The AM-20 is a highly versatile, solid-state analog meter capable of a variety of user programmable display modes. It is designed to meet the requirement in many applications for a rugged, high input impedance meter that has instantaneous response and is immune to the vibration, sticking and overshoot problems associated with needle-type meters.
The meter’s display consists of 20 LED segments individually driven by 20 comparators divided into a left side set and a right side set of ten comparators each.
The user can select and adjust the three internal reference voltages that are applied respectively, to the left side of the left comparator set, the center point where the two comparator sets are joined in series and the right side of the right comparator set. The meter’s circuitry detects when the input signal corresponds to the voltage at any one of the 20 points along the two comparator divider networks with a step accuracy of better than 0.1%. The meter can be adjusted so that both comparator sets have an equal reference voltage across them which will produce a linear full scale display, or if required, they can have a different reference voltage which will enable each half of the meter’s display to have a different scale or sensitivity.