With a 36R resistor, this limited the current to 16mA. With a 360R resistor, this limited the current to 10.8mA, and with 3 LEDs, the voltage drop across the LEDs was 9.9v, meaning that 0.6v was being dropped across the resistor (11-6.6). With the original design, with 2 LEDs, the voltage drop across the LEDs was 6.6v, meaning that 3.9v was being dropped across the resistor (11-6.6). The supply that I was using was about 10.5VDC. I have attached the schematic diagram, and the PCB layout.īoth boards are connected together using jumper wires along the edge.ĭO I *REALLY* USE 360R AND 36R RESISTORS?Īs an update, I have been using Blue Flat Top LEDs, with a forward voltage drop of about 3.3v 20mA. Having etched, and drilled the boards, populate them as shown in the two photos. You can use any PCB manufacturing process you like. I printed the PCBs out using my laser printer, and photocopied the layouts onto PressnPeel Blue film. Just download either the 50hz, or 60hz firmware depending on where you live.Īnother update - I have modified the clock to allow Minute LEDs to be used around the edge - Have a look at the last step of this instructable for details.įirst, you will have to dowlload the PCB files - they are attached. I have realised that people in other countries (USA) may want to construct the clock, so I have modified the firmware to cater for 60Hz countries. This clock uses mains to ensure that it stays accurate. I am in Australia, where the mains frequency is 50 Hz (50 cycles per second). If you want an arduino version of this project, then have a look here: Please visit my web site for further information. I am now able to sell all sorts of components, ranging from complete clocks, through to kits, through to individual modules and components. The clock module in the center is 150mm x 150mm, and the enclosure surround is 300mm x 300m craftwood, painted with automotive paint. There are two new photos of a completed clock kit, mounted in an enclosure, and hanging in my dining room. I saw a cool clock on the Make Blog the other day ( ), and thought 'Hey - I can make one of those', so here it is! This is a project to tell the time using words. Major updates - A much better enclosure for this clock has been designed, and a better controller using an AtMega controller now exists.
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