EDN

EDN, May 26, 2011

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A43_EDN-1-3V_2-25x10:Layout 1 4/4/11 11:56 AM LINE OUTPUT TO DAC HIGH VOLTAGE DC-DC Converters RT MICROPHONE INPUT R TO ADC TO VBIAS 100 to 1000 VDC out High Power 3 Watts Figure 1 The internal microphone bias resistor and the externally connected therm- istor form a voltage divider. temperature calibration, you should get temperature errors of 1 to 2K with a 10-kΩ thermistor at room temperature. Accuracy degrades to 3 to 5K over the thermistor's operating temperature. You can download simple, free, and open-source software in Java that you can use as a simple ohmmeter, thermometer, or chart recorder under Windows or Linux. You can download a Java executable or the Java source code (Reference 1). You should consider adding protec- tion to the sound card's audio I/O ports by inserting series resistors. Typically, a few kilohms is all the circuit needs. You can also use an inexpensive USB (Universal Serial Bus) sound card to spare and protect your PC sound card's inputs. You can add second and third EDN 110526DI5148 Figure 1 DIANE thermistors to your system by adding an external resistor divider (Figure 2). This approach lets you use both audio channels and a third thermistor at the microphone input. In addition to using thermistors, you can use the sound card with other resistive sensors, such as photoresistors or potentiomet- ric displacement sensors. You can even connect capacitive sensors if you add some more components and signal pro- cessing (Reference 2).EDN REFERENCE 1 Gingl, Zoltan, and Peter Kocsis, "Sound-card thermometer/ohmmeter," http://bit.ly/kt6TLA. 2 Klaper, Martin, and Heinz Mathis, "2-Pound RLC Meter impedance mea- surement using a sound card," Elektor, June 2008, pg 64, http://bit.ly/l2lyzl. LINE OUTPUT TO DAC Ultra Miniature Size 0.55" x 0.75" x 0.4" 100-1000 VDC Output Hi-Efficiency/Excellent Load Regulation Single Output with Center Tap Shown Actual Size Input Over Voltage/Over Temperature Protection Remote Shutdown • 100 to 1,000 VDC Outputs • Input Voltage, 5V, 12V, 24V, 28V DC Standard • Isolated - Input to Output • Ultra Miniature - 0.55"x 0.75"x 0.4" • Excellent Load Regulation • Hi Reliability/Custom Models •Military Upgrades/Environmental Screening Available • Call Factory 800-431-1064 RT LINE INPUT R TO ADC www.picoelectronics.com For Full Product Specifications Figure 2 You can add second and third thermistors to your system by adding an external resistor divider. MILITARY • COTS • INDUSTRIAL DC-DC CONVERTERS & POWER SUPPLIES TRANSFORMERS & INDUCTORS 143 Sparks Ave, Pelham, NY 10803-1837 E-Mail: info@picoelectronics.com PICO Electronics,Inc. NEW! SA Series

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