“My wife and I meet friends and family once a week to play Bingo at a local restaurant/bar. We sit at a long table. Facing me is a man with impaired hearing and vision. The room is very noisy and the man often has to ask his wife to repeat many of the numbers called out. So I decided to make the two-unit Bluetooth-coupled system pictured above. On my unit I enter the number called and he sees it on his unit.
The transmitting unit has a 12-key telephone type keypad. Five of the keys (1, 4, 7, *, 0) are programmed to enter the BINGO alphabetic character of each new number called. This unit also has a 4-character display, with 14-segment LED alpha-numeric characters showing the complete number (e.g., B-15).
The receiving unit has the same display, whose size and brightness is more than adequate for the intended viewer. While the transmitting unit sits flat on the table, the receiving unit can also be tipped up for better viewing.
Each unit has a toggle switch that switches between power-on operation and power-off charging of the internal Li-ion 9V battery, via the barrel jack shown. A blue LED on each unit shows when Bluetooth has connected.
Note: In the following I will denote the transmitting unit as Master and the receiving unit as Slave.”