Introduction to the Tool:

The HP 547A current tracer is a hand-held probe that is used in troubleshooting the digital circuits .Its used to Locate the low impedance faults in the electrical systems.The current tracer has a cylindrical ,flat tip,this tip is used to trace the current activity in the circuits.Close to the tip of the tracer there is a small wheel that is used to adjust the sensitivity of the  tracer for1mA to 1A.The current tracer has a lamp indicator ,the brightness of the lamp is a function of  the magnitude of the current going through the  node.The tracer must be powered from the same power source of the circuit under test .The current tracer  requires less than 75mA to operate.

The current tracer mustn't be laid on a ground unless that ground has the same potential  as the negative lead of the tracer.

Figure #1:shows the current Tracer.

Indication of the presence of the current is provided by the lighting of the indicator lamp located near  the tip of the tool.

The current tracer operate on the principle that whatever is driving a low-impedance fault node must be delivering the majority of the current. Tracing the path of this current directly lead to the fault.

1. soldering-bridge.
2. shorted conductors in cables
3. stuck data buses
4. short in voltage distribution network.
5. stuck wire-AND structure.
6. shorted inputs
7. gate to gate faults

The following conditions must be applied in order to use the current tracer properly.

1. the circuit must conduct current .
2. the current tracer tip must be held perpendicular to the circuit under test.

The current tracer is used in the troubleshooting techniques  whenever a low -impedance is discovered .First the  sensitivity of the probe should be adjusted by placing the probe tip  against the length of the circuit and adjusting the current sensitivity wheel located near the tip untill the indaction lamp is on.By following the current path in the circuit and observing the indicator light the current tracer will lead to the  fault that is responsible for the abnormal current flow. In case this method doesn't work the node can be derived by using the logic pulse.

The current tracer is useful in detecting small and large currents .The current tracer is specfically useful when a bad logic level is detected .Once the bad logic is detected the current tracer can be used to  locate the fault in the circuit.This tool is too powereful in determining openned or shorted pins in IC's .A combination of the logic pulser and the current tracer is often used in detecting the faults in the digital circuits. The logic pulser is used to produce the current and the current tracer is used to trace that current untill the fault is discovered.