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The project described here is a low-cost solution to transmit a video or digital signal up to 300 Meters over a twisted pair cable. The project has been designed using the AD8131 chip which is a differential driver for the transmission of high-speed signals over low-cost twisted pair or coaxes cables. The project can be used for either analog or digital video signals or for other high-speed data transmissions. It is capable of driving either Cat3 or Cat5 twisted pair or coax with minimal line attenuation. The AD8131 has on-chip resistors that provide for a gain of 2 without any external parts. Several on-chip resistors are trimmed to ensure that the gain is accurate, the common-mode rejection is good, and the output is well balanced. This makes the AD8131 very suitable as a single-ended-to-differential twisted-pair line driver. The board works with +/-5V DC (Dual 5V) supply, RCA connector J1 to feed single-ended Video or digital signal, connector CN2 is used to connect the twisted pair cable (CAT5), D1 Power LED, Resistor R7 and R8 terminate the line at transmitting side.

The AD8131 is a differential or single-ended input to differential output driver requiring no external components for a fixed gain of 2. The AD8131 is a major advancement over op amps for driving signals over long lines or for driving differential input ADCs. The AD8131 has a unique internal feedback feature that provides output gain and phase matching that are balanced to −60 dB at 10 MHz, reducing radiated EMI and suppressing harmonics. Manufactured on the Analog Devices, Inc. next-generation XFCB bipolar process, the AD8131 has a −3 dB bandwidth of 400 MHz and delivers a differential signal with very low harmonic distortion.

- Supply +/-5V DC
- Fixed Gain 2
- Single-Ended Video or Digital Signal Input – RCA Connector
- Differential Output – Screw Terminal
- Low Balance Error
- Output Impedance 100 Ohms
- PCB Dimensions 36.67 x 24.77 mm”

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