I said I wasn't going to do it...but laying in bed at 3AM, my brain and I don't always agree.
Five pushbuttons and five 4PDT relays. Expand or decrease...it's "N" relays with "N-1"PDT contacts.
The contacts and coils are not physically oriented in the schematic. The contacts above each coil are on the 4 other relays. Just an easy way to visualize what's happening.
In the schematic, coil on relay C is powered through NC contacts AC, BC, DC, and EC on the other four relays. The contacts on relay C...CA, CB, CD, and CE...are in the NO position ...opening the path to the 12v on each of the other coils. If the button for relay A is pushed all its contacts...AB, AC, AD, and AE...go to NO removing power from the other coils. The NC contacts on relays B, C, D, and E...BA, CA, DA, and EA...provide power to A's coil, latching it on. At power-up all the relays would be off, until a button was pushed.
The output is just whatever you put parallel to the relay coils.
This is why we now use PIC's!
Ken
Another 3am realization.
When first powered up, all the relay contacts are in the NC position, so all coils see 12V at the same instant. All coils try to pull their contacts to the NO position. The first relay to get it's contacts moved would be latched. This could be random, weighted, or chatter. I think if an electrolytic cap were placed across one of the pushbottons, it would hold that one on long enough to assure it was always selected. This is still playing with the original request of 5 relays and 5 pushbottons.