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-railmounting
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

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.