I found the old text to go with the diagram; this device
has worked for me for over 20 years and I hope it will be useful
for you................

In the August 1975 issue of Popular Electronics author Lou Garner
wrote in a story called "A simple On-Board Tester" about this fairly
simple piece of test equipment.

The device can be used with any type of oscilloscope and consists of a
6 volt filament transformer, three 1/4 watt resistors and two test probes.
Half  the filament voltage is applied to a voltage divider consisting of 
220 ohm and 100 ohm, yielding 1 volt ac on top of resistor 1000 ohm.
This voltage can be applied to any component or combination of components
across which the test leads are placed. The current is limited to one
milliampere by the 1K resistor.

The voltage across the probes is connected to the horizontal input  of a scope
while the voltage across the 1K resistor as a result of the current through
it is connected to the vertical input.

What we see on the scope is a voltage  across a component under test
versus the current through the component.

Resistors:     open   horizontal line
              10000   10 degree
               1000   45 degree
                  0   vertical line
Capacitor       .1uF  shallow ellipse
               2.6uF  circle
                50uf  narrow vertical

Transformer           ellipse depending on impedance

Diode      germanium  right angle display
           silicon    right angle one side longer
                      (any leakage showing less sharp angle)

Transistor            test as two diodes
                      (base to emitter and base to collector)

IC's                  input for gates and counters show a certain
                      signature display
                      outputs display a different signature
                      a short will show a vertical line
                      an open will show a horizontal line

In circuit testing is done with NO power applied to the equipment
under test.
With some experience one is able to test components in and out of
circuit and troubleshoot without danger of a damage to components.

--- 200 Ohm---------o---------o--------------  Vert. Oscilloscope
                    |         |
                    |         1 K Ohm
 to the 3V          |         |
 winding of a       |         o--------------  Ground    
 6 volt             |         |
filament         100 Ohm      |
transformer         |         V RED component test lead
--------------------o----------------------- Hor.  Oscilloscope
                    V BLACK component test lead


Date: 6 Oct 1996 03:17:48 GMT

Original Subject: curve trace

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