BCD to 5x7 display decoder using relays.
(Corresponds to the display of 0 to 9)
This is a 5x7 display decoder that displays the decimal digits 0 to 9 from a 4-bit sequence.
This circuit consists of 20 SPDT relays.
Since a method for finding the minimum number of contacts in differential sequence circuits was recently established, it is now possible to design just about any kind of decoder.
However, this circuit was derived after spending half a day exploring just two of the 41 potential combinations; it is possible that a circuit requiring fewer than 20 contacts could be found in the future.
Ver2
http://everycircuit.com/circuit/6439461411618816
