svkatz80 @ fritzing.org build a nice LED clock. He writes:
This clock is based on ATmega328p microcontroller, with combination of DS1307 – Real Time Clock, MAX7219 – 64 LEDs drivers, 74HC595 – shift registers, DS18B20 – temperature sensor, GL5528 – photoresistor, LEDs and other electronic components.
- Clock with RGB seconds — Four 74HC595 control 10 RGB leds. But TLC5940 is a better choice.
- Ellipse clock — Three MAX7219 control all LEDs. No shift registers needed.
Each MAX7219 can control 64 LEDs. For ellipse clock I used tree of them. The first one controls 2 hour’s digits (2x7x4=56 green leds + 6 blue leds + 2 dots between hours and minutes ). The second one controls 2 minute’s digits (2x7x4=56 green leds + 6 blue leds). The third MAX7219 controls second’s 60 red leds .
For making a 7 segment digits, I used 5×7 cm prototype PCB circuit board. Before solder the LEDs, I wired the board for 4 digits and 7 segments each of four boards with copper wire. See circuit.
As a main board I used a coroplast (polygal) sheet. Just print the sketch and make on polygal holes with a needle for LEDs.
ATmega328p based LED wall clock - [Link]
Kevin Rye writes about his Mini 7-Segment clock V2 project:
Now for the moment of truth. I crossed my fingers and connected a battery pack. Woo hoo! It works! I love that feeling you get when you spend weeks working on a project, it all comes together in the end and it just works. With the electronics working, it was time to put it in the enclosure. I cut the end off a SparkFun 5V DC power supply and soldered on a 2-pin Dupont connector. I then secured everything with a little heat shrink tubing. I then took the acrylic panels that I designed and had laser-cut from Ponoko and secured them to the clock via some screws and standoffs.
It looks amazing! I’m really happy with the way that it came out. I also really like the “kelly” green segments on this display.
Mini 7-Segment clock V2 - [Link]
pinomelean @ instructables.com writes:
Numitrons are neat display devices similar to nixie tubes but designed for much lower voltages. Numitrons are basically incandescent displays in which filaments create the segments.
They have a steampunk look that i liked so much. I bought 6x IV-9 russian numitrons in ebay, they were about 3$ each, they’re pretty cheap!
At that time i didn’t know what to do with them, but then i thought about a clock. Using software from a single LED display clock i made this impressive numitron clock.
Single digit numitron clock - [Link]
Dave celebrates the classic 555 timer IC by building the Evil Mad Scientist “three fives” discrete timer kit. Some scope measurements and an explanation of the internal 555 timer circuitry follow.
EEVblog #555 – 555 Timer Kit - [Link]
This is a 7 segment clock displaying HH:MM:SS using PIC16F84A and 4017 digital IC. Complete source files are included.
PIC16F84A Digital Clock - [Link]
Having obtained a reasonably reliable 10MHz lab reference (see here) I decided to calibrate my Frequency Counter only to find that the stock oscillator provided in the HP 53151A is absolutely terrible – a joke even! I looked around for an “010 High Stability Timebase Option” but they are rare — and if you can find one not installed in a counter they are very expensive – in the few hundred dollars range at least — and buying one from HP is, well, expensive in the extreme. There are many second-hand 10MHz OCXO modules available, these are mostly stripped from old telecommunications, satellite or cellular equipment so they are plentiful and relatively cheap to buy too. I decided to make a clone 010 option board for my counter using a second-hand OCXO bought from e-bay. I designed a PCB to get a professional finish as well as a reliable upgrade for my counter. The main goal was to make an option board that just like the original could be automatically calibrated using the internal software and front panel controls so I had to use the same DAC chip (which is now obsolete) and basic topology of the original option board to make it work.
DIY HP/Agilent 53131A 010 High Stability Timebase Option - [Link]
This is a collection of Maxim’s newest real-time clock ICs.
This real-time clock IC operates with very low current and is compatible with high-ESR crystals for a space saving, low-cost design. Read the rest of this entry »
The TS3004 is a single-supply, timer IC fully specified to operate over a supply voltage range of 1.55V to 5.25V while consuming 1.9μA supply current. Requiring only a resistor to set the base output frequency (or output period) at 25kHz (or 40µs) with a 50% duty cycle, the TS3004 timer/oscillator is compact, easy-to-use, and versatile. Optimized for ultra-long life, low frequency, battery-powered/portable applications, the TS3004 joins the TS3001, TS3002, TS3003, TS3005, and TS3006 in Touchstone’s CMOS timer family.
TS3004: A 1.55V TO 5.25V, 1.9µA, 0.005Hz TO 300kHz RESISTOR-TUNABLE TIMER IC - [Link]
Kevin Rye posted his Mini 7-segment clock:
I finally got in my OSH Park PCBs for my mini 7-segment clock. It’s using the DP5050 PCB layout. I used the SparkFun 7-seg display, but unfortunately, they screwed up the pinouts on the footprint and pins 10 and 12 are pin-swapped. I had to jumper the pins on the back to get the colon to work.
Mini 7-segment clock project - [Link]
Kevin Rye built this E-Paper clock and wrote a detailed explanation on his blog describing the build:
I still have to put the finishing touches on the code. Instead of having the display constantly update, I’d like to set an alarm on the DS3231 RTC to go off once a minute, and only update the display on alarm. Hopefully I’ll save some battery power that way. As of now, the battery only lasts a couple of days. I built in a USB battery charger to make it easier to charge it. I got my PCBs in from OSHPark and put it all together in an 80mm x 80mm Sick of Beige case. Check it out!
E-Paper clock in a Sick of Beige case - [Link]