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
--
W.Thiel
Date: 6 Oct 1996 03:17:48 GMT
Original Subject: curve trace