Machined Gear Clock - PIC 16F628A Based

October 28, 2009 Category : Gear, Tech & Gadget | Tags : Gear Clock, Machined Gear Clock 0 Comment

We have looked no imperfection of homegrown clocks in our time, also while dominant are cute for their time, few are honorable of subsisting lauded in this way. Alan Parekh’s Gear Clock is a fabulous mishmash of machined gears, energized together in a vogue that tailed in an authentic time-telling widget. Hop on past the break to see this thing spin, still be positive to keep the mute button for the lead-in. Certainly ‘Sound Check’ was not empowered.

Overview
The intersection of the clock is a PIC 16f628A microcontroller (PDF). This microcontroller keeps an internal oscillator though an external 20MHz crystal oscillator is enduring applied since it will have to keep precisely track of time for weeks & months.

Buttons
The interface is very elementary, it consists of paired buttons. When the left button is pushed the clock progresses time operating the motor. When the right button is pushed the clock rebates time conducting the motor. The solitary issue is when you want to set time by some hours you would have to stay the button pushed for a long time. The stepper motor is also still activated to control the gears from misconstruing. To whip this issue when both buttons are pushed the stepper motor is deenergized also the minute gear could be turned independently.

Motor
The motor is an unipolar stepper motor that has been landed from an old 5 1/4 inch floppy drive. This is the motor that conducted to shift the discover write heads back also forth, to fetch one of this power & size you will require to set a nice aged one. There are many styles & sizes of steppers so it may reap a bit of grooving to find an effectual one. Recent floppy drives do not grip steppers with this classification of torque.

This motor runs 1.8 degrees per beat which shows that with 200 pulses it will drive one full rotation. Because it’s an unipolar motor it is spare for the PIC to energize it with only 4 transistors. You will also lack to be alert of motors with unmatched digit of pulses per rotation though 200 is the most dominant.

Gears
The gears are formulated out of MDF. They were colored to grip a metallic appearance but the look I had been going for existed not captured. Originally I had been considering of producing the gears display like they were formed of metal then left to rust for a few dozen decades. I identified some cool products that would deliver me that rusted result still they were a bit too priceless. I returned for a pot of Krylon Black Metallic Hammered Finish shade. The example on the lid is a very nice black with delicate fed of gray. I reflect this could be from a wretched batch due to the finished appearance is not as black as it should be. It further made capturing portraits of the last clock a bit mighty after even with modest lighting the look had been terrible.

The gear arrangement is as follows:
* 72 tooth hour gear
* 72 tooth intermediate gear with a 18 tooth secondary
* 72 tooth minute gear with a 24 tooth secondary
* 9 tooth motor gear

To prevail the precise timing the 9 tooth motor gear is converged 4 steps every 9 seconds. By driving 4 steps at a time the motor fixed ways could be uncomplicated after the motor is straightly at rest with the regular coil recharged.

Code
The code is conceptually split into two constituents, there is an iterative loop that controls the pins for an adapt in state also checks if the internal clock holds crossed the 9 second notify. If one of those terms has followed the stepper motor is punched properly.

The difference part of code is snag driven also it conserves track of time. A reprieve is stimulated every 0.1 seconds also changes an internal clock as required. There is an authentic running clock inside, if you attach the clock PIC pin 6 to a computer serial port working at 9600 bps you will watch the internal clock calculates update once per second. The clock value in this implication is fleeting since it is never appeared also will not be the same as what the gears are showing but this same code would be operated in tomorrow’s project which will serve this code show time.

Images