Clock Building

I’ve been thinking about building a clock for a while. I ordered a bunch of parts back in July 2008 with the idea I’d have some clocks made for Christmas presents. Well Christmas 2008 has come and gone and no clocks have been made.

I was going to build a clock with some big 1-inch 7-segment displays, orange ones. I was thinking it could be a “Mantle Clock” but ideas have come and gone and while I did have a prototype on a breadboard, I’m taking a different approach now.

Originally I romanced the idea of using an oscillator and discrete logic. I wasn’t about to go to transistors and diodes, but CMOS 4000 series and TTL 7400 series were the plan. I had a crystal oscillator set up and the prototype worked, about as well as a 50 year old clock that needed a tune up.

I’m sure the breadboard might have been part of the problem, also with somewhere just shy of 20 chips it had a pretty big footprint. I figured I’d use stacked boards, and maybe etch or have boards made for the clock. Well on the shelf it went.

Now I’m at it again, this time I’m planing on using a microcontroller. Possibly with the Arduino libraries. I’m hoping to make it use DHCP and SNTP with a WizNet Ethernet module. Looks like most of the parts are out there, just need to do the integration and hardware build.

I keep thinking about the project and I’m hoping to use this blog a little to get my ideas down so I can start building.

I haveĀ  a case in mind. I just found a little 5-volt power supply on Ebay so I can have an internal power supply. I’m toying with some blue 7-segment displays, not sure if I’ll use 4 .8-inch or 6 .5-inch displays. I have a bunch of real-time clock chips ready to go.

I fancy the idea of not multiplexing the display and I have some great 7-segment drivers that would work. Multiplexing the display means having the ability to show non-numeric characters which the drivers don’t support. My drivers have their own latching buffers though and that means if I use them I don’t have to worry about the display falling apart if the CPU is busy talking to the network or RTC module. Adding four to six driver chips though makes the hardware more complicated.

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