TX-221A: Single channel for automotive
TX-221B: Dual channel for automotivve
TX-221C: Single channel for home entertainment
TX-221D: Dual channel for home entertainment

Specifications:
Power requirement: 12V DC/200mA
Infrared wavelength: 850nm
Modulation:±75KHz
Carrier frequency:
- channel A: R 2.8 MHz / L-ch 2.3 MHz
- channel B: R 3.8 MHz / L-ch 3.2 MHz(For dual channel)
Effective distance: 10 meters(straight)
Distortion:1%
Frequency response: 20Hz to 20KHz
Power input tolerance: normal 11V to 13V or 5V to 13V
S/N ratio:>55dB
Power consumption:1.0W
Auto input range:0.1V to 3V(RMS)