Weather Station Project Temperature Light Dark Sensor Wind Speed Wind Direction 1

Light/Dark Sensor Construction Circuit Connection The circuit is built based on LDR (photo resistor) an operational amplifier 741 The LDR is used as a light sensor which resistance change with intensity of Light Op Amp 741 amplifies voltages going out from LDR to reach the PLC specification 0-10V V Counts 2

Light/Dark Sensor Objectives Characteristic of LDRMain Objectives of the device The LDR Characteristic shows decrease resistance compare to increase light intensity (LUX) Ideally the sensor should detect even small changes in light intensity and convert them to relative voltage between 0-10V 3

Light/Dark Sensor Results Device ResultsOp Amp Input LDR Measurements 4

Light/Dark Sensor Conclusions Final Conclusions and changes The main goal was achieved. The device works and detect light changes. Sensitivity regulation is possible by changes in potentiometer's resistance, however the resolution stays on the low level. It means that the sensor works in mode on/off and doesn’t detect small changes in the light intensity. The supply voltage was decreased from 12V to 9V to provide suitable power source from two batteries 4.5V connected in series. By changes in power supply the “Dark Voltage” drops from 11.22V below 10V and can be detect by PLC. Despite the device doesn’t work as was assumed at the beginning of the project it’s still can be used in the project as Light/dark sensor or cloud detector. 5

Wind Direction Sensor Design For this instrument we decided to show wind direction in its 8 most uses directions, N, NE, E, SE, S, SW, W, NW. The design of the instrument is quite simple, each directional point has its own resistive circuit which all connect to a common single resistor across which the voltage is measured to give us our direction. It is essentially a voltage divider circuit. We divided our 10V supply voltage by 8 (No. Of directions) and chose resistor values for each directional circuit in order to scale our voltage output evenly across 8 steps (as can be seen in the table below). 6 Direction Contacts AD MODULE PLC WIND VANE PYTHON MySQL APACHE WEB SERVER INTERNET EXPLORER

Wind Direction Sensor Design The device is fed by a 10V DC supply through the directional arrow’s shaft and on to the direction contacts sticking up from its box, and according to what direction the wind is blowing a different voltage output is generated. The directional arrow can only be in contact with one circuit at a time so as not to give a false reading. It is based on the more complicated vane that measures wind direction in 360 degree format. With the addition of more directional circuits our model could measure wind direction in the same manner, in theory. 7

Wind Direction Sensor Results 8

Wind Direction Sensor Conclusions 9 We are quite pleased with how well this instrument turned out, it is durable and its success lies in its simplicity. Because we used a 0-10v DC supply to begin with we could connect the vane directly to our PLC which was helpful and because there is a substantial difference between each of our 8 input voltages it is unlikely that an error could occur in the PLC.

Temperature Variable Assembly LM 324N: Used to amplify voltage using negative feedback Resistor values R i =474 Ω R f =10 kΩ Gain ( ) = With these resistor values, we got a gain of 22.09, which enabled us to get a good voltage swing (0-10 volts) from our LM35 temperature sensor. V out V in RfRiRfRi = 1+ V out V in Soldered cables with heat shrink LM35 temperature sensor LM 324N Instrumentation amplifier

Amplified VoltageTemperature o C Complete Assembly

Temperature v Amplified Voltage

Block Diagram & Conclusions Conclusions Max. operating temperature from LM35 = 100  C Min. operating temperature from LM35 = 0  C – Unsuitable for detecting negative temperatures Amplified output voltage is linearly proportional to the temperature (  C) Low power consumption Good output voltage swing from amplifier for A/D conversion in the PLC 9V Battery LM324N amplifier PLC A/D card (12 bit) PLC A/D card (12 bit) PC SCADA System LM35 (0-35  C) LM35 (0-35  C) V V counts Website Display HTML language