Throwing Star LAN Tap Kit - 10/100Mbps Passive Ethernet Monitor Soldering Kit - Great Scott Gadgets

Description

The Great Scott Gadgets Throwing Star LAN Tap Kit enables the assembly of a passive Ethernet monitor designed to capture and analyze packets transmitted between network devices. Once assembled, the circuit connects directly to the monitored Ethernet link through two RJ45 connectors labeled J1 and J2. The remaining two ports, J3 and J4, forward traffic to computers analyzing the transmission. Each monitoring port receives data transmitted in one direction, allowing network protocol analysis, connection diagnostics, and authorized security testing using Wireshark or tcpdump.

The device features a fully passive design that requires no external power supply. The monitoring ports connect only to the receive lines of the monitoring stations, with no connection to their transmit lines. This prevents the monitoring computers from sending packets into the monitored network. The Throwing Star LAN Tap supports monitoring of 10BASE-T and 100BASE-TX traffic. Two 220 pF capacitors are used to degrade signal quality in Gigabit Ethernet connections, forcing negotiation of a lower speed, typically 100 Mbps. The circuit does not support direct monitoring of 1000BASE-T traffic at full Gigabit speed.

The kit requires soldering and includes a Throwing Star LAN Tap printed circuit board, four Amphenol RJHSE5080 RJ45 connectors, and two 220 pF capacitors. Assembly involves inserting the connectors into positions J1-J4, soldering their leads, and installing capacitors C1 and C2. The manufacturer provides assembly and operating instructions, along with open-source design files created in KiCad. The kit is suitable for learning through-hole soldering, analyzing Ethernet communication, and building laboratory setups for network protocol testing.

Features

• General information
  • Manufacturer: Great Scott Gadgets
  • Model: Throwing Star LAN Tap Kit
  • Device type: passive Ethernet traffic monitor
  • Product form: DIY soldering kit
  • Application: network traffic monitoring and analysis
  • External power supply: not required
• Ethernet communication
  • Supported monitoring standards: 10BASE-T and 100BASE-TX
  • Monitored transmission speeds: 10 Mbps and 100 Mbps
  • Bidirectional traffic monitoring through two independent receive-only ports
  • No direct support for monitoring 1000BASE-T at 1 Gbps
  • Forcing lower-speed negotiation on 1000BASE-T connections using capacitors C1 and C2
  • Compatible with packet analysis tools, including Wireshark and tcpdump
• Connectors and operating principle
  • Number of RJ45 Ethernet connectors: 4
  • J1 and J2 connectors: connection to the monitored Ethernet link
  • J3 connector: monitoring traffic in one direction
  • J4 connector: monitoring traffic in the opposite direction
  • Monitoring ports: receive-only, with no connection to the monitoring stations' transmit lines
  • Passive operation: no active switching circuits or external power supply
• Construction
  • Printed circuit board with component and connector markings
  • RJ45 connectors: Amphenol RJHSE5080
  • Capacitors: 2 × 220 pF, through-hole mounting
  • Capacitor lead spacing: 2.54 mm
  • Component assembly: through-hole soldering (THT)
  • Open-source hardware design
  • Design files created in KiCad

Kit Includes

• Throwing Star LAN Tap printed circuit board - 1 pc.
• Amphenol RJHSE5080 RJ45 connectors - 4 pcs.
• 220 pF through-hole capacitors - 2 pcs.