  Circuit codes are constructed from induced cycles in the graph of the $n$
dimensional hypercube. They are both theoretically and practically important,
as circuit codes can be used as error correcting codes. When constructing
circuit codes, the length of the cycle determines its accuracy and a parameter
called the spread determines how many errors it can detect. We present a new
method for constructing a circuit code of spread $k+1$ from a circuit code of
spread $k$. This method leads to record code lengths for circuit codes of
spread $k=7 \text{ and } 8$ in dimension $22\le n\le 30$. We also derive a new
lower bound on the length of circuit codes of spread 4, improving upon the
current bound for dimension $n\ge 86$.
