Here we have a square LED clock kit. Square not because it's so much more interesting than circular, but because there is no way I could have designed it to fit in 60 LEDs going around the circumference of a circle inscribed in a 5 cm square, it was a very close thing as it was, with it going around the perimeter of a square of length L=5 cm, 4*L distance, without it being only pi*L in length. This time, it comes with a tiny, tiny 5 cm (1.95 inch) board. Sure, it's bigger than a wristwatch display, but it's pretty darned small for fitting 89 normal sized LEDs on it, and a full-sized DIP chip, and the other components. At this size, it does not have room for an alarm speaker. It is thus the revision of the clock which does not contain an alarm. Another thing this board does not have, by necessity, is a voltage regulator. Consider this a project for someone who is starting out powering the thing from a more regulated power supply. The chip works with anything from 3 to 6 volts DC, it's not TTL, but still, you wouldn't want to directly give it the output of an unregulated transformer-rectifier nominally putting out 9 or 12 or 15 volts DC. But it does have 2 advantages over the version with the alarm in exchange - be sure to read the long second-to-last paragraph for an explanation of them. But in addition to saving me a speaker in the kit, it was also less expensive to have the circuit boards made for me because they are smaller, and so the price is less on this one. Other than the lack of an alarm feature, it is much the same type of clock which is shown here, it's just that this time it comes with an actual board! And no alarm. The first version of the program, written in 2002, before the alarm was added to it in 2003. It's cramped as it is, trying to fit in room for a speaker would be impossible. But you get some extra other features in exchange for not having an alarm. Read the long 2nd to last paragraph to find out about them.
Other clock kits with boards (more expensive):
Circular ring (3.9 inch board) (click here)
Zig-zag ring (3.9 inch board) (click here)
Infinity (1.95 x 3.9 inch board) (click here)
Tiny 5 cm square ring (1.95 inch board) (you are here)
Dice clock (1.95 x 3.9 inch board) (click here)
Other clock kits without boards (less expensive, but in some ways better because the board is less personal and rather small):
The same type of clock as this but with an alarm and without the green board (click here)
The dice clock (click here)
The green board you see there is a square which is 1.95 inches on a side. Click on the picture to see it big, and use the left and right arrow keys to move around.
First of all, I want to make 2 things clear:
1. You are not buying the clock in the picture. That one is my demonstration piece. It took me too long to solder together for me to throw around that with a 20 or even 30 dollar pricetag. That would be half minimum wage or less. It took long enough just to get the components together to make the kit.
2. You are buying a kit. You get 90 LEDs (one spare), a programmed microcontroller, resistors, capacitors, a crystal, etcetera, a circuit board, and an information sheet on specifics you'll need to get it right. This does NOT include a power supply. You need to give it 3 to 6 volts DC from somewhere. You also need a soldering iron and solder.
By the way, there are 2 completely different versions of the program, one which controls a "AM" LED which is on in the morning and a "PM" LED which is on in the evening, and a different version which controls only the PM LED, which is off in the morning. If you only want one LED to denote AM/PM, you can't use the version that controls them both, because it will turn on other LEDs when it tries to turn on the AM LED which won't be there. Please tell me which version you want or I will choose for you.
A demonstration of the version of this clock with the alarm can be seen here (make sure to be patient when downloading this, and make sure to have some kind of pop-up ad killer in place: mediafire will definitely zap you if you don't):
It is not only a clock but a calendar too. You give it the year modulo 4, the month, the day in month, the day in week, hour, minute, second. Press one of the 2 buttons to get it to show you the date (the 5th picture shows this - it displays the date March 1 - today as of when I wrote this), where the 12 hours represent the month and the minutes/seconds represents the day in the month. All LEDs flash 11 times per second. That really gets your attention, and epileptics beware. The ring of 60 LEDs shows you the minutes AND the seconds. The seconds flash twice a second on top of the 11 cycle per second flashing. Also they advance one per second. It also automatically adjusts for daylight saving time as it is right now in the US. So beware if you're in a place that doesn't do daylight/standard transitions or does it at a different time. When you first turn it on, it also asks you if you want it to run clockwise or counterclockwise (as if flashing 11 times a second wasn't trippy enough) and then it asks you for a "fudge factor" to make it more precisely keep time. I threw it in there because I found the 32768 Hz crystals aren't particularly accurate. It's a parameter that starts at 1:59 (no adjustment) and has 240 possible values and is shown by the times 12:00 through 3:59. Each one forward adds 1/8192 of a second to the clock every 15 seconds. What it amounts to is that each one makes it get faster by 4.921875 seconds per week. In other words, if you ran it for a week and it got 2 minutes slow with this starting parameter set to "1:59", you could turn it off and back on and set it to "2:23" at the beginning, and then it will get 1.875 seconds slow every week. The version with the alarm has neither of these features, where you can make it go clockwise or counterclockwise, or this settable time accuracy calibration parameter, so those are advantages that only this version without the alarm have. To see a demonstration of this version of the clock, without the alarm (it's a big clock, made by hand on a big slab of cardboard and not a 5 cm machine-made circuit board, but aside from being before the addition where you get to choose whether it's clockwise or counterclockwise, it behaves the same as the program on the microcontroller in this kit), watch this:
Please feel free to check out our other electronic items at medexamtools.com/diodes.htm. These can be added into your order for combined shipping as well (the shopping cart system will do it automatically).