Tri-Colored LED Shows State of Tri-State Driver
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-16
This article describes a method of visually indicating which state a tri-state logic output driver is in. Although it is fairly easy to determine when a driver is in either the high or low state, determination of when it is in the high impedance state is difficult. Also, without the use of an oscilloscope it is difficult to detect whether the output driver has pulses of both high and low levels. A tri-color LED (light emitting diode) along with a pair of resistors can be used to easily indicate all three states as well as indicate whether pulses are present.