Octopus Tester

Features

• Classic Octopus Tester
  • Based on design example (N5BL)
• Out of circuit component tester
  • Useful for matching parts like diodes
• In circuit component tester
  • Test 2 units and compare signatures on scope
• Use 6.3V "filament" transformer
  • 8.91V - Vpeak
  • 17.82V - Vpeak-peak
  • Typical transformer
    • 1.38 in L, 2.38 in W, 1.38 in H
• 1mA, 10mA "scale" switch
  • Pot adjustments to set current (accommodate transformer and line voltage variances)
• 2 BNC jacks
• Plus, Minus Banana jacks
• AC powered
  • C13 jack with switch
  • 1A Fuse
• Build into Bud Box CU-1945
  • 6.21 in W x 3.76 in D x 2 in H
  • Comes with screws and rubber feet

Scope Setup

• Scope set to X-Y for voltage-vs-current measurement of part
  • Press button above time adjustment knob
  • Time Base XY
  • Look at scope pattern for device signature
  • Shows voltage/current phase relationships
  • 50 mS timebase
  • Connect to XY on scope (X=CH1, Y=CH2)
  • CH2 gets set to INVERT

X-Y Patterns

Resistors

• Resistor - slope line
  • Slope = resistance value
• 1 mA setting = 8901 ohms, 1:1 slope
• 10 mA setting = 890 ohms, 1:1 slope

Capacitors

• Oval shape
• 0.3uF, 60 Hz, 8841 ohms
• 3uF, 60 Hz, 884 ohms
• 1 uF cap, 1mA selection

• 1 uF cap, 10mA selection

Zener

• 3.9V Zener
• 1 mA switch setting

• 10 mA switch setting

Schematics

• Adjust RV1/RV2 for total resistance (fixed resistor plus pot)
  • 891 - 1 mA switch setting (RV2)
  • 8910 - 10mA switch setting (RV1)

Cutouts on Bud Box CU-1945

Parts

• Transformer
• Enclosure