pads.

[rdl]

All this discussion on construction methods is good, but for something this simple I'd use the perfboard as pictured in the first post. I wouldn't even think twice.

[shapirus]

Nothing wrong with perfboard for a prototype. Clean it after soldering with IPA (no not the beer).
There's even a handy layout app.
https://www.electroschematics.com/veroboard-design-software/

Wow that's a nice idea. No download links however, unless I missed the obvious.

There's another app that can do it, seemingly in active development, free&open source: https://veecad.com/downloads.html

[tggzzz]

I use those boards all the time and they work just fine.

For somethings, yes. For others, no.

You need to match the tools to the problem. No surprises there.

[jpanhalt]

I use solderable breadboards with more than one THP hole per pad.  Ones that mimic the "standard" solderless breadboard are available from a variety of sources, including eBay.  Check SparkFun for some pictures.  I do my layout using Eagle and my own rules, often blue on bottom for existing traces and red on top for wired connections) to take advantage of schematic capture.  Attached are two pictures of a simple project.  You can make a template of your breadboard and reuse it repeatedly.