The matrix has seven columns, one for each segment on the display ... [Fran]’s circuit using a 555 and a 4017B decade counter to make a display count down to 0.

At its heart the device simply counts the oscillations of an input signal for one second, then latches the total to the 7-segment displays before zeroing the counter block and starting over.

seven-segment display (Image courtesy of LXD, Inc.) In their natural state, liquid crystals line up with the orientation "rubbed" into the front and rear glass panels. The rubbings are microscopic ...