Model 218
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110 Instruments Model 218 Temperature Monitor Model 218 Temperature Monitor Features Operates down to 1.2 K with appropriate sensor 8 sensor inputs Supports diode and RTD sensors Continuous 8-input display with readings in K, °C, V, or Ω IEEE-488 and RS-232C interfaces, analog outputs, and alarm relays Available in two versions: Model 218S and 218E Product Description The Model 218 is our most versatile temperature monitor. With eight sensor inputs, it can be used with nearly any diode or resistive temperature sensor. It displays all eight channels continuously in K, °C, V or Ω. The measurement input was designed for the demands of cryogenic temperature measurement, however, the monitor’s low noise, high resolution, and wide operating range make it ideal for noncryogenic applications as well. Sensor Input Reading Capability The Model 218 has eight constant current sources (one for each input) that can be configured for a variety of sensors. The inputs can be configured from the front panel or via a computer interface, and are grouped in two sets of four. Each set of four inputs is configured for the same sensor type (i.e., all 100 Ω platinum or all silicon diodes). Two high-resolution A/D converters increase the update rate of the Model 218. It can read sensor inputs more quickly than other scanning monitors because it does not have to wait for current source switching. The result is 16 new readings per second, allowing all inputs to be read twice each second. Inputs can be turned off to obtain a higher reading rate on fewer sensors. Temperature Response Curves The Model 218 has standard temperature sensor response curves for silicon diodes and platinum RTDs. It can support a wide variety of temperature sensors because a unique 200-point user curve can be stored for each of the eight inputs. CalCurves™ for Lake Shore calibrated sensors can be stored as user curves. The built in SoftCal™1 algorithm can also be used to generate improved curves for DT-470 diodes and platinum RTDs that are stored as user curves. The Lake Shore SoftCal™ algorithm for silicon diode and platinum RTD sensors is a good solution for applications requiring more accuracy than a standard sensor curve but not in need of traditional calibration. SoftCal uses the predictability of a standard curve to improve the accuracy of an individual sensor around a few known temperature reference points. 1 www.lakeshore.com Lake Shore Cryotronics, Inc. (614) 891-2244 fax: (614) 818-1600 e-mail: info@lakeshore.com

Model 218 Temperature Monitor Instruments 111 Interface Features of Model 218S and Model 218E 218S 218E Feature Numeric keypad Front panel curve entry Alarms RS-232C interface IEEE-488 interface Two analog voltage outputs Eight relays Line input assembly Terminal block with relays and RS-232C or printer interface analog voltage outputs (218S only) IEEE-488 interface (218S only) Sensor inputs Interface The Model 218 is available with both parallel (IEEE-488, 218S only) and serial (RS-232C) computer interfaces. Each input has a high and low alarm which offer latching and non-latching...

112 Instruments Model 218 Temperature Monitor Typical Sensor Performance – see Appendix F for sample calculations of typical sensor performance Example Lake Shore sensor Temp Nominal resistance/ voltage Typical sensor sensitivity7 Silicon Diode DT-670-SD with 1.4H calibration Silicon Diode DT-470-SD-13 with 1.4H calibration GaAlAs Diode TG-120-SD with 1.4H calibration 100 Ω Platinum RTD 500 Ω Full Scale PT-103 with 1.4J calibration 1.4 K 77 K 300 K 500 K 1.4 K 77 K 300 K 475 K 1.4 K 77 K 300 K 475 K 30 K 77 K 300 K 500 K 4.2 K 77 K 300 K 420 K 1.2 K 1.4 K 4.2 K 100 K 4K 4.2 K 10 K 100 K 4.2...

Model 218 Temperature Monitor Sensor Input Configuration General Diode/RTD Measurement type 4-lead differential Excitation 8 constant current sources Supported sensors Diodes: Silicon, GaAlAs RTDs: 100 Ω Platinum, 1000 Ω Platinum, Germanium, Carbon-Glass, Cernox™, and Rox™ Standard curves DT-470, DT-500D, DT-670, CTI-C, PT-100, and PT-1000 Input connector 25-pin D-sub Ambient temperature Power requirement Size Weight Approval Instruments 113 15 °C to 35 °C at rated accuracy, 10 °C to 40 °C at reduced accuracy 100, 120, 220, 240 VAC, (+6%, -10%), 50 or 60 Hz, 18 VA 216 mm W × 89 mm H × 318...