So Where’s My Low Voltage DC Wall Socket?

What are the evocative sounds and smells of your childhood? The sensations that you didn’t notice at the time but which take you back immediately? For me one of them is the slight smell of phenolic resin from an older piece of consumer electronics that has warmed up; it immediately has me sitting cross-legged on our living room carpet, circa 1975.

"Get ready for a life that smells of hot plastic, son!" John Atherton [CC BY-SA 2.0], via Wikimedia Commons.
“Get ready for a life that smells of hot plastic, son!” John Atherton [CC BY-SA 2.0], via Wikimedia Commons.
That phenolic smell has gone from our modern electronics, not only because modern enclosures are made from ABS and other more modern plastics, but because the electronics they contain no longer get so hot. Our LCD TV for instance nowadays uses only 50 watts, while its 1970s CRT predecessor would have used several hundred. Before the 1970s you would not find many household appliances that used less than 100 watts, but if you take stock of modern electrical appliances, few use more than that. Outside the white goods in your kitchen and any electric heaters or hair dryers you may own, your appliances today are low-powered. Even your lighting is rapidly being taken over by LEDs, which are at their heart low-voltage devices.

There are many small technological advancements that have contributed to this change over the decades. Switch-mode power supplies, LCD displays, large-scale integration, class D audio and of course the demise of the thermionic tube, to name but a few. The result is often that the appliance itself runs from a low voltage. Where once you would have had a pile of mains plugs competing for your sockets, now you will have an equivalent pile of wall-wart power supplies. Even those appliances with a mains cord will probably still contain a switch-mode power supply inside.

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How Has Amazon Managed To Make Hackers Love Alexa?

Our hackspace has acquired an Amazon Dot, courtesy of a member. It mostly seems to be used as a source of background music, but it has also spawned a seemingly never-ending new entertainment in which the hackspace denizens ceaselessly bait their new electronic companion with ever more complex and esoteric requests. From endless rephrasing and careful enunciation of obscure early reggae artists to try to settle a musical argument to hilarious mis-hearing on the part of our silicon friend, the fun never stops. “Alexa, **** off!” it seems results in “I’m sorry, I can’t find a device of that name on this network”.

amazon-dot-always-listeningThat is just the experience of one hackspace, but it evidently does not end there. Every other day it seems that new projects using Alexa pass through the Hackaday timeline, so it looks as though Amazon’s online personal assistant has been something of a hit within our community.

Fair enough, you might say, we’re always early adopters of any new technology. But it’s a development over which I wonder; am I alone in finding it surprising? It’s worth taking a moment to look at the subject.

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Detecting Water With and Without Headaches

In Texas — at least around Houston — we don’t have basements. We do, however, have bilges. Both of these are subject to taking on water when no one is paying attention. A friend of mine asked me what I thought of an Instructable that showed how to make a water sensor using a few discrete components. The circuit would probably work — it relied on the conductivity of most water to supply enough current to a bipolar transistor’s base to turn it on.

It is easy to overthink something like this, so I told my friend he should go with something a little more old-fashioned. I don’t know the origin of it, but it is older than I am. You can make a perfectly good water detector with things you probably already have around the house. My point isn’t that you should (or shouldn’t) construct a homemade water sensor. My point is that you don’t always need to go to the high-tech solution.

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My Beef with Ham Radio

My amateur radio journey began back in the mid-1970s. I was about 12 at the time, with an interest in electronics that baffled my parents. With little to guide me and fear for my life as I routinely explored the innards of the TVs and radios in the house, they turned to the kindly older gentleman across the street from us, Mr. Brown. He had the traditional calling card of the suburban ham — a gigantic beam antenna on a 60′ mast in the backyard – so they figured he could act as a mentor to me.

Mr. Brown taught me a lot about electronics, and very nearly got me far enough along to take the test for my Novice class license. But I lost interest, probably because I was an adolescent male and didn’t figure a ham ticket would improve my chances with the young ladies. My ham ambitions remained well below the surface as life happened over the next 40 or so years. But as my circumstances changed, the idea of working the airwaves resurfaced, and in 2015 I finally took the plunge and earned my General class license.

The next part of my ham story is all-too-familiar these days: I haven’t done a damn thing with my license. Oh, sure, I bought a couple of Baofeng and Wouxun handy-talkies and lurked on the local repeaters. I even bought a good, solid HF rig and built some antennas, but I’ve made a grand total of one QSO — a brief chat with a ham in Texas from my old home in Connecticut on the 10-meter band. That’s it.

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Sensing a Magnet with Local Sourcing

I had a small project going on–never mind exactly what–and I needed to detect a magnet. Normally, that wouldn’t be a big problem. I have a huge hoard of components and gear to the point that it is a running joke among my friends that we can be talking about building something and I will have all the parts we need. However, lately a lot of my stuff is in… let’s say storage (again, never mind exactly why) and I didn’t have anything handy that would do the job.

Options

If I had time, there are plenty of options for detecting a magnet. Even if you ignore exotic things like SQUID (superconducting quantum interference device) there’s plenty of ways to detect a magnet. One of the oldest and the simplest is to use a reed switch. This is just a switch made with a thin piece of ferrous material. When a magnet is nearby, the thin piece of metal moves and makes or breaks the contact.

These used to be common in alarm systems to detect an open or closed door. However, a trip to Radio Shack revealed that they no longer carry things like that as–apparently–it cuts into floorspace for the cell phones.

I started to think about robbing a sensor from an old computer fan or some other consumer item with a magnetic sensor onboard. I also thought about making some graphene and rolling my own Hall effect sensor, but decided that was too much work.

Browsing

I was about to give up on Radio Shack, but decided to skim through the two cabinets of parts they still carry just to get an idea of what I could and could not expect to find in the future. Then something caught my eye. They still carry a wide selection of relays. (Well, perhaps wide is too kind of a word, but they had a fair number.) It hit me that a relay is a magnetic device, it just generates its own electromagnetic field to open and close the contacts.

I picked up a small 5 V reed relay. They don’t show it online, but they do have several similar ones, so you can probably pick up something comparable at your local location. I didn’t want to get a very large relay because I figured it would take more external magnetic field to operate the contacts. You have to wonder why they have so many relays, unless they just bought a lot and are still selling out of some warehouse. Not that relays don’t have their use, but there’s plenty of better alternatives for almost any application you can think of.

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You Can Have My LM386s When You Pry Them From My Cold Dead Hands

Everyone has a chip-of-shame: it’s the part that you know is suboptimal but you keep using it anyway because it just works well enough. Maybe it’s not what you would put into a design that you’re building more than a couple of, but for a quick and dirty lashup, it’s just the ticket. For Hackaday’s [Adam Fabio], that chip is the TIP120 transistor. Truth be told, we have more than one chip of shame, but for audio amplification purposes, it’s the LM386.

The LM386 is an old design, and requires a few supporting passive components to get its best performance, but it’s fundamentally solid. It’s not noise-free and doesn’t run on 3.3 V, but if you can fit a 9 V battery into your project and you need to push a moderate amount of sound out of a speaker, we’ll show you how to get the job done with an LM386.

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Crypto Features: They’re Not For Girls

If you have worked in an office that contained a typewriter, the chances are you’ve been in the workplace for several decades. Such has been the inexorable advance of workplace computing. It’s a surprise then to discover that one of the desirable toys from many decades ago, the Barbie Typewriter, is still available. Are hipster parents buying toy versions of vintage office machinery for their children to use in an ironic fashion?

Gone though are the plastic versions of mechanical typewriters that would have been the property of a 1970s child. The modern Barbie typist has an electronic typewriter at her fingertips, with a daisy-wheel printer. We’re treated to a teardown of the recent models courtesy of Crypto Museum, who reveal a hidden feature, Barbie’s typewriter can encrypt and decrypt messages.

Now the fact that a child’s toy boasts a set of simple substitution cyphers is hardly the kind of thing that will set the pulses of Hackaday readers racing, after all simple letter frequency analysis is hardly new. But of course, the Crypto Museum angle is only part of this story.

This toy is made in a suitably eye-watering shade of pink, and sold by Mattel with Barbie branding. But it didn’t start life as a Barbie product, instead it’s licensed from the Slovenian manufacturer Mehano. The original toy makes no secret of the crypto functions, but though they persist in the software on the Barbie version they are mysteriously absent from the documentation. The achievements of American women are such that they have given us high-level languages and compilers, or their software has placed men on the Moon, yet it seems when they are young a brush with elementary cryptology is beyond them in the way that it isn’t for their Slovenian sisters. This is no way to nurture a future Grace Hopper or Margaret Hamilton, though sadly if your daughter is a Lisa Simpson this is just one of many dumbed-down products she’ll be offered.

If you see a Barbie electronic typewriter in a yard sale or similar, and you can pick it up for a few dollars, buy it. It’s got a simple daisywheel printer mechanism that looks eminently hackable. Just don’t buy it for your daughter without also printing out the Crypto Museum page for her as the missing manual.

When the Martian lander running her code has touched down safely, you’ll be glad you did.

Via Adafruit.