Development of a low-cost data acquisition system for ...

ASIA LIFE SCIENCES Supplement 9: 263-274, 2013 The Asian International Journal of Life Sciences

Development of a low-cost data acquisition system for total solar insolation and temperature monitoring

STEVEN RWABONA K ATASHAYA1* and RICHARD OPIO OCAYA2 This paper reports on the design, development and application of a solar energy LQWHJUDWRU LQVWUXPHQW 6,  WKDW LV VSHFL¿FDOO\ LQWHQGHG WR EH D ORZ FRVW VROXWLRQ IRU VRODU energy measurements and research. The use of the high-performance PIC18 series embedded FRQWUROOHUDOORZVKLJKLQWHJUDWLRQRIWKHGDWDDFTXLVLWLRQVXSHUYLVLRQDQGXQLYHUVDOVHULDO EXV86% FRQQHFWLYLW\$VWDQGDUGL]HGVRIWZDUHGULYHUDOORZVFXUUHQW0LFURVRIW:LQGRZV operating systems to enumerate the device as a USB 2.0 device capable of full-speed data UDWHVRIXSWR0%LWVV7KHHPEHGGHGFRGHLVZULWWHQLQWKH&ODQJXDJHDQGWKHFRQWURO SURJUDP LV ZULWWHQ LQ 9%1(7 7KH LQVWUXPHQW XVHV ERWK KDUGZDUH DQG VRIWZDUH EDVHG ]HUR RIIVHW FRPSHQVDWLRQ DQG JDLQ IRU HDFK RI WKH WHQ LQSXW FKDQQHOV WKHUHE\ DOORZLQJ ORZOHYHO KLJKLPSHGDQFH VLJQDOV WR EH PHDVXUHG DQG ORJJHG DFFXUDWHO\ 7KH SURJUDP output is in a form that can be accessed directly by most spreadsheet programs, making the DFTXLVLWLRQDQGSURFHVVLQJRIWKHGDWDVHDPOHVV7KHHDVHRILQVWDOODWLRQDQGXVDJHPDNHVWKH LQVWUXPHQWHVSHFLDOO\YDOXDEOHDVDORZFRVWEXWSUHFLVLRQPHDVXUHPHQWWRROIRUVRODUHQHUJ\ measurement based on pyranometers, although the versatility built into the instrument HQDEOHVLWWREHXVHGIRUJHQHUDOSXUSRVHGDWDDFTXLVLWLRQ:HSUHVHQWDFRPSDULVRQRIWKH designed instrument against a commercial Kipp and Zonen unit connected to calibrated S\UDQRPHWHUVWKURXJKERWKUDZS\UDQRPHWHUGDWDDFTXLVLWLRQDQGDQDFWXDOLQWHJUDWLRQUXQ We also present typical results of temperature monitoring. Keywords: solar energy monitoring, temperature, solar integrator, instrumentation, microcontroller 'HSDUWPHQW RI 3K\VLFV DQG (OHFWURQLFV 1RUWK :HVW 8QLYHUVLW\ 0D¿NHQJ &DPSXV 3ULYDWH %DJ ;0PDEDWKR6RXWK$IULFD 2 'HSDUWPHQWRI3K\VLFV8QLYHUVLW\RI)UHH6WDWH4ZDTZD&DPSXV3ULYDWH%DJ;3KXWKDGLWMKDED 9866, South Africa * &RUUHVSRQGLQJDXWKRUVWHYHQNDWDVKD\D#QZXDF]DNDWDVKD\DVU#JPDLOFRP

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Received 03 July 2013; Accepted 26 August 2013 ©Rushing Water Publishers Ltd. 2013

Printed in the Philippines

Katashaya & Ocaya 2013 INTRODUCTION

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Data acquisition system for monitoring sunlight & temperature IRUDW\SLFDOS\UDQRPHWHUVHQVRUHOHPHQW0HGXJXHWDO%URRNV 7KH second is based on a direct connection of a K-type thermocouple for temperature measurement. The instrument, henceforth referred to as the Solar Integrator version 6, LQFRUSRUDWHVSDVWOHVVRQVOHDUQWIURPWZRSUHYLRXVYHUVLRQVWRJHWKHUZLWK QXPHURXV UHTXHVWV IURP SHHUV WR DGGUHVV RWKHU DGGLWLRQDO SUDFWLFDO LVVXHV :H VKRZ WKDW LW PHHWV WKHVH FKDOOHQJHV DQG IRUPV D UREXVW LQVWUXPHQW WKDW LV KLJKO\ marketable and easy to proliferate.

DESCRIPTION OF THE SI3 SYSTEM

7KH PDLQ GHVLJQ WKHPH RI WKH 6, LQVWUXPHQW ZDV ORZFRVW DQG IXOOVSHHG USB 2.0 compliance. Figure 4 is a block diagram of the SI3 instrument. It FRQVLVWVRIDVLQJOH3,&IKLJKSHUIRUPDQFH3,&SURFHVVRUIURP0LFURFKLS 7HFKQRORJ\ 0LFURFKLS   D VLQJOH )XWXUH 7HFKQRORJ\ 'HYLFHV 86%  interface controller, the FT232RL, and ten non-inverting input amplifiers. In earlier YHUVLRQVRIWKHLQWHJUDWRUWKHLQSXWDPSOLILHUVZHUHVSHFLDOLVWORZRIIVHWDPSOLILHUV EXLOW DURXQG WHQ 23$ RSHUDWLRQDO DPSOLILHUV 7R ORZHU FRVWV HYHQ IXUWKHU WKH WHQ DPSOLILHUV ZHUH LPSOHPHQWHG XVLQJ RIIWKHVKHOI RSHUDWLRQDO DPSOLILHUV LQ WZR VLQJOH SDFNDJHV 23&  DQG WZR TXDG SDFNDJHV /0  7KHVH ODWWHU DPSOLILHUVH[KLELWVXEVWDQWLDOLQSXWRIIVHWVWKDWZHUHREVHUYHGWRSURGXFHRXWSXWV DV KLJK DV  P9 XQGHU ]HUR LQSXW FRQGLWLRQV 7KH HODERUDWH RIIVHW DGMXVWPHQW VFKHPH GHVFULEHG EHORZ UHDOL]HV DPSOLILHUV ZKRVH SHUIRUPDQFHV PDWFK WKRVH based on OPA111 a fraction of the cost. The PIC processor is configured to run at 0+]XVLQJDSKDVHORFNHGORRS3// FORFNGHULYHGIURPWKH)75/GHYLFH 6RPHRIWKHSRUWSLQVRIWKH)75/GHYLFHFDQEHFRQILJXUHGXVLQJDVRIWZDUH XWLOLW\FDOOHG)7352*WKDWLVIUHHO\GRZQORDGDEOH)7', 7KHXVHRI D VWDQGDUGL]HG )7', GULYHU IURP WKH PDQXIDFWXUHU¶V RZQ ZHE VLWH JXDUDQWHHV D ZLGHDFFHVVDQGJXDUDQWHHGVXSSRUWRIWKH)75/GHYLFH7KHPXOWLSOH[HGFORFN RXWSXWRIWKH)75/LVRQHRIVHYHUDOKDUGZDUHRSWLRQVWKDWFDQEHFRQILJXUHG XVLQJ WKH :LQGRZV XWLOLW\ 7KH )75/ LV LWVHOI FRQILJXUHG WR XVH DQ LQWHUQDO crystal. These oscillator configurations collectively eliminate the need for external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in portable devices such as mobile phones and cameras, especially as their cost per PHJDE\WHFRQWLQXHWRIDOO7KLVZLOOPDNHLWHDVLHUWRH[FKDQJHGDWDZLWKDFRPSXWHU DQGZLOODOVRLPSURYHUHSHDWUDWHVIRUSURFHVVHVWKDWRFFXULQVKRUWHUWLPHLQWHUYDOV For many applications such as solar energy monitoring the combined repeat UDWHVRIRQHVHFRQGRUPRUHDUHPRUHWKDQVXIILFLHQW7KHFRQWUROVRIWZDUHUXQQLQJ RQWKH:LQGRZVRSHUDWLQJV\VWHPFDQEHDGMXVWHGIRUVORZHUUHSHDWUDWHV7KH3,&

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Katashaya & Ocaya 2013 SURFHVVRU FRGH ZDV ZULWWHQ LQ WKH & ODQJXDJH IRU KLJK SHUIRUPDQFH DQG VSHHG Both the assembled PIC target or HEX file and the .NET control program are DYDLODEOH IURP WKH DXWKRUV XQGHU FHUWDLQ XVDJH FRQGLWLRQV 7KH PDLQ :LQGRZV FRQWUROSURJUDPLVZULWWHQLQWKH1(7IUDPHZRUNDQGVXSSRUWVIUDPHZRUNVWR ,QNHHSLQJXSZLWKWKHDLPRIVWUHDPOLQLQJWKHRSHUDWLRQRIWKHFRPSOHWHV\VWHP IRUPRVWHQGXVHUVWKHXVHULQWHUIDFHZDVFDUHIXOO\GHVLJQHG,WLVFHQWHUHGDERXWD VLQJOHSDQHOZLWKZKLFKLQWHUDFWLYLW\LVPDLQO\WKURXJKSRLQWDQGFOLFNDVOLGHUDQG context sensitive menus. It includes numerous help features such as screen tooltips and an unambiguous reporting style for instantaneous system status on the program SDQHOV7KHVHDVSHFWVRIWKHXVHULQWHUIDFHDUHGHVFULEHGLQWKHIROORZLQJVHFWLRQV Unlike earlier versions, the present design permits the target computer to run other WDVNVFRQFXUUHQWO\ZLWKRXWQRWLFHDEOHGHWHULRUDWLRQLQRYHUDOOV\VWHPVSHHG

)LJXUH$QLQVSHFWLRQRIWKHFRQWHQWVRIDW\SLFDOGDWD¿OHXVLQJDWH[WHGLWRU 7KHGHIDXOWRXWSXWZULWWHQWRWKHGLVNGDWDILOHLVFXPXODWLYHRULQWHJUDO$VDQ example, in the context of a calibrated global spectral pyranometer connected to a channel, data that is integrated per second gives a sense of the total solar insolation at the locality. By toggling a checkbox control on the panel the control program can EHFRQILJXUHGWRVWRUHGLUHFWFKDQQHOLQSXWYDOXHLQVWHDG7KLVDOORZVWKHLQVWUXPHQW WREHXVHGDVDJHQHUDOSXUSRVHGDWDDFTXLVLWLRQV\VWHPMXVWDVHDVLO\7KHRXWSXW RI WKH 6, GDWD DFTXLVLWLRQ LV VWRUHG DV D VSDFHGHOLPLWHG WH[W ILOH WKDW LV HDVLO\ H[SRUWHGWRPDQ\SURFHVVLQJSURJUDPVVXFKDV0LFURVRIW([FHO0LFURFDO2ULJLQ 0DWODEDQGVRRQ)LJXUHVKRZVWKHOD\RXWRIDW\SLFDOGDWDILOH The digital hardware. 7KH6,V\VWHPZDVFRQVWUXFWHGLQWZRSKDVHVERWKSKDVHV FXOPLQDWLQJ LQ D VHSDUDWH SULQWHG FLUFXLW ERDUG 3&%  7KH ILUVW SKDVH ZDV WKH UHDOL]DWLRQRIWKH3,&IHPEHGGHGSURFHVVRUFLUFXLWRQD×FP2 board that DOVR KHOG WKH 86%  SHULSKHUDO FRQWUROOHU $[HOVRQ   7KH WHQ PXOWLSOH[HG $'& LQSXWV ZHUH EURXJKW RXW WR WKH HGJH RI WKH ERDUG WR DOORZ JHQHUDO SXUSRVH FRQQHFWLRQ RI  WR  YROW DQDORJXH VLJQDO OHYHOV IURP DQ\ VRXUFH 7KLV ERDUG LV SRZHUHGRIIWKH86%SRUWDQGGUDZVDERXWP$P: IURPWKHSRUWZKHQ

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Data acquisition system for monitoring sunlight & temperature WKH3,&LVUXQQLQJDW0+]DQGHQJDJHGLQFRQWLQXRXVGDWDDFTXLVLWLRQDQGGDWD WUDQVIHUV7KHVHFRQGSKDVHZDVWKHFRQVWUXFWLRQRIWKHORZQRLVHORZRIIVHWLQSXW DPSOLILHUV RQ D ×20 cm2 3&% 7KH QRQLQYHUWLQJ LQSXW RI HDFK DPSOLILHU ZDV WHUPLQDWHGZLWKNŸUHVLVWRUWROLPLWQRLVHSLFNXS ,Q WKH 6, GHVLJQ WKH DPSOLILHUV DUH SRZHUHG IURP D PDLQV GHULYHG ± YROW VWDELOL]HGVXSSO\7KHDPSOLILHUERDUGGUDZVDERXWP$SHUDPSOLILHURUP: LQWRWDO7KHWRWDOSRZHUFRQVXPSWLRQRIWKH6,LQVWUXPHQWDWIXOORSHUDWLRQGRHV QRWH[FHHGP:PDNLQJLWDFDQGLGDWHIRUEDWWHU\SRZHUHGDSSOLFDWLRQV'XHWR WKHQHHGWRPLQLPL]HQRLVHSLFNXSE\WKHGHFLEHOJDLQDPSOLILHUVLWZDVGHFLGHG not to derive the dual rail supply from the USB port of the controlling computer. 1RWRQO\ZRXOGWKLVQHFHVVLWDWHDPRUHHODERUDWHGHFRXSOLQJDQGVKLHOGLQJVFKHPH IRUWKHDPSOLILHUVIURPWKHUHDFWLYHVZLWFKLQJSURFHVVHVWKDWDUHDQLQWHJUDOSDUWRI VZLWFKHGPRGHSRZHUVXSSO\6036 RSHUDWLRQEXWLWZRXOGDOVRLQFUHDVHFRPSRQHQW FRXQWDQGFRVWGXHWRDQDGGLWLRQDO6036FRQWUROOHU7KHSK\VLFDOGLPHQVLRQVRI the instrument can be made even smaller if surface mounted components are used DOWKRXJKLWZDVQRWRISULPDU\FRQFHUQLQWKHSURWRW\SH

Figure 2. A block diagram of the Solar Integrator system. The firmware. 7KH ILUPZDUH SURJUDP ZDV ZULWWHQ LQ WKH & ODQJXDJH XVLQJ WKH 0LNUR&3URFRPSLOHU0LNUR(OHNWURQLND &RGLQJLQ&VLPSOLILHVWKHIORDWLQJ SRLQWFDOFXODWLRQVWKDWDUHSDUWRIWKHGDWDDFTXLVLWLRQSURFHVV)LJXUHVKRZVWKH SURJUDPPLQJRIWKHILUPZDUH7KHSURFHVVRULVLQHIIHFWDVODYHGHYLFHWKDWVHWV XS DV\QFKURQRXV FRPPXQLFDWLRQV ZLWK WKH )75/ GHYLFH DW  EDXG 7KH latter then implements USB 2.0 connectivity. As can be seen in Figure 4, the actual FLUFXLWVFKHPDWLFLVVLPSOH+RZHYHUPXFKRIWKHZRUNGRQHLVLQWKHSURJUDPPLQJ RI WKH ILUPZDUH DV ZHOO DV WKH :LQGRZV EDVHG FRQWURO VRIWZDUH ZULWWHQ LQ WKH

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)LJXUH)ORZFKDUWRIWKH6,¿UPZDUH Input amplifiers and offset control. The input amplifiers of the SI3 instrument DUHLPSOHPHQWHGXVLQJVWDQGDUGTXDGSDFNDJHVIRUZKLFKWUDGLWLRQDOO\WKHUHLVQR provision for direct input off-set trimming. For amplifiers intended for precision LQVWUXPHQWDWLRQ DSSOLFDWLRQV VXFK DV VRODU GDWD JDWKHULQJ XVLQJ ORZRXWSXW OHYHO VHQVRUV VRPH PHFKDQLVP WR DGMXVW RIIVHWV PXVW EH LPSOHPHQWHG LQ DGGLWLRQ WR VRIWZDUHEDVHGGDWDFRUUHFWLRQ7KHVROXWLRQXVHGLQWKH6,LQVWUXPHQWLVEDVHG RQH[WHUQDOELDVFLUFXLWVWKDWLQMHFWDFRQWUROOHGYROWDJHOHYHODWWKHLQSXWIHHGEDFN

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Data acquisition system for monitoring sunlight & temperature resistor thereby shifting the input level offset to a desired level centred at zero 1DWLRQDO6HPLFRQGXFWRU )LJXUHVKRZVWKHJHQHUDOVFKHPHWKDWLVXVHGIRU each of the 10-input amplifiers in the SI3. In addition, the primary consideration PDGH LQ WKH GHVLJQ RI WKH RIIVHW DGMXVW FLUFXLWU\ KDV EHHQ WR NHHS WKH HIIHFWLYH loading by the potentiometers on the ±YROWSRZHUOLQHVPDOOLQWHUPVRIWKHWRWDO FXUUHQWGUDZQE\WKHGLYLGHUQHWZRUNV

Figure 4. Detailed schematic diagram of the embedded controller and the USB.

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Figure 6. Appearance of the main SI3 user interface.

SYSTEM PERFORMANCE

7KHSHUIRUPDQFHRIWKHGHVLJQHGV\VWHPZDVJDXJHGLQWKUHHZD\V7KHILUVW WHVWZDVDHVWKHWLFLQQDWXUHE\VXEMHFWLQJWKH6,LQVWUXPHQWWRVHYHUDOXVHUVDQG JDXJLQJWKHHDVHZLWKZKLFKWKHXVHULQWHUIDFHVZHUHRSHUDWHG,WZDVUHSRUWHGO\ stable, repeatable and easy to set up. In the second test the sustained throughput DQG UHSHDW UDWHV ZHUH JDXJHG ,Q WKH ILQDO WHVW WZR YDULDEOHV ZHUH PHDVXUHG VLPXOWDQHRXVO\RQWZRFKDQQHOVQDPHO\WHPSHUDWXUHRIERLOLQJZDWHUVXEMHFWHGWR ambient cooling over a short period of time and an integration test for photovoltaic voltage levels from a simple pyranometer.

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Data acquisition system for monitoring sunlight & temperature Sustained throughput and repeat rate. While all ten inputs of the SI3 are WKHRUHWLFDOO\ FRQYHUWHG ZLWKLQ —V WKH RYHUKHDGV DVVRFLDWHG ZLWK GDWD WUDQVPLVVLRQ FRQWURO RYHU WKH DFTXLVLWLRQ SURFHVV WKH GDWD IUDPLQJ LQ D XQLTXH IRUPDWIRUWUDQVPLVVLRQDQGUXQQLQJRSHUDWLQJV\VWHPDQGILUPZDUHWDVNVLQFUHDVH WKH DFTXLVLWLRQ WLPH SHU FKDQQHO VXEVWDQWLDOO\ 7KH UHOLDEOH GDWD UHSHDW UDWHV RI WKH LQVWUXPHQW IRU DOO WHQ FKDQQHOV DPRXQW WR  PLOOLVHFRQGV 7KLV ILJXUH ZDV obtained under the condition that a channel convert command is issued from :LQGRZVUHFHLYHGE\WKH6,GHFRGHGDFWHGXSRQWKHDQDORJXHFKDQQHODFTXLUHG DQGWUDQVPLWWHGEDFNWR:LQGRZVDQGWKHQWKHVHTXHQFHUHSHDWHGXQWLODOOFKDQQHOV KDYHEHHQDFTXLUHG2QFHWKLVF\FOHLVFRPSOHWHDGGLWLRQDORYHUKHDGVDULVHGXULQJ WKHGLVNZULWLQJRIGDWDIUDPHGLQDIRUPDWWKDWHQFDSVXODWHVDGDWHDQGWLPHVWDPS DQGWKHDFTXLUHGDQDORJXHGDWDIRUDOOWKHFKDQQHOV7KLVRYHUKHDGDOVRLQFOXGHV WKHIORDWLQJSRLQWFDOFXODWLRQVWKDWDFTXLUHWKHDQDORJXHGDWDDSSHQGWKHJDLQDQG VRIWZDUH EDVHG RIIVHW DGMXVWPHQWV XSGDWHV WKH YDULRXV RQ VFUHHQ FRQWUROV EHIRUH repeating the cycle. Application to solar energy monitoring. 7KHIROORZLQJDSSOLFDWLRQVDUHXVHGRQO\ WR LOOXVWUDWH WKH VXLWDELOLW\ RI WKH 6, LQVWUXPHQW WR DFTXLUH DQG SURFHVV W\SLFDO UHDO ZRUOG VLJQDOV ,W LV LQWHQGHG RQO\ WR EH LOOXVWUDWLYH RI LQWHJUDO WUHQGV UDWKHU than as an accurate trend of total solar energy for the accurate extraction of solar HQHUJ\SDUDPHWHUV,QSUDFWLFHWKH6,LVLQWHQGHGWREHXVHGZLWKSXUSRVHO\EXLOW and calibrated pyranometers and other intended sensors. A simple pyranometer ZDV EXLOW DURXQG D SKRWRGLRGH RSHUDWHG LQ D SKRWRYROWDLF FRQILJXUDWLRQ EXLOW DURXQG WKH SULQFLSOHV GHVFULEHG LQ 0HGXJX HW DO  0XNDUR HW DO   ,Q WKH ILUVW WHVW WKH VHQVLWLYLW\ RI WKH KRPHPDGH S\UDQRPHWHU ZDV GHWHUPLQHG WKURXJK GLUHFW FRPSDULVRQV RQ GLIIHUHQW GD\V DW PD[LPXP LQVRODWLRQ EHWZHHQ WKH VLPSOH S\UDQRPHWHU ZLWK D FDOLEUDWHG .LSS DQG =RQHQ &03 S\UDQRPHWHU ZLWKDVHQVLWLYLW\RI—9:P2. The sensitivity of the homemade pyranometer ZDVIRXQGWREH“ P9:P2. The second test involved integrating solar insolation over one day, 14th$SULO7RGRWKLVWKHFRPPHUFLDOS\UDQRPHWHUZDV FRQQHFWHGWRDQ(SSOH\SUHFLVLRQVSHFWUDOS\UDQRPHWHU(363 ZKLOHWKHKRPHPDGH S\UDQRPHWHUZDVFRQQHFWHGWRWKH6,LQVWUXPHQWWRJDXJHWKHSHUIRUPDQFHRIWKH ODWWHUUHODWLYHWRDFRPPHUFLDOXQLW)LJXUHVKRZVWKHGDWDREWDLQHGLQRXUORFDOLW\ Application to temperature monitoring. The second test involves the direct FRQQHFWLRQRID.W\SHWKHUPRFRXSOHWRRQHRIWKHLQSXWVRIWKH6,ZLWKRXWDQ\SULRU conditioning. The K-type thermocouple (Omega 2013) typically has a coefficient of —9o& :LWK D FROG MXQFWLRQ DW DPELHQW WHPSHUDWXUH RI oC it generates about  P9 ZKHQ WKH KRW MXQFWLRQ LV DURXQG oC. In the simple test 1 kg of boiling ZDWHULVDOORZHGWRFRROGRZQLQDJODVVFRQWDLQHUWRDPELHQWWHPSHUDWXUHDVLWV WHPSHUDWXUHLVPRQLWRUHGXVLQJWKH.W\SHWKHUPRFRXSOHRYHUDSSUR[LPDWHO\WZR KRXUV)LJXUHVKRZVWKHFRROLQJFXUYHDVVDPSOHGE\WKH6,DWVLQWHUYDOV

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Figure 9. Integrated solar energy using a home-made global pyranometer versus D .LSS  =RQHQ S\UDQRPHWHU ZLWK D FDOLEUDWLRQ IDFWRU RI  P9:P2 and —9:P2UHVSHFWLYHO\7KHWRWDOLQVRODWLRQIRUWKHGD\ZDVN:P2.

Figure 10. Water cooling data obtained using a direct connection of a K-type thermocouple to one input of the SI3 instrument.

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Data acquisition system for monitoring sunlight & temperature CONCLUSION We have described the design and construction of the SI3 instrument WKDW FRQWHQGV IRU WKH WLWOH RI EHLQJ WUXO\ ORZ FRVW DQG KLJK SHUIRUPLQJ DV D GDWD DFTXLVLWLRQ LQVWUXPHQW ZLWK IXOOVSHHG 86%  FRPSOLDQFH 7KH HVWLPDWHG FRVW RIWKHILQLVKHGLQVWUXPHQWLVDERXW86DQGWKHHQFORVXUHZDVWKHVLQJOHPRVW costly component in the finished instrument. We have described the competing UHTXLUHPHQWVRIWKHGHVLJQDQGDGGUHVVHGVRPHRIWKHLQVWUXPHQWDWLRQFKDOOHQJHV WKDWDW\SLFDOLQVWLWXWLRQDOUHVHDUFKHUPLJKWKDYHZLWKUHVSHFWWRUHOLDEOHORZFRVW instrumentation. The success of the SI3 instrument is due to careful design and RSWLPL]DWLRQRIWKHILUPZDUHDQGWKHFRQWUROOLQJ1(7IUDPHZRUNSURJUDP0DQ\ RIWKHORJLFDOIXQFWLRQVDUHLPSOHPHQWHGLQWKHVRIWZDUHUDWKHUWKDQLQWKHKDUGZDUH DOORZLQJDVLPSOHUKDUGZDUHGHVLJQDVVKRZQLQ)LJXUH7KH6,LQVWUXPHQWLV VWDEOHKDVUHSHDWUDWHVRIPVWHQLQSXWVDQGZRUNVZLWKFXUUHQWYHUVLRQVRI 0LFURVRIW :LQGRZV LQFOXGLQJ ;3 DQG YHUVLRQV  DQG  7KLV ZLOO HQVXUH WKDW LW continues to be usable for the foreseeable future. It logs in a format that makes it VWUDLJKWIRUZDUGWRDVVLPLODWHWKHGDWDGLUHFWO\LQWRSURFHVVLQJHQYLURQPHQWVVXFK as spreadsheets programs. The turnaround time from setting up an experiment and interpreting the results is therefore reduced.

LITERATURE CITED

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