DC Power Supplies
There are two distinct types of DC power supplies that convert the AC power line voltage into DC voltage to operate electronic devices. Linear supplies use a transformer, rectifier diodes, a regulator, and filtering to produce relatively clean DC, but they are limited to a narrow range of power input voltages and are usually physically large. Switching supplies offer a wider range of power input voltages and are usually smaller in size, but often have switching frequency noise on their DC output. Both types are available in a variety of packages, but most DIN-rail-mounting units are switching supplies.
Because ASG's devices draw relatively low current, the chart of recommended power supplies shown below is based on the number of similar units being powered at the same time. All the power supplies listed below are available from national electronic component distributors such as Digi-Key, Mouser, Newark Electronics, or Allied Electronics at unit prices from $40 to $120. Output Number TDK Lambda Mounting Phoenix Contact Mounting ASG Product
|Output Volts DC||Number Devices||TDK Lambda Part Number||Mounting||Phoenix Contact Part Number||Mounting||AFG Product Application|
|12 V||12||DSP10-12||DIN rail||2868538||DIN rail, tabs||DCSE LVDT|
|15V||8||DSP10-15||DIN rail||MR, ME, LV LVIT|
|24 V||6||DSP10-24||DIN rail||LVIT, S2A, SC-200|
|24 V||10||2868535||DIN rail, tabs||LVIT, S2A, SC-200|
|24 V||16||DSP30-24||DIN rail||2868648||DIN rail, tabs||LVIT, S2A|
|24 V||16||2866446||DIN rail only||S2A, SC-200|
Data Acquisition Systems
For analog data acquisition (DAQ) input to a PC, the simplest products to utilize are generally USB-based instruments. There are several USB-DAQ choices offered by National Instruments (NI), or their subsidiary, Measurement Computing Corp. (MCC), (which offers more economical DAQ products) that work with ASG products. Typically, USB-based DAQ systems can operate from the 5-Volt DC power of a USB port, so an additional power supply is normally not needed. These DAQ systems work with all the popular NI software like LabVIEW and Signal Express.
DAQ systems are usually used with an analog voltage input, and the majority of ASG products offer a single-ended, ground-referenced DC voltage output up to 10 Volts full scale. Most DAQ systems have at least 8 single-ended analog inputs, and some have differential inputs as well. A DAQ with a differential input capability is of particular benefit for use with sensors that have their DC output off-ground, like some types of DC-LVDTs that offer either a 3-wire connection with a 1-6 Volt grounded output, or a 4-wire hook up with a 0-5 Volt output in which the return side of the output is floating 1 Volt above the ground of the sensor’s power supply.
Recommended USB DAQs for single-ended inputs are the MCC USB200 series and the NI USB-6000 series. Recommended USB DAQs for both single-ended and differential inputs are the MCC USB-1208 series and the NI USB-6008 series. All have a resolution of 12 bits, with a variety of sampling rates available. Detailed product information is available on the respective websites of the suppliers: mccdaq.com or ni.com.