In 1703 Isaac Newton, recently named president of the Royal Society, wished to revitalize that staid organization of prominent British scientists. To this end, he appointed his lab assistant, Francis Hauksbee, to be the official curator, instrument maker and experimentalist. Hauksbee’s initial demonstrations were of various air pumps that he had devised, but these less […]
Thank Stephen Gray for wire and insulators
Stephen Gray, astronomer, instrument maker and electrical experimenter, lived in England from 1666 to 1736. Despite challenges of ill health and intermittent poverty, his systematic investigation of electrical conduction laid the groundwork for telegraphy, which about a century later, changed the world. A problem in the life of this amiable seeker of knowledge was being […]
Boolean Algebra and Logic Gates
As first realized, computers were power-hungry, noisy contraptions of clacking gears for performing analog operations, and electromechanical relays capable of cascading digital on-off (true-false) states. Pneumatic and hydraulic computing mechanisms were also proposed. First vacuum tubes and then solid-state devices made computers a practical reality. The initial inspiration for electronic computers was George Boole’s works […]
Digital modulation basics and considerations
The first step in transmitting radio-frequency signals through space is to create a pure carrier at the transmitter. This electrical wave must be of stable, unvarying amplitude, frequency and phase. A quartz crystal oscillator frequently serves the purpose. Information can be conveyed when the carrier is modulated. At the receiver, the carrier is demodulated, separating out an […]
Basics of digital-to-analog converters
By David Herres Typical real-world phenomena (most sensor output, acoustic information in air-pressure variations, temperature fluctuations, etc.) are analog rather than digital in nature. If translated into an electrical signal, they will vary continuously on a sliding scale rather than being encoded in discrete steps, binary or otherwise. If digital processing and memory are to […]
Basics of analog-to-digital converters
We straddle two realms, analog and digital. The output of a sensor, musical instrument, the human voice, and most of the signals that originate in the real world are analog. Today most information processing is digital. This works well in terms of audio and video quality, but analog data must be converted by an analog-to-digital converter (ADC) […]
Basics of harmonics
Waveforms other than those that are pure sine waves or sinusoidal will have a portion of their energy in frequencies other than the fundamental. These frequencies are known as overtones. Some but not all overtones are harmonics. The difference is in how we define them. A harmonic has a frequency that is a whole integer multiple […]
Basics of non-sinusoidal waveforms
By David Herres A non-sinusoidal waveform is one that is not a sine wave and is also not sinusoidal (sine-like). This may sound like a minor distinction but actually there are some substantive implications. A sine wave is the graph of the sine function, usually with time as the independent variable. A cosine wave is […]
Basics of op amps
By David Herres A vacuum-tube operational amplifier (op amp) was conceived in the early years of the Second World War and achieved great success as a means of directing artillery in conjunction with radar. In the decades that followed, implementation as a discrete semiconductor and IC integration, along with circuit refinements, have made the op […]
Basics of the 555 timer chip
By David Herres The most successful IC, if sales volume is an indication, has been the 555 timer. With production averaging over a billion a year, this simple timer-oscillator sees widespread use in the world of electronics, wherever a blinking light, audio tone or bounce-free switch, to mention some prominent applications, is needed. The 555 […]