The logarithmic response of the amplifier described in this paper is derived by extracting an output proportional to the time required for the voltage across a parallel resistance condenser combination to decay to a small fixed value. The input voltage is sampled with a 400‐cy converter. Accordingly, the amplifier is restricted to a resolving time of 1/400th of a second. A logarithmic response over four decades with a deviation of less than 1% of the maximum output is secured. The immediate purpose of the amplifier is to aid in the study of the transients associated with photocells.