I’ve mentioned it earlier than, and I’ll say it once more, it’s a humorous outdated world, and no mistake. Once I first commenced writing Half 1 of this ever-growing mini-series, for instance, I actually anticipated to cowl every part I wanted to say in a single column. By the point I reached the top of that column, nevertheless, I knew there was going to be a Half 2.
It was solely after I was in the course of Half 2 that I noticed we had been destined to see Half 3, and—to be trustworthy with you—at this stage within the proceedings I don’t see how we are going to escape a Half 4. On the intense facet, I’m actually having fun with this collection. I solely hope you’re having as a lot enjoyable as me.
Earlier than we proceed, in case you are a grizzled curmudgeonly outdated engineer who has served your time within the trenches, because it had been, you might really feel the next is just too “light-weight” to warrant a spot on the illustrious Design Information web site. I urge to disagree for a number of causes. Let’s begin with the truth that Design Information is dwelling to a variety of group members, a lot of whom are simply beginning out of their careers. Additionally, it scares me what number of digital engineers come out of school with out having ever wielded a soldering iron in anger. These are the parents who will actually profit from the easy suggestions and methods proven right here.
On the finish of my earlier column, I introduced you with a poser. This began with my displaying an image of a portion of a breadboard circuit that includes two teams of eight 150-Ω resistors together with their full-length leads plugged straight into the breadboard. I’ve included a barely totally different view of those resistors within the picture beneath.
Two teams of eight resistors. CLIVE “MAX” MAXFIELD
Subsequent, I posed two questions. First, I requested when you may envisage any potential issues which may come up from doing issues this manner? The reply to that is easy-peasy lemon squeezy. It’s not unusual for somebody to brush towards one of many flying leads or for one thing else to happen that causes two or extra of the resistor’s results in contact. This will result in some very fascinating (usually intermittent) errors which can be a ache within the nether areas to debug.
Second, I requested when you may consider a cheap-and-cheerful resolution that will make issues neater and fewer liable to failure whereas additionally providing the chance to hurry up future prototyping tasks. The reply to that is the subject of this column.
One resolution is to buy pre-packaged resistors introduced in twin in-line (DIL) packages. For instance, contemplate the Bourns 4100R Sequence units. In case you take a look at the 4100R Sequence Information Sheet, you will note that these can be found with totally different numbers of resistors in quite a lot of configurations (remoted resistors, bussed resistors, and twin resistors).
Those we’re fascinated about right here could be eight remoted resistors in a 16-pin DIL package deal. These definitely present the smartest resolution for what we’re doing, however they aren’t the most affordable choice with regards to prototyping. Additionally, they provide solely a comparatively restricted variety of resistance worth choices. As destiny would have it, no matter worth I’m hoping for is usually not a type of which can be out there.
However flip that frown the other way up right into a smile as a result of there’s another choice. In earlier columns, I’ve talked about my good friend, Joe Farr, who hails from a small village outdoors of London. Joe is a whizz with respect to each {hardware} and software program. He’s constructed an electronics workshop in his again yard that has me drooling with envy.
One cause I really like chatting with Joe is that I all the time be taught one thing from him. For instance, after I confirmed him the image of the breadboard with all of the resistors, he mentioned that if he’s ever doing something a couple of time, he sometimes solders these parts onto a small breakout board (BOB).
Joe prompt that that is what I ought to do with my resistors, in order that’s what I did. The 2 predominant choices begin by taking a chunk of stripboard or prototyping board. I opted for the latter on this case, thereby saving myself from having to chop any tracks utilizing a utility knife or a particular stripboard monitor chopping instrument.
We’ve got two predominant choices at this level. We will both use a fine-toothed hacksaw to chop the board between the rows and columns of holes (see [a] within the picture beneath) or we are able to use a utility knife to attain the board alongside the suitable columns and rows after which snap it alongside the rating marks (see [b] within the picture beneath).
Sizing the board. CLIVE “MAX” MAXFIELD
I opted for the later strategy on this case. Whichever method you utilize, it doesn’t damage to run a file over the perimeters to easy issues out a tad.
The subsequent factor we’re going to want is a few 0.1 in. pitch header pins which can be long-tailed on each side. These stick out 6.25 mm on each side with a 2.5-mm piece of plastic within the center, making them 15-mm lengthy in complete.
The picture beneath exhibits two 8-pin strips of those header pins, two particular person pins, our cut-down piece of prototype board, eight 150-Ω resistors, and a small breadboard. You wish to use an outdated breadboard for this form of factor as a result of flecks of solder and fragments of wire can get caught within the holes. These may cause all types of issues when you subsequently attempt to use the breadboard to implement a working circuit, so it’s best to mark the board “NOT FOR USE!” (I simply did this to my very own board whereas I used to be excited about it.)
Making ready the elements. CLIVE “MAX” MAXFIELD
What are the 2 particular person header pins for? I’m glad you requested. I used these pins to create a bit jig to bend my resistor leads as proven within the picture beneath. The way in which I’m bending my pins, it’s loads simpler to take action on this 2-pin jig than it might be on the 16-pin rig with which the opposite pins are likely to get in your manner.
Making ready the elements. CLIVE “MAX” MAXFIELD
As soon as we’ve gathered all of the elements, the following step is to plug the 2 8-pin strips both facet of the breadboard’s centerline as proven above. Additionally, insert the 2 single pins towards the opposite facet of the board, together with a little bit of “spacer board” (which I forgot to point out).
Jig to bend resistor leads. CLIVE “MAX” MAXFIELD
Observe that I additionally employed a skinny strip of prototyping board underneath the resistor on the 2-pin jig to maintain the header pins separated. Truly, the best way wherein you bend your wires is one other resolution you’ll have to make. As you possibly can see within the picture above, my private selection is to go for full loop.
We are going to return to this consideration in a second, however first we should make a small digression as a result of this subsequent level is VERY IMPORTANT. You could be tempted to solder each the breakout board and the resistors to the header pins on the identical time. DO NOT DO THIS! It’s extraordinarily necessary to solder the breakout board first as illustrated within the picture beneath.
Solder the breakout board first. CLIVE “MAX” MAXFIELD
Whereas soldering the breakout board, you wish to use a fairly scorching soldering iron and let the solder wick (get sucked via) the through all the best way to the opposite facet. In case you attempt to solder the resistor on the identical time, you might discover the solder doesn’t penetrate during the board. On this case, while you plug the board into your mission breadboard, you might discover the header pins separate from the breakout board (unhappy face).
Whereas I consider this, when you haven’t soldered earlier than, however when you really feel you’d wish to dip your toes into the soldering waters, then could I make so daring as to recommend an ideal e book known as The Fundamental Soldering Information Handbook that was written my good good friend Alan Winstanley.
OK, now let’s return to the subject of bending the resistor wires. As soon as we’ve soldered the header pins (see [a] within the picture beneath), one choice is to easily bend the resistor leads at 45°, solder the resistors to the header pins, and snip off any extra lead (see [b] within the picture beneath).
Which manner do you bend? CLIVE “MAX” MAXFIELD
An alternate is to twist the leads via a full 360° circle, solder the resistors to the header pins, and snip off any extra lead (see [c] within the picture above). In both case, I might solder the resistors from the underside (that’s “backside” within the context of those diagrams) as a result of—based mostly on the best way I maintain my soldering iron—this retains current joints out of the best way of recent ones.
Which of those strategies is finest? That relies on what you imply by “finest.” Joe favors the 45° bend method as a result of he all the time thinks by way of remodeling issues, which is a standard prevalence when you find yourself prototyping. The 45° bend makes it less complicated to organize and solder, and simpler to take away if required later.
By comparability, I are likely to favor the complete 360° circle strategy as a result of my mindset tends towards mission-critical and safety-critical functions wherein “failure just isn’t an choice,” as they are saying. On the draw back, this strategy takes longer to organize, it will increase the possibility of forming undesirable solder bridges with adjoining pins as a result of the joint is larger, and it’s much less amenable to being reworked. Alternatively, that is one solder joint that isn’t going to fail simply.
As Joe sagely says: “To every is personal.” It’s exhausting to argue with logic like that. My completed eight x 150-Ω resistor breakout board is proven beneath (I’m sorry concerning the fuzzy picture).
Eight x 150-Ω resistor breakout board. CLIVE “MAX” MAXFIELD
Along with being cheap-and-cheerful, some great benefits of this strategy embody the truth that you should utilize the precise element values you want, and you’ll mix-and-match values when you want. You aren’t going to have issues with resistor leads touching one another, and you’ll shortly swap one breakout board for an additional if the necessity arises. In my case, for instance, I would determine to modify to a 7-segment show whose LEDs have a special ahead voltage drop, thereby requiring me to change the values of my current-limiting resistors. Talking of which, the picture beneath exhibits my spiffy new breakout board (higher right-hand nook) within the context of the clock mission I’m at present creating.
CLIVE “MAX” MAXFIELD
Properly, that’s all for now. Till subsequent time, I welcome your insightful feedback, penetrating questions, and sagacious strategies. Additionally, you probably have any breadboarding suggestions and methods you’d care to share, please be at liberty to e mail me at [email protected].
