Patent ID: 6205201
Filing Date: 2001-03-20
Classification: H04M

Abstract:
A tester for precisely testing the current supplying capacity in a telephone line comprising:test circuitry supported within a housing and having two electrical inputs and at least a first indicator indicating a safe current condition between said two electrical inputs, a second indicator indicating an unsafe current condition between said two electrical inputs, and a third indicator indicating polarity; anda connector having two terminals each connected to an associated one of said inputs;wherein said two electrical inputs include a first input and a second input, and wherein said test circuitry further comprises:a first zener diode having a cathode connected to said first input, and an anode;a second zener diode having a cathode connected to said second input, and an anode;a first resistor connected between the anodes of said first and second zener diodes;a polarity light emitting diode having a cathode connected to ground and an anode;a second resistor connected between said cathode of said second zener diode and said anode of said polarity light emitting diode;a first diode having an anode connected to said first input and a cathode;a third resistor having a first end connected to said cathode of said first diode, and a second end;a normal indicator light emitting diode having a cathode connected to said second end of said third resistor, an anode connected to ground;a fourth resistor having a first end connected to said anode of said first zener diode and a second end;a first capacitor connected between said cathode of said first diode and ground;a second capacitor connected between said second end of said fourth resistor and ground;a fifth resistor having a first end connected to said second end of said fourth resistor, and a second end;a sixth resistor having a first end connected to said second end of said fifth resistor, and a second end;a comparator integrated circuit having a positive input connected to said second end of said fifth diode, a negative input connected to ground, and a first input connected to said second end of said sixth resistor, and a second input connected to said cathode of said first diode; anda warning light emitting diode having an anode connected to said second end of said third resistor and a cathode connected to said output of said comparator integrated circuit.