Model 950. Tunable Filter Instruments

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Rolf Rose
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Single Channel- Certified Description Frequency Devices instruments furnish the user with an 8-pole low-pass or high-pass filter that is tunable by front panel controls.

1 Single Channel- Certified Description Frequency Devices instruments furnish the user with an 8-pole low-pass or high-pass filter that is tunable by front panel controls. The controls allow the user to select a corner frequency between 1 Hz and 5 khz with 6 steps from each of two selectable ranges. Tunable Filter Instruments The instrument exhibits an input impedance of 1 Meg Ω shunted by 47pF to a single ended signal source. When configured in the differential mode, the instrument has a common mode rejection ratio (CMRR) which exceeds 6d; in this mode the instrument presents an input impedance of 2 Meg Ω shunted by 47pF to a double ended single source. Front panel gain control also enables the operator to select a gain factor of, 1, or 2d. Standard operational features include: 1) djustable Frequency Control 2) Differential Input mplifiers 3) djustable Gain Control 4) Off-set djustment 5) NC Connectors for Signal I/O vailable Low-Pass Models: Page 95L8 8-pole utterworth L8L 8-pole essel vailable High-Pass Models: Page 95H8 8-pole utterworth Compact size and manual rotary switch front panel controls make 95 instruments a popular, cost effective, easy-to-use solution for signal conditioning applications in the following areas: nti-aliasing Filters iomedical/iotechnology pplications Data Recording/Playback Data Smoothing EKG/EEG Signal Filtering FDM/PCM Signal Filtering Medical Research Industrial Process Control Seismic nalysis Vibration nalysis 1 General Specifications:

2 LOCK DIGRM Tunable Filter Instruments GIN (d) INPUT 1d d 2d - + OUT DIFF MP 8-POLE TUNLE FILTER OUTPUT MP OFFSET OFFSET NULLED TYPICL DJUSTMENT FUNCTION CORNER FREQUENCY TUNING TYPICL FRONT PNEL NC CONNECTOR ON 95 TUNELE CTIVE FILTER CORNER 2 FREQUENCY 5 IN Hz - GND INPUT GIN (d) OFFSET + R N G E x1 x1 OUT 2

3 Tunable Filter Instruments L8 95L8L H8 Product Specifications Low-Pass Low-Pass High-Pass Transfer Function 8-Pole, utterworth 8-Pole, essel Transfer Function 8-Pole, utterworth Range fc 1 Hz to 5. khz 1 Hz to 5. khz Range fc 1 Hz to 5. khz Theoretical Transfer ppendix ppendix Theoretical Transfer ppendix Characteristics Page 9 Page 4 Characteristics Page 29 Passband Ripple. d. d Passband Ripple. d (theoretical) (theoretical) DC Voltage Gain ±.1 d typ. ±.1 d typ. Voltage Gain ±.2 d to 1 khz (non-inverting) ±.2 d max. ±.2 d max. (non-inverting) ±.5 d to 12 khz Power andwidth 12 khz Stopband Stopband ttenuation Rate 48 d/octave 48 d/octave ttenuation Rate 48 d/octave Cutoff Frequency fc ± 2% max. fc ± 2% max. Cutoff Frequency fc ± 2% max. ccuracy ±.5% typ. ±.5% typ. ccuracy ±.5% typ. ± 2% max.± 2% max. ± 2% max. Stability ±.1%/ C typ. ±.1%/ C typ. Stability ±.1%/ C typ. ±.2%/ C max. ±.2%/ C max. ±.2%/ C max. mplitude -3 d -3 d mplitude -3 d Phase Phase -36 Filter ttenuation.12 d.8 fc 1.91 d.8 fc Filter ttenuation 8. d.31 fc 3.1 d 1. fc 3.1 d 1. fc 6. d.42 fc 6. d 2.37 fc 6. d 4.52 fc 3.1 d 1. fc 8. d 3.16 fc 8. d 6.7 fc. d 2. fc Total Harmonic Total Harmonic 1 khz <-9 d typ. <-9 d typ. 1 khz <-88 d typ. Narrow and Noise 5 mv rms typ. 5 mv rms typ. Narrow and Noise 1 mv rms typ. (5 Hz - 1 khz) (5 Hz - 1 khz) 3

4 Location of Front Panel Terminals and Controls Location of Front Panel Terminals and Controls C&D ON - GND INPUT TUNELE CTIVE FILTER 95 GIN (d) OFFSET R x1 N G E x1 CORNER 2 FREQUENCY 5 IN Hz OUT G I H E Location of Rear Panel Terminals and Controls K F J PR.1 SELECT SN: v 95L8L 23v FUSE (25V.1) (25V.1) NOM. FREQ. 6 Hz 5 Hz corcom L M WRNING: Do not remove covers, no user serviceable parts inside. Contact: Frequency Devices for service, tech@freqdev.com MDE IN U.S. FRONT PNEL. POWER Status Lamp: This red LED indicates whether or not the power to the analog filter circuitry of a instrument is on.. INPUT Switch: This three position toggle configures the instrument for either differential inputs (-), a singleended input (), or input nulling (GND) which grounds both the () and () input terminals. C. & D. () and () Input Terminals: This pair of shielded, female NC connectors accept signal inputs () and (). The instrument applies a noninverting gain to input () and an equal but opposite inverting gain to input () while the GIN switch sets the magnitude of differential gain to, 1, or 2 d. The NC shields have been internally connected to the instrument ground. E. GIN Switch: This three-position toggle switch selects an overall filter gain of, 1, or 2d. F. OFFSET djust: This adjustment is intended to zero the offset that results from the instrument s own circuitry and does not provide for wide range offset to remove dc input signals. G. CORNER FREQUENCY Selector Switch (1-5Hz): This six position rotary switch selects the digit value of the corner frequency. The switch selectable values are 1, 2, 5, 1, 2 and 5, H. MULTIPLIER Selector Switch: This two-position toggle switch multiplies by a factor of either 1 or 1x, the value set on the CORNER FREQUENCY selector switch. I. OUT Terminal: This terminal is a female NC connector. The shield on the NC is internally connected to the instrument ground. RER PNEL J. IDENTIFICTION LEL: This label identifies the date of manufacture, serial number, filter type and operating power requirements. K. POWER CONNECTION: Denotes power plug location. L. POWER ON/OFF Switch: twoposition toggle switch on the back panel Power Module that interrupts/completes the power circuit. M. Voltage Selector Module: 115V Operation The power module window shows the operating voltage (115V or 23V). t time of shipment, the voltage window will be set to the 115V position. 23V Operation For 23V operation, use a small flathead screwdriver to pry open the fuse module door. Remove the fuse cartridge, fuse clip and single fuse for 115V operation. Install two 5 X 2 mm 25V,.1 fuses into the fuse cartridge, rotate and insert fuse cartridge so 23V is visible in fuse module door when closed. 4

5 Initial Setup Select desired operating voltage 115 Vac or 23 Vac. See note "N" page four. Set the POWER ON/OFF Switch to ON. continuously lit POWER lamp indicates power applied. llow the instrument a three-minute warm-up period to achieve thermal equilibrium. To perform initial adjustment and/or operational testing, set the remaining front panel controls as follows: a) The CORNER FREQUENCY switch and the MULTIPLIER to the desired corner frequency. b) The OFFSET control to approximately mid-range. c) The GIN switch to the desired value. e) The INPUT switch to ground (GND). Connect a dc-coupled oscilloscope, of vertical sensitivity 1mV/CM or better, or a digital voltmeter (DVM) to the instrument front panel NC connector labeled OUT. Set the OFFSET control for a zero-volt reading on the scope. Subsequent changes of CORNER FREQUENCY and GIN control settings will introduce a small dc output offset, which should be zeroed for critical applications. Leaving all other controls unchanged, set the Input Switch to (-) and apply a 5Vdc signal simultaneously to input NCs () and (). The voltage measured at the OUT NC should be 5-5=OVdc. This completes preliminary test and adjustment. Corner Frequency Selection To select a corner frequency, simply set the CORNER FREQUENCY switch and the MULTIPLIER switch for the desired numerical value. Operation and pplication Guide Lines The Differential Input The instrument utilizes a differential input amplifier to reject prevalent forms of electrical interference, while presenting desirable input characteristics to the signal source requiring filtering. The differential input configuration is ideal for measuring the difference between two values rather than the values themselves. ridge circuits utilizing strain gages, thermocouples and a variety of other types of transducers generate differential full-scale output voltages in the order of millivolts that are often superimposed upon volt-level reference and noise values. The importance of CMRR In actual system environments, each signal and power return conductor can generate an interference voltage proportional to the net conductor resistance and the electrical current level. ny such interference voltages appear as common mode signals to the amplifier, and are rejected as such. Circuit model illustrating relationship between filter's differential input amplifier and external signal and error sources. INPUT SIGNL ND NOISE VOLTGE SOURCES V CM V V R S SIGNL COMMON (+) (±) R CM+ + R D 2d 1d R CM- - d DIFF MP DIFFERENTIL INPUT MPLIFIER GIN = K OUTPUT MPLIFER OUT R S COUPLED POWER LINE NOISE VOLTGE ±Vs COM +Vs (±) (+) Vo = K(V - V) + Vcm/CMRR : WHERE K = 1, 1 ND 1 FOR GIN SETTINGS OF, 1 ND 2d RESPECTIVELY. SEE TEXT FOR REMINING TERMS. DENOTES FRONT PNEL CCESS V P C POWER SUPPLY SIGNL COMMON 5

6 Specifications C and rated Power Input) Input Characteristics Input Impedance: Differential 2 MΩ Shunted by 47pF Single Ended 1 MΩ Shunted by 47pF Input Voltage: Linear Differential 2V p-p (Gain Set at d) Max Safe Differential ny Continuous Value between ±75V Max Safe Common Mode ny Continuous Value between ±75V ias Current 4 n typ.; 2 n max. Common Mode Rejection ratio with 2kΩ source unbalance and d Gain > 6d, dc to 5kHz d (RMS) d (RMS) Typical Common Mode Rejection Ratio essel filter type set to 5 khz filter corner frequency, d gain setting. Output Characteristics Full Power andwidth Related Output Short Circuit Output Current Output Protection Output Impedance Offset Voltage dc to 5kHz 1V p-p for R L = 5W 2V p-p for R L = 2kW +/-1 m continuous +/-2 m without damage Short Circuit to Ground Only 5 Ω djustable to Zero at Front Panel (Range +/-5mV dc) d (re:1v RMS) d (re:1v RMS) Frequency (Hz) Typical Output Noise -2 essel filter type set to 5 khz filter corner frequency, d gain setting, input grounded Power Supply C Line Operation: Power 6 Watts max. Voltage Frequency Range-Rear Panel: 115 V 15 to 5/6Hz 23 V 21 to 5Hz Fuse.1 mp Frequency (Hz) (Hz) Temperature Operating Temperature: C to +5 C Storage Temperature -25 C to +7 C Mechanical Dimensions Weight Case Material Color 2.375"H x 7."W x 8.3"D 6.3cmH x 17.75cmW x 21.8cmD 1.5 lbs;.68 kgs. S plastic PC one Signal plus common mode voltage cannot exceed 2V peak for a linear output. 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. IN-95-6

7 8-Pole ppendix essel Low-Pass Theoretical Transfer Characteristics 1 f/fc mp Phase Delay (Hz) (d) (deg) (sec) Normalized Group Delay: The above delay data is normalized to a corner frequency of 1.Hz.The actual delay is the normalized delay divided by the actual corner frequency (fc). ctual Delay = Normalized Delay ctual Corner Frequency (fc) in Hz Normalized Time (1/f sec) 7 sales@freqdev.com Web ddress: Fax on Demand: 978/ mp (d) Delay (sec) Step Response (V/V) Normalized Frequency(f/fc) Normalized Time (1/f sec) Frequency Response Delay (Normalized) Step Response 1.5

8 Low-Pass ppendix 8-Pole utterworth Theoretical Transfer Characteristics 1 f/fc mp Phase Delay (Hz) (d) (deg) (sec) Normalized Group Delay: The above delay data is normalized to a corner frequency of 1.Hz.The actual delay is the normalized delay divided by the actual corner frequency (fc). ctual Delay = Normalized Delay ctual Corner Frequency (fc) in Hz Normalized Frequency(f/fc) 8 sales@freqdev.com Web ddress: mp (d) Delay (sec) Step Response (V/V) Delay (Normalized) Normalized Time (1/f sec) Frequency Response Step Response Normalized Time (1/f sec)

9 High-Pass ppendix Theoretical Transfer Characteristics 1 f/fc mp Phase Delay (Hz) (d) (deg) (sec) mp (d) 8-Pole utterworth Frequency Response Normalized Frequency(f/fc) 1.Normalized Group Delay: The above delay data is normalized to a corner frequency of 1.Hz.The actual delay is the normalized delay divided by the actual corner frequency (fc). ctual Delay = Normalized Delay ctual Corner Frequency (fc) in Hz 9 sales@freqdev.com Web ddress:

Models 900CT & 900BT. Tunable Active Single Channel Certified Filter Instrument

Models 900CT & 900BT. Tunable Active Single Channel Certified Filter Instrument Tunable Active Single Channel Certified Filter Instrument Description Frequency Devices instruments are single channel; 8-pole low-pass or high-pass, front panel tunable filter instruments. The controls