Hello DigiKey Technical Support Team,
I am currently conducting an Acoustic Emission (AE) experiment on a steel specimen using the Pencil Lead Break (PLB) test. I am looking for a suitable cable to connect my bare PZT AE sensor to an AE preamplifier.
My experimental setup is:
Pencil Lead Break (PLB) on steel specimen
↓
PZT AE sensor
↓
BNC-to-Alligator Clip Cable
↓
AE Preamplifier
↓
AE Data Acquisition System
What I am actually doing
During my experiment, I perform a Pencil Lead Break (PLB) test on the surface of a steel specimen. The PLB produces a transient mechanical/acoustic emission in the specimen.
The PZT sensor is mounted on the steel specimen and converts the mechanical/acoustic wave generated by the PLB into a small electrical signal.
This electrical signal is then transferred through the BNC-to-alligator cable to an AE preamplifier. The preamplifier amplifies the sensor signal, after which the amplified signal is sent to my AE acquisition system for recording and analysis.
I am interested in extracting AE signal features from the PLB test, so it is very important that the signal recorded by the AE system represents the actual signal generated by the specimen/sensor and is not significantly contaminated by environmental or electrical noise.
The problem I am facing
My main concern is electrical/environmental noise pickup in the cable between the PZT sensor and the preamplifier.
Since the PZT sensor produces a relatively low-level electrical signal, I am concerned that the cable could pick up unwanted signals from the surrounding environment, such as:
- electromagnetic interference (EMI)
- electrical noise from nearby equipment
- 50/60 Hz mains interference
- noise from power supplies or other electronic equipment
- electromagnetic fields from motors or other laboratory equipment
If this unwanted noise is picked up before the preamplifier, it could be amplified together with the actual AE signal. Therefore, I want to minimize noise pickup before the signal reaches the preamplifier.
This is why I am specifically looking for a cable with good shielding and appropriate construction for low-level AE measurements.
Why I am concerned about the BNC-to-alligator cable
The PZT sensor I am using has bare electrical terminals, so I cannot simply use a normal BNC-to-BNC cable directly from the sensor.
Therefore, I need a BNC-to-alligator-clip cable to make the electrical connection to the PZT sensor.
However, I understand that in many BNC-to-alligator cables, the coaxial cable portion is shielded, while the final red and black wires leading to the alligator clips may be exposed/unshielded.
This is my main concern.
For example, if the cable has good coaxial shielding but the last portion near the PZT consists of exposed red and black wires, I would like to understand whether these exposed conductors could act as an antenna and pick up environmental electrical noise before the signal reaches the preamplifier.
What I need to know about the cable
I am considering the following type of cable:
BNC male → RG174/U coaxial cable → red/black alligator clips
Before purchasing, I would like your technical advice regarding the following:
1. Shielding
What exactly is the shielding construction of this cable?
Is the coaxial section shielded using a tinned copper braid, foil, or another shielding method?
2. Shield coverage
What is the actual braid/shield coverage percentage?
Is it 90% or greater?
If the manufacturer specifies shielding coverage, could you please provide the exact value?
3. Alligator-clip section
Most importantly, is the section from the end of the coaxial cable to the red/black alligator clips also shielded?
Or are the red and black conductors completely exposed/unshielded?
If they are unshielded, approximately how long is this exposed section?
4. Effect on AE measurements
Would the unshielded red/black section be a significant concern when the cable is used between a low-level PZT AE sensor and an AE preamplifier?
In other words, could this exposed portion pick up environmental/electrical noise that would subsequently be amplified by the preamplifier?
5. Suitability for my application
Based on the complete setup described above, would you consider this cable suitable for:
PZT AE sensor → cable → AE preamplifier → AE acquisition system
for a PLB test on a steel specimen?
6. Shield continuity
Is the cable shield electrically continuous all the way from the BNC connector to the point where the alligator-clip conductors begin?
How is the shield terminated at the BNC connector?
7. Shielding effectiveness
Does the manufacturer provide any specification for the cable’s shielding effectiveness, rather than only stating the braid coverage percentage?
I am particularly interested in actual performance against electromagnetic/electrical noise.
8. Characteristic impedance
Is the cable 50 Ω RG174/U?
If so, is 50 Ω characteristic impedance appropriate for the connection between a PZT AE sensor and an AE preamplifier?
9. Low-level signal transmission
Is this cable recommended by the manufacturer for carrying low-level sensor signals, or is it primarily intended as a general-purpose test lead?
10. Better alternative
If this cable is not ideal for my application, could you please recommend a BNC-to-alligator cable available from DigiKey that would be better suited for low-level AE measurements?
Ideally, I am looking for a cable where the shielding is maintained as close as possible to the PZT sensor/alligator-clip connection, rather than having a long exposed red/black section.
My main requirement
My priority is not cable cost or flexibility. My main objective is:
to minimize environmental/electrical noise pickup between the PZT sensor and the AE preamplifier so that the AE acquisition system records the actual AE signal generated by the PLB test as accurately as possible.
Therefore, I would particularly appreciate your recommendation from an instrumentation/low-level signal measurement perspective, rather than simply confirming that the cable is electrically compatible.
If possible, please provide:
- the exact shielding construction,
- braid coverage percentage,
- whether the alligator section is shielded,
- exposed lead length,
- shielding effectiveness, if available,
- and the specific cable/part number you would recommend for this application.
Thank you for your technical assistance.