I was extremely satisfied (and proud) of the way that the enclosure turned out for the rework of my 7490 Clock. The electronics on the other hand, is another story.
The innards of that clock were from a prototype I built in 2001. It was a proof of concept. It led to the design of what would become an extremely well-polished and accurate clock.
Since it was one of the first things I ever built, I decided to put it in an enclosure of its own and consider it too as a finished product.
The problem was that the prototype never ran properly. It worked, just not as well as it should. Needless to say, I tried to fix it in the way of an Arduino upgrade. On paper everything should run perfectly, but in the real world, it just doesn’t. The clock bounces all over the place. It’s more of a random number generator than a clock. I really thought that moving away from the 60Hz line signal as a timebase to a solid 1Hz signal from a DS3231 RTC would solve all my problems. At the end of the day, it boils down to the fact that it’s all soldered together on a DIY homebrew PCB. The holes that I drilled are too big for the pins; resulting in some pretty shoddy-looking soldering. It’s a noisy circuit, and I’m sure there’s some grounding issues in there too.
Large 7-Segment Clock – [Link]
In digital electronics, fan-out is defined as the number of gate inputs that the output of a single logic gate can feed. It is very important in digital systems for a single logic gate to drive other gates or devices. In this case, a buffer can be used between the logic gate and the devices it will drive. Clock buffer is also called as fan-out buffer. The IDT clock buffer clock divider and clock multiplexer portfolio includes devices with up to 27 outputs. Differential outputs such as LVPECL, LVDS, HCSL, CML, HSTL, as well as selectable outputs, are supported for output frequencies up to 3.2 GHz and single-ended LVCMOS outputs for frequencies up to 350MHz.
Modern digital systems often require many high quality clocks at logic levels that are different from the logic level of the clock source. Extra buffering may be required to guarantee accurate distribution to other circuit components without loss of integrity. Many systems require low jitter multiple system clocks for mixed signal processing and timing. The circuit shown in interfaces the ADF4351 integrated phase-locked loop (PLL) and voltage-controlled oscillator (VCO) to the ADCLK948, which provides up to eight low voltage differential signaling (LVDS) outputs from one differential output of the IDT 8SLVD1208-33. The IDT8SLVD1208-33I is characterized to operate from a 3.3V power supply. Guaranteed output-to-output and part-to-part skew characteristics make the IDT8SLVD1208-33I ideal for those clock distribution applications demanding well-defined performance and repeatability. Two selectable differential inputs and eight low skew outputs are available. The integrated bias voltage reference enables easy interfacing of single-ended signals to the device inputs. The device is optimized for low power consumption and low additive phase noise.
Fan-out buffers and clock dividers are general-purpose clock building block devices that can be used in any number of applications. They are ideal for clock and signal distribution in a large variety of systems, from personal computers to consumer electronics or industrial systems, as well as high-performance networking and communications systems.
Increasing Outputs from a Clock Source – [Link]
I used to get the feeling that it wasn’t obvious enough that I really enjoy working with embedded systems. I decided to change that by designing a binary timepiece that is portable, easy to use, has long battery life, and has a very barebones “circuits and components” feel to it. After wearing the final product for about a month now, I feel like I was successful on all of those goals:
The Binary Wristwatch – [Link]
VFD Modular Clock IV-18 SMT edition is a special solder-free kit version of the original VFD Modular Clock . The firmware is mbed based and is freely available at http://developer.mbed.org/teams/Akafugu/code/vfd_modular_clock_mbed/
- IV-18 8-digit Russian VFD Display Tube
- Open source mbed based firmware
- LPC1347 ARM Cortex-M3 64kb microcontroller
- GPS (option)
- Four Letter Word
- Easy to update firmware with no special drivers required (LPC1347 usb bootloader)
VFD Modular Clock IV-18 SMT – [Link]
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]