Friday, December 24, 2010

Wood block LED clock (part 2)

Making wooden enclosure.

Box can be made from any available material i.e. wooden boards, MDF or plywood.

I had some MDF sheets in my scrap container so I've build simple frame from narrow panels of 1/2" MDF.
Before joining pieces together I've applied some carpenter's glue to matching surfaces. Glue fills gaps and add extra strength to joint.

All parts fastened with 1" wooden screws. To avoid material splitting I've drilled 1/8" pilot holes for screws and made countersinks.

Front and back panels are made from 1/4" MDF and attached to frame with glue and screws. Wooden putty can be applied over top of screw heads to make surface even and smooth.

It's a good habit to keep scrap material just in case. 

Wednesday, December 15, 2010

Wood block LED clock (part 1)

Clock controller and LED matrix.

For this project I've picked up few obsolete chips that have been sitting in a drawer for a long time waiting for occasion.

Clock's brain is based on PIC16LF876A microcontroller running at 10MHz.
Basically, only function of microcontroller is to monitor two buttons and occasionally read data from real time clock and display time and date. 

Yes, it's too powerful chip for such a simple application but I prefer to have spare I/O pins and memory room in case I need to upgrade design or add some extra features.

Clock is showing current time by turning ON and OFF predefined number of LEDs of the same color. LED pattern is chosen randomly and microcontroller generates new LED pattern every second.   
If button 1 is pressed clock shows current day and month in the same manner for a 30 seconds then switches back to time showing mode. Button 2 is used to activate time or date setting mode.

Real time clock is NJU6355 chip with 4-line serial interface and operating voltage 2 - 5V.
RTC is bundled with 32768 Hz watch crystal and 3V lithium coin cell battery CR 2032 as a backup power source. Battery is connected in series with diode and supplies 3V to RTC only when main power 5V is absent.

Controller assembled on a single sided PCB, made using heat toner transfer method, as usual;-)

Thursday, December 2, 2010

Wood block LED clock (intro)

Wood block clock. I've seen it. I liked it. I've made my own. 

Yes, I like to work with wood and I like to experiment with microcontrollers and other electronic stuff so I've combined few popular ideas and recreated this exotic LED clock encapsulated in chunk of wood.
Wooden block clock showing time 18:36.
Yes, there are no digits displayed. Instead lights of different color represent ones and tens of minutes and hours.