Timezone clocks

Projects
Participants	Katje
Skills	Electronics, PCB design, Programming, Networking, TCP/IP, NTP.
Status	Planning
Niche	Electronics
Purpose	Fun

Intro

I thought it would be a fun idea to have some clocks above the entrance way between the main space, and the aux space.

Feature wish list:

• NTP based time, so as to avoid need to change clocks to keep time or for DST.
• LED based displays (Easy to use/see)
• 24 hour clock.
• KISS design that doesn't solely rely on funky code to work.

Basic design thoughts

Example 7 segment display

74HC4543 driver chip, this allows latching of input so all 4 or 6 digits needs just 4 data pins, and 1 pin per digit for latching.

Design questions?

4 digits or 6?

Having 5 clocks with seconds displayed where sink may not be spot on perfect could really jar. Maybe have a 6 digit version for local time, with 4 digit display for the others?

45mm or 56mm ?

Which micro?

Arduino pro mini is cheap, small and should have enough grunt, but could be an interesting challenge getting TCP/IP, NTP, Timezones, DST, and clock functionality all in 2k of ram.

Techwolf12: ESP8266-12 is very cheap (around 6 euro), is programmable by Arduino and has buildin Wifi.

Wired or wifi?

We'll need wires to power it, so ethernet + PoE may be the simplest solution?

Techwolf12: When using the ESP, you will need 3.3v.

Timezones

Which timezones to use?

• Boston
• London
• Amsterdam
• Moscow
• Sydney

Design

Have created an initial draft idea for a design. Schematic: File:LEDClock-sch.pdf

It's based on a 74hc137 3 to 8 multiplexer, and a 74hc4511 BCD to 7 segment decoder. Will test proof of concept with 0.56" displays.

Status

2017-03-16

Schematic design complete, parts ordered to produce prototype. Prototype PCB for 4 digit version based on 0.56" displays designed. Courage still needed to hit the order button...

2017-03-02

Crazy idea discussed on the mailing list.