Simple Wireless RF Network Cable Tester Circuit

Simple Wireless RF Network Cable Tester Circuit is like X-ray for internet wire.

It can catch radio signal inside cable like ethernet, modem or satellite TV but there is no need to touch the wire.

It is very easy to use for checking cable working or not.

Just hold tester near the wire and it will show if signal is there or not.

No need to unplug or fight with messy cable as this small circuit will help one to check fast and easily.

Circuit Working:

Parts List:

This is wireless cable tester which helps to find if RF signal inside network cable.

There is no need for Tester to touch the cable it can catch signal from 2 feet away.

This circuit is good for ethernet, modem or dish TV cable.

When signal is there LED light turns ON.

Tester has two part: one is front part and other is signal amplifier.

Front side has RF detector then signal goes to amplifier.

Detector part has coil L1, diode D1, capacitor C1 and resistor R1, R2.

Coil L1 is small coil with 5mm round made with 10 turns of copper wire.

Diode D1 is fast Schottky type.

Capacitor C1 blocks extra signal to stop problem.

Amplifier uses IC3140 chip which is fast chip and uses very low current.

It works from 5V to 36V.

When antenna long rod comes near cable coil L1 catches signal and diode D1 sends this signal to IC1 chip.

IC1 is set to make weak signal stronger as it uses resistor R3 for feedback.

When signal comes IC1 gives output high and LED lights up.

This means signal is inside the cable.

Formulas:

Here are some formulas for making resonant circuit and antenna in RF system:

LC Resonant Frequency:

f = 1 / 2π√LC

where,

• L is the coil inductance
• C is the capacitor value

Antenna Length for Half Wave Dipole:

L = c / 2f

where,

• L is the antenna length
• c is the speed of light which is about 3 x 10⁸ m/s
• f is the signal frequency

Bandwidth of LC Circuit:

BW = f₀ / Q

where,

• f₀ is the center frequency
• Q is the quality of LC circuit

For full design and need for more calculation it also depends on what frequency and modulation one uses.

How to Build:

To build a Simple Wireless RF Network Cable Tester Circuit one need to follow the below mentioned assembling steps:

One side of coil L1 connects to the place where resistor R1 and R2 join.

• Other side of coil L1 connects to diode D1 anode side
• Diode D1 cathode side connects to pin 2 inverting input of IC3140.
• Capacitor C1 connect between pin 6 output and pin 2 of IC.
• Resistor R3 also connect between pin 6 and pin 2 of IC3140.
• Pin 3 non-inverting input of IC3140 connect to ground.
• LED with one resistor current limit go between pin 6 and positive power (V+).
• Power supply: connect +V to pin 8 and -V to pin 4 of IC3140.
• Telescopic antenna connect to coil L1.

Note:

• Be sure circuit is build properly and all wire and parts must be tight and safe.
• If needed change the parts values to get better signal to detect and for sensitivity.

Conclusion:

To conclude Simple Wireless RF Network Cable Tester Circuit is very useful tool.

It can check RF signal in cable with fast and easy way without a need to touch the cable.

This type of circuits are very good for technician and installer who work with network wire.

References:

Datasheet IC CA3140