This little piece of tech whimsy came about after a discussion with some older friends who were finding it hard to remember what day it was! So the idea for a Day Clock was born. Although fairly simple in design it actually took a fair while to construct. The circuit uses a timer module from one of those cheap mains sockets that can be programmed to turn on and off several times a day on each day of the week. This was used becase it was, (a) cheap and, (b) a very easy way of creating a 24 hour square wave. The signal out of those modules is only 1.5V so a level shifter was used to up that to 12V, the signal was then sent to a decade counter. Seven of the decade counter outputs were used to drive a relay/lamp driver which in turn drives the short LED strips which indicate the days. The mask with the days on it was printed on a laser printer using a transparency, there is a sheet of translucent white plastic between the LEDs and the transparency which acts as a diffuser. The rest of the construction was from strip wood and bits of scrap mahogany.