The two voltmeters represent scopes BNC channels X-Y mode.
The switches represent probe scopes.
When they are all open (probe not connected to anything), the scope will display a horizontal line, when the scope probes are shorted ( last switch closed on 1uohm resistor), the scope will display a vertical line. The tracer places a constantly changing sine wave voltage across the probed device. Here the vertical axis shows the current through the probes and the horizontal axis shows the voltage across the probes. As the sine wave changes, the scope trace loops around in accordance with the associated current and voltage readings from the probe. Probing different electronic components will produce a variety of unique scope patterns.
First pot. near transformer regulates voltage (in reality is a selector on multiple transformer secondary exits (4 6 8 12 volt).
The other pot. limit maximum amount of current that can flow through device in test.
Here are some typical curves that the tracer will display:
Open Circuit - horizontal line
Short Circuit - vertical line
Resistor - diagonal line, slope varies with the value
Capacitors and Inductors - ellipses, shape varies with value
Diodes - L shaped curve
Zener Diodes - squared Z shaped curve
Transistor EC - tall L shaped curve
Transistor EB - squared Z shaped curve
Transistor BC - L shaped curve (same as diode)
Varistor - S shaped curve
EC can take some seconds to show right shape.
