Issue No. 04 - April (1969 vol. 18)
D. Steinmeyer , Emerson Electric Company Electronics and Space Division
Placing a fixed resistor in parallel with an adjustable resistor will cause the resistance of the combination to vary as the logarithm of the setting of the adjustable resistor over a limited range. Calculated compromises between accuracy and range cover ?0.1 percent over a 2.5:1 range to ?10 percent over a 175:1 range. A table of intermediate values is given.
D. Steinmeyer, "Logarithm Function Generated by Parallel Resistors", IEEE Transactions on Computers, vol. 18, no. , pp. 379-381, April 1969, doi:10.1109/T-C.1969.222668