While I'm at it, I might as well explain my project and you can tell me if it seems like it would work. I am attempting to build a bicycle speedometer. I will have a magnet on the bike wheel and a sensor that pulses on each pass of the magnet. The length before the pulses tells me the elapsed time and the velocity can be calculated from that. Since v=d/t, velocity is inversely proportionate to time, I needed a analog circuit that produced such a relationship. The analog voltage from that circuit is run through a analog-to-digital converter and run to a digital display.
That's the general description, but I'm struggling to find a op-amp log generator circuit that is not too monstrous.