I’ve said it before, and I’ll say it again — it’s amazing to me how one thing leads to another in this life. Just a couple of weeks ago, for example, I posted a Cool Beans column on LED Effects with Toggle Switches.
The original idea was to prototype the effects I’ll be using with my Prognostication Engine. Each of the toggle switches and pushbutton switches on this bodacious beauty has two tricolor LEDs associated with it, which provides us with the ability to flaunt our creativity.
But then I started to think. What if we had only a single unicolor LED to accompany each toggle switch (just saying the words “single unicolor LED” brings a little tear to my eye, but I’m trying to be brave). The obvious solution is that if the switch is On or Off, we turn the LED On and Off, respectively. While functional, however, this would be a tad boring; surly we can add a little pizazz.
As a result of my cogitations and ruminations, I’ve started to write a mini-series of articles about these LED effects for my monthly column in Practical Electronics, which is the UK’s premier electronics / computing / maker / hobbyist magazine.
The first of these columns will introduce some of the effects we could implement using a single unicolor LED with our toggle switch (this column will appear in the March 2020 issue, which will hit the streets the first week in February). For your delectation and delight, I’ve launched a Cool Beans Blog YouTube Channel, and I just created this video showing the toggle switch and unicolored LED in action.
In subsequent columns, we will experiment with bicolored LEDs and tricolored LEDs, and also having two LEDs associated with each toggle switch, but we digress…
In a follow-up Cool Beans column, I introduced the LogiSwitch Arduino Uno Workbench Proto-Extender Kit in the context of my Prognostication Engine LED effect experiments. This led to a more in-depth Say “Hello” to the LogiSwitch Workbench column on Altium’s website.
This past weekend, I found myself with a little free time on my hands, so I decided to recreate an experiment that was originally performed by my chum Mike Pelkey, who is the creator of the Workbench board. Mike used his Workbench to drive three breadboards, each carrying nine LEDs. Not to be outdone, I decided to use 15 LEDs on each of my breadboards, giving me a grand total of 45 LEDs.
Yes, of course I created videos and uploaded them to the Cool Beans Blog YouTube Channel. I started with this video in which we connect the Arduino Uno to the breadboards using flying leads.
The problems with flying leads are that (a) things quickly get confusing and (b) when I’m moving stuff around I almost invariably inadvertently pull some of the leads, after which I spend an inordinate amount of time trying to figure out which leads go where. The solution is presented in this video in which we replace the flying leads with one of Mike’s Workbench boards.
The Workbench plugs into the Arduino Uno using standard footprint headers, thereby allowing us to plug more shields on top. The great thing is that the Workbench also brings all of the Arduino’s digital (D0 to D13) and analog (A0 to A5) input/output pins (plus 3V3, 5V, and GND) out to three of the board’s edges, from whence they can be made available to our breadboards. The result is to allow us to drive our 45 LEDs without using a single flying lead.
Even better, the Workbench itself comes equipped with three uncommitted LEDs and three uncommitted tactile momentary pushbutton switches. These switches are debounced using your choice of LogiSwitch.net’s LS18 or LS118 debouncer chips, whose operations are detailed in my recent Quit Bouncing Around column.
So, there you have it — a bunch of columns and a brand spanking new YouTube Channel. Are you as excited about all this as me? (Hint, the answer I’m hoping for is “Yes,” but please feel free to let your creative juices flow in the comments below.)
“single unicolor LED” that can be used to indicate ON/OFF by simply illuminating the LED or not, right?
Not so fast.
These days it is no longer fashionable to have an LED lit to indicate ON and unlit to indicate OFF. That would be too simple and pedestrian, and not waste any extra power.
Nowadays you need an OFF light illuminated, usually red, when the device is off. Or, at least, mostly off, since you need actual power to light the OFF light. You also need an ON light, usually green, to indicate “not OFF”.
As a wee engineer bairn I remember joking about adding an off light to products. Fellow designers would always chuckle as it usually was meant to poke fun at sales/marketing folks who were interested in new “features” that the competitors didn’t have, regardless of how engineeringly senseless (new term!) they were. It was a product differentiator and would force competitors to follow suit.
Now we have off lights as I’ve witnessed on many new model TVs.
I missed my calling. I should have gone into sales/marketing. Heavy sigh…
It does sound silly when you say “a LED to indicate the device is off” — but it can be handy. When I plug my power supply into the wall, I find it reassuring when its green LED lights up to indicate it’s seeing power. And when I plug the notepad into the power supply, the fact that a white LED illuminates tells me that it’s getting power.
To be honest, I had totally neglected to think about the use of a LED to indicate the overall system status — I’ve been thinking of them just in the context of switch-LED combos. I will touch on the system status part in my next column. Personally, I quite like a LED to indicate the system is off (but it has power and it’s ready to rock and roll)
The purpose of my articles in Practical Electronics is to explore the various possibilities. Currently we’ve looked at only a few effects using a single unicolor LED. There are a couple more effects using this setup I’ve been thinking of for my next column , after which we’ll move to bicolor and tricolor LEDs.
Power off LEDs are fair enough, they indicate that the equipment has power but is off, eg standby mode. With a two colour LED you can indicate 3 conditions: Power Off, ower On (Standby) and On (working). Show me a TV these days that does not have this!
I agree — furthermore, I like this approach. As I said in my previous comment, I’ve only been thinking in terms of a bunch of toggle switches, each with a unicolor LED — I’d completely forgotten to think about a separate “System LED” — I’ll be adding this to my next Practical Electronics column.
The TV in my bedroom has on and off indication. Fortunately they are two individual LEDs. I found the off one disturbed my sleep so it is now covered with black (to match the TV frame) electrical tape.