Techniques and Strategies for Building Electronic Circuits

this video is about developing techniques and strategies for prototyping electronic circuits its surface mount I can barely see this stuff anymore I've been building these electronics prototypes for decades and for sure they're not getting any bigger you got to learn how to work with this stuff that little sensor that you fell in love with it's probably only available in surface mount you've got no choice you got to find ways to deal with this stuff here's an example of a project that I did for a client that had a super crazy tight timeline I had to finish this faster than fast so I got my board designer working on the circuit board he's doing all surface mount layout it's gonna be a tiny little thing at the same time while he's working on that I'm building this I get the same surface mount parts that I really need to test I make my own homemade scratch-and-sniff circuit boards lay delve all on there check out that those blocks work combine it on this bigger board with my microcontroller which is through-hole so I can probe it I can connect to it I can get to things but at the same time I'm checking out the real design so when I get this working I know that the circuit board that my designers building is going to work because I've validated the hardware I've actually even written the code before I even get my first circuit board back I slash the development time of the whole project probably in half what we really need is a super quick and super cheap way to make little tiny surface mount boards to solve our problems now not in three days not in two weeks but now basically get it done so you can finish your project no waiting now I'm going to show you exactly how to do it let's take a dirt cheap and ubiquitous exacto blade and transform it into an awesome specialized tool take your dremel tool and grind the sharp side down completely dull cut off the tip at an angle your blank should look like this grind a relief into the flat backside finish it to look like this with a nice hook shape and a sharp V point test it out on a piece of blank circuit board it should cut clean and easy it's easy to resharpen it over and over if it gets dull here's where this technique really shines I had to work with these microchip MCP 9700 temperature sensors which come in this ridiculously small five pin SC 70 package a grain of rice Dwarfs this part it was totally impossible to work with this unless I made some kind of adapter board in about 10 minutes I was able to create this adapter board that made working with it convenient and easy problem solved once you have finalized your schematic design it's time to build you need to totally agonize over the data sheets confirm the pin layout of every part really carefully lay out your board using straight lines these are the easiest to cut each island becomes a node in your circuit place the components to make the best use of these islands for circuit nodes that require jumpers leave enough room to comfortably solder a jumper don't leave any floating nodes connect any large unused copper areas to ground use your magic scratching tool to cut through the copper be sure to completely isolate each Island use a constant gentle pressure increase the pressure if it's not cutting all the way through the copper use your continuity tester to check that there are no shorts before you move on use steel wool to bring the copper to a shine scrub the board in two directions this helps remove any tiny copper hairs that could short the board before you solder any parts on thoroughly check every island for shorts this is critical you don't want to find a short after soldering parts onto the board what's the board thoroughly don't be shy place a small blob of solder on one side where each part sits on the board using tweezers to hold the parts remelt each solder blob and ease the part down into position don't move until the solder is cooled the part does not lie flat gently push it down with the tip of your tweezers while reheating the solder joint hold it until the solder cools parts with polarity like LEDs and Diet should be checked before installation for correct orientation once you have all the parts placed go around and solder all the leads on all the parts Brij unwanted cuts with small pieces of wire install jumper wires nose is required install teflon tubing over the wires after soldering one end in place Tinh the other end of the wire and solder it to the other node you test your board when all connections have been completed give it a good cleaning with isopropyl alcohol test it again to make sure everything is good I tend to avoid solderless breadboards for all but quick tests and simple circuits they become a total fail as soon as you encounter high currents high frequencies or any significant complexity when you have hundreds of connections the low reliability of the spring contact starts to really become problematic you already have enough to think about why ad nightmarish flaky connections to the mix I always have a big stock of both 1/32 inch and 1/16 inch double clad fr4 PC board material the thin stuff is great for small adaptor boards and modules that you intend to stick on a bigger board it's also really easy to cut the thicker 1/16 material is great for larger boards perforated breadboard is great for building super robust and reliable circuits that can operate for years there are two kinds of perforated board copper clad and Baer I use both types with 40 thousands holes on one hundred thousand centers this fits the standard dip IC package anytime you have high currents high frequencies or small signals which these days is most of the time a board made where the ground plane will always perform better saving you from a lot of potential nastiness I tend to overdo this a little with my prototypes but it's good practice to get in the habit of building and thinking this way overdoing it causes no harm this may seem counterintuitive but I like to build my boards with a ground plane on the top this makes wiring on the bottom easier as there is less chance for things too short to make this work you must relieve the copper around any hole that passes a component lead or wire this is mandatory but really easy just take a small drill and manually cut a small ring of copper away from the holes with your finger don't be tempted to use a power drill here bad idea wire wrap has been around forever but seems to be waning in its popularity but it's still a great technique especially when building high pin count digital stuff with lots of ICS wire wraps sockets have square pins that bite into the wires it wraps around creating gas tight super reliable connections in the process if you must wrap around pin solder it to be sure wire wrap wire is also a lifesaver when you need to solder wires onto something really small kind our insulated number 30 gauge wire is tiny and soldered really well the insulation also holds up to soldering note that wire wrapped wire is good to about 1 amp maximum surfboards allow you to mount fine pitch surface mount parts and wire to them at a much larger physical pitch in the zone where our fat sausage fingers are workable these surfboards come in all sizes and shapes stock up on these so you have them at the ready I often use copper shielding tape to create power buses or heavy current traces on my boards place these on the bottom of your board is needed make lap joints by overlapping the tape be sure to rub down the tape with a plastic pen capped or really stitch it down well solder over the joints to make that solid connection be careful not to overheat the tape as the adhesive melts at low temperature pierce the foil from the copper side before you try to insert a part lead or pin then solder them in place teflon tubing is a wonderful thing it's so much easier to cut a little piece of teflon tube with a razor than it is to try to strip a tiny length of hookup wire the best part is that teflon doesn't melt you can solder the hell out of it and it remains pristine rather than melting into a wad of goop use clean bare 24 gauge copper wire to make your point-to-point connections slip teflon tubing on wherever there is a danger of shorting it's easy to slip tubing over component leads as well use rosin core 60/40 tin-lead solder for prototypes it just performs so much better when doing handwork than the lead-free stuff a temperature controlled soldering iron is a must overheating is the quick way to ruin stuff flux is your friend it always improves the behavior of any soldering operation just be sure to clean it off with alcohol when you're done it gets harder to clean with every hour you leave it there it can also cause subtle problems by creating leakage paths on you bored which can make high impedance circuits like crystal oscillators fail to work properly standardize your breadboard interconnects with a hundred thousandths of an inch pitch pin type connector system I like the molex KK 254 connector system it's a really good compromise on a lot of levels collect a kit of headers and housings in a few different pin counts 2 4 6 8 12 and 20 pins is a good start by the fancy expensive crimper by the manufacturer there is no alternative if you really want to make a reliable connection it's going to be painfully expensive but anything else is going to be totally blanking definitely think about reducing your mental workload at all times when you're developing a hardware you're gonna cycle back and forth between testing and fixing your Hardware over and over and over again every time you do this you're gonna be wasting time if you have to unscrew a bunch of stuff and spend a lot of time putting it all back together when you're done when you put it all back together and you're about to throw that power switch and you feel the anxiety in your guts that's because there's way too much going on you need to simplify that process add labelled connectors so all you have to do is just plug things in the way they were before and turn it on and you don't have to have that anxiety that it's going to blow up because you you mixed up the wires because that's always what happens too many connectors too many little screw terminals and if you have to put those back every single time you're gonna get it wrong and you're gonna blow up the hardware and it's gonna happen at the worst possible time and you're gonna hate yourself for it when you're designing and building stuff it's really smart to think modular after all electronics is all just a bunch of blocks anyway so when you're going to build something break out those blocks build and test them separately make sure that they're good and then combine them together onto a motherboard as known-good entities you'll save yourself eons of time fiddling around with things that don't work the way you expected thanks for watching hope you enjoyed and learned please like and subscribe

Channel: Leo's Bag of Tricks

Views: 20,800

Rating: 4.9818869 out of 5

Keywords: prototypes, electronic design, DIY, money saving, time saver, fabrication, Printed circuit board, product design, product development, engineering, rapid prototype, tips, tricks

Id: vq968AFgPhg

Length: 14min 11sec (851 seconds)

Published: Wed Feb 26 2020

Reddit Comments

[u/[deleted]]

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[u/amazingsynth]

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[u/mud_tug]

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