# A circuit with displays

Here is a puzzle I drew some time ago.

The answer is a single word. • What’s the goal? – Jonathan Harbaugh Aug 24 '18 at 4:56
• @JonathanHarbaugh I've clarified that the answer is one word, thank you. – Mariia Mykhailova Aug 24 '18 at 4:59

ECHO

The wiring is as follows:

[1+2+3]
[ 1+2 ]   [2+3]
[1+3+4]   [3+4]
[1+2+4]

The already-lit panels seem to be complete, which indicates

Wire 1 = Both left segments
Wire 2 = Top and bottom segment
Wire 3 = Middle segment
Wire 4 = Both right segments

Put them all together and on the left four panels you get

[E]
[C]
[H]
[O]

Here are some observations:

It seems that each signal corresponds to some subset of the segments, with each display combining the segments in some way. My initial guess is that each display shows the segments that exactly one of the input signals contains.

The two displays on the right respectively combine signals 2,3 and 3,4. Since adding 1 to either of these results in no segments lighting up, all of the segments in these two displays must be contained in signal 1. This leaves the two left segments of signal 1 undetermined, for a total of four possibilities. Trying all four, the only combination gives a recognizable symbol for all signals is
Signal 1: 3
Signal 2: H
Signal 3: O
Signal 4: E

But I'm pretty sure 3HOE isn't a word, so perhaps I've made a faulty assumption somewhere or there's another way to extract the answer.

• Perhaps (ROT13) gur jbeq vf FUBR? – Mr Pie Aug 24 '18 at 10:36