ENGINEERING
182�� BASIC ELECTRONIC CIRCUITS LAB
LAB
PROCEDURE
1.
LOCATE the following PIECES and PARTS in your
ELECTRONIC PARTS KITS or on the TABLE:
A power
supply with wire leads, a Digital Multi-Meter (DMM), a switch, two 330 ohm
resistors (orange/orange/brown color bands), a 2200 microfarad capacitor, a
light emitting diode (LED), a wire jumpers kit, and a prototyping board.
2.
UNPLUG the power supply from the outlet.
3.
On the prototyping board, CONNECT one LEAD of the
SWITCH to a POWER (+5 Vdc) hole.� CONNECT the other LEAD to a hole in any one
of the 5-hole terminal sets.
4.
CONNECT a 330 ohm resistor from that same set to
another nearby set.
5.
CONNECT an LED from that nearby set to ground.� Note that the LED must be oriented properly
for it to work.� The lead with a
spearhead shape to it inside the LED is the positive lead.
6.
CONNECT LEADS from the POWER SUPPLY to the
prototyping board.� INSURE that the
POSITIVE LEAD goes to the GREEN POST while the NEGATIVE LEAD (ground) goes to
the BLACK POST.� At the same time,
CONNECT JUMPER WIRES from the POSTS to the POWER BUS sets.� The +5 (GREEN POST) should wire to the RED
STRIPED sets while the GROUND (BLACK POST) should go to the BLUE STRIPED sets.
7.
PLUG IN the POWER SUPPLY to the 120 Vac ELECTRICAL OUTLET.
8.
PRESS SWITCH LEVER and the LED should EMIT
LIGHT.� RELEASE the LEVER and the LED
should STOP EMITTING LIGHT.
9.
SET the DMM to a 20 Vdc
range (three �clicks� counterclockwise from OFF position).
10. LOCATE
the points AA, BB, and CC on the SCHEMATIC DRAWING.� Now LOCATE the SAME ELECTRICAL POINTS on your
prototyping board.
11. PRESS
and HOLD the SWITCH LEVER.
12. PLACE
BLACK DMM LEAD so it CONTACTS BLACK POST METAL (or equivalent point CC).� PLACE RED DMM LEAD so it CONTACTS POINT AA.� RECORD the
13. PLACE
BLACK DMM LEAD so it CONTACTS BLACK POST METAL (or equivalent point CC).� PLACE RED DMM LEAD so it CONTACTS POINT BB.� RECORD the
14. RELEASE
the SWITCH LEVER.
15. CONNECT
ANOTHER 330 OHM RESISTOR in PARALLEL with the EXISTING RESISTOR.
16. REPEAT
STEPS 11 THROUGH 14.� Does the LED output
seem different?� If so, how is it
different?
17.
CONNECT a 2200 MICROFARAD CAPACITOR from the HOLE
SET of the JUNCTION OF THE SWITCH LEAD AND RESISTOR LEAD ( AA ), TO the SYSTEM
GROUND (SETS OF HOLES MARKED BLUE).�
INSURE THE CAPACITOR LEAD
MARKED � (negative) IS CONNECTED TO THE BLUE MARKED HOLES (ground).
18. PRESS
the SWITCH LEVER.
19. NOTE and
RECORD what happened to the LED OUTPUT.
20. RELEASE
THE SWITCH LEVER.� NOTE and RECORD what
happened to the LED OUTPUT.
21. PRESS
the SWITCH LEVER, WAIT a moment, then RELEASE the SWITCH LEVER.� BEGIN TO COUNT when you release the SWITCH
LEVER.� HOW LONG does it take for the LED
to BE COMPLETELY OFF?� TRY THIS A FEW TIMES AND RECORD AN AVERAGE
TIME in seconds.
22. USE the
DMM to MONITOR point AA (RED LEAD TO AA, BLACK LEAD TO CC).� Now REPEAT STEP 21 BUT COUNT the TIME it
takes for the VOLTAGE LEVEL at AA to DROP TO 1.7 Vdc
after the SWITCH LEVER is RELEASED.
23. REMOVE
ONE of the 330 OHM REISITORS and REPEAT STEPS 21 and 22.
24. YOU HAVE
COMPLETED THE MEASUREMENT STEPS FOR THIS LAB !
ENGINEERING 182��
BASIC ELECTRONICS
MEASUREMENT RECORDING AND NOTATIONS:
STEP 12(one resistor):���
_____________� Volts�� ���
STEP 13(one resistor): _____________ Volts
STEP 12(two resistors):����
___________� Volts��� ���
STEP 13(two resistors): ___________�
Volts
What can you conclude about the variation of voltage
across the LED?
�
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Is a diode (LED) a regulator (�maintainer�) of
voltage?�� Explain� your answer.
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Notes for Step 16:�
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Notes for STEP
19:____________________________________________________________________
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Notes for STEP 20:�
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Time for LED to completely turn off:� ____________________ seconds (STEP 21, 2
resistors).
Time for voltage level to reach 1.7 Vdc:� _________________ seconds (STEP 22, 2
resistors).
Time for LED to completely turn off:� _____________________ seconds (STEP 21, 1
resistor).
Time for voltage level to reach 1.7 Vdc:� __________________ seconds (STEP 22, 1
resistor).
What can you conclude about the
effect of resistance (along with capacitance) on the time response of the
circuit?_______________________________________________________________________________
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