Ammeter based Clock

This is totally a different project and a very cool idea to implement. The project is about using ammeter to display the time by changing the amount of current entering through it. Moreover, this one also doesn’t require modification to the ammeter unlike the other projects which normally involve replacing the face plate of the meter. The project utilizes a 0-100mA meter which are easily available on the internet at a very cheap price. In addition to the meter, it utilizes an Arduino Pro mini and Ohm’s law to vary the current. The Arduino generates a PWM to vary the viable voltage over a resistor which is connected to the meter. The current generated, in principle with the Ohm’s law, would be scaled in such a path as to move the needle on the meter to the comparing hour, moment, or second. For the second and minute meters a NPN transistor was used in switching mode to deliver more current. A high precision RTC named ChronoDot has been used to keep track of the time and is easily available online.… Continue reading

Digital clock with voltmeter based display

There are several digital clocks with analog displays around. They are somewhat unique giving the feel of the retro. With proper enclosure such clock becomes great design element. Following project was inspired by Alan Parekh multimeter clock. Originally there were three analog multimeters used in voltage mode to display hours, minutes and seconds. In this project there are three analog voltmeters used with their faces printed to match time scale – one for hours, one for minutes and third for seconds. The clock code runs on PIC16F628A but time is synchronized every 30 seconds to master clock. Analog displays are driven through transistors by generating PWM signals that are equivalent to DC voltage. This part is fairly easy to implement on microcontroller. The clock also has a Chime circuit based on ISD1730 that gives “tick tock” seconds sound. Continue reading

Yet another meter clock

It seems that meter clocks gained some popularity among hobbyists. Probably because it’s a bit challenging and great looking projects. This one is based on AT89C5051 microcontroller. Circuit is pretty simple where timing is counted by DS1307 chip and analog meters are controlled by sending voltage levels through DAC converters and amp buffers. Clock is graded to 24 hour scale and can show hours, minutes and seconds on three meters. To see more packaging examples follow here. Continue reading

Analog Meter Clock

You have endless of spare times during weekend, and you don’t know what to do with the free times? Well, if you have deep interest with the analog meter, then analog meter clock project will keep you busy for the whole weekend or more! This project is based on an Arduino board, where it can reuse an old 5vdc wall-wart for the power supply. PWM mode is being used on the AVR and it’s quite easy for most of the home hobbyists. Although it was a little bit of work to manage PWM at the assembly language level, but the dev environment for Arduino makes it easy to be used. Honestly, the clock logic is a very straightforward thing, where it’s simply a bunch of nested “for” loops to count from 0-59; 0-59; 0-23 and all these values will be written to the appropriate PWM port. Beside that, you’ll need to apply the calibrate mode. This mode is an interrupt that writes the appropriate max value to the meters (23:59:59) and with this mode, it allows you to adjust the… Continue reading