Cons of SMD adapters in breadboards  - Page 1
Forum section: electronics / beginners

author: Pahriuon
author_rank: Newbie
timestamp: December 22, 2016, 04:52:42 am
content: Hello y'all,How are you guys doing?I have a general question regarding using SMD adapters and breakout boards on breadboards, have you ever faced any issues with them? Did the circuit behave in a highly unusual way?

author: suicidaleggroll
author_rank: Super Contributor
timestamp: December 22, 2016, 05:09:31 am
content: All sorts of things can go wrong, mostly due to lack of adequate decoupling for the IC (most want the decoupling cap very close to the power pins, not really possible with a big breakout board, legs into a breadboard, over to a through hole MLCC somewhere nearby) and a lot of capacitance on the breadboard contacts. The decoupling problem can affect anything, the breadboard capacitance typically only affects high speed (eg: >10 MHz) circuits.

author: Kleinstein
author_rank: Super Contributor
timestamp: December 22, 2016, 07:28:10 am
content: Because of the decoupling problem one should have decoupling cap(s) directly soldered on the adapter board, even if this mean using a wired cap soldered just on top.Even if not absolutely needed (e.g. only slow OP) on the adapter it comes handy to have decoupling on the adapter, as it leaves more space on the breadboard and less things to go wrong. For breadboard I have a DIP LM324 with decoupling directly soldered to the chip. I should do that with a few of the DIP8 too.The normal header pins are quite large and thus cause some stress to the breadboard. Thinner pins might be better, but are more expensive and not that easy to get.

author: Pahriuon
author_rank: Newbie
timestamp: December 22, 2016, 09:59:34 am
content: Quote from: Kleinstein on December 22, 2016, 07:28:10 amYou're talking about the adapter pins right? Or male pins that you buy separately and solder to the adapter and then attach the whole thing to the breadboard?

author: KL27x
author_rank: Super Contributor
timestamp: December 22, 2016, 09:44:21 pm
content: Yeah, 100 mil spaced square header pins are pretty standard in size, about 25 mils, square. This is actually lots thinner than say leads on TO220 and whatnot. Personally, I have only had problems with breadboards when stuffing in such things as large leads.If breadboard has problem with 25 mil square pins, buy a better breadboard. This size pin is staple for breadboarding/prototyping in my shop. My breadboards all handle standard pin header and will still contact IC legs, no problem. I try to avoid stuffing anything bigger than 25 mils, though. The larger and flat component leads will often be bent, or twisted 90 degree, to go in sideways.One con is breadboard space. Oftentimes, the adapter is going to cover some of the available holes. On my SMD adapters I make habit to use extra long header pins sticking up thru the pcb. I usually use wire wrap to jumper connection on the breadboard. Even if you do not, the long pins sticking up give you somewhere to clip a probe. And eventually, one day you will find a need for more spot to make multiple connections. Same thing with any temporary pin header cable I might make for prototyping. Long pins sticking out both directions. This way, when the cable is plugged into programmer/logic analyzer, etc, I can clip scope probes or add more wire wrap connections on that end, too.

author: TheDane
author_rank: Regular Contributor
timestamp: December 23, 2016, 11:03:37 am
content: If I breadboard a prototype, I think of the adapter board like an expansion card in a PC.Decoupling of supplies, impedance matching of (high speed) I/O signals, ground plane/current loops in the entire system, fuse, close surge/voltage protection if extra ESD sensitive, mechanical robustness so the prototype can be handled somewhat roughly (by others than me, or moved/stored and 'forgotten' about - until possibly worked on again) - yeah, accidents and yanks happenBuilding something on a PCB isn't the same as building it apart - that's what EMC is all about. Practice and testing is a great way to learn, but it takes time and costs- SMD adapters are a great way of using really tiny components (that might not even be avaliable in leaded versions) in a design - and I have a lot of different sized boards that, if something blows - are easier to repair, rather than take a crack at a whole breadboard assembly moving parts, etc.There are pro's - and then there are con's./<--->