I’m not sure why it is but, electronic hobbyists like to make clocks. We seem to be thrust towards them like electrons to a phosphor coated screen in a cathode ray tube. Although, at a much lower velocity. Nevertheless, I somewhat recently decided it was time to make a clock for myself. I quickly came up with several ideas of the physical implementation e.g. alarm clock, ceiling projected display etc. but, as I found out that is the easy part. I was able to distill every clock design down to the need for an (acceptably [more on acceptable accuracy later]) accurate time base, most likely 1Hz and that is what this post “Part 1″ will focus on. I will attempt to offer rational explanations as to why I decided to do things the way I did because, in case you didn’t know, there are more ways to make a time base than there are numbers on a clock’s face. Here’s how I cut my teeth skinning this kitten.
Real Time Clock - [Link]
This is a new and improved version of “Warm Tube Clock” – the open source Nixie clock project. Important hardware changes between this new version and the previous one are:
- Timekeeping is more accurate and is done by DS3231 (or DS3232) RTC IC
- There is no DS18S20 temperature sensor – the internal one of RTC IC is used instead
- Backup battery is not powering AVR anymore, but only the RTC IC
- There is no “slide switch” to control the alarm – now it is done in firmware
- Crystal on PCB is optional and can be chosen up to 16 MHz. It clocks AVR and GSCLK pin of TLC59401 IC
- Pin-compatible with previous version of Nixie “shields”
Warm Nixie Tube Clock – [Link]
There are many projects that require an accurate 1Hz clock signal, most involving the measurement of time, or controlling something based on time. There are timers, time clocks, nixie and other real time clocks, and many others. In my case, I wanted to build a very simple frequency counter. That circuit, in essence, simply counts how many pulses happen within 1 second. To make the counter as accurate as possible I needed my 1 second counting period to be as accurate as possible.
Crystal Controlled 1Hz Time Base - [Link]
Spiritus of Yekaterinburg, the Russian Federation, built this analog projection clock with a mirror and a surface-mount white LED. [via]
Analog Projection Clock – [Link]
After staring at the Union Square clock about 100 times, I decided to replicate it at home, so that I can watch the digits scroll by on my desktop. I named the clock after one of my favorite quotes from the video game Call of Duty: Black Ops, where the protagonist is politely asked for the meaning of a certain set of numbers which are being displayed on Nixie tubes. I feel it fits the piece, as even some native New Yorkers mistakenly believe that the display is the debt clock or something (that’s over in Midtown).
As a review, the clock is read like so: hh:mm:ss:msm:ss:mm:hh, which means that the time is read normally at first (military time), then it goes into milliseconds, then backwards milliseconds, then seconds, minutes and hours until midnight, in that order. Int he example picture, it is 19:30 with 9 seconds and 9 tenths of a second, the middle is usually a blur (set to hundredth of a second), then its 4 hours, 29 minutes, 50 seconds and 9 tenths of a second until midnight.
Fifteen-Digit Nixie Clock - [Link]
I needed a variable slow speed clock to help me debug a design I’m creating with a bunch of CPLDs. Given the current focus on the venerable 555 timer IC, I thought rather than using my usual AVR/PIC solution I’d create something with the handy little timer.
555 based FPGA/CPLD debugging oscillator - [Link]
I made this ChronoBlot a while back, but now that I have a Bus Pirate, I can easily test it out, set the clock, and set the alarm (and write scripts to help with that), so I’ll be updating it soon and wanted to track it on this projects forum.
ChronoBlot DIY remake of the ChronoDot – [Link]
I really like nixie and numitron clocks, but I never worked with them before. So I decided to give it a go. I choose numitrons because of 2 reasons: first of all nixies need a higher voltage than numitrons to work. Nixies need around 170V DC and numitrons only 4,5V so they are safer to work with and don’t need a special powersupply.
Numitron clock & thermometer – [Link]
In this Countdown Timer project, a 555 IC, a counter IC and a transistor switch to activate a relay either ON/OFF(mode selected by a jumper) as soon as the counting period is over. The circuit consists of an oscillator, a ripple counter and two switching transistors.
Simple Count Down timer Project – [Link]
Named ‘El Relojito’ (relojo = watch in spanish), this seemingly simple design is a great project for anyone ready to move past the rank of ‘amateur’. 60 LEDs surround the 7-segment leds telling you the time. A PIC micro controls all the action. The write-up is in spanish, but the schematic/pictures should be enough to guide you. [via]
Simple LED Clock PCB Design - [Link]