How To Select Just About Any Electronic Part

Sometimes you see an excellent post somewhere else on the web, and then discover that it is one of a series of similarly good posts that you completely missed when they were published. If you are a Hackaday scribe you are left wondering how you managed to pass them by, and then why on earth you didn’t think of writing them yourself.

Such is the case with [Sanket Gupta]’s excellent series for Octopart, of posts titled “How to select a…” and then a class of component. It was the latest, “How to select a voltage regulator” that caught our eye first, but then we found the previous installments dealing with capacitors, resistors, inductors, connectors, IC packages and MCUs. Each one provides a basic primer for the engineer, in terms of both parts selection based on capability and on suitability for manufacturing, and while you may think that only an inexperienced reader might find benefit in such pieces the reality is that everybody can learn something.

So if you are involved in choosing electronic parts, no matter at what level, take a look at this series. If you know everything [Sanket] has to say then we congratulate you on your mastery of the field, however we think most readers will find them to be an interesting and useful resource.

Header image: Kae [Public domain].

Make Your Own Reed Switches

[Lucid Science] shows us how to make some simple reed switches. Reed switches are simple components that detect a magnetic field and can close or open a circuit once detected. While not really a thing of beauty, these DIY reed switches should help you out if you just can’t wait to order some or you fancied trying your hands at making some components from scratch.

Reed switches normally come in very small form factors so if you need something small then this may not be for you however the video does show you on a macro scale the fundamental workings of a reed switch. To make your own reed switch you need only a few parts: some copper, enamelled wire and magnets. They really are simple devices however sometimes it’s easy to overlook how simple some things are when they are so small that you can’t really see how they work.

Making your own components from scratch is probably the best way to understand the inner workings of said component. In the past we have seen some pretty awesome self built components from these beautiful DIY Nixie tubes to even making your own LEDs

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Hacker’s Wishlist: What Must-Have Components Let You Build Anything?

We’re putting in a parts order at the end of the week, yet we don’t have a specific project in mind. Trying to wrap your noggin’ around a bill of materials to build anything is tough, but that’s the gist of stocking components for a hackathon.

So we put it to you: what components can’t you live without when you roll your sleeves up for some good old fashioned hardware hacking?

What Can You Build in Two Days?

multiplierThis parts order is for the badge hacking at this year’s SuperCon. What we saw last year was amazing considering the parts we had available. What you see above is the back of the conference badge with a lot of caps and diodes added to it. It’s a voltage multiplier that [Sprite_TM] built onto his badge to get the 9V input up to a 1000V output.

So diodes and caps, check. They’ll be on the order. But we want to know what you would add to a parts order where anything is possible? Let us know in the comments below.

Unlock Beast Mode

Part of the fun last year was starting from a badge that had no circuitry built onto it at all. [Brian Benchoff] joked in his coverage of the hacking that this year’s badge would just be a piece of copper clad FR4 — a great idea and challenge accepted. In addition to the normal badge, for those willing to test their mettle, we want you to go for Beast Mode. We’ll have copper clad (single and double-sided) and protoboard on hand.

We’re looking for Manhattan style, dead bug, and any other elegant, interesting, or hacky method of rapid prototyping. Bring along your own pre-spun or home-etched boards — if they’re not already populated you can do that in the badge hacking area. If you want to learn the awesome X-Acto knife method of carving up copper clad, Zach Fredin will be helping out in the badge hacking area. You’ll also find Voja Antonic, Paul Stoffregen, and others hanging out there too.

But What About the Badge?

2016-supercon-badge-circuitYes, there is a hardware badge and it’s a doozy this year. Voja Antonic designed it and published a great explanation last week. It’s based around a PIC18LF25K50 and features an LED Matrix and user inputs. This will be a lot of fun for the firmware hackers, but why not get in on the hardware hacking action while you’re at it?

The back of the badge has a 9-bin breakout header (2x 3V, 2x Gnd, 5x GPIO). This pin header is 0.1″ pitch so you can design in advance for any add-on circuits you might want to build. We’ll also have connectors on hand to use in your hacks.

Last year Paul Stoffregen’s Teensy audio workshop was hugely popular and one of the most interesting badge hacks added a Teensy, audio board, and LCD to the mix to create a spectrum analyzer with waterfall display. I’m sure we’ll see some hacks that reach that level this year. But it’s a welcoming and jovial environment; even if you never blinked an LED there will be throngs of people waiting to cheer your accomplishment in the name of getting everyone in the world excited about hardware.

Seriously Though, What Components Should We Order?

Tools are going to be no problem this year since we have the Supplyframe Design Lab at our disposal. But we really are putting in a parts order this week and need your advice. We’ll have the usual suspects: pin headers, shift registers, voltage regulators, level converters, 7400 series logic and 555 timers, extra battery holders, passives, etc.

Even if you’re not in on the hacking, let us know what you can’t live without. What’s your analog hacking wishlist? What type of sensor breakouts would you like to see people playing with? Sound off in the comments below.

Portable Workbench Crams An Entire Workspace Into One Box

Making on the go is sometimes required in today’s busy lives, and if you find yourself traveling — say, off to university like [ZSNRA] — then a convenient solution is required. To that end, a portable electronics workbench was built in the shape of a relatively nondescript plywood box.

Plywood and foam-core are the main materials used in building this maker’s bug-out box, with two fir runners along the bottom so the case is not resting on the hinges. Inside, [ZSNRA] has packed a staggering amount of hardware which results in an 11kg suitcase.

Power StackHere goes — deep breath now: wires, solder, resistors, transistors, capacitors, diodes, clips, switches, logic chips, non-logic chips, an Arduino, ATmegas, fuses, pliers, wire strippers and cutters, angle cutters, tweezers, a 66-piece screwdriver set, a desoldering pump, 12 needle files, a hacksaw blade, a multi meter, oscilloscope, power source, four outlets built into the case(!), steel wool, a third hand, a soldering station, two handbooks, and a breadboard.



The work surface is an ESD mat on the inside of the case’s front face that is comfortable enough to work with, though we are surprised that it doesn’t also fold out somehow to create an even larger work-space.

For an elegant — if slightly less mobile — workbench solution, check out The Tempel. Now if you’re looking for ideas on how and what to carry we still think [Kenji Larsen] has the ultimate hacking kit.

[Thanks for the tip, Zaphod! via /r/electronics]

Capacitors Made Easy The Hackaday Way

If you build electronic circuits on a regular basis the chances are you will have used capacitors many times. They are a standard component along with the resistor whose values are lifted off the shelf without a second thought. We use them for power supply smoothing and decoupling, DC blocking, timing circuits, and many more applications.

Different capacitor applications. By Elcap (Own work) [CC0], via Wikimedia Commons
Different capacitor applications. By Elcap (Own work) [CC0], via Wikimedia Commons
A capacitor though is not simply a blob with two wires emerging from it and a couple of parameters: working voltage and capacitance. There is a huge array of capacitor technologies and materials with different properties. And while almost any capacitor with the right value can do the job in most cases, you’ll find that knowing more about these different devices can help you make something that doesn’t just do the job, but does the best possible job. If you’ve ever had to chase a thermal stability problem or seek out the source of those extra dBs of noise for example you will appreciate this.

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Most Of What You Wish You Knew About Coils Of Wire But Were Afraid To Ask

If you are a novice electronic constructor, you will become familiar with common electronic components. Resistors, capacitors, transistors, diodes, LEDs, integrated circuits. These are the fodder for countless learning projects, and will light up the breadboards of many a Raspberry Pi or Arduino owner.

There is a glaring omission in that list, the inductor. True, it’s not a component with much application in simple analogue or logic circuits, and it’s also a bit more expensive than other passive components. But this omission creates a knowledge gap with respect to inductors, a tendency for their use to be thought of as something of a black art, and a trepidation surrounding their use in kits and projects.

We think this is a shame, so here follows an introduction to inductors for the inductor novice, an attempt to demystify them and encourage you to look at them afresh if you have always steered clear of them.

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The Curse Of The 40673: Zombie Components That Refuse To Die

As a fresh-faced electronic engineering student while the first Gulf War was raging in a far-off desert, I learned my way through the different families of 74 logic at a university in the North of England. 74LS was the one to use, the story went, because it’s quick and doesn’t use much power. At the time, there was an upstart on the scene: 74HC. Now that’s really quick. New. Exotic, even.

Thus an association was formed, when you want a quick logic function then 74HC is the modern one to go for. It could have been a lifelong love affair, but over twenty years, after many factors of speed increases and some RF tricks with gates we wouldn’t have dreamed of back then, it’s over. There is a whole world of newer logic families to choose from, and while HC is still good at what it does, it’s well past time to admit that it may just have been superseded.

40673s, probably now worth more by weight than anything else on four legs.
40673s, probably now worth more by weight than anything else on four legs. (Thanks are due to [Brandon Dunson] and Tanner Electronics)
 A tendency to cling to the past with logic families is pretty harmless. Like [Adam Fabio]’s TIP power transistors they’re pretty cheap, still very much in production, and still do most jobs demanded of them excellently. But what prompted this piece was a far more egregious example of an old component still being specified: the RCA 40673 dual-gate MOSFET. Launched in the mists of time when dinosaurs probably still roamed the earth, this static-sensitive four-pin TO72 found a home in a huge variety of RF amplifiers, oscillators, and mixers. It worked well, but as you might expect better devices came along, and the 40673 was withdrawn some time in the 1980s.

Unfortunately, nobody seems to have told a section of the amateur radio community about the 40673’s demise. Or perhaps nobody’s told them that many scrap analogue TV tuners of a certain age will yield a perfectly good newer replacement for free. Because even today, thirty years after the 40673 shuffled off this mortal coil, you can still find people specifying it. If you have a stash of them in your junk box, they’re worth a small fortune, and yours could be the bench with the throng of people at the next ham radio convention.

A different but equally annoying manifestation of the phenomenon comes when the device everyone likes to specify is not very old and very much still in production, but the designer hasn’t taken the time required to check for a cheaper alternative. Nobody ever got fired for buying IBM, they say, but perhaps they should be fired for specifying an AD8307 logarithmic amplifier in an amateur radio power meter. Don’t take this the wrong way, it’s a beautiful chip and probably a lot of work at Analog Devices has gone into laser-trimming resistors to make it perform to an extremely demanding specification. But eleven dollars for a chip? When a cursory search will turn up Maxim’s MAX9933 which does a perfectly good job in this application at well under two dollars? Someone isn’t doing their homework.

Sometimes there are components for which there are no perfect replacements. Germanium point-contact diodes, for example. 1N34As and OA91s are becoming like hen’s teeth these days, and though Schottky diodes can replace them in many applications, there are still a few places if you’re a radio person you’ll hanker for the original.  There are suppliers on Alibaba who claim to manufacture 1N34s, but the pictures always look suspiciously like 1N4148s, and anyway who can find a home for a hundred thousand diodes? (Hang on, this is Hackaday. There will be someone out there with a hundred-thousand-diode project, you can count on it.)

OK, maybe germanium diodes are an edge case and the examples above have a radio flavour, but you get the picture. What the full-blown rant in the previous paragraphs has been building up to is this: a plea for designers to do their homework. Please try to design every project for the next two decades, and as though any extras in the component price come from your company’s bottom line. (We’ll make exceptions for building something for which the whole point is a retro circuit. An Apple I replica like the Mimeo 1 needs old logic chips for artistic purposes.)

Is there a vital electronic engineering skill that’s being lost here perhaps? Back when the Internet was the sole preserve of boffins and Tim Berners-Lee hadn’t yet plugged his hypertext ideas into it, we relied on catalogs. Big paper-bound books the size of telephone directories were our only window into the exciting world of electronic components. If you’re an American yours was probably from Radio Shack, but for most UK-based hackers and makers who couldn’t get their hands on a commercial account from RS or Farnell that meant the Maplin catalogue. Before they moved in a consumer-electronics direction, they were a component specialist whose catalogue with its distinctive spaceships on the cover could be bought at large newsstands.

It’s difficult to describe the impact of electronics catalogues in the ’70s and ’80s to someone who has known only the abundance of information from the WWW. These publications were our only window into the world of electronic components. They contained significant excerpts from semiconductor data sheets, and we read their wealth of information from cover to cover. We knew by heart what each device was capable of, and we eagerly devoured each new tidbit of information as it arrived.

In short, when we specified a component, we did so with a pretty good knowledge of all the components that were available to us.

By comparison, nowadays we can quickly buy almost any device or component in production from a multitude of suppliers. There are millions more devices available, and if RS or Farnell don’t have the part then Mouser or Digi-Key are sure to provide. The WWW allows us to find what we need in short order, and the miracle of global distribution means that we can have it delivered within 48 hours almost wherever we live.

CPC's very aptly-named Big Book
CPC’s very aptly-named Big Book

Which means that all the new devices are available to us, but we’ve lost the ability to keep on top of them. We’ve become information rich, but knowledge poor. Printed catalogs still exist, but the sheer volume of information they contain forces brevity upon their entries and expands the size of the publication to the point at which it becomes an unwieldy work of reference. We therefore tend to stick with the devices and components we know, regardless of their cost or of whether they have been superseded, and our work is poorer for it.

We need to relearn the skill of inquisitiveness when it comes to the parts we use, and to rediscover the joy of just browsing, even if the medium is now a huge suppliers’ web site rather than a paper catalog. Otherwise we’ll still be looking at circuit diagrams containing 74LS logic and 40673 MOSFETs in the 2030s, and that can’t be a good thing!

There is of course also a slightly macabre alternative scenario. The highest online price we found for 40673s was over $30 each, so if a producer can make that kind of silly money then there’s a danger that RCA’s successors will see a business model in exhuming the corpse and re-animating it, thus ensuring that we’ll never be free of the undead. We need to make sure that doesn’t happen!

Zombie image credit: By Fabien Rougié (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons