LOGIC PROBE KIT
MODEL LP-535K
Instruction & Assembly Manual
Elenco Electronics, Inc.
Copyright © 1999 Elenco Electronics, Inc. Revised 2002 REV-A 753272
PARTS LIST
If you are a student, and any parts are missing or damaged, please see instructor or bookstore.
If you purchased this kit from a distributor, catalog, etc., please contact Elenco Electronics (address/phone/email is at the back of this manual) for additional assistance, if needed. DO NOT contact your place of purchase
as they will not be able to help you.
RESISTORS
Qty. Symbol Description Color Code Part #
1 R4 470Ω 1/4W 5% yellow-violet-brown-gold 134700
4 R5, R6, R7, R9 1kΩ 1/4W 5% brown-black-red-gold 141000
2 R1, R11 20kΩ 1/4W 5% red-black-orange-gold 152000
1 R10 33kΩ 1/4W 5% orange-orange-orange-gold 153300
1 R3 560kΩ 1/4W 5% green-blue-yellow-gold 165600
1R2 1MΩ 1/4W 5% brown-black-green-gold 171000
1 R8 15MΩ 1/4W 5% brown-green-blue-gold 181500
CAPACITORS
Qty. Symbol Value Description Part #
1 C1 68pF Discap (68) 216816
1 C2 220pF Discap (220) 222210
2 C3, C4 .001µF Discap (102) 231036
1C6 .01µF Discap (103) 241031
1C7 .1µF Discap (104) 251010
1C5 .47µF 50V Electrolytic (Lytic) 254747
1C8 47µF 10V Electrolytic (Lytic) 274742
1C9 47µF 50V Electrolytic (Lytic) 274747
SEMICONDUCTORS
Qty. Symbol Value Description Part #
2 D8, D10 1N4001 Diode (epoxy) 314001
4 D2, D3, D4, D9 1N4148 Diode (glass) 314148
1 D1 1N5232 Zener Diode 5.6V (bag with capacitors) 315232
1 D5 L-323 GD LED Green Triangular 35323G
1 D6 L-323 ID LED Red Triangular 35323I
1 D7 L-934 YDT LED Yellow 359344
1 U2 3086 Integrated Circuit 333086
1 U1 74HC14 Integrated Circuit 39HC14
MISCELLANEOUS
Qty. Symbol Description Part #
1 PC Board 517030
1 SP1 Speaker 40Ω 521602
1 S1 Switch Slide SPDT 541025
1 Logic Probe Tip 616000
1 Case (two parts) 623019
2 U1, U2 Socket IC 14-pin 664014
1 Label 724009
1 Manual 753272
1 Cord Power 863080
4” Tubing #20 890020
0.6” Shr ink Tubing Red 3/32” 891020
1 Solder Tube 9ST4
-1-
-2-
IDENTIFYING RESISTOR VALUES
Use the following information as a guide in proper ly identifying the value of resistors.
BAND 1
1st Digit
Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
BAND 2
2nd Digit
Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green 5
Blue 6
Violet 7
Gray 8
White 9
Multiplier
Color Multiplier
Black 1
Brown 10
Red 100
Orange 1,000
Yellow 10,000
Green 100,000
Blue 1,000,000
Silver 0.01
Gold 0.1
Resistance
Tolerance
Color Tolerance
Silver +
10%
Gold +
5%
Brown +
1%
Red +
2%
Orange +
3%
Green +.5%
Blue +.25%
Violet +
.1%
Bands
1 2
Multiplier
Tolerance
IDENTIFYING CAPACITOR VALUES
Capacitors will be identified by their capacitance value in pF (picofarads), nF (nanofarads), or µF (microfarads). Most
capacitors will have their actual value printed on them. Some capacitors may have their value printed in the following manner.
Resistors
Capacitors
PARTS IDENTIFICATION
Switch
Speaker
Discap
Diodes
Epoxy
Glass
Integrated Circuit (IC)
IC Socket
LEDs
Yellow
Integrated Circuits
Green Red
Tip
Tubing
Top Cover
Bottom Cover
Power Cord
Label
PC
Board
+
Electrolytic
The value is 10 x 1,000 =
10,000pF or .01µF 100V
The letter M indicates a tolerance of +
20%
The letter K indicates a tolerance of +10%
The letter J indicates a tolerance of +
5%
Note:
The letter “R” may be used at times to
signify a decimal point; as in 3R3 = 3.3
Second Digit
First Digit
Multiplier
Tolerance
103K
100V
Maximum Working Voltage
For the No.01234589
Multiply By 1 10 100 1k 10k 100k .01 0.1
Multiplier
The LP-535 Logic Probe Kit tests different types of digital logic circuit families.
Working Voltage 4 - 16VDC
Current Consumption Max 5mA @ 5V
Max 15mA @ 15V
Frequency Response Over 50MHz
Minimum Detectable
Pulse Width 10nsec
Input Impedance 1MΩ
Input Overload Protection 70V AC/DC (10s)
Supply Voltage Protection 50V AC/DC (10s)
Operation Temperature 0
O
C to 50OC
Switch Selectable Audio Indicator HI Level
CIRCUIT DESCRIPTION
SPECIFICATIONS
-3-
INPUT LED STATES SOUND
SIGNAL LO HIGH PULSE
Probe not connected to power.
*
Interpreting
the LEDs
LED On
LED Off
LED Blinking
No Sound
Sound
*
*
Logic tip is not connected or Logic “0” no
pulse activity.
Logic “1” no pulse activity.
Logic “0” with positive single pulses.
Logic “1” with negative single pulses.
Logic “0” with positive continuous pulses.
Logic “1” with negative continuous pulses.
This information for switch to the sound position.
The Elenco Model LP-535 Logic Probe Kit is a
convenient and precise instrument for use in the
measurement of logic circuits. It displays logic levels
(high or low), sounds high level, and voltage
transients down to 10 nanoseconds. To detect the
high and low logic levels, the LP-535 uses two
inverters, U1A and U1B (see the Schematic
Diagram). One inverter dr ives the LO (green) LED
and the other, the HI (red) LED.
The red LED lights when the input voltage is more
than 50% of the supply voltage. The function of the
switch for TTL or CMOS levels input signal makes up
the special circuit on the base of transistors from U2
and additional components. The outputs of U1A and
U1B are connected to differential circuits C3/R3 and
C4/R7. These differential circuits select signals,
when the test signals are the pulses. After the
differential circuits, the short pulses go through
inverters U1C and U1D to the yellow LED. This LED
blinks when the detecting diode D4 opens. At this
time, capacitor C6 discharges. The lit time of the
yellow LED depends upon the value of C6. The LP535 is equipped with a sound circuit. When the input
signal is HI, the oscillator (U1E, U1F) is started and
the frequency through switch S1 passes to the
speaker.
Introduction
Assembly of your LP-535 Logic Probe Kit will prove to be
an exciting project and give you much satisfaction and
personal achievement. If you have e xperience in soldering
and wiring techniques, then you should have no problem
with the assembly of this kit. Care must be given to
identifying the proper components and in good soldering
habits. Above all, take your time and follow these easy
step-by-step instructions. Remember, “An ounce of
prevention is worth a pound of cure”. Avoid making
mistakes and no problems will occur.
Safety Procedures
• Wear eye protection when soldering.
•
Locate soldering iron in an area where you do not have to
go around it or reach over it.
• Do not hold solder in your mouth. Solder contains lead
and is a toxic substance. Wash your hands thoroughly
after handling solder.
• Be sure that there is adequate ventilation present.
Assemble Components
In all of the following assembly steps, the components
must be installed on the top side of the PC board unless
otherwise indicated. The top legend shows where each
component goes. The leads pass through the
corresponding holes and the board is turned to solder the
component leads on the foil side. Solder immediately
unless the pad is adjacent to another hole which will
interfere with the placement of the other component. Cut
excessive leads with a diagonal cutter. Then, place a
check mark in the box provided next to each step to
indicate that the step is completed. Be sure to save the
extra leads for use as jumper wires if needed.
Soldering
The most important factor in assembling your logic probe
kit is good soldering techniques. Using the proper
soldering iron is of prime impor tance. A small pencil type
soldering iron of 25 - 40 watts is recommended.The tip of
the iron must be kept clean at all times and well
tinned. Many areas on the PC board are close together
and care must be given not to form solder shorts. Size
and care of the tip will eliminate problems.
For a good soldering job, the areas being soldered must
be heated sufficiently so that the solder flows freely. Apply
the solder simultaneously to the component lead and the
component pad on the PC board so that good solder flow
will occur. Be sure that the lead extends through the
solder smoothly indicating a good solder joint. Use only
rosin core solder of 63/37 or 60/40 alloy.
DO NOT USE ACID CORE SOLDER! Do not blob the
solder over the lead because this can result in a cold
solder joint.
Heat Sinking
Electronic components such as transistors, IC’s, and
diodes can be damaged by the heat during soldering. Heat
sinking is a way of reducing the heat on the components
while soldering. Dissipating the heat can be achieved by
using long nose pliers, an alligator clip, or a special heat
dissipating clip. The heat sink should be held on the
component lead between the part and the solder joint.
-4-
CONSTRUCTION
Mount Part
Bend Leads to Hold Part
Solder and Cut Off Leads
Foil Side
Rx - 100Ω 5% 1/4W Resistor
(brown-black-brown-gold)
Heat Sink
(this can be ordered as part of Elenco’s Solder Ease
Kit Model SE-1).
Soldering Iron
Solder
Heat Sensitive
Component (Diode)
PC Board
-5-
What Good Soldering Looks Like
A good solder connection should be bright, shiny,
smooth, and uniformly flowed over all surfaces.
Soldering a PC board
1. Solder all components from the copper foil side
only . Push the soldering iron tip against both the
lead and the circuit board foil.
2. Apply a small amount of solder to the iron tip.
This allows the heat to leave the iron and onto
the foil. Immediately apply solder to the
opposite side of the connection, away from the
iron. Allow the heated component and the
circuit foil to melt the solder.
3. Allow the solder to flow around the connection.
Then, remove the solder and the iron and let the
connection cool. The solder should have flowed
smoothly and not lump around the wire lead.
4.
Here is what a good solder connection looks like.
Types of Poor Soldering Connections
1. Insufficient heat - the solder will not flow onto
the lead as shown.
2. Insufficient solder - let the solder flow over the
connection until it is covered. Use just enough
solder to cover the connection.
3. Excessive solder - could make connections
that you did not intend to between adjacent foil
areas or terminals.
4. Solder bridges - occur when solder runs
between circuit paths and creates a short circuit.
This is usually caused by using too much solder.
To correct this, simply drag your soldering iron
across the solder bridge as shown.
A poorly soldered joint can greatly affect small current flow in circuits and can cause equipment f ailure . You can
damage a PC board or a component with too much heat or cause a cold solder joint with insufficient heat.
Sloppy soldering can cause bridges between two adjacent foils preventing the circuit from functioning.
Solder
Soldering Iron
Foil
Solder
Soldering Iron
Foil
Component Lead
Soldering Iron
Circuit Board
Foil
Rosin
Soldering iron positioned
incorrectly.
Solder
Gap
Component Lead
Solder
Soldering Iron
Drag
Foil
ASSEMBLE COMPONENTS TO THE PC BOARD
* Resistors R2, R4, R6, R7 and R9 are to be installed the standard way as shown on page 4.
SP1 - Speaker
(see Figure A)
D8 - 1N4001 Diode (epoxy)
(see Figure B, vertical)
C9 - 47µF 50V Electrolytic Cap.
(see Figure C)
S1 - Switch Slide
(Solder and cut off excess leads.)
R11 - 20kΩ 5% 1/4W Resistor
(red-black-orange-gold)
(see Figure D)
D10 - 1N4001 Diode (epoxy)
(see Figure B, standard)
C8 - 47µF 10V Electrolytic Cap.
(see Figure C)
U2 - 14-pin IC Socket
U2 - 3086 Integrated Circuit
(see Figure E)
R8 - 15MΩ 5% 1/4W Resistor
(brown-green-blue-gold)
(see Figure D)
R6 - 1kΩ 5% 1/4W Resistor *
(brown-black-red-gold)
D2 - 1N4148 Diode (glass)
D3 - 1N4148 Diode (glass)
D4 - 1N4148 Diode (glass)
(see Figure B, standard)
C2 - 220pF (220) Discap
R3 - 560kΩ 5% 1/4W Resistor
(green-blue-yellow-gold)
(see Figure D)
C4 - .001µF (102) Discap
R5 - 1kΩ 5% 1/4W Resistor
(brown-black-red-gold)
(see Figure D)
R10 - 33kΩ 5% 1/4W Resistor
(orange-orange-orange-gold)
(see Figure D)
C5 - .47µF 50V Electrolytic Cap.
(see Figure C)
C7 - .1µF (104) Discap
D1 - 1N5232 5.6V Zener Diode
(bag with capacitors) vertical
(see Figure B)
C6 - .01µF (103) Discap
C3 - .001µF (102) Discap
U1 - 14-pin IC Socket
U1 - 74HC14 Integrated Circuit
(see Figure E)
D9 - 1N4148 Diode (glass)
(see Figure B, standard)
D7 - Yellow LED
7/16” x 2 Tubing #20 (black)
(see Figure F)
R9 - 1kΩ 5% 1/4W Resistor *
(brown-black-red-gold)
D6 - Red Triangular LED
D5 - Green Triangular LED
5/16” x 4 Tubing #20 (black)
(see Figure F)
R2 - 1MΩ 5% 1/4W Resistor *
(brown-black-green-gold)
R1 - 20kΩ 5% 1/4W Resistor
(red-black-orange-gold)
(see Figure D)
C1 -
68pF (68) Discap
R7 - 1kΩ 5% 1/4W Resistor *
(brown-black-red-gold)
R4 - 470Ω 5% 1/4W Resistor *
(yellow-violet-brown-gold)
Figure C
Electrolytic capacitors
have polarity. Mount the
capacitor with the positive
lead in the hole marked (+)
on the PC board.
Polarity
Marking
(–)
(+)
Figure A
Mount the speaker with
the positive (+) lead in the
hole marked (+) on the PC
board as shown.
Polarity Marking
Figure B
Diodes have polarity, so be sure that the
band is in the correct direction, as shown
on the top legend of the PC board.
Band
Figure D
Mount the resistor
on end as shown.
-6-
Band
PC Board Marking
-7-
Figure G
Figure H
Figure I
FINAL ASSEMBLY
Attach and solder the logic probe tip to the foil side of the PC board as shown in Figure G.
Solder the power cord to the foil side of the PC board as shown in Figure H. The red wire goes to the pad
marked J2 and the black wire goes to the pad marked J3.
Tip
Foil Side of
PC Board
Solder
Foil Side of
PC Board
Power Cord
Red
Black
Tab
Tab
Mount the PC board onto the bottom case aligning the two
tabs with the two holes in the PC board (as shown in
Figure I). Then, snap the top case on.
Top Case
Bottom Case
Figure E
Insert the IC socket into the PC board
with the notch in the direction shown on
the top legend. Solder the IC socket into
place. Insert the IC into the socket with
the notch in the same direction as the
notch on the socket.
Notch
IC
Socket
PC Board
Figure F
Mount the LED as shown with the black tubing spacers. Be sure that
the flat side is in the same direction as marked on the PC board.
7/16”
5/16”
Flat Side
Long
Lead
Flat Side
Black
Tubing
Black
Tubing
INPUT LED STATES SOUND
SIGNAL LO HIGH PULSE
Probe not connected to power.
*
Interpreting
the LEDs
LED On
LED Off
LED Blinking
No Sound
Sound
*
OPERATING INSTRUCTIONS
*
Logic tip is not connected or Logic “0” no
pulse activity.
Logic “1” no pulse activity.
Logic “0” with positive single pulses.
Logic “1” with negative single pulses.
Logic “0” with positive continuous pulses.
Logic “1” with negative continuous pulses.
This information for switch to the sound position.
-8-
Figure J
Peel the backing off of the label and stick the label onto the
top case as shown in Figure J. Then, slide on the red
tubing onto the tip as shown. Shrink the tubing by heating
it with your soldering iron. Be sure that the soldering iron
does not contact the tubing or plastic case.
Label
Red Tubing
Tip
To operate the logic probe, connect the two alligator
clips to the circuit DC power supply (the red clip to
the positive voltage and the b lac k clip to g round). BE
SURE THE POWER SUPPLY IS UNDER 35V OR
DAMA GE MAY OCCUR T O THE PROBE. The green
LED will light. Touch the probe tip to the circuit node
to be analyzed. If the voltage of this point is >
50%
of the voltage power supply, the red LED will light to
indicate the HI level voltage. If the sound switch is in
the SOUND position, you will hear the beeper tone
for the HI level voltage. If the sound switch is OFF,
the same results occur with the LEDs but without
sound.
When there are single pulses on the probe tip, the
yellow LED will flicker with the frequency of input
pulses. For continuous pulses, the yellow LED will
stay lit.
-9-
TROUBLESHOOTING
Contact Elenco Electronics if you have any problems. DO NOT contact your place of purchase as they will not
be able to help you.
1. One of the most frequently occurring problems is poor solder connections.
a) Tug slightly on all par ts to make sure that they are indeed soldered.
b) All solder connections should be shiny. Resolder any that are not.
c) Solder should flow into a smooth puddle rather than a round ball. Resolder any connection that has
formed into a ball.
d) Have any solder bridges formed? A solder bridge may occur if you accidentally touch an adjacent foil
by using too much solder or by dragging the soldering iron across adjacent foils. Break the bridge with
your soldering iron. (See Figure K).
2. Be sure that all components have been mounted in their correct places.
a) Be sure that the electrolytic capacitors C5, C8 and C9 have been installed correctly. These capacitors
have polarity, so the negative and positive leads must be in the correct holes as marked on the top
legend side of the PC board.
b) Be sure that the LEDs are mounted as shown in Figure F.
c) Be sure that the integrated circuits U1 and U2 are mounted with the notches in the same direction as
marked on the PC board.
d) Be sure that the speaker SP1 is mounted with the positive (+) lead in the correct hole as marked on the
PC board.
e) Be sure that the power cord has been installed correctly. The red wire goes to the pad marked J2 and
the black wire goes to the pad marked J3. (See Figure K).
f) Be sure that the diodes are mounted with the band in the same direction as mar ked on the PC board.
Foil Side of PC Board
Figure K
-10-
GLOSSARY
Alternating Current (AC) Non-polarized power that is constantly changing back and forth
between positive and negative.
Anode The positive terminal of a diode or other polar ized component.
Capacitor Electrical component for accumulating energy.
Cathode The negative terminal of a diode or other polarized component.
CMOS (Complimentary Metal Oxide Semiconductor) A type of transistor
circuit which uses P- and N-type field-effect transistors.
Current The flow of electrons.
Diode An electronic component that changes alternating current to direct
current.
Direct Current (DC) Voltage that has polarity.
Frequency The number of cycles per second produced.
Impedance In circuit, the opposition that circuit elements present to alternating
current.
Input Impedance
The impedance seen by source when a device or circuit is connected
across the source.
Integrated Circuit (IC) Any of a huge number of semiconductor packages that contain entire
elements.
Inverter The circuit where the output state is the opposite of the input state.
Light Emitting Diode (LED) A semiconductor device that glows when power is applied to its
electrodes.
Logic Probe An electronic test device that detects the status of a signal.
Oscillator A device that moves back and forth between two boundaries.
PC Board Printed Circuit Board.
Power Supply An electronic circuit that produces the necessary power for another
circuit or device.
Pulse A sudden change from one level to another, followed after a time by a
sudden change back to the original level.
Resistor
An electronic component that obstructs (resists) the flow of electricity.
Speaker Component that converts electrical energy into sound energy.
Troubleshoot To find and fix the problem with something.
TTL (Transistor-Transistor Logic)
A type of integrated circuit logic that uses bipolar junction transistors.
Voltage The electromotive force that “pushes” electrons through conductive
materials.
Zener A type of diode that acts as a voltage regulator by restricting the flow
of voltage above its rating.
Elenco Electronics, Inc.
150 W. Carpenter Avenue
Wheeling, IL 60090
(847) 541-3800
http://www.elenco.com
e-mail: elenco@elenco.com
SCHEMATIC DIAGRAM
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