Voltage enhancement circuit for central station monitored alarm systems

Claim 1

In combination with a centrally monitored alarm system of the type having at least one alarm detection device at a first location, an alarm monitoring panel at a second location, and electrically conductive lines interconnecting said device and said panel, the lines having an input terminal at said first location and an output terminal at said second location, the lines having an internal resistance between said terminals which is a function of the distance between said locations and therefore a function of the length of the lines, the detection device having a source of voltage of substantially fixed or constant magnitude or level which is applied to the input terminals of the lines in one condition of the alarm detection device, a portion of the voltage applied to said input terminals being dropped across said internal resistance and an output portion of the voltage applied to said input terminals appearing at said output terminals, and the monitoring panel including indicator means for providing an indication of said one condition of the alarm detection device when said output voltage portion at said output terminal has a magnitude above a minimum detectable level; and voltage enhancement means interposed between said source of voltage and said line input terminal for increasing the magnitude or level of said voltage source at said input terminal to at least partially compensate for said voltage portion dropped across said line internal resistance, whereby the voltage at said output terminal may be increased to at least said minimum detectable level irrespective of the length of the interconnecting lines.