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WB6DHWWB6DHW
PC-Based RLC Meter KitPC-Based RLC Meter Kit
Proposed Buildathon Project:Proposed Buildathon Project:– April 2011 Radio Play Days (16 Apr 2011)April 2011 Radio Play Days (16 Apr 2011)– Build simple $20 kit in one play day sessionBuild simple $20 kit in one play day session– Learn some electronics while we’re at itLearn some electronics while we’re at it– Minimal hand-holdingMinimal hand-holding– Have fun, tooHave fun, too
Kit:Kit:– Furnished by Dave Brainerd WB6DHWFurnished by Dave Brainerd WB6DHW– No toroids, no SMTNo toroids, no SMT– Measures R, L, and CMeasures R, L, and C– Easy build (25 components)Easy build (25 components)
ComponentsComponents
User-furnished partsUser-furnished partsTwo stereo M-M 1/8” cablesTwo stereo M-M 1/8” cablesHookup wireHookup wire2 alligator clips2 alligator clipsOne USB-A to USB-B cableOne USB-A to USB-B cable
RequirementsRequirements– PC with soundcard and free USB portPC with soundcard and free USB port
Soundcard MUST have Soundcard MUST have stereostereo input input USB just for 5V powerUSB just for 5V power
– Fairly accurate DMMFairly accurate DMM– (downloadable) Software(downloadable) Software– Soldering iron and solderSoldering iron and solder– Diagonal cutters and needle-nosed pliersDiagonal cutters and needle-nosed pliers– A (Pana)vise would be niceA (Pana)vise would be nice– User-furnished partsUser-furnished parts
Two stereo M-M 1/8” cablesTwo stereo M-M 1/8” cables Hookup wireHookup wire 2 alligator clips2 alligator clips One USB-A to USB-B cableOne USB-A to USB-B cable
Completed Completed Kit:Kit:
SchematicSchematic
Build StagesBuild StagesPower Supply Negative Power Supply Resistance Ladder
OpAmps & I/O Calibration
TheoryTheory– ApplyApply reference reference
signal to voltage signal to voltage dividerdivider
– MeasureMeasure reference and reference and output signalsoutput signals
– Calc Calc Unknown Unknown impedanceimpedance(ohms: R & X)(ohms: R & X)
Resistor Ladder SelectionResistor Ladder Selection
Rm L-From L-To C-From C-To
10 12.99 uH 12.99 mH 0.1299 uF 1299 uF
100 129.9 uH 129.9 mH 0.01299 uF 129.9 uF
1k 1.299 mH 1299 mH 1.29 nF 12.9 uF
10k 12.99 mH 12.99 H 1299 pF 1.29 uF
100k 129.9 mH 129.9 H 12.99 pF 0.129 uF
Rm XL_From XL_To Xc_From Xc_To
10 0.1 100 1k 0.1
100 1 1k 10k 1
1k 10 10k 100k 10
10k 100 100k 100k 100
100k 100k 1M 10M 1k
LFXCF
X
L
C
***2***2
1
the measurement of inductances and resistances calls for values of Rm that are proportional to the expected value of the component being measured; the value of Rm for capacitors is inversely proportional to the expected value
TheoryTheory–
– X is capacitive or inductive X is capacitive or inductive reactancereactance
– Voltage Divider consists of Voltage Divider consists of RRmm and and ZZ??
– VVrr = reference (AC) voltage, = reference (AC) voltage,VVx x = measured (AC) voltage= measured (AC) voltage
– Calc: Calc: ZxZx, Given:, Given:– VVrr
VVxx
RRmm
2X 2R?Z
MeasurementsMeasurements
ReferencesReferences– These slides: These slides:
http://www.wb5rvz.com/presentations/RLC_Buildathon.ppthttp://www.wb5rvz.com/presentations/RLC_Buildathon.ppt
– Build Notes: Build Notes: http://www.wb5rvz.com/rlc_meter/http://www.wb5rvz.com/rlc_meter/– Kit Resources: Kit Resources: http://wb6dhw.com/RLC_Meter.htmlhttp://wb6dhw.com/RLC_Meter.html
ArticlesArticles– QSTQST– QEXQEX
SoftwareSoftware PurchasePurchase: :
http://wb6dhw.com/For_Sale.html#RLC_Meterhttp://wb6dhw.com/For_Sale.html#RLC_Meter Any Questions???????????Any Questions???????????