Recommended way to make a permanent one-off circuit - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: March 22, 2023, 11:33:59 pm
content: Hi,I would appreciate some help figuring out the best way to make a permanent one-off circuitDo 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

author: BillyO
author_rank: Super Contributor
timestamp: March 23, 2023, 01:07:40 am
content: 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.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: March 23, 2023, 01:15:58 am
content: If your board is small, the best way is to get them done at a fab house for less than $5.

author: rthorntn
author_rank: Frequent Contributor
timestamp: March 23, 2023, 01:22:57 am
content: 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.

author: james_s
author_rank: Super Contributor
timestamp: March 23, 2023, 01:53:08 am
content: 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.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 23, 2023, 03:43:40 am
content: 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.

author: themadhippy
author_rank: Super Contributor
timestamp: March 23, 2023, 04:41:32 am
content: 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.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 23, 2023, 06:14:07 am
content: 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 socketThis one is from Leo's Bag of Tricks:Techniques and Strategies for Building Electronic Circuits

author: james_s
author_rank: Super Contributor
timestamp: March 23, 2023, 06:42:36 am
content: Quote from: themadhippy on March 23, 2023, 04:41:32 amThrow 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.

author: John B
author_rank: Frequent Contributor
timestamp: March 23, 2023, 07:58:16 am
content: 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.

author: shapirus
author_rank: Super Contributor
timestamp: March 23, 2023, 09:03:21 am
content: 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.

author: tggzzz
author_rank: Super Contributor
timestamp: March 23, 2023, 10:24:36 am
content: This is a common problem, andmanysolutions 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 athttps://entertaininghacks.wordpress.com/2020/07/22/prototyping-circuits-easy-cheap-fast-reliable-techniques/

author: Peabody
author_rank: Super Contributor
timestamp: March 23, 2023, 02:08:10 pm
content: You might consider having a supply of these on hand:https://www.ebay.com/itm/292319384009

author: BillyO
author_rank: Super Contributor
timestamp: March 23, 2023, 03:47:48 pm
content: 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.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 23, 2023, 04:55:41 pm
content: Poor man does wirewrap soldering instead of wrapping.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 23, 2023, 05:28:03 pm
content: 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!

author: dietert1
author_rank: Super Contributor
timestamp: March 23, 2023, 05:41:11 pm
content: 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

author: rhb
author_rank: Super Contributor
timestamp: March 23, 2023, 05:53:24 pm
content: 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

author: tggzzz
author_rank: Super Contributor
timestamp: March 23, 2023, 06:10:15 pm
content: Quote from: BillyO on March 23, 2023, 03:47:48 pmWirewrap 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.

author: tggzzz
author_rank: Super Contributor
timestamp: March 23, 2023, 06:20:07 pm
content: Quote from: rhb on March 23, 2023, 05:53:24 pmManhattan 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 fromhttps://entertaininghacks.wordpress.com/2020/07/22/prototyping-circuits-easy-cheap-fast-reliable-techniques/See there for more examples and products

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: March 23, 2023, 06:22:15 pm
content: 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.

author: rdl
author_rank: Super Contributor
timestamp: March 23, 2023, 06:26:01 pm
content: 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.

author: shapirus
author_rank: Super Contributor
timestamp: March 23, 2023, 06:31:09 pm
content: Quote from: Terry Bites on March 23, 2023, 05:28:03 pmWow 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

author: tggzzz
author_rank: Super Contributor
timestamp: March 23, 2023, 06:35:12 pm
content: Quote from: Ground_Loop on March 23, 2023, 06:22:15 pmFor somethings, yes. For others, no.You need to match the tools to the problem. No surprises there.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 23, 2023, 06:39:29 pm
content: 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.

author: rhb
author_rank: Super Contributor
timestamp: March 23, 2023, 07:43:53 pm
content: Quote from: tggzzz on March 23, 2023, 06:35:12 pmAmen!If you *really* want to quantify electrical performance of a particular construction style, connect an SMA-F connector to a 50 ohm non-inductive load using that method and subject it to the tender mercies of a Tek 11801 sampling scope and a 20GHz SD-24 TDR head. 3 mm copper foil on single sided FRG4 is good up to several GHz. A tip I learned from Thomas H. Lee of Stanford in his excellent "Planar Microwave Engineering". Best radio book ever.I have the kit to do this. So long as the requested setup is simply a 50 ohm SMD load connected to the SMA-F, I'm willing to run a few tests of the performance.Every impedance discontinuity will be obvious with fraction of a mm resolution.One approach would be to use copper foil from the SMA-F and then put a segment of each method leading to the load. I like to make little boards to demonstrate stuff using the 11801. So having gotten curious about the difference between expectation and reality I'm going to put together a few test cases. Suggestions welcome. Because it's all time domain you can see each segment separately with several segments in series.Have Fun!Reg

author: Infraviolet
author_rank: Super Contributor
timestamp: March 23, 2023, 08:06:31 pm
content: I can recommend stripboard (also called veroboard) for if you're in a hurry. But if you aren't in a rush then PCB fabrication is so cheap thesedays that it is worth it for even little things like this, and an actual PCB gets you solder mask to prevent shorting by contact with metallic objects and silkscreen so you can put labels and notes to self about pin functions.

author: tggzzz
author_rank: Super Contributor
timestamp: March 23, 2023, 08:20:56 pm
content: Quote from: rhb on March 23, 2023, 07:43:53 pmPlease stop making me jealous. The best I can do is a 140ps/4GHz Tek 1502.One trick I sued to sell a surplus one at a harvest was to have a 20cm long wire and run two fingers along it. The two fingers were clearly visible on the displayBefore anyone thinks that's ridiculously fast, I've measured jellybean logic with a ~250ps transition time (74LVC1G family). Yes jellybean logic hits microwave frequencies; deal with it actually a microstrip, but that doesn't change the point.

author: dietert1
author_rank: Super Contributor
timestamp: March 23, 2023, 08:53:35 pm
content: Yes, i remember using twisted pairs of that transformer wire for fast signals, with stubs less than 2 or 3 mm. Result is similar to those LVDS double traces on FPGA proto boards. Anyway in air 1 nsec is 30 cm wavelength, so even a single wire on the small protoboard should be good enough for that. One thing to avoid is ground bounce, so one needs a redundant Gnd network.One reason why i am rarely drawing boards for prototypes is i don't need to and i prefer not to work out designs to send them to a chinese company where i don't know anybody.Regards, Dieter

author: rhb
author_rank: Super Contributor
timestamp: March 23, 2023, 10:34:42 pm
content: Quote from: tggzzz on March 23, 2023, 08:20:56 pmI managed to pick up a 1502 and really like it. It's much more portable. The 11801 is a beast. But oh so cool. I bought one after I bought one of Leo Bodnar's pulsers and saw the supplied test printout using a CSA803A and SD-30. I had to have one and managed to get one for ~$150. It required reseating all the connectors several times to get it to boot and run the diagnostics which revealed the NVRAM had failed. Once I replaced that it's been fine since.Sadly, there are no schematics available. The Tek Museum has all the records from a member of the design team. But the lawyers don't want to vet the material for release. There is a bunch of 3rd party stuff in them.Happily, I later picked up a 2nd unit, so I've got a parts mule if I run into problems. Even better, I now have 4x SD-22, 1x SD-24, 4x SD-26 and an SD-32 in an SD-30 enclosure I bought on ebay from Tek. It has the 2.8 connector and the scope reports it as a 32. My guess is it was a prototype to test whether changing the connector would increase the BW. I have a 2.8 to 3.5 adapter on it and that reduces the BW to the SD-30 spec. I've not done a detailed comparison and even if the parts are the same, the 32 may have required selecting the best parts.

author: amyk
author_rank: Super Contributor
timestamp: March 24, 2023, 02:58:14 am
content: If it's simple enough I'd not even bother with a PCB and just go for point-to-point wiring.

author: donlisms
author_rank: Frequent Contributor
timestamp: March 24, 2023, 11:11:09 am
content: That was good enough for Jim Williams.

author: n4u
author_rank: Contributor
timestamp: March 24, 2023, 11:16:28 am
content: When it works then its ok - dont bother in opinions. For low frequency cirsuit without care about noises u may even solder it all with wires without any other connections. As long as it meet the requirements its ok.

author: rhb
author_rank: Super Contributor
timestamp: March 24, 2023, 04:48:25 pm
content: Quote from: donlisms on March 24, 2023, 11:11:09 amIt did indeed. But there are not many in the Jim Williams or Bob Pease category. I have used the Williams-Pease style many times, but it's generally difficult to make significant design changes. Those usually require another board. But hey, if you can design the first transistor op amp in the breakroom at Fairchild over lunch on a visit from Philbrick where Bob worked at the time, neatness *doesn't* count ;-)BTW It was not an IC. It was discrete dies wirebonded together inside the can.Have Fun!Reg

author: ccktek
author_rank: Regular Contributor
timestamp: March 24, 2023, 06:43:45 pm
content: Another enthusiastic vote for Manhattan. You can quickly make pads of various sizes from PCB material with one of those inexpensive metal hole punch kits. The pads are glued down with superglue, ready for soldering in seconds. They can be removed with a sharp sideways tap with a screwdriver.https://www.amazon.com/ABN-Power-Punch-Heavy-Duty/dp/B07D7HJQ5Z/ref=psdc_2225057011_t1_B00OM4GVX0

author: edpalmer42
author_rank: Super Contributor
timestamp: March 25, 2023, 05:59:24 pm
content: As a Time-Nut, I needed a circuit that would square up an input signal and divide the frequency down to reduce the number of phase wraps. I used a piece of copper-clad board and dead bug components. It looks absolutely horrible!Then I tried to measure the Allen Deviation noise floor ...... okay, not so horrible after all!Ed