I would like to build a circuit to pulse a voltage (.3 volt) and be able to vary the timing of the pulse from 1 minute to 4 minutes. Right now I have a steady voltage of .3 of a volt and would like to take it to 0 volts every minute and be able to vary it up to 4 minutes. Can I do this with a 555 timer and potentiometer and other associated components? What would the schematic look like? Thanks for any help. Arden