1. WB6DHW PC-Based RLC Meter Kit

2.  Proposed Buildathon Project: –April 2011 Radio Play Days (16 Apr 2011) –Build simple $20 kit in one play day session –Learn some electronics while we’re at it –Minimal hand-holding –Have fun, too  Kit: –Furnished by Dave Brainerd WB6DHW –No toroids, no SMT –Measures R, L, and C –Easy build (25 components)

3. Components User-furnished parts Two stereo M-M 1/8” cables Hookup wire 2 alligator clips One USB-A to USB-B cable

4.  Requirements –PC with soundcard and free USB port  Soundcard MUST have stereo input  USB just for 5V power –Fairly accurate DMM –(downloadable) Software –Soldering iron and solder –Diagonal cutters and needle-nosed pliers –A (Pana)vise would be nice –User-furnished parts  Two stereo M-M 1/8” cables  Hookup wire  2 alligator clips  One USB-A to USB-B cable

5.  Completed Kit:

6.  Schematic

7. Build Stages Power Supply Negative Power Supply Resistance Ladder OpAmps & I/O Calibration

8.  Theory –Apply reference signal to voltage divider –Measure reference and output signals –Calc Unknown impedance (ohms: R & X)

9. Resistor Ladder Selection RmL-FromL-ToC-FromC-To 1012.99 uH12.99 mH0.1299 uF1299 uF 100129.9 uH129.9 mH0.01299 uF129.9 uF 1k1.299 mH1299 mH1.29 nF12.9 uF 10k12.99 mH12.99 H1299 pF1.29 uF 100k129.9 mH129.9 H12.99 pF0.129 uF RmX L _FromX L _ToXc_FromXc_To 100.11001k0.1 10011k10k1 1k1010k100k10 10k100100k 100 100k 1M10M1k 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

10.  Theory –X is capacitive or inductive reactance –Voltage Divider consists of R m and Z ? –V r = reference (AC) voltage, V x = measured (AC) voltage –Calc: Zx, Given: –V r  V x  R m

11. Measurements

12.  References –These slides: http://www.wb5rvz.com/presentations/RLC_Buildathon.ppt –Build Notes: http://www.wb5rvz.com/rlc_meter/ http://www.wb5rvz.com/rlc_meter/ –Kit Resources: http://wb6dhw.com/RLC_Meter.html http://wb6dhw.com/RLC_Meter.html  Articles –QST –QEX  Software  Purchase: http://wb6dhw.com/For_Sale.html#RLC_Meter http://wb6dhw.com/For_Sale.html#RLC_Meter  Any Questions???????????