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More than Circuit EngineeringTelephone Line Employment Indicator
Ñõåìû >> Circuits in Practical Use >> Telephone Line Employment IndicatorTelephone Line Employment Indicator
Telephone Line Employment Indicator or Telephone Modem State (off line / on line) it is very useful for the modem users. Voltage 1.9 V on the base of Q1 (ÂC879) is set by the divizor R1, R2 in the mode when a tube «lies» i.e. the voltage in a line is maximally. Thus Q1 – is opened, and Q2 – is closed and a light-emitting diode does not radiate. At the removal of tube or when modem is on line, the voltage in a line and accordingly on the base of Q1 falls. Therefore transistor Q1 is closed and transistor Q2 is open, and light-emitting diode signaling about employment of line.
Telephone Line Employment Indicator
added 10.04.08 00:14:46 | 
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