The Hymn Number Board type HNB-1 by LEDDED Lights Ltd. provides easily-readable large, seven-segment numbers with red LED sections and is primarily intended for mounting on a wall in a church.
The unit has five rows of three large digits plus a smaller one at the start of each row to indicate that the following three-digit number is a Hymn 'H' or a Psalm 'P'.
The backboard is made of dark oak and a dark red acrylic cover allows only the lit numbers to be seen. Mounting is by one or more screws, but it may simply be hooked over a peg or nail.
Selection of numbers is achieved through a single push-button underneath, or via a remote push-button for more convenient control if the board is mounted high up.
Numbers are selected in turn and changed by a simple procedure. Hold the push-button and the decimal point lights up to indicate the current digit. If held for a few seconds, it will advance to the next digit in turn. When on the one you want to change, simply release the button and any brief pushes thereafter will advance the number in ascending order on the release. When done, press and hold to advance to the next digit. The selection 'roll-over' from the last number to the first and also from last digit to first digit.
The number sequence includes H, P, and Blank. Some 90 seconds after the last push, the decimal point will turn off but that digit will remain selectable.
All displays can be dimmed together. After power-up, the digit to be selected will be the first one in the top row. This gives an easy way to start again with selections if a mistake was made.
An internal battery maintains the selections so that when the time next comes to change the numbers, the amount of work is minimized.