标签: control

I was chatting to Daniel Guidera the other day. Daniel is the graphic artist who works with EE Times.   During our conversation, Daniel informed me that he's a member of a gaggle of graphic artists who search out, share, and discuss the graphical nuances of old adverts (hey, everyone is entitled to have a hobby).   A few days ago, Daniel shared this link from the History's Dumpster website, whose mission it is to save glorious trash, kitsch, music, fashion, food, history, ephemera, and other memorable and forgotten, famous and infamous pop culture junk of yesterday and today from the landfill of time...   The main topic of conversation was a TV remote control system called the ChannelScan, which you could use to jazz up an existing TV equipped only with an electromechanical channel selector knob. Although it may have been the height of sophistication in its day (I doubt it, but I'm prepared to give it the benefit of the doubt), in hindsight the ChannelScan really was a bit of a clunker. The hand-held controller was connected by a 25-foot wire to the actuator, which had to be physically attached to the VHF channel knob on the front of the TV. The actuator unit contained an AC-powered motor, which was used to turn the VHF channel knob.   It's not hard to imagine that having a 25-foot cable snaking its way across your family room was a recipe for "interesting times." I can easily visualize my dad and I watching a soccer game on TV and my mom sauntering across the room carrying some tasty treats when... ker-thump... food flying everywhere, plus we just missed the winning goal!   Actually, the history of TV remote controls is quite interesting. In the early days, different companies tried all sorts of weird and wonderful ideas based on the technologies available at the time. These systems included ultrasound (dogs hated this one) and visible light (so turning on a house light could trigger a channel change by mistake). Eventually, manufacturers moved to infrared and, more recently, wireless controllers.   Now, although we might smirk condescendingly at some of the early efforts, I'm here to tell you that they could be a real blessing to some users. I remember when I was about eight years old and my granddad (on my mom's side) had a stroke that completely paralyzed him down one side. (As an aside, there have been such amazing advances in recent years with regard to rehabilitating stroke victims that -- if we had known then what we know now -- my granddad might have been afforded an almost complete recovery.)   Since granddad couldn’t look after himself, he came to live with us. We only had a small "two up, two down" house, so we turned our dining room into granddad's living/sleeping room. My mom and dad purchased a second-hand black-and-white television to go in granddad's room (it was actually bigger and better than the one we had in our family room, but I'm not bitter LOL).   The problem was that this was the early 1960s and TV remote controls were rare items; I don’t think anyone in my family had actually seen one in the flesh, as it were. Thus, when granddad wanted to switch to another channel, he had to ask one of us to do it for him. This may not seem like a terrible burden, especially when you recall that we had only two or three channel options in those days of yore, but granddad was a "channel flicker" for his time -- he constantly worried that he was missing something interesting on "the other side" and he loved to switch back and forth between channels. Come on, admit it, you sometimes do the same thing, but it's a lot easier when you have a modern remote control in your hand.   My dad mulled over this problem for quite some time. I remember the day when he returned home from work carrying a 5-foot long wooden broom pole. Using his pocket knife, he whittled one end down to a 1/4" diameter pointer, and then he presented the finished product to granddad.   This may not seem like much when you hear me waffling on about it here, but I remember how this changed my granddad's life. You cannot imagine just how empowering this was; no longer did he have to ask for our aid -- he was the master of his own channel-surfing destiny -- the baron of broadcast; the king of communications; the emperor of entertainment; but we digress...   More recently, we have the concept of the "Universal Remote Controller." Don’t make me laugh! In our family room we currently have three large controllers -- one for the cable box, one for the television itself (for some reason the cable controller can't handle the TV's volume), and one for the DVD player. On top of that, we have two smaller controllers -- one for the Apple TV and one for the Amazon Fire TV Stick. And, now I come to think about it, we also have a bunch of Wii controllers scattered around.     There are another three controllers in our study, two in our bedroom, and I daren't even take a guess at the number of additional devices that are lurking around the house.   What's the answer to this madness? Well, I firmly believe that voice control is going to be the wave of the future, perhaps a more advanced version of the interface sported by the Amazon Echo (see also Have you heard of the Amazon Echo? ). And, if we look a little further out, I think this voice control will be augmented by embedded vision that supports capabilities like gesture control. Can you imagine being able to point at the TV and spread your fingers apart to zoom in on a particular play in a football match, for example; also to be able to pan around the screen, rewind, fast-forward, and zoom out again, all with a flick of a finger and a twist of the wrist?   As John Lennon might have said: "You may say that I'm a dreamer... but I'm not the only one..." What are your thoughts on all this? Will we one day be freed from the need to surround ourselves with a plethora of "Universal" remote controls, or are we destined to be obliged to move into larger houses just to have the room to store all of the little scamps we'll need to make it through the day?

Good grief--how time flies! I first determined to build my Bodacious Acoustic Diagnostic Astoundingly Superior Spectromatic (BADASS) display way back in the mists of time we used to call April 2014, so this project has already been running for around two thirds of a year.   On the one hand, this does seem like a rather long time. On the other hand, when I think of how much is involved, and also how I'm interleaving this with a bunch of other projects, it really doesn’t seem all that bad.   In this column I thought I'd bring you up to date with the current state-of-play, and also explain the comedy of errors I've been making recently. But before we plunge into the fray with gusto and abandon, on the off-chance you aren’t overly familiar with this project, the following table of article links will describe how we've gone from an initial concept like this...     ...to the present incarnation of my little beauty, which looks like the following (note that this image was taken in my driveway after I'd finished working on it this past weekend, which explains the houses in the background):   Phew! When I come to look back on all of these articles, I think it's amazing I've come as far as I have in only eight months (LOL). And so we come to the recent series of mishaps that I've been fighting my way through.   Here's the main cabinet sitting on our back porch. I brought it outside because -- for some reason -- I couldn’t manage to take a decent picture inside. I routed out the main panel in the middle, while my master-carpenter chum, Bob, made the surrounding cabinet.   I must admit that I was quite proud of this because it was the first time I'd ever routed anything. The only slight slip-up was the left-most vertical channel in which I set the jig up the wrong way, but since this won’t be seen by the user, I'm not losing any sleep over it.   In the image below we see the large display panel and the smaller control panel -- both made out of hardboard (pressed-board) painted to look like brass -- attached to the main front panel. This scene all looks so innocent, doesn’t it? In reality, however, there were numerous "gotcha's" that reared up to bite me.   Let's start with the display and control panels. Initially, I created these out of 1/8" hardboard, which I lovingly crafted to fit into my routed front panel. I'm not a woodworking expert, so this took me quite a lot of time. When it came to drilling the holes for the acorn nuts around the edges and the array of lenses in the middle, I worried that there would be small but annoying errors if I did this by hand. Thus, my chum Willie whipped up an engineering drawing to drive a CNC machine, and my friend David at a fabrication facility just down the road ran the panels through his machines.   Unfortunately... David made a similar mistake to mine -- he subtracted 7/32" instead of adding it to the 0,0 point, with the result that all of the holes ended up 7/16" out of whack.   "Oh dear," we both said (or words to that effect). This was a bit of a blow, and no mistake, but these things are sent to try us, so I got another piece of pressed board and we tried again. This time David drilled the holes first, and then carpenter Bob shaped the panels to match the routed areas.   Now I ran into a new problem, which was that the original hardboard was 1/8" thick, while the new sheet was 3/16" thick, which meant it protruded in front of the main front panel by 1/16" instead of being flush. "Oh, well," I thought, that doesn’t really matter. Actually, if the truth be told, having the display and control panels protrude by 1/16" actually looks rather good. "Things all work out well in the end," I said to myself, cheerfully, little realizing the horrors that were to come... Just to remind ourselves, we left the cabinet in the state shown below, with the display and control panels attached to the main front panel using brass acorn nuts. Ah, if only that were all that was holding things together. As fate would have it, however, before I attached the acorn nuts, I realized that the hardboard was bowing out a little in the middle. "I'll never need to take these panels off again," I thought, "so there won't be any problem if I glue them to the main front panel."   So that's that I did. I lay the whole cabinet on its back, glued the display and control panels in place (using the four corner bolts to lock in the alignment), and weighted everything down with books until the glue had set. Then I removed the books, stood the cabinet up, and attached the remaining acorn nuts and bolts, leaving things as shown above.   It was only then that I turned the cabinet around to look at things from a rear perspective. You can only imagine my disbelieving horror when I observed that the vertical channels I'd routed were obscuring the edges of the holes for the Fresnel lens/LED assemblies as shown below.   "Well, that's a tad unfortunate," I said to myself (or -- you guessed it -- words to that effect). Now, it wouldn't have been a major effort to widen these channels in the main panel using my router, if only some plonker hadn't gone and glued the display panel onto the main panel (sob sob).   This is where another Bob comes into the picture. (I'm like the little boy in The Sixth Sense movie -- "I see Bobs everywhere"). This Bob is ensconced in the office next to me. While I was bemoaning my fate to Bob, he explained that he is a master at making mistakes, which has helped hone his skills for rectifying them again. After I'd explained the problem, Bob helped me to devise a solution.   In the image below we see the simple jig Bob and I concocted to allow me to widen the channels without having to remove all of the acorn nuts and bolts. The router bit is set to such a precise depth that it completely removes the main panel material whilst leaving the rough backside of the hardboard totally unscathed.   Now we were really cooking on a hot stove, as it were. The following two images show the cabinet with its 16 x 16 = 256 array of Fresnel lens/brass washer assemblies attached (once again, both of these images were taken in my driveway after I'd finished working on my little beauty this past weekend, which explains the houses in the background).       Well, when I say "attached"... as fate would have it, there's a teeny-weeny problem. The body of each plastic Fresnel lens is threaded, and each lens comes with an associated plastic threaded ferrule-type thingamabob that screws on behind the panel to hold its lens in place.   Initially, I was thinking that these ferrules would be all I would need to attach the lens-washer assemblies to the display panel. The thing is that the brass washers hold the lenses a little way in front of the panel, so only a small portion of the threaded backside of the lens protrudes through the back of the panel. If only the panel were 1/16" inch thinner -- but no, some drongo had to go and replace the original 1/8" thick panel with a 3/16" version.   Isn't it amazing how little decisions can come back to bite one downstream in the development process? The end result is that I now need to glue the ferrules onto the backside of the lenses. The ideal adhesive should be something that works with hardboard and with different types of plastics (including PVC derivatives, which is what the ferrules appear to be made out of). This adhesive should be thin enough to be applied with a paintbrush or by dipping the end of the ferrule into it. It should give me a "work" time of say 20 to 30 minutes so I can pour some into a small bowl and work with it without it drying out too quickly. It should dry white or transparent so as to not absorb any of the light from the LEDs, and it should not dry brittle because I don't want it to crack if I move the cabinet around. Do you have any suggestions?   I don't know about you, but even with these little "gotchas," I think this BADASS Display starting to look very, very cool. The next step -- after I've finally fixed the lens-washer assemblies in place -- is to add the LEDs and the control electronics. I have all of this standing by. I really think there is a good chance I will have everything completed by the end of the Christmas holidays (apart from the final programming, of course). Watch this space for ongoing developments...

When I was 18 and my young brother Andrew was 5, I made a little control panel to keep him amused. This was in 1975, so the technology available to me was somewhat limited. All I had was a sheet of pressed board on to which I mounted a bunch of switches wired to little incandescent 6V bulbs mounted behind coloured plastic domes. I also had a small 1/4-inch reel-to-reel tape recorder. I used this to record things like a countdown along the lines of "Here we go on a mission to the moon... Commander Andrew James Maxfield is the pilot in charge... all systems are go... the countdown commences... 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, liftoff ." This was followed by lots of rocket-sounding noises. Andrew and I would sit under our parents' dining table draped with a large bedsheet (the table was draped, not me and Andrew), and we would play with this thing for hours. It's amazing to think back to a time when simply flicking a switch and seeing a coloured light turn on was such an interesting experience. The reason I'm waffling on about this is that I just saw the most incredible video on YouTube. I cannot imagine how long it took this guy to build this project for his son. What I do know is that, if Andrew and I had access to something like this back in 1975, we'd still be playing with it now. What do you think? Are you tempted to build something like this for one of your siblings, or perhaps for a niece or nephew?  

Several days ago, Eugene Polley (1915 – 2012) passed away. An engineer and engineering manager for Zenith Electronics, Eugene was most widely known for inventing the first wireless remote control for television. These days, younger folks take things like remote controls for granted, but it's not all that long ago that the entire idea seemed revolutionary. For example, when I was a kid of about six years old (circa 1963), my grandfather had a stroke, so he came to live with us. We only had a small house, so we turned the dining room into a bedroom for him. The stroke left granddad completely paralyzed down one side, which resulted in him spending most of his time in bed. This explains why we got the second TV in our house (black and white, of course), because this gave granddad something to do. On the front of the television were four push-buttons, which you used to swap channels. Actually, we had only three channels in those days, so the fourth button was a spare, I guess. We didn't have a remote control. I don't think my parents had even heard about such a thing. Instead, my dad purchased a wooden broom pole, which granddad used to push the buttons on the TV from the comfort of his bed. It's strange to think that this pretty much counted as state-of-the-art for those days. The thing is that I remember granddad being "as happy as a clam" because he could change the channel himself whenever he wished—he no longer had to request someone to do it for him, so this humble broom pole was empowering in its own way. I wonder what granddad would have thought about today's high-definition color televisions with their hundreds of channels. I also wonder what granddad would have thought about modern remote controls, which are jam-packed with buttons and functions. Last but not least, I wonder what Eugene Polley would have thought about The Clicker , which is an all-in-one uber-gadget that fuses the remote control with the ever-important bottle cap opener in one sleek device.     Described as being "Engineered to withstand the manliest of man caves and case after case of openings," The Clicker is programmed with over 800 factory pre-sets and works with almost all major cable and satellite dish boxes. The Clicker supports twin view and Picture-in-Picture functions for multiple game watching, and can be universally programmed for up to eight components, including your TV, DVD player, Cable box, DVR, Satellite, CD and AMP. Hmmm, I'm still trying to wrap my brain around this (grin).  

I've always considered system-level debugging as one of the most difficult engineering challenges. It requires experience and mentoring (neither of which you'll get in school); the ability to think both outside and inside the box; the stamina to examine and re-examine all your assumptions, data, and tests; and use of multiple disciplines as you work through a problem that may involve one or more of circuitry, software, and mechanical functions. And then there those dumb but simple problems that turn out to not be problems at all, just a misreading of the observed symptoms. I recently had some intermittent buttons on the keypad of a TV remote control—one of those $10 universal ones you can buy anywhere. Sure, I could have just tossed it out, but that's no fun. I had opened this one before, and the problem was one I've seen on many such remotes, cordless phones, and similar units. They use a keypad assembly made of conductive elastomer dots which are supposed to complete a circuit on the PC board. In time, the dots start oozing some gunk as the dot material begins to decompose, and the gunk inhibits any low-resistance circuit closure through the dot. I have a two-phase repair process: first, I clean the dots and the associated PC board with alcohol or degreaser. If that doesn't work, I glue small circles of aluminum foil onto each elastomeric contact, so real metal is now closing the circuit, while the gunk can no longer interfere. Sure, it's a lot of work, but it is oh-so-satisfying. But this last go-round had me puzzled for a few minutes. Here's why: I had the remote control mounted in an angled vise—the kind you use when working on PC boards—so it wouldn't move around as I worked on it. I went through my usual cleaning steps, and was ready for a check of all the keys on the unit. This remote control has a tiny LED in the upper corner, which flashes whenever you push any button, which gives a nice bit of user feedback, and is also handy for checking that I cleaned all the keys. Wait a moment: the LED was on, even when no keys were depressed. I figured that one or more of the keys was stuck "on", so I checked the PC board for shorts, a stray filament of wire, anything. Everything seemed OK. So, I next took out the battery (in preparation for some continuity checks with the ohmmeter), and the LED stayed on even then. This meant one of several things: perhaps the unit included a supercap along with the battery, or it had some sort of harvesting circuit—but those were unlikely in such a cheap, toss-away unit. Or I had found my path to fame and fortune, with an LED which was self-powered and needed no external source (infinite efficiency!), but that too was unlikely. Hmmm...maybe I was misinterpreting the situation? Then reality came, as I inadvertently moved my hand between my bench lamp and the remote control—and the LED went out. Long story short: that little LED was capturing and reflecting the illumination from the bench lamp, so it looked as if it was a light source, when it was not. Since the position and angle between the lamp and the LED was not changing, the LED was reflecting and thus "on" all the time. It was a simple optical effect, and the cleaned-up keys of the keypad were actually fine. The reason I didn't see the LED come on as each button was pushed was that the LED's internally reflected glow from the bench lamp was much stronger than the powered-on illumination of the LED; in effect, the LED's powered output was swamped by the reflection it was delivering (it's a variation of the theme of noisesignal). This is clearly a fairly trivial debug problem. While I assumed at first that it was a problem with the electronic circuitry, or mechanical buttons on the keypad, it was neither. Instead, it's another lesson for my learning-experience logbook, and fortunately it's a low-cost one. Have you ever had debug problems where the evidence and your assumptions proved to be way off from the reality? And how did you find out?