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How Data Acquisition Can Benefit from Reed Relays - Application Guide
In data acquisition (DAQ) applications, measurements need to be taken from a wide range of transducer and sensor types. Many produce a voltage in response to a condition; for example, a photovoltaic (PV) cell reacting to light or a Hall effect sensor reacting to the presence of a magnetic field. In other cases, a fundamental property/characteristic of the sensor is relative to its environment, as is the case with a resistance temperature detector (RTD) or a dielectric sensor used to measure moisture content.
The outputs/properties of the transducers are then conditioned into signals for feeding into data logging instrumentation (data loggers) or to act as inputs into closed loop control circuitry.
In many cases, multiple sensors or transducers are employed; for example, several RTDs might be used to measure temperature in different locations. However, it is impractical to have a signal conditioning circuit for each sensor. Instead, it is more efficient to poll the sensors. Moreover, common signal conditioning circuitry can be used with different sensor types (see Figure 1). The circuitry’s gain and perhaps filtering are controlled to make best use of the sensors’ range.
Above, a diagram showing the steps of a data acquisition system.
Reed relays are ideal for connecting the signal conditioning circuitry to the sensors for a variety of reasons, including their low thermal EMFs, low leakage currents and capacitance, and hermetically sealed contacts protecting from environmental contaminants and ensuring reliable performance up to 1 billion operations.
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Contents of the application guide:
- Introduction to Data Acquisition
- The Role of Reed Relays in DAQ Systems
- Comparing Relay Technologies
- Reed Relay Terminology
- Recommended Products
- Why Pickering Electronics for Reed Relays
Recommended Reed Relays for use in Data Acquisition Applications
Ultra High Density Reed Relays
These relays have a maximum switch current of 1A (up to 20W), and the maximum carry current is 1.2A. Fast operate and release times (as low as 80μs or less) make these relays suitable for high-speed test systems. Body dimensions from (W x H x D): 3.9 x 9.5 x 3.9mm. Available forms: 1 Form A contact configuration.
High Density Reed Relays
These relays have a maximum switch current of 1A (up to 20W), and the maximum carry current is 1.2A. Switches feature sputtered ruthenium contacts for long life and high reliability. Body dimensions from (W x H x D): 6.6 x 9.5 x 3.7mm. Available forms: 1 Form A, 1 Form A Coax, 2 Form A, 1 Form B, and 1 Form C contact configurations.
Miniature High-Voltage Reed Relays
These relays have switching voltages up to 1.5kV and standoff voltages up to 5kV. The maximum switch current is 1A (up to 25W) and the maximum carry current is 1.5A. High coil resistance options (up to 6.8kΩ). Thermal EMF devices are between 3 and 10μV. Relays can endure temperatures as high as 150°C if requested. Body dimensions from (W x H x D): 12.5 x 6.6 x 3.7mm. Available forms: 1 Form A, 2 Form A, and 1 Form B contact configurations.
High Voltage Reed Relays
These relays have switching voltages up to 12.5kV and minimum standoff voltages up to 15kV. The maximum switch current is 3A (up to 200W) and the maximum carry current is up to 5A. Option of PCB pins, chassis, PCB mounting, and flying leads. Body dimensions from (W x H x D): 58.4 x 19.0 x 12.6mm. Available forms: 1 Form A, 1 Form B, and 1 Form C contact configurations.
High Coil Resistance Reed Relays
These relays have a maximum switch current of 1A (up to 20W), and the maximum carry current is 1.2A. Featuring high coil resistances (up to 6kΩ), devices are ideal for portable instruments. Body dimensions from (W x H x D): 8.13 x 15.24 x 4.8mm. Available forms: 1 Form A, 2 Form A, 1 Form B, and 1 Form C contact configurations.
Low Thermal EMF Reed Relays
These relays have a maximum switch current of 1A (up to 20W), and the maximum carry current is 1.2A. Devices feature low thermal EMF (around 1μV or less) and low power consumption. Body dimensions from (W x H x D): 20.1 x 9.4 x 7.4mm. Available forms: 1 Form A, 2 Form A, 1 Form B, and 1 Form C contact configurations.
Industry Standard Size Reed Relays
These relays have a maximum switch current of 1A (up to 20W), and the maximum carry current is 1.2A. Featuring superb contact resistance stability and ultra-high insulation resistance. Body dimensions from (W x H x D): 19.1 x 7.6 x 4.8mm. Available forms: 1 Form A, 2 Form A, 1 Form B, 1 Form C, and 2 Form C contact configurations.
Low Capacitance Reed Relays
These relays have a maximum switch current of 1A (up to 20W), and the maximum carry current is 1.2A. Ultra-low capacitance levels of typically 0.1pf, compared to typically 2.5pF for a standard device. Body dimensions from (W x H x D): 19.1 x 8.1 x 4.8mm. Available forms: 1 Form A contact configuration.
Coaxial Reed Relays
These relays have a maximum switch current of 1A (up to 20W), and the maximum carry current is 1.2A. Devices with 50 and 75Ω coils are suitable for up to 5GHz, making them ideal for RF Signal Switching, RF switched tunable filters, and High-Speed Digital Switching. Available in thru-hole and SMT. Body dimensions from (W x H x D): 12.5 x 6.6 x 3.7mm. Available forms: 1 Form A and 1 Form B
