Basic Flip-Flop using relays.
(It's not a latch circuit)
I made a FF that can be used in this Every circuit using relays.
I had a hard time because I usually use a latch circuit, but I forced myself to make it work.
Maybe this is not the minimum number of relays used.
The D latch was placed in the empty space in the lower right corner.
Basic logic gates
http://everycircuit.com/circuit/5024011746279424
