I am wondering which is more effective. The circuit would use 1 pot to change a pulse from 1hz to (60-120hz). The circuits I have built require a large range to be able to do this. An example is it takes 1/2 turn of the pot to go from 1hz to 1.5hz then 1/4 of the turn to go from 1.5hz to 20hz and the remainder from 20 to 60 quite rapidly. Outside of using a pic to register the pot and change the value accordingly can this be done?

 

A standard 555 circuit is the way to go. You may want to tailor your pot is it's not giving you the control you want. See the links here.

 

I am wondering which is more effective. The circuit would use 1 pot to change a pulse from 1hz to (60-120hz). The circuits I have built require a large range to be able to do this. An example is it takes 1/2 turn of the pot to go from 1hz to 1.5hz then 1/4 of the turn to go from 1.5hz to 20hz and the remainder from 20 to 60 quite rapidly. Outside of using a pic to register the pot and change the value accordingly can this be done?

Have you tried using a multiturn pot?

 

It sounds like you are using a linear pot. You should use a log taper (audio taper) pot. Your control of rotation vs. frequency will be much smoother.

 

But he wants a log freq effect?

A linear pot on a 555 gives linear period change, which is log freq change. A standard 555 circuit and linear pot should get pretty close to his desired spec.

 

An example is it takes 1/2 turn of the pot to go from 1hz to 1.5hz then 1/4 of the turn to go from 1.5hz to 20hz and the remainder from 20 to 60 quite rapidly

Are you saying that is a disadvantage of circuits you have tried, or is it the response you actually want? Do you want a linear frequency response to pot variation, i.e 1/4 rotation gives 30Hz, 1/2 gives 60Hz, .... ?