Don't try this with an electronic calculator!
Circular Slide Rules
Halden Calculex - Pocket-watch style slide rule. Complete with leather case and instruction book. $595.
SIC 1610 Professional -Double-sided circular with the following scales: E1,B,CI,C,D,A,K,LL0,LL1,LL2,LL3, L,P,DI,D,C,T,S,T,S,T,ST,LL0',LL1'LL2'LL3'. Made of aluminum with plastic facing on both sides. Independently rotating discs on both sides. Mint-in-box, with vinyl case, instructions and warranty card. $495.
Amphenol Smith Chart and Circular Slide Rule - A wonderful find! One side is a Smith Chart; the other side is a (high resolution) circular slide rule. Complete with instruction folder to hold the rule. (Sold)
Concise 380 Electrical Engineering Circular Slide Rule Calculates Surge Impedance, Resonant Frequency, Inductive and Capacitive Reactance, Wave-length, Frequency, and Decibel ratios. Complete with case and manual. Somewhat rare. $350.
Star Sliding Disk No. 120. Really neat, double-sided circular. Made by the same folks who made the plastic-faced Picket circulars. I will try to get a picture up soon. Complete set includes slip case, instruction booklet and original box. (Sold)
Pickett 101-C Circular Slide Rule. Scales are (obverse) C, CI, A, Af, L, F', LL2, LL1, DS, DT, M, (reverse) C, S, ST, T, Decimal Equivalents. The 101C has three independent cursors. (This item is not for sale).