EXERCISE 1.
1 – INSTRUMENT FAMILIARIZATION
Objective:
To set up a power source by using typical lab power supplies and instruments.
DISCUSSION:
The F.A.C.E.T. DC FUNDAMENTALS trainer system requires the use of a DC power source and a
multimeter. The DC power source applicable provides +15Vdc and -15Vdc at 1A with a regulation factor
of 1%.
The Instruments applicable to the F.A.C.E.T. based DC trainer include the following:
Base Unit: This is the heart of the FACET system, the base unit provides power, signal
generation, and fault insertion capabilities. It supplies regulated DC voltages (±15V, 5V) and
currents for powering circuits under test. Generates various waveforms (sine, square, triangle) to
stimulate circuits. Injects pre-defined faults (open circuits, short circuits, component value
changes) into the training circuits.
Multimeter: Measures voltage, current, and resistance in the circuit.
Breadboard: Provides a platform for building and experimenting with circuits.
Training Boards: FACET comes with various themed training boards, each focusing on specific
electronic concepts and components.
Components: Boards are pre-populated with resistors, capacitors, transistors, diodes, LEDs, and
other basic electronic components.
Circuit Diagrams: Each board has a corresponding schematic diagram printed on the surface,
aiding in troubleshooting and understanding.
Fault Indicator LEDs: LEDs light up when specific faults are inserted, guiding students towards
the faulty component.
Accessories: FACET offers additional accessories like jumper wires, probes, and component kits
to expand training possibilities.
During the course of this practical, digital multimeters were used.
A digital multimeter displays the actual value directly in numbers. Digital multimeters are available with
or without a feature called autorange. A typical autorange model is shown in Figure 1-5(a), along with a
standard model that does not feature autorange [Figure 1-6(b)]. The outward difference between the two
is the absence of a RANGE switch on the autorange model. The standard model requires a user to select
both a FUNCTION to be measured (volts, amperes, ohms) and the RANGE (1V, 10V, 18, 109, etc.) of
that function. The autorange model still requires the user to select a function, but the range is
automatically adjusted by the multimeter.
Figure - Standard and autorange multimeters
The multimeters shown in Figure 1-5 represent popular digital multimeters used in actual laboratories.
Typical features are described below:
1. Function Switch — a seven-position switch used to select one of the seven multimeter functions:
off, volts AC (V~), volts DC (V...), ohms, diode checking, amps AC (A~), and amps DC (A...).
2. Numerical Display — shows the value of the quantity being measured.
3. Function Display — also shows the function selected.
4. Range Switch — a five-position switch used to select the range of the quantity being measured.
5. Multimeter Input — used for volts, ohms, and diode checking.
6. Multimeter COM (common) Input — usually connected to the common point in the circuit being
measured.
7. Multimeter Input — measures current up to 300mA.
8. Multimeter Input - Measures current up to 10A.
PROCEDURE
NOTE: This procedure is based upon power supplies and instruments described in the discussion section
above.
1. The power source was connected to the AC line. The power sources were turned off:
2. All variable voltage controls (may be marked VOLTAGE ADJUST) were turned fully
counterclockwise (CCW).
3. The power source(s) was turned on.
4. The red and black test leads were connected to the multimeter (red to the voltage input and black
to the common input).
5. The multimeter was turned on. The DC volts function was selected.
6. The multimeter black test lead was connected to the power supply COM (common) jack (may be
black or marked with a minus sign).
7. The multimeter red test lead was connected to the power supply positive Jack (may be red or
marked with a plus sign). The connection was completed as shown in Figure 1-6.
Figure – Voltage measurement circuit
8. The power supply variable voltage control (output adjust) was slowly adjusted until the
multimeter read 15Vdc.
9. The digital multimeter test leads connected to the power supply jacks were reversed. The
multimeter reading was recorded.
10. The multimeter black test lead was connected to the other power supply COM
11. The multimeter red test lead was connected to the matching power supply positive output jack.
12. The positive variable supply voltage control was slowly adjusted until the multimeter read
15Vdc.
13. The power supply was turned off. The multimeter was disconnected from the power supply, and
turned off.
CONCLUSIONS:
1. A DC power supply and a multimeter can be used to adjust both supplies to 15 Vdc.
2. A DC power supply can be used as either a positive or a negative supply depending upon where the
common reference point is established.
