Kerry Wong writes:
DS3232 is an extremely accurate RTC with a guaranteed accuracy of 2.5 ppm (0 °C to 40 °C), which translates into an error of just 80 seconds over the course of a year under the worst case scenario. I had done a few projects using this chip before (you can read about them here).
While by default DS3232 is already very accurate, we can push its accuracy even higher by adjusting its aging offset register (8bit). This adjustment works by adding or subtracting the corresponding capacitance to or from the oscillator capacitor array. The adjustable range is represented as 2′s complement (-128 to 127) and each LSB change corresponds to roughly 0.1 ppm of change in frequency. So the overall adjustment range can be achieved programmatically is roughly ±13 ppm.
DS3232 clock frequency calibration - [Link]
This timer project can be used to switch ON/OFF any device after a set time, this circuit can be used in lots of application like switched ON/OFF Radio, TV, Fan, Pump, kitchen timer, the circuit describe here its unique in its own.
Project has been designed around two CMOS IC CD4001 and CD4020. Two gates of CD4001 make the oscillator and rest has been configured as flip-flop, BC547 transistor is to drive the Relay. Circuit is pretty simple, has jumpers to set the required time duration, Preset is to set the 1Hz oscillator. SW1 is to start the timer, SW2 Power on/off project. Relay output switch contacts can handle 230V AC @ 5Amps
Long Duration Timer - [Link]
SiTime SiT8008 is a programmable MEMS oscillator reaching quartz precision but with higher reliability and lower g-sensitivity. Also SiTime is one of companies who received investments from Rosnano – Russian high-tech investment fund.
The trick is that to reach maximum Q-factor (up to ~186’000 according to patents) MEMS resonator must operate in vacuum. So they package resonator _inside_ the die in hydrogen atmosphere, then anneal it in vacuum so that hydrogen escapes through silicon. So we see here only a cap with contacts to “buried” MEMS resonator. We were unable to reach the resonator itself without x-ray camera or ion mill.
SiTime SiT8008 – MEMS oscillator : die-shot - [Link]
This is a quick project for a timer. Recently I finished my UV light exposure box and thought that it will be convenient to have a build in timer to switch off the light after preset time.
Simple timer with PIC16F628A - [Link]
sameer @ sgprojects.co.in writes:
Here I’m introducing a simple and very useful project to store the running time of any device. The running time in minutes can be seen on a 7-segment display and can be reset at any time to it’s initial zero condition by pressing a switch. It can be easily installed by connecting it in parallel with any device.
Digital Time Keeper - [Link]
Once all the components and headers were soldered in, I attached my Arduino and configured it as an ISP. I then burned the bootloader for an Arduino Uno.
I then connected my FTDI programmer and uploaded the blink sketch.Success!
Wow, that LED is super bright! It’s actually blinding and kind of hard to look at. With that, I swapped out the resistor for a 1K one in order to bring the brightness down.
Knowing that the Atmega worked, it was time to solder in the rest of the components, except for the display. Again, I don’t want to come this far and then waste a $15 LCD.
LCD clock version 2 - [Link]
Markus Gritsch build another bedside table alarm clock, the schematic and source code is available here:
recently some vintage bubble displays popped up at various places , so I felt the urge to build another bedside table alarm clock, this time a really tiny one, roughly the size of an AAA battery.
Bubble display alarm clock - [Link]
Marcus Linderoth built a clock using a TI MSP430g2553 microcontroller and a HPDL-1414 display, that is available at Github:
After having ported Contiki to the Launchpad, I was eager on doing something with it. I built this simple clock with a vintage HPDL-1414 “smart four-character 16-segment alphanumeric” display and a msp430g2553.
Clock with retro display - [Link]
This is another common device people use everyday, in which a circuit drives the motor found in our watches or clocks to determine the time.
The circuit is mainly operated by PCA1462U IC, specially suited for battery-operated quartz-crystal controlled wrist watches. The quartz crystal is used to input an oscillated signal to the PCA1462U IC then produces an output of pulses that drives the stepping motor ON.
The IC used in this circuit is specialized for this application featuring an amplitude regulated 32KHz oscillator, with excellent frequency stability resulting in a high immunity from oscillator-to-leakage currents. The loss of motor steps is not possible because of an on-chip detection on the induced motor voltage, this output is applicable for different types of bipolar stepping motors. This IC also has a very low current consumption; typically 170 nA, and the time calibration of the pulses is electrically programmable and reprogrammable (via EEPROM).
- PCA1462U CMOS integrated circuit
- 1.55V dc power source
- Quartz Crystal Oscillator
- Stepper Motor
Quartz-crystal Controlled Wrist Watch - [Link]
Electro-Labs informed us about his latest project:
One of the most enjoyable part of being an electronics person is creating your own gadgets and using them in daily life. In this article, we are building one of those with the help of SoloPCB design tools, a digital desk clock with temperature display feature.
The brain of the circuit is a Microchip PIC18F252 microcontroller. It acquires precise time information from DS1307 real time clock via I2C interface and displays it on four digit 38 mm seven-segment display with the help of MAX7219CNG display driver. The temperature data is read by the on-chip ADC module of the microcontroller from LM335 temperature sensor which outputs 10mV per kelvin degree linearly. The temperature data is also displayed periodically.
DIY Digital Desk Clock with Temperature Display – Part 1 - [Link]