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An earth-leakage protection device is a safety device used in electrical installations to prevent shock. It consists of either a current sensing mechanism, or a voltage sensing mechanism.
Common circuit diagram symbols (US ANSI symbols) An electronic symbol is a pictogram used to represent various electrical and electronic devices or functions, such as wires, batteries, resistors, and transistors, in a schematic diagram of an electrical or electronic circuit. These symbols are largely standardized internationally today, but may ...
In the case of a fire alarm, 6 mA could be normal, 15 mA could mean a fire has been detected, and 0 mA would produce a trouble indication, telling the monitoring site the alarm circuit had failed. Some devices, such as two-way radio remote control consoles, can reverse the polarity of currents and can multiplex audio onto a DC current.
A digital current loop uses the absence of current for high (space or break), and the presence of current in the loop for low (mark). [1] This is done to ensure that on normal conditions there is always current flowing and in the event of a line being cut the flow stops indefinitely, immediately raising the alarm of the event usually as the heavy noise of the teleprinter not being synchronized ...
The first types of small modular telephone connectors were created by AT&T in the mid-1960s for the plug-in handset and line cords of the Trimline telephone. [1] Driven by demand for multiple sets in residences with various lengths of cords, the Bell System introduced customer-connectable part kits and telephones, sold through PhoneCenter stores in the early 1970s. [2]
A simplified PAL device. The programmable elements (shown as a fuse) connect both the true and complemented inputs to the AND gates. These AND gates, also known as product terms, are ORed together to form a sum-of-products logic array.
The following other wikis use this file: Usage on af.wikipedia.org Muurprop; Elektrisiteitsvoorsiening; Usage on arz.wikipedia.org فيشة الكهربه حسب البلد
The switches for each key are connected to the microprocessor chip using a matrix circuit. Even though the SY77 has 61 keys, only two small ribbon cables of wiring comes from the keyboard matrix. There are at least two limitations with this system. The first is that it provides only a crude binary on/off signal for each key.