News from OHMIC Instruments

Tips For Using OHMIC’s Ultrasound Power Meters

TIP #3 – Use degassed water for best results. Why: Degassed water has an oxygen content of less than 5 ppm, this is recommended for...


Moisture Control In High Temperature Molding

Controlling the moisture in rubber and plastic manufacturing improves quality and increases yield, resulting in higher profits...


How The ABS-300 Absolute Humidity Sensor Works

The ABS-300 is a thermal conductivity absolute humidity sensor. This sensor measures the absolute humidity by quantifying the difference in thermal conductivity of dry air and air containing water vapor. The sensor consists of...


Evaluation: Ultrasound Output Power Levels Tested

The Ultrasonic Standards Group of the National Institute of Standards and Technology (NIST) evaluated two of OHMIC’s digital power meters, Models UPM-DT-1 and UPM-DT-10, to verify their stability and accuracy of measurement. The power meters were tested between 50 milliwatts and 10 watts using a 4.768 MHz lithium niobate NIST standard ultrasound transducer. The following are some excerpts taken from the NIST report:

"An experimental investigation of the operating characteristics of the ultrasound power meter designated UPM-DT-1 s/n 207 has allowed estimation of its accuracy … for values of applied power … the precision of the measured values is about 2 mW. The fractional errors for … power below 50 mW ranged from 7% to 13%….. while the fractional errors … between 50 mW and 1 Watt ranged from 0.1% to 3.67%…. with an average absolute value of 1.7%. From the results, it is estimated that measured values differed from true values of applied ultrasonic power by an amount not greater than the sum of 0.002 W and three percent of the true values … between 0.05 W and 1.0 W. From the results for the instrument designated UPM-DT-10 s/n 188, it is estimated that measured values differed from the true values of applied ultrasonic power by an amount not greater than the sum of 0.01 W and three percent of the true values … between 0.16 W and 10 W."


Choosing a Humidity Sensor: A Review of Three Technologies

This discussion of the operating principles of capacitive, resistive and thermal conductivity humidity sensors also addresses their advantages, disadvantages and applications. The most important specifications to keep in mind when selecting a humidity sensor are...


How to Use Ohmics’ SC-500 or HC-610 Sensor to Display or Use in Controlling

There are many types of humidity sensors, but few incorporate electronic signal processing. Two widely used units, The Honeywell HIH-4000-01 (Ohmic # HC-610) hybrid capacitive sensor and Ohmic’s Model SC-500 resistive sensor with signal conditioner, are sensors with integrated signal conditioners. They produce a linear DC voltage output vs. %RH making them easier to work with. Fig. 1 below shows these two units, characteristics, and output equations. There are many applications for these integrated sensors in data acquisition, monitors, RH display, and controllers...