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Pulsed DC (PDC) or pulsating direct current is a periodic current which changes in value but never changes direction. Some authors use the term pulsed DC to describe a signal consisting of one or more rectangular ("flat-topped"), rather than sinusoidal, pulses. [1] Pulsed DC is commonly produced from AC (alternating current) by a half-wave ...
An insulation monitoring device monitors the ungrounded system between an active phase conductor and earth.It is intended to give an alert (light and sound) or disconnect the power supply when the resistance between the two conductors drops below a set value, usually 50 kΩ (sample of IEC standard for medical applications).
In the non-tripped state, the outputs periodically pulse low. The protective device checks the output, to make sure it does indeed go low when commanded. If not, the output may have failed or has shorted to 24V somewhere else. Between OSSD1 and OSSD2 the pulse intervals are staggered to check for crisscrossed wiring between the two. [1]
In the electrical schematic shown, a typical light dimmer based on a silicon-controlled rectifier (SCR) dims the light through phase-angle control. This unit is wired in series with the load. Diodes (D2, D3, D4 and D5) form a bridge, which generates pulsed DC. R1 and C1 form a circuit with a time constant.
Optoelectronics (or optronics) is the study and application of electronic devices and systems that find, detect and control light, usually considered a sub-field of photonics. In this context, light often includes invisible forms of radiation such as gamma rays , X-rays , ultraviolet and infrared , in addition to visible light.
Pulse-width modulation (PWM), also known as pulse-duration modulation (PDM) or pulse-length modulation (PLM), [1] is any method of representing a signal as a rectangular wave with a varying duty cycle (and for some methods also a varying period). PWM is useful for controlling the average power or amplitude delivered by an electrical signal.
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Its output approximates a voltage-shifted version of the input's upper envelope. Between the circuit's input and output is a diode that performs half-wave rectification , allowing substantial current flow only when the input voltage is around a diode drop higher than the output terminal.