How to make a digital clock: Picaxe

Digital clock using PicaxeThis is the finished clock. Use it for parts locations.

9-10-2010 – Updated program added that is void of errors. I’m not sure what I was thinking 2 years ago.

Basic Program for Picaxe V2

11-11-2008 – Program for Picaxe chip and parts list posted. This is now a complete project! Enjoy.

11-6-2008 – New schematic and board posted! If you have any questions about how to make a PCB, please search the net before posting questions. Make and Instructables are great starting points. The program will be written and posted soon. This will be a stable clock with many improvements that were neglected in earlier projects. (Surge suppression with capacitors on the power supply, caps and a ground ring on the real time clock’s crystal)

Parts List: ( unless noted) $55 total average cost
1 – 604-1033-ND – 1.0F cap – $3.94EA
1 – 67-1443-ND – 4-digit 7-segment display – $7.40EA
1 – 300-8301-ND – 32.768kHz crystal – $.28EA
2 – P813-ND – 10uF cap – $.14EA
2 – 490-3752-ND – 6pF cap – $.34EA (Use 3pF caps 490-3717-ND…6pF is a design error)
1 – DS1305+-ND – real time clock – $5.06EA
1 – MAX7221CNG+ – display driver -$10.81EA
6 – SW400-ND – tact switches – $.18EA
1 – CFR-25JB-4K7 – 4.7k resistor – $.06EA
1 – CFR-25JB-2K2 – 2.2k resistor – $.06EA
6 – CFR-25JB-1K0 – 1k resistor – $.06EA
8 – CFR-25JB-10K – 10k resistor – $.06EA
1 – LM7805CT – 5v voltage regulator- $.45EA
1 – PC6-S – single side copper clad board – $5.10EA
1 – 28480 – 28×1 picaxe chip – $10.50EA – HVWTECH.COM
1 – 17040 – 4MHz ceramic resonator – $1.95EA - HVWTECH.COM
1 – 1586162 – 9v 500mA wall-wart – $4.95EA – JAMECO.COM (or free from something at home)
wire,solder,etchant,IC sockets (if desired)

Digital Clock Schematic (PDF) (Be sure to use 3pF caps on the crystal)
Digital Clock Board (PDF)
Digital Clock Program (BAS) [Download the version posted above...this one is broken. ]

Etching PCBEtching PCB
Photos open up in a new window. Thumbnails are used on this page for quick loading.
Left photo is the toner transfer and drilling steps.
Right photo is etching process. Acid is dark when etching is finished and is like a black mirror.

Needed: Copper clad board (6″x6″ is good), glossy photo paper, iron, permanent marker, copy machine

  1. Print board PDF in black/white at 100%. If you are unsure about the sizing, print it and check the hole spacing with a DIP IC. If the holes do not line up, check the Adobe print settings.
  2. Take your printout and a piece of glossy photo paper to the copy machine. Copy the board layout to the photo paper at the darkest setting and highest toner contrast.
  3. Cut out the board layout and place it toner side down onto the copper clad board. Iron it at the highest setting the iron has (I did it at 400 degrees F). Iron until the paper has completely stuck to the copper board. Allow it to cool. Once cooled, slowly peel paper and check that it has transferred (photo 1).
  4. If anything does not transfer, try to repeat the ironing and cooling process. If you can’t (photo 2), then use permanent marker to draw your traces (photo 3).
  5. Once your traces are completed, drill your holes (photo 4). Use a #67 bit (.0320) for most of your holes. Small bits are tiny, brittle, and expensive, but they are also the best hole size. Check Ebay for these if you cannot find them locally.
  6. Once your holes are drilled, mark them again with permanent marker in case there is any bare copper showing.
  7. Etch in Ferric Chloride or whatever you choose to etch with. Some people use liquid pool acid and peroxide, but it is only at your own risk (right photo).
  8. Once your PCB is etched, you can clean the toner and marker off with acetone and scotch brite. Make sure that the copper is nice and shiny, and avoid fingerprints, dirt, and oil once they are clean.
  9. Solder the parts onto the board as indicated by the board layout and schematic. This is the most time consuming part. Make sure the parts belong there before you solder. This is the main reason why the clock doesn’t work. It’s tricky to get things where they belong. TAKE YOUR TIME!





(10-15-2008) While doing quality checks on my work, I have found some errors that need to be addressed. I sincerely apologize for this. I want you to be able to learn with as little opposition as possible. This tutorial will be changed slightly. It will still be geared towards the solderless breadboard, but will also have a step to make a printed circuit board to finish your project.

(8-26-2008) Note: When designing this circuit, I left off some important items. The 7805 voltage regulator should have capacitors connected to it to suppress any surges. Capacitors do not pass DC (direct current), but a surge is somewhat like AC (alternating current), and it will send it to ground. Adding this step will create a filtered power supply. You’ll need 2 – 10uF caps rated at 25v Digikey p/n P813-ND. Connect the positive leads of the caps to the 9v and 5v pins of the 7805 (pin 1 and 3), and then connect the negative leads to the ground pin (pin 2). If you used the PCB first clock tutorial posted in July 08, just drill some holes in the traces and solder these parts in, or just solder them to the traces.

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About robbie

I am an electronics enthusiest and a ham radio operator (W1RCP). I like to play with electronics. It's fun and educational. I looked forward to working in the engineering field in the future. I have a BS in Electronics Engineering Technology from DeVry University. I also have an Associate's degree in Marketing Management from Moultrie Tech, and a diploma in Electronics from MTC.

8 thoughts on “How to make a digital clock: Picaxe

  1. Pingback: A digital clock of mine gets an upgrade « Tech Tut

  2. Pingback: Update to: How to make a digital clock: Picaxe « Tech Tut


    Sorry for taking so long to reply. I am in school and I rarely have time to check. Try the above line without the ‘ before pin 1. It may have commented out the important part of the line.

  4. I have two questions:
    First: If i manage to correct that syntax error, what is wrote above with the PIN1 then i get another error that Error: Unknown symbol – PIN1, what shall i do?
    Second one: How do i load this program on the PicAxe? With serial cable, or i have to build a programmer for it?

  5. The unknown symbol might be that you are using a newer version of the Picaxe program. I just looked at what I assume is a new manual because they have a different pin naming scheme.

    I believe that PIN1 should now be B.1.

    On page 43 it shows you how to make a serial programmer and how to connect it to the Picaxe chip for programming.

    This shows how long it’s been since I have used Picaxe.

    I hope this helps.

  6. Depending on what you put in it and where you source your parts it can range from $25 to infinity dollars. Using display driver ICs really drives the cost up quickly.