Salts monitoring device

Claim 1

A small portable monitor usable by an unskilled person for measuring the quantity of total dissolved ionized salts in an undiluted sample comprising: power supply means for providing in operation a first voltage level and a second and substantially lower voltage level with reference to the power supply ground; reference voltage generating means including a first alternating current generating means across the first and second voltage levels and providing a first alternating current output cycling between the first and second voltage levels above ground; a voltage divider having a first leg of relatively high impedance connected between the first alternating current output and a center point and a second leg of relatively low impedance connected between the center point and the second voltage level to provide a second alternating current output from the center point of the voltage divider of substantially reduced magnitude set a predetermined and controlled level above the second voltage level; an operational amplifier connected into a voltage follower configuration wherein the second alternating current output provides the input to the operational amplifier and the first voltage level and the ground provide the power supply to the operational amplifier and wherein the output of the operational amplifier is the final output of the reference voltage generating means; a conductivity sensing probe assembly including two spaced electrodes adapted to be submerged in an undiluted sample to be tested, said electrodes being made from a material which is not ionized by the undiluted sample; amplifier means energized by the power supply means and having an input and output; circuit means connecting one electrode of the probe assembly to the output of the operational amplifier and the other electrode to the input of the amplifier means thereby providing an input level to the amplifier as a function of the quantity of the total dissolved ionized salts in the sample; indicator means responsive to the output of the amplifier means providing an indication having a predetermined relationship to the quantity of the total dissolved ionized salts in the sample.