Analog signals exhibit amplitude that varies along a continuum between minimum and maximum values. Digital signals, of course, exist at separate predetermined levels or increments. The most common implementation is binary, used to represent Boolean algebra and truth-table entries. The unit of information is either high or low with nothing between. Theoretically any pair of […]
Memory depth and sampling
rate in oscilloscopes
A modern oscilloscope consists first of a front end, the purpose of which is to acquire the signal from the device or equipment of interest. The signal is amplified or attenuated as needed. Then it moves to the analog to digital converter (ADC) for digitization. The next step is for this digital information to be […]
Basics of bandwidth in an oscilloscope
The bandwidth specification in an oscilloscope is applicable to digital as well as analog instruments. Early oscilloscopes, or more properly oscillographs, consisted of a magnetically-driven pen that would ink a trace on a turning paper cylinder, which provided the time base. Frequency response, of course, was severely limited by the mass and inertia of the […]
Electrical metallic tubing basics
There are a number of metal and nonmetallic raceways in common use. Conduit is a subcategory. Electrical Metallic Tubing (EMT), a familiar sight in commercial and industrial facilities, plays a minor role in residential wiring, where it is used only when enhanced protection is needed. EMT is the common thin-wall tubing joined with set crew […]
Steinmetz and magnetic hysteresis
Charles Proteus Steinmetz was born April 9, 1865, the day Lee sent a message to Grant announcing his willingness to surrender, thus ending the American Civil War. Steinmetz lived in the U.S. until the Jazz Age was in full swing. He was a consummate mathematician and electrical engineer. The great achievement in his life work […]
Basic motor testing with multimeters and ammeters
When an electric motor fails to start, runs intermittently, runs hot, or continually trips its overcurrent device, there my be a variety of causes. Sometimes the trouble lies within the power supply, including branch circuit conductors or motor controller. Another possibility is that the driven load is jammed, binding or mismatched. If the motor itself […]
Basics of universal electric motors
For a rotary electric motor to work, there must be two magnetic fields, one associated with the stator and the other with the rotor. At least one of these fields must be moving so the rotor’s magnetic field constantly pursues the stator’s magnetic field, thus creating rotary mechanical motion and energy output. One of the […]
Oscilloscope pioneers Murdock and Vollum
and the founding of Tektronix
In the 1930’s, Melvin J. (Jack) Murdock owned and operated a radio and appliance store at the corner of Foster Road and 67th in Southeast Portland, Oregon. Despite the severe economic depression at the time, Murdock’s enterprise prospered. He acquired a reputation for expertise and integrity. In addition to an affable disposition, he took a […]
Howard Vollum, the father of oscilloscope triggering
Howard Vollum (pronounced VAH-lum) was the key figure in the development of the oscilloscope as we know it today. Following World War Two, Vollum worked with a few friends to found Tektronix, and the small group of veterans set about manufacturing oscilloscopes. They saw the need for a better instrument. Prewar oscilloscopes could measure only […]
Tesla and his induction motor
When Nikola Tesla (1856-1943)was 28, he relocated to New York City to work for Thomas Edison. There was far more opportunity in New York than back in Serbia, which at the time was dominated and constrained to an agrarian economy by the Austro-Hungarian Empire, itself in decline. In the new world Tesla saw opportunity everywhere […]