Description The D51 is designed specifically to provide the C-message weighting frequency response specified in Bell System Technical Reference 41009 for telephone message circuit noise measurement. The theoretical C-message characteristic simulates the perceived response of the human ear to telephone noise. All D51 Series filters provide a close ± 1dB approximation to the theoretical C-message weighting function from 60 Hz to 5.0 kHz.   Applications Telephone Message Circuit Noise Measurement Test Equipment Theoretical Frequency Response Frequency Hz Attenuation dB Tolerance +/-dB 60 55.7 1 100 42.5 1 200 25.0 1 300 16.5 1 400 11.4 1 500 7.5 1 600 4.7 1 700 2.7 1 800 1.5 1 900 0.6 1 1000 0.0 0.1 1200 0.2 1 1300 0.5 1 1500 1.0 1 1800 1.3 1 2000 1.3 1 2500 1.4 1 2800 1.9 1 3000 2.5 1 3300 5.2 1 3500 7.6 1 4000 14.5 1 4500 21.5 1 5000 28.5 1   Specifications (@ 25°C and Vs ±15 Vdc) Analog Input Characteristics Impedance: 10 kΩ min. Source Impedance1: 600 Ω max. Bias Current 2: 0 Voltage Range: ± 10 Vpeak Max. Safe Voltage: ± Vs Analog Output Characteristics Impedance(Closed Loop): < 1 Ω typ., 10 Ω max. Linear Operating Range: ± 10 V Maximum Current3: ± 2 mA Offset Voltage: ± 5 mV Offset Temp. Coeff.: 50 µV / °C Noise4: 50 µVRMS Gain (non-inverting) 0 ± 0.1 dB @ 1 kHz Power Supply (± Vs) Rated Voltage: ± 15 Vdc Operating Range: ± 5 to ± 18 Vdc Maximum Safe Voltage: ± 18 Vdc Quiescent Current: ± 1.5 mA typ., ± 2.0 mA max. Temperature Operating: 0 to + 70°C Storage: -25 to+85°C Notes: Maximum allowable series input resistance if gain accuracy's are to be maintained. Capacitor coupled. Output is short circuit protected to common. DO NOT CONNECT TO ±Vs. DC to 50 kHZ excluding DC offset with input grounded. Pin-Out and Package Data Filter Mounting Assembly - See FMA-01S We hope the information given here will be helpful. The information is based on data and our best knowledge, and we consider the information to be true and accurate. Please read all statements, recommendations or suggestions herein in conjunction with our conditions of sale which apply to all goods supplied by us. We assume no responsibility for the use of these statements, recommendations or suggestions, nor do we intend them as a recommendation for any use which would infringe any patent or copyright.