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2. Types of Sensors Tested. Voltage Regulator acting as a temperature sensor (Models LM234, LM 235)Manufactured by ST (www.st.com)Photo transistor acting as a light sensor (Model LM135)Manufactured by Fairchild Semiconductors (www.fairchildsemi.com). 3. Applications of Sensors. Voltage Regulator
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1. Sensors Presentation October 7, 2003
Scott Chao
Allison Douglas
Kristin Lee
2. 2 Types of Sensors Tested Voltage Regulator acting as a temperature sensor (Models LM234, LM 235)
Manufactured by ST (www.st.com)
Photo transistor acting as a light sensor (Model LM135)
Manufactured by Fairchild Semiconductors (www.fairchildsemi.com)
3. 3 Applications of Sensors Voltage Regulators
Used in Hi-Fi systems, TVs, VCRs, and other electronic equipment
Photo Transistor
Emitter/detector pair is used in sensing motion. e.g. If you needed to measure how fast something was going and/or its position the emitter and detector could sense the motion and output to a logic system
4. 4 Information on Fairchild Infrared Sensors Range for detecting an object by reflection can be from 0 mm to 400 mm
Dust, however, can impair this range
All are constructed using silicon chips, which can detect the entire visible spectrum
The photosensors are built with a daylight filter that prevents most visible light in the environment from reaching the detector chip
Response to light sources may be noticeable.
5. 5 Temperature Sensor Information The circuit output (calibrated or not) can be given by the equation: V_ot + (VO_to * T/T_o)
where T is the unknown temperature and T_o is the reference temperature (in °K).
Nominally the output is calibrated at 10mV/°K.
6. 6 Experimental Results – LM235 Temperature sensor LM235960.7 ohm resistorV+=5.00 V DCoutput = 2.5282 V DC at room temp
If we blew hot air on it or held it the voltage increased
7. 7 Experimental Results – LM235
8. 8 Experimental Results – LM123 Used two orientations of the LED; straight up, parallel with the transistor and bent toward the transistor
Measured output with and without a box to block ambient light.
R_transistor = 4.6 OhmsR_LED = 992 Ohms Vcc = 5v
LED and transistor parallel:Without box: Vout = 4.95 VWith box: Vout = 4.778 V
Separated without box – Vout = 4.97 VSeparated with box – Vout = 4.99 V
LED bent towards transistor:Without box – Vout = 4.77 VWith box – Vout = 4.6 V
9. 9 Experimental Results – LM135
10. 10 Experimental Results – LM234 Temperature sensor LM234R1= 231.97 ohmsR2 = 9.94 kohmsR3 = 661.37 ohmswith C1=1.5 nF, Vo = 4.33 Vwith C1=3.05 nF, Vo = 4.33 V
Most likely faulty values
11. 11 Experimental Results – LM234
12. 12 Next Steps Relate analysis of outputs to ozone sensors outputs
Will test ozone sensors when we receive them
Will take apart existing cell phones to determine size, power limitations