A Word Clock

Step 6: PCB layout, Overlay and Schematic files

To make construction simpler - here is a PDF of the PCB layout and component overlay.

[Update - 21Dec2009] I have updated the PCB file to allow construction of a 6 inch x 6 inch (150x150) display.  This allows construction on commonly available (in Australia) board stock - I have also repaired a layout fault that resulted in a misalignment with the headers and the pcb mounts.

You will need to scale the output to get the PCB to be the correct size!

The file uploader mucked around with the resolution of the schematic making it difficult to read - I have uploaded a PDF of it, so people can see a high resolution version.

I have been asked for the parts list. Here it is:

U1 PIC 16F877
U2 78L05

D1 1A Bridge
D2 1N914
D3 5V1 Zener
D4 1N914
D5 1N914
D6 1N914

D10-D126 5mm Blue LED

X1 4Mhz resonator

All resistors 1/4 watt
R1-R24 470R
R25 10R
R26 10R
R27 4K7
R28 4K7
R29 4K7
R30 4K7
R31 10R
R32 100K
R33 4K7
R34-R77 470R

C1 100uF/25V
C2 10uF/25V
C3 0.1uF

Q1-Q24 2N2222, BC547 etc

J1, J3 2 Way PCB terminal Block
J2 3 Way PCB terminal Block
J4 5 pin header (0.1)

PB1, PB2 Momentary Action Push Buttons (Time set)
B1 4.5v Battery Pack (3xAAA Cells)
XFRMR 1 7.5V AC / 400Ma Transformer

Display PCB
Controller PCB
Stencil PCB

4x 3mm screws
2x 10mm spacers
11 30mmx170mm PCB Strips (Light Baffles)
25 30mmx15mm PCB Strips (Light Baffles)
40 Pin IC Socket
Hot Melt Glue

I have also added the 'C' Source code as a download.

Several people have asked for the original source PCB layout file - I have attached it - It is *NOT* in eagle cad format - it is in express PCB format - A PCB drawing tool that is free of charge from express PCB. I hope it is useful to you.

Comments

[Emanuelg]

Hey. im 15 years old and i'm wanting to make this project at school. I live in New Zealand :) and i'm wondering how much the whole thing costs. I have a budget of $60 nz dollars. p.s useful nz electronic sites are jaycar nz. cheers :)

[drj113]

he he   buzzle.....  One day, I will actually look at what ends up on the screen and my spelling will improve....  One day - I am only 43 :-)    Puzzle.....

[ritchie56]

this is really cool and I like the stencil on the back design as well. How about this for another alternative - box each letter separately, that way you can have words running diagonally and even vertically. It would look like one of those circle the word puzzles. You could even have a crossword themed clock. the bluish-green glow made me first think it was EL - nice effect!

[drj113]

Thanks - I have been toying with making a crossword - but that takes a bucket load of space - your idea of a 'circle the word' buzzle sounds great though - I will have a play.

Doug
 :-)

[ytumer]

 When you printed the WordClock-Stencil.pcb to a pdf file how did you manage to invert the colours? i.e. make the letter white and the background black.

cheers

[drj113]

I invert the colors (make black white and white black) by using the 'advanced' feature of the AGFA postscript drivers on Windows.

I don't have an AGFA printer - I just install the AGFA postscript driver, and under the advanced tab, I select 'Negative' and 'Print to file'.  That way, when I print using that printer, it automatically inverts the drawing colors for me, and saves the result into a postacript file on my hard disk.  Then, I open the Postscript file using 'Ghostscript', and export it to PDF.

The specific driver that I have loaded is for an AGFA Accuset-800SF.

Yes - it is a little fiddly, but it saves me from making a photographic negative for some of the other work I do.

[Patrick.Firganek]

another question: did you use low current LED's oder normal LED's?

[drj113]

I used normal LEDs - The Blue ones I used are 16000mcd.

[ytumer]

 Hi Doug! Just ordered my PIC programmer today and I'm now thinking about which LEDs to use... you said you use 16000mcd flat top LEDS, would 16000mcd be a little too bright for home use?  I know your's stays at work under bright light.

Is 6000mcd ok or should I be looking for 12000mcd LEDs?

Thanks in advance!

P.S. my first instructables build :D

[drj113]

I have built clocks with alll brightness of LEDs, and have not had many problems with them at all - the 6000mcd are not as bright, but work beautifully in a domestic room.

The 16000mcd are extremely bright, and if anything, may be too bright for a bedroom (when trying to sleep..)

[ytumer]

 Cheers for the prompt reply Doug, really appreciate it.

[akhilbhas]

Can you send me the hex file to my id or upload it in the site?
my id is [e-mail]

[boozo]

hey i noticed that some of the led in the display psb is not connected like the r,u,n,e,z,l and the line from the j4 prog to the r27 is not complete plz help me .. and i read you have made a update to your new psb i couldn't find it anywhere .

[drj113]

Send me an email - and I will send you the most recent PCB file if you want to make your own.  Alternately, I am able to supply pre etched and drilled PCBs for you.

My email address is [e-mail] - just remember to specify whether you are interested in the PIC version or the Arduino version

[akhilbhas]

i cant download those files .............pls help

[drj113]

What files are you interested in - I know that with Instructables.com, you do need to rename the file after itis downloaded.

[akhilbhas]

i'm new to this site ....thanks for your help............... now i need htc.h header file i cant find it any where

[drj113]

htc.h is included in the high tec C compiler for the PIC

[theladyk8]

So how much PCB stock should I order total? (To include the baffles and the base..)

Thank you! :)

[bignin]

Thank you for the great post.  I would just like to know what the final dimensions are for the clock? (either english or metric works)

Thanks again.

[drj113]

The clock is about 150mm x 150mm and is about 45mm deep

[retrac.noremac]

this is such a cool clock concept
i would love to have a watch like this

[Patrick.Firganek]

hello,

my LED's arrived and built them onto the display board. mainly it works, but some words like half or to,... do light a little bit. I tryed to replace the resistor for the LED's to 220ohm but it doesnt worked. I changed the transistors BC547C and then 2 words stopped lighting. But there are always some words that wont stop light. What shall i do? I searched for short cuits on the layout ,but its all right. 

What could that be? 

greetings

[drj113]

The best way to debug the display - is to unplug the microcontroller, and using a jumper wire pushed into the ic socket, tie each display pin to the 5V supply.  That way, you can focus on a single set of leds, and get all of the hardware going without worrying about the micro.

I found that the batch of 500 very cheap blue LEDs I brought from EBAY had a few faults.  The fault appeared as the LEDS being shorted internally, so they wouldn't light.

Focus on one word (start with the IT IS pair), get that working by looking for shorts / opens on the board, faulty LEDS, transistors backwards, etc, and once you can turn it on and off with the jumper on the microcontroller socket, move on to the next word (Half), etc, etc

Let me know how you go.  There are a lot of words to check (24), but you can do it!

[Patrick.Firganek]

no no, you didnt understand. The program and the microcontroller works perfect. But all words with !2! LED's do light a little when they should be off. When they should be on then they do that. Its like the BC547 is in work-mode but the microcontroller does give a LOW level. This means there should be a shortcurt at the transistors. But there isnt.
 

[drj113]

It sounds like there is a huge amount of leakage across the transistor.

The BC547 is notorious for having diferent pinouts for diferent manufacturers.  Are you 100% sure that they are in the correct way around?  I have seen cases where they are pinned EBC from one manufacturer, and CBE from another....

I have a multimeter with a transistor testor that I use that helps me with orientations.

You may have success in building a simple circuit on a breadboard, that duplicates one of the LED drivers (2 leds, 2 resistors, a BC547, and a 9V battery supply.  Experiment with the orientation of the transistor to determine the exact way round the thing should go for you.

[Patrick.Firganek]

ok the problem is solved. the transistors were soldered wrong. the collector has been been on ground and the emitter on the LED side. I switched them and now it works perfectly.
So now i can go over to the case. I will put this all into a wood case and then take a plexiglas panel for the front. On this plate i will spray the letters.  
At the moment im working on a board for the transformator, which is placed in the box, too. 

I will keep you guys up to date :)

Greetings

[drj113]

I have just done a tawl around this site, and this Instructable is pretty good for telling what the pinout should be.

http://www.instructables.com/id/Test_a_Bi_polar_Transistor_out_of_circuit/

[rayads786]

 Hi, i've downloaded express PCB and tried to print the PCB onto some acetate so i can make the PCB at home but i cant get it to print at the correct size!

any suggestions

[drj113]

In Australia, I use A4 paper, and I print it in Landscape mode.

I have also had success in printing to PDF, that way it guarantees the correct printout size, and gives me a file I can print later.

[wham29]

Doug, I'm having troubles opening up the rev 2 Schematic. Is there anyway you can make it a PDF file?

[drj113]

Hi,

The schematic on Page 5 is a PDF file - in my browser, I just have to click on it, and it opens in Adobe.  Some people have reported that files may download with .tmp file extensions - if that is happening with you , just rename the file to being a .pdf file.

Doug

[wham29]

Doug you are the man.  I recieved the new schematics.  Thank you.  Now i'm almost complete, just wanting on some parts.

[wham29]

I'm still having problems. could you maybe e mail me directly with a copy?  It's [e-mail].  I'd really appreciate it.
Thanks,
Wes

[chile19]

Doug, what program do you use to make the .pcb file? I use PCB Wizard and it can`t open it.
Thanks

[drj113]

I use a program called 'ExpressPCB' - it is a free download from expressPCB.com

[rajf]

Love this project, exactly the type of clock I've always wanted. Its been years since I've done any electronics but if feel this is worth the experimentation.

Just ordered my PIC programmer and am doing some serious reading to understand what the hell to do with it!

Thank you for the detailed write up.

[drj113]

That is realy great - Welcome to the wonderful world of being able to build your own microcontroller projects :-)

[scorpio41]

Nice work Doug ! This is going to be my first Instructables "make" Just one question :- On the schematic, you show a 4K7 going from the base of Q20 to I presume the positive rail, why does this transistor need the extra bias ? Regards Lee

[drj113]

Ahhh.... A 'really irritating design feature' of some PIC microcontrollers is that RA4 on the microcontroller is an open collector Output - so it has no drive to the positive rail. (It only pulls anoutput down, not up). This is probably to make interfacing to high voltage outputs easier.... To make RA4 a usefull output, you have to add a pull up resistor to the supply. If I had a dollar for every time I forgot that......... :-)