Kevin Rye’s GPS clock project :
I’ve been working on this clock for a long time, and a lot of effort has been put into it. I’ve learned so much from this project. I do have to admit some parts of the code aren’t as elegant as they should be, but it works. With the code complete, all that’s left to do is try my hand at designing a 3D printed joystick for the 5-way switch.
GPS Clock Assembly - [Link]
Joe @ hobbyelectronics.net:
Here you will find complete construction details including circuit diagrams, PCB layouts and PIC firmware (and the source code). The code was written in Proton PIC BASIC but the good news is that there is now a free version of this compiler available for download; AMICUS18.
PIC Digital Thermometer & Clock - [Link]
by Ashish Kumar and Pushek Madaan @ edn.com:
In our modern era, digital logic has become the core of all the electronics circuits either in the form of an FPGA, microcontroller, microprocessor, or discreet logic. Digital systems use many components that must be interconnected to perform the required functions. The vital element for proper operation of such a digital system is a CLOCK signal that enables all these digital components to communicate and establish synchronization between them. Hence, we always need a source to generate this clock signal.
This source comes in the form of an oscillator. Although most of today’s microcontrollers have an integrated RC oscillator, the clock generated by such an internal RC oscillator is typically not good enough to support the precision required for communication with other modules in the system. Thus, an external oscillator is required that can provide a clock signal to the complete system and yet meet all the requirements for precision, signal integrity and stability.
Oscillators: How to generate a precise clock source - [Link]
by Alan @ kalshagar.wikispaces.com:
I found those beautiful vintage IV9 & IV16 tubes and I had to use them, clock being the perfect candidate. I made already mutliple others based on what was supposed to be a WordClock (hence the project name) only, but became more diversified. I did also a first test with a chainable 5cm x 5cm tube board, this is a 5cm x 10cm dual board improved version.
When I made this project and designed it the idea I had was of course the design (very important) but also reusability and pragmaticallity regarding the components used. What I mean by the latest is that you never really know what component you’ll have at hand, depends on your provider, the component availability, it’s price, or even the package DIP or SMD. Hence the board can work with 3 different type of RTC clocks: just use your favorite or the one in your shelf stock. Personally I love the Maxims DS3231 and DS3234 which are temperature compensated (to a fantastic extend for the DS3234), and both are accessed through different protocols: SPI for the DS3234 and TWI for DS3231. There’s also the EPSON RTC4543 for those living in Japan like me. So again depending of what else you need to wire, choose your poison: all the pins of the MCU are accessible and there’s even a small zone for some DIP components.
The top board uses 74HC595 for maintaining the displayed digits: they come very cheap but I didn’t want to be stuck to the DIP or SMD model (having both in stock), so the board can use any of the two. Same goes with the current limiter resistors: SMD, through hole or even resistor array, your pick. And of course there’s a SMD or DIP led footprint under each tube for the blingbling! (single color, not RGB led)
IV9 & IV16 tube numitron clock - [Link]
by tomasz.watorowski @ mightydevices.com:
A time has come for me to say ‘hello’ to the mid-XX century technology of Neon numerical displays, also known as Nixie tubes. Despite being quite hard to obtain and utilize I’ve decided to make a nice looking clock which (hopefully) would make a perfect Christmas present, and since the Christmas is all about sharing I thought It would be nice to go Open Source about it.
After few weeks of work I’ve ended up with neat single board design that makes the whole thing cheaper and easier to manufacture than the usual double board solutions (separate board for nixie lamps/divers, and another for microcontroller, power supply, high voltage dc/dc conversion, etc.). All of the circuitry is laid out on the back of the clock so it does not interfere with the old-school look of the Nixie displays.
IN-12 Nixie Clock - [Link]
by pinomelean @ instructables.com:
Ever since i discovered nixies i wanted to make a clock with them, but all the designs i found were for 4 or more nixies, required a custom power supply and a complicated driving system.
As the cheap guy i am, i didn’t want to buy lots of nixies or components to make such complicated circuits. And after ages looking for a simple clock design i came up with this page.
IN-12 nixie clock - [Link]
The most popular RTC for the Arduino is the DS1307. However, it does have some drawbacks, the most notable of which is that its operating voltage is 5v, which means it cannot be used with 3.3v projects. The Maxim DS1339 however, features a wide tolerance of voltages from 2.97V-5.5V with the typical voltage as 3.3v, a battery backup, two alarms, and a trickle charger. The breakout board here packages the DS1339 with the components and connections necessary to use with your Arduino projects easily.
MAX DS1339 RTC Real Time Clock for Arduino - [Link]
RTC or real-time clock is a kind of computer clock for keeping track of the recent or most current time. Commonly, RTCs are present in almost all or any device, which are electronic in nature that needs to keep time accurate. Meanwhile, temperature sensors are devices that gather data concerning the temperature from a source and convert it to a form that can be understood either by an observer or another device. These sensors can be in various forms and are used for a wide variety of purposes, from simple home use to extremely accurate and precise scientific use. They play a very important role almost everywhere that they are applied; knowing the temperature helps people to pick their clothing before a walk outside just as it helps chemists to understand the data collected from a complex chemical reaction.
The circuit uses a PCA8565 CMOS real time clock and calendar optimized for low power consumption. A programmable clock output, interrupt output and voltage-low detector are also provided. All address and data are transferred serially via a two-line bidirectional I2C-bus with a maximum bus speed of 400kbit/s. The built-in word address register is incremented automatically after each written or read data byte. It also includes a MCP9801 digital temperature sensor capable of reading temperatures from -55°C to +125°C. Temperature data is measured from an integrated temperature sensor and converted to digital word with a user selectable 9 to 12 bit Sigma Delta Analog to Digital Converter. The MCP9801 notifies the host controller when the ambient temperature exceeds a user programmed set point. The ALERT output is programmable as either a simple comparator for thermostat operation or as a temperature event interrupts. Communication with the sensor is accomplished via a two-wire bus that is compatible with industry standard protocols. This permits reading the current temperature, programming the set point and hysteresis and configuring the device. Address selection inputs allow up to eight MCP9801 sensors to share the same two-wire bus for multizone monitoring. Small physical size, low installed cost and ease of use make the MCP9801 an ideal choice for implementing sophisticated temperature system management schemes in a variety of applications.
The board is basically a carrier for the two IC’s that make up the Real Time Clock (RTC), PCA8565 and the Digital Temperature Sensor, MCP9801. It conveniently combines the two for applications that require RTC and temperature sensing. A particularly useful feature of this RTC is that it can detect power down and record the time at that event. This is ideal for connecting to a microcontroller that does not have an RTC.
I2C Temperature Sensor & Real Time Clock - [Link]
by df99 @ instructables.com:
This is an OLED clock I built using an Arduino Micro, a tiny OLED 128×64 display using the SSD1306 controller and I2C interface, and a precision DS3231-based real-time clock module with rechargeable battery backup. It features a menu system for setting the RTC (no serial port or USB required)
DS3231 OLED clock with 2-button menu setting and temperature display - [Link]