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]
by Jeremy Cook @ makezine.com:
Most of us have probably seen clocks or numerical displays that flip sequential boards to display the next number in a sequence. If you wanted to take that a step further, you could make a replica of “Dottie,” which flips small dots as pixels. As the great video below says, it makes a “pleasant mechanical flipping sound all day.” It also tells the date, chimes every 15 minutes, and gives an animation show once an hour.
Dottie the Flip Dot Clock - [Link]
Kevin Rye writes:
I’m in the very early stages of prototyping a nixie clock. I picked up some MJE340 power transistors to switch on some IN-3s. I can then use a digital pin on my Arduino to turn on the IN-3s through the transistor. I’ll then have myself a blinking colon for my nixie tube clock.
Flashing a Nixie with an Arduino - [Link]
by Sound Guy @ instructables.com:
You may be familiar with a website in the UK called Colour Clock (http://thecolourclock.co.uk/) which converts the time into a hex value and then uses that value to update the background color. It’s very hypnotic and once you get used to how it works you can actually tell where you are in the day just by glancing at the screen from across the room.
I had an Arduino Uno R3 and an Adafruit 1.8″ Color TFT Shield w/microSD and Joystick that I was trying to use for another project that kept stalling out. One night just for fun I decided to see if I could recreate the Colour Clock and it only took a couple hours. If you’re familiar with Arduino you could easily swap parts out for a simple TFT breakout board and something tiny like a Beetle and make a very compact unit. You could even wear it as a badge.
Arduino TFT Color Clock - [Link]
Meter clock: keeping “current” time. Read more about the clock:
I’ve seen a few meter clocks in my travels of the web, and I love the idea. A few days ago, I decided that I must have one of my own. Such began the “How to do it” pondering cycle. I had seen builds where the face plate of the meter is replaced. This works, but I wanted to try and find a way to do it without modifying the meter, if possible. After some more ponderation, I came up with what I think is a serviceable idea.
I came across this style of milliamp meter on Amazon. They’re not quite 0-60 mA, but the 0-100 mA (a 0-20mA meter for the hours) is close enough. And they were cheap. So yay.
Part of my requirements were that the clock run off of an Arduino Pro Mini I had lying around, and with minimal additional parts. In order to drive the meters with some degree of precision, I would use the PWM pins to vary the effective voltage across a resistor in series with the meter. This would, by the grace of Ohm’s Law, induce a current that, based on the PWM duty cycle, would be scaled in such a way as to move the needle on the meter to the corresponding hour, minute, or second.
One minor issue came up in the form of the max current the GPIO pins on the ATMega328 chip can source/sink. The pins can source/sink a maximum of 40mA, a bit far from the 60mA needed for the minutes and seconds meters. Enter the transistor.
Using a simple NPN transistor switch circuit, I was able to provide the current for the minute and second meters from the 5V supply. The PWM signals switch the respective transistors on and off, effectively varying the voltage across the resistors in series with the meters.
The resistor between 5V and the meter is actually 2 1/4 watt 100 Ohm resistors in parallel for an effective resistance of 50 Ohms. The two in parallel was necessary as 5V x 0.06A = 0.3W (more than 0.25 that a single 1/4W resistor can handle safely).
Meter clock: keeping “current” time - [Link]
Brett’s new masterclock is Arduino-controlled and keeps very accurate time by periodically synchronizing with the DCF77 “Atomic” Clock in Mainflingen near Frankfurt, Germany. The DCF77 library for Arduino is used to decode the time signal broadcasted from the atomic clock. The time is displayed as hours, minutes, and seconds on six 1″ seven segment LEDs. A 4×20 I2C LCD display is also used in the project to display additional info such as display brightness, sync information, signal quality, auto tune’d frequency, auto tuned quartz accuracy, etc. Both the displays are auto-dimmed based on the surrounding light intensity using an LDR sensor and pulse width modulation technique. His clock also includes a bluetooth link for updating the Arduino firmware from a PC without an USB cable.
Very accurate master clock synchronized to the DCF77 time signal - [Link]