Global Specialties PB-505A User manual

User Manual
PB-505A
Deluxe Circuit Design Trainer

2
Global Specialties
globalspecialties.com
451-054-000_rA
© 2021 Global Specialties. All rights reserved.
Unauthorized duplication of Global Specialties documentation materials is strictly
prohibited. Customers are permitted to duplicate and distribute Global Specialties
documentation for internal educational purposes only.
Table of Contents
Symbols and Terms ..................................3
Denitions .........................................3
General Safety Information ............................4
Compliance and Certications ..........................7
Introduction ........................................8
Features & Applications ...............................8
Courseware ........................................9
Description of Individual Features .......................11
Specications .......................................15
Checking out the PB-505A.............................17
Breadboarding Techniques ............................20
Warranty Information .................................21
Service ............................................22

globalspecialties.com
Global Specialties
3
Symbols and Terms
The following symbols may appear on the product or in the documentation.
Definitions
POLLUTION (P) – addition of foreign matter solid, liquid or gaseous (ionized gases),
that may product a reduction of dielectric strength or surface resistivity.
• Degree 2 (P2) – only non-conductive pollution occurs except that
occasionally a temporary conductivity caused by condensation is
expected.
MEASUREMENT CATEGORY (CAT) – classication of testing and measuring circuit
according to the type of mains circuits to which they are intended to be connected.
• CAT II – measuring circuits connected to utilization points of the low-voltage
mains installation.
Caution Symbol (ISO 7000-0434) – Statements or instructions that must be consulted in order
to nd out the nature of the potential hazard and any actions which must be taken.
A statement calling attention to an operating procedure, practice, or condition, which if not
followed correctly, could result in damage to or destruction of parts or the entire product.
A statement calling attention to an operation procedure, practice, or condition, which if not
followed correctly, could result in injury or death to personnel
Power on. This is the AC mains connect/disconnect switch on the trainer.
Power off. This is the AC mains connect/disconnect switch on the trainer.
This symbol is used to denote an AC signal
This symbol is used to denote the chassis ground
CAUTION
WARNING

4
Global Specialties
globalspecialties.com
451-054-000_rA
General Safety Information
To avoid personal injury and/or product damage, review and comply with the
following safety precautions. These precautions apply to both operating and
maintenance personnel and must be followed during all phases of operation, service,
and repair of this meter. Before applying power be sure to:
• Read and understand the safety and operational information in this manual.
• Apply all the listed safety precautions.
• Verify that the voltage selector on the back of the unit is set to the correct
line voltage. Operating the instrument at an incorrect line voltage will void the
warranty.
• Make all connections before applying power.
• Do not operate the instrument in ways not specied by this manual or by
Global Specialties.
Failure to comply with these precautions or with warnings elsewhere in this manual
violates the safety standards of design, manufacture, and intended use of the
instrument. Global Specialties assumes no liability for a customer’s failure to comply
with these requirements.
Dry Conditions
WARNING Hands, shoes, oor, and work bench must be dry. Avoid making
measurements with dampness, or other environmental conditions
that might aect safety.
Cleaning
CAUTION Use a soft cotton cloth lightly moistened with a mild solution of
detergent and water. Do not allow any portion to be submerged at
any time. Dry thoroughly before attempting to make measurements.
Do not use solvents or expose to solvent fumes as they may cause
deterioration or damage.
Do not Operate:
• In the presence of noxious, corrosive, ammable fumes, gases, vapors,
chemicals, or nely-divided particulates.
• In environments where there is a danger of any liquid being spilled on the
meter.
• In air temperatures exceeding the specied operating temperatures.
• In atmospheric pressures outside the specied altitude limits or where the
surrounding gas is not air.

globalspecialties.com
Global Specialties
5
Only for use in pollution degree 2 environments where non-conductive pollution
occurs except occasionally when a temporary conductivity caused by condensation is
expected.
Electrical Power
CAUTION This instrument is intended to be powered from a CATEGORY II
mains power environment. The mains power should be 115 VAC or
230 VAC (±10%) at 50/60 Hz. Use only the power cord supplied with
the instrument and ensure it is appropriate for your country of use.
Slide the switch on the back of the trainer to select the appropriate
input making sure the correct fuse is installed. This trainer consumes
less than 50 W.
Fuse Replacement
WARNING Set the power switch to the OFF or Oposition and disconnect the
power cord before inspecting or replacing the fuse. Open the black
fuse holder (located at the back of the trainer below the input power
receptacle) with a small, at-head screwdriver. Remove the old fuse,
replace it with a new one, and reinstall the fuse holder. Use only 5 x 20
mm type T 1.5 A / 250 V or 0.75 A / 250 V Fuses.
Ground the Instrument
CAUTION To minimize shock hazard, the instrument case must be connected to
an electrical safety ground. This instrument, and the chassis, is
grounded through the ground conductor of the supplied, three-
conductor AC power cable per IEC 60320-1. Do not alter or bypass
the ground connection. Failure to use a properly-grounded approved
outlet and the recommended three-conductor AC line power cable
may result in injury or death. Unless otherwise stated, a ground
connection on the instrument’s front is for a reference of potential
only and is not to be used as a safety ground.
Indoor Use:
This instrument is intended to be used in an indoor pollution degree 2 environment.
The operating temperature range is 0 °C to 40 °C and the operating humidity range is
up to 80% relative humidity with no condensation allowed. Measurement results may
be outside specications if the instrument is used in non-oce-type environments.
Such environments may include rapid temperature or humidity changes, sunlight,
vibration and/or mechanical shocks, acoustic noise, electrical noise, strong electric

6
Global Specialties
globalspecialties.com
451-054-000_rA
elds, or strong magnetic elds.
Do not Operate:
If the instrument is damaged, appears to be damaged, or if any liquid, chemical, or
other material gets on or inside the instrument, remove the instrument’s power cord,
remove the instrument from service, label it as not to be operated, and return the
instrument to Global Specialties for repair. Notify Global Specialties of the nature of
any contamination of the instrument.
Not for Critical Applications:
This instrument is not authorized for use in contact with the human body or for use as
a component in a life-support device or system.
Do not Touch Live Circuits
Do not Attempt Servicing:
WARNING Instrument covers must not be removed by operating personnel.
Component replacement and internal adjustments must be made by
qualied service-trained maintenance personnel who are aware of
the hazards involved when the instrument’s covers and shields are
removed.
Under certain conditions, even with the power cord removed,
dangerous voltages may exist when the covers are removed. To
avoid injuries, always disconnect the power cord from the instrument,
remove all other connections (for example, test leads, probes, etc.),
discharge all circuits, and verify there are no hazardous voltages
present on any conductors by measurements with a properly-
operating voltage-sensing device before touching any internal parts.
Verify the voltage-sensing device is working properly before and after
making the measurements by testing with known-operating voltage
sources and test voltages. Do not attempt any service or adjustment
unless another person capable of rendering rst aid and resuscitation
is present. Hazardous voltages may be present in unexpected
locations in circuitry being tested when a fault condition in the circuit
exists.

globalspecialties.com
Global Specialties
7
Use Correctly Sized Wires
CAUTION Use only standard 4 mm banana plugs when connecting to power
supplies.
Solid core wires no larger than 20 AWG must be used for connections
to the solderless breadboards.
Compliance and Certifications
CE Compliance
This product meets the essential requirements of the applicable European Directives
as follows:
2014/30/EU: Electromagnetic Directive (EMC)
2014/35/EU: Low Voltage Directive (LVD)
Standard IEC 61010-1
2011/65/EU + AMD2015/863: Reduction of Hazardous Substances
Directive (RoHS 2)
ANNEX III Exemption 6(c)
Disposal
(Applicable in the European Union and other European countries with
separate collection systems). This product is subject to Directive 2012/19/
EU of the European Parliament and the Council of the European Union on
waste electrical and electronic equipment (WEEE), and in jurisdictions
adopting that Directive, is marked as being put on the market after August
13, 2005, and should not be disposed of as unsorted municipal waste.
Please utilize your local WEEE collection facilities in the disposition of this
product.

8
Global Specialties
globalspecialties.com
451-054-000_rA
Introduction
The PB-505A Circuit Design Trainer is a versatile, time-saving tool for circuit
designers, engineering technicians, students, and hobbyists. A large breadboard area
and a wide choice of built-in circuit accessories allow rapid and accurate construction
of virtually any type of analog or digital circuit.
Circuit power is provided by three power supplies, two variable and one xed. The
circuit breadboard area includes over 2500 contact points. A multiple-waveform
digital function generator supplies sine, triangle, and square wave output for analog
circuits. A built-in speaker may be used for analog output.
Outputs also include a TTL-level square wave generator, two debounced pushbutton
switches, and a bank of eight logic switches. Eight logic indicators may be used
to display high and low logic levels. Two built-in potentiometers and two SPDT
switches are provided for circuit control and adjustment. Connections to external test
equipment or signal sources may be made using the two BNC connectors on the
front panel.
The PB-505A eliminates the clutter and confusion that often results when
constructing sophisticated circuits. Alligator clips and similar connectors are seldom
needed. Solderless breadboards on the PB-505A allow insertion of components or
wires of up to 20 gauge.
A detailed panel layout and description of the PB-505A is given in the section
“Description of Individual Features”.
Features & Applications
The PB-505A Circuit Design Trainer is a robust electronics trainer suitable for all
levels of electronics instruction and design. Utilizing the PB-505A, students will learn
valuable hands-on breadboarding techniques and build a solid foundation in circuit
experimentation, construction and analysis. Experienced designers will nd the PB-
505A an invaluable instrument, providing a reliable platform for the most advanced
and demanding design applications. The PB-505A can be used to construct basic
series and parallel circuits to the most complicated multi-stage microcomputer
circuits, incorporating the latest in industrial technology. Use the PB-505A to
construct a wide variety of experiments, including but not limited to:
• Opto-Device Circuits
• Clocks
• Multivibrators

globalspecialties.com
Global Specialties
9
• Oscillator Circuits
• Timers
• Function Generator Circuits
• Logic Circuits
• Gates
• Counters
• Flip-Flops
• Analog-to-Digital Converters
• Digital-to-Analog Converters
• Medium Scale Integration Circuits
• Phase Lock Loops
• Operational Ampliers
Courseware
Courseware is available separately through our website or as part of the PB-
505ALAB package. The PB-505ALAB package oers comprehensive course
instruction covering the following areas:
Electronic
Fundamentals Digital Electronics
Fundamentals of Electricity Number Systems & Codes
Ohm’s Law Binary, Decimal, Hexadecimal, Octal &
ASCII
Series Circuits Logic Gates & Boolean Algebra
Parallel Circuits Combinational Logic Circuits
Combinational Circuits Flip-Flops
Current Control Digital Arithmetic
Closed, open, shorts Counters & Registers
Switches Integrated Circuit Logic Families

10
Global Specialties
globalspecialties.com
451-054-000_rA
Thevenin’s Theorem TTL Logic
Wheatstone Bridge MOSFETS
Capacitors CMOS
Inductors Interfacing CMOS & TTL
Phase Shift Circuits Medium Scale Integration
Impedance Decoders
Resonant Circuits Encoders
Transformers Data Conversion & Acquisition
Rectiers & Filtering Microcomputer Concepts
Integrated Circuits
Transistor Ampliers
Oscillators
Power Control Circuits

globalspecialties.com
Global Specialties
11
Description of Individual Features
In order to properly use the full capabilities of the PB-505A, it is highly recommended
that the user become familiar with the panel layout and the features of the
components. See Figure 1.
Generator
Digital Function
Push Buttons
Logic Switches
Potentiometers SPDT Switches
Speaker
Voltage Adjustments
Bus StripsAC Power Supply
7 Segment Display
Logic Probe
Logic Indicators
DC Power Supplies
BNC Connector
Figure 1 PB-505A Components

12
Global Specialties
globalspecialties.com
451-054-000_rA
AC Line Input
The PB-505A can run o of 115 or 230 VAC. The unit comes standard with a 250 V /
1.5 A type T fuse for the 115 VAC setting. In order to use with 230 VAC, please slide
the switch on back to 230 V and replace the fuse with a 250 V / 0.75 A type T fuse.
Power Supplies
By combining the three DC power supplies on the PB-505A, the user may work
with virtually any type of integrated circuit or discrete component. The xed 5 V / 1A
supply has become an industry standard for powering digital IC’s. Integrated circuits
which require +5 V, +12 V, and -5 V are easily accommodated by the PB-505A. The
variable supply output voltages may be changed by adjusting the knobs at the top on
the front panel. The positive and negative outputs are continuously variable from +1.3
at 150 mA to +15 V 500 mA and -1.3 at 150 mA to -15 V at 500 mA. Both variable
supply outputs are referenced to circuit common. This creates a split supply which is
often used with dierential and operational ampliers (op amps).
In addition to the DC power supplies, the PB-505A also provides a 12.6 volt center-
tapped AC supply. This allows the user to construct any of half-wave and full-wave
rectied power supplies on the breadboarding area and apply power by simply
connecting jumper wires to the three AC supply output jacks.
Digital Function Generator
The multi-waveform digital function generator provides continuously variable
frequency signals from 0.1 Hz (for extra-low frequency work) to radio frequency
signals of 100 kHz. The frequency is selected in two ranges, with a LED screen to
easily view the current settings. The generator can be set in increments of 0.1 Hz
or 0.1 kHz in their respective ranges as desired. The sine wave output is factory
adjusted for minimum distortion. The triangle waveform is adjusted for best linearity.
The standard square wave and TTL level outputs are both set at a 50% duty cycle.
The low output impedance of the sine, square, and triangle waveforms (600 Ω)
assures maximum coupling of the output signal to the device being driven. All outputs
can withstand a continuous short circuit to ground. The signal amplitude can be
adjusted from 0 to 20 Vpp with an open circuit and 0 to 10 Vpp with a 600 Ωload.
Logic Indicators
Sixteen LEDs, eight red and eight green, make up eight Logic Indicators that will
display logic high and low conditions based on either TTL or CMOS thresholds,
selectable by the user. Operating voltage can also be selected by the user to be
either at +5 V, or +1.3 V to 15 V at the setting of the +V supply. This selection should

globalspecialties.com
Global Specialties
13
be the same as the operating circuitry that is to be monitored. The red LEDs will light
when the voltages at the inputs are 2.2 V or higher when in the TTL position, or 70%
of the operating voltage or higher when in the CMOS position. The green LEDs will
light when the voltages at the inputs are 0.8 V or less when in the TTL position, or
30% of the operating voltage or less when in the CMOS position. An unconnected
input, or an input not at a valid logic level, will cause both LEDs to be o. Note that
the thresholds determined by the TTL positions are only accurate when the +5 volt
range is selected. The 100 kΩ input impedance ensures minimal loading eects of
the circuit under test.
Debounced Pushbuttons (Pulsers)
The PB-505A uses clocked ip-ops to provide debounced pushbutton switch
functions. The pushbutton circuitry has open-collector outputs which can sink up
to 250 mA each. This type of debouncing gives the user a sharp, glitch-free trigger
source which assures reliable operation in digital circuits. Each pushbutton has a
normally-open and a normally-closed output. If necessary, a pull-up resistor can
connect any pulser output to any of the positive voltage sources.
Potentiometers
Two potentiometers are provided on the trainer. The resistance values chosen
(1 kΩ and 10 kΩ) may be used in common circuit applications such as volume
controls, DC oset controls for op amps, and timing circuit controls. All leads for both
potentiometers are available and uncommitted.
BNC Connector
The PB-505A may be connected to other pieces of equipment via a BNC connector.
This allows the use of shielded cable to minimize noise and interference.
Switches
Two single pole, double throw (SPDT) switches are provided for general switching
functions. All leads are available and clearly marked on the PB-505A for easy
connection. Eight switches are congured as Logic Switches to provide a convenient
source of digital outputs. These switches will provide logic levels of zero V (ground)
for a logic low, and logic high levels of either +5 V or +1.3 to +15 V at the voltage
setting of the +V supply. The high level is determined by the setting of the +5/+V
switch. This arrangement makes connecting special digital circuitry such as an eight-
bit input port quick and easy, and allows compatibility with virtually any logic family.

14
Global Specialties
globalspecialties.com
451-054-000_rA
Logic Probe
The logic probe is a tool used for checking the boolean states of logic, either 1 or
0. The red “HI” LED lights up for when the logic is high or a 1. The green “LO” LED
lights up when the logic is low or a 0. Mem mode will remember the logic and keep
the corresponding LED lit while in PULSE mode the LEDs will subsequently turn o
after the pulse.
7-Segment Displays
The trainer comes with two BCD to seven segment displays. Each one is labeled for
ease of use for applications such as digital counters. Refer to their respective truth
table to conrm correct circuit connections.
CAUTION Integrated circuits can be destroyed if a voltage is applied to their
inputs that is higher than the operating voltage of the ICs. Always
insure that the setting of the +5/+V high-level switch is in the correct
position before making connections to any device.

globalspecialties.com
Global Specialties
15
Specifications
All specications apply to the unit after a temperature stabilization time of 20 minutes
over an ambient range of 20°C ± 5°C
Description Specication
AC Line Input 115 VAC @ 60Hz or 230 VAC @ 50 Hz (switchable)
Power Supplies
Fixed DC: +5 VDC 1.0 A max, current limited
Ripple <5 mV
Variable DC: +1.3 VDC ±0.05 V @ 150 mA to +15 VDC @ 500 mA
Ripple <5 mV
Variable DC: -1.3 VDC ±0.05 V @ 150 mA to -15 VDC @ 500 mA
Ripple <±5 mV
Fixed AC: - 12.6 VAC center-tapped @ 100 mA
Binding Posts (7) Ground, +5VDC, Variable ±VDC Power Supply Outputs, and AC
Transformer center-tapped output
Pulsers
(2) Pushbutton-operated, open-collector output pulsers. Each with 1
normally-open, 1 normally-closed output. Each output can sink up to
250 mA.
Logic Probe
Detects Logic High, Logic Low and Single Shot events.
Logic High: 2.2V (nominal) in TTL mode, 70% of Vcc in CMOS mode.
Logic Low: 0.8V in TTL mode, 30% of Vcc in CMOS mode.
Memory Mode: Detects single shot events and holds indication until
Pulse/Mem switch is toggled
Digital Function Generator
Frequency Range: 0.1 Hz to 100 kHz in two ranges
Output Voltage: 0 to +10Vpp into 600 Ω Load (20Vpp in open circuit),
short circuit protected
Output Impedance: 600 Ω except TTL
Output waveforms: Sine, Square,Triangle & TTL
Sine Wave Distortion: <3% @ 1 kHz typical
TTL Pulse: Rise & fall time <25 ns, drives 100 TTL Loads
Square Wave: Rise and fall times <0.5 µs

16
Global Specialties
globalspecialties.com
451-054-000_rA
Description Specication
Logic Switches
(8) Logic Switches select Logic High and Logic Low
Logic Low Level: Ground
Logic High Level: Switchable between +5 V and the variable positive
power supplies
Switches (2) Single Pole Double Throw (SPDT) - uncommitted
Logic Indicators
LEDs: 16 LEDs; (8) red to indicate logic high and (8) green to indicate
logic low
Logic High Threshold: 2.2 V (nominal) in TTL/+5 V mode, 70%
(nominal) of selected operating voltage in CMOS mode
Logic Low Threshold: 0.8V (nominal) in TTL/+5 V mode, 30%
(nominal) of selected operating voltage in CMOS mode
Connectors (1) BNC - uncommitted
Potentiometers (2) 1 kΩ and 10 kΩ - uncommitted
Speaker 8 Ω, 0.25 W - uncommitted
Displays (2) BCD to 7-Segment Display Circuits include (2) red LEDs and
decoder/driver circuitry
Breadboards
Removable breadboard Plate (PB-4) with 3360 tie-points with 200
additional bus strip tie-points internally connected to power supply
outputs and ground
Weight 10 lbs
Dimensions 380 mm x 265 mm x 140 mm

globalspecialties.com
Global Specialties
17
Checking out the PB-505A
The PB-505A may be checked out for proper operation by making a few simple
measurements and connections. Begin by connecting the AC line cord to a suitable
receptacle. The two 7-segment displays should light when the power switch is turned
on.
Using a DC voltmeter, check for +5 V between the ground terminal and the +5 volt
terminal. Repeat the measurement for the positive (+) variable supply terminal and
the negative (-) variable supply terminal. Check the variability of each supply by
turning the appropriate adjustment knob.
To test the logic indicators, switch the +5/+V operating voltage switch to the +5
position. The TTL/CMOS threshold switch can be in either position. With no input
to the logic indicators, all LEDs should be turned o. Connect one end of a jumper
wire to the + 5 V terminal and the other end to logic indicator 1; the red LED of logic
indicator 1 should light. Repeat this test for logic indicators 2 through 8. Disconnect
the jumper from the +5 volt terminal and connect it to the ground terminal. Connect
the other end to logic indicator 1; the green LED of logic indicator 1 should light.
Repeat this test for logic indicators 2 through 8.
The digital function generator may be tested by connecting its output to one of the
speaker inputs. Connect the other speaker input to the ground terminal (or one of
the connectors on the ground bus strip). Set the frequency to 60 Hz and select the
square wave. Move the amplitude control upward until you hear a tone coming from
the speaker. Step through any range of frequencies up to 20 kHz (this upper limit
may vary as it depends on the user’s own hearing) and the pitch should change.
Push the waveform buttons to select sine, square, and triangle. A changing but
clearly audible tone should be heard in each position.
If an oscilloscope is available, you may check the digital function generator for proper
waveform and frequency using standard measurement techniques.
The debounced pushbuttons can be checked by connecting one side of a resistor
(20Ω to 100 KΩ) to +5 volts and the other side to PB1-1, the NC point. Then connect
PB1-1 to LED-1 with the Logic Indicator +5/+V switch in the +5 position, the red
LED should light when PB1 is pressed and the green LED should light when PB1

18
Global Specialties
globalspecialties.com
451-054-000_rA
is released. Next, move the connections from PB1-1 to PB1-2, the NO point. Now
the red LED should be lit when PB1 is not pressed, and the green LED should be lit
when PB1 is pressed. Repeat these steps to test PB2.
The logic switches can be tested by connecting the output of logic switches 1 through
8 to the input of logic indicators 1 through 8. Switch the logic switch +5V/+V high
level switch to +5, and switch the logic indicator +5/+V operating voltage switch to
+5. Select the CMOS position on the logic indicator TTL/CMOS threshold select
switch. Now the logic indicators should reect the conditions of the logic switches,
that is, red LEDs will indicate switches in the high (logic “1”) position and green
LEDs will indicate switches in the low (logic “0”) position. Move each switch between
its high and low position to verify proper functioning. Switch the logic switch +5/+V
high level switch to +V and the logic indicator +5/+V operating voltage switch to +V;
the relationship between the switch positions and the logic indicator display should
remain the same, regardless of the setting of the 1.3 - 15 volts +V supply.
By using an ohmmeter, you can check the potentiometers. To do so, select an
appropriate range for measuring 10 kΩ and connect the ohmmeter leads to R1-1
and R1-2. With R1 rotated fully counterclockwise a reading of 0 Ω ohms should be
observed. As the potentiometer is rotated clockwise, the resistance reading will be
seen to increase linearly up to 10 kΩ ± 20%. Now move the ohmmeter lead from
R1-1 to R1-3; with R1 fully clockwise the ohmmeter will read zero ohms, and the
resistance will increase linearly to the full value noted previously as the potentiometer
is rotated counterclockwise. Select an ohmmeter range appropriate for 1 kΩ and
repeat these steps on R2 to verify its function.
To test SPDT switch S9, put S9 in the up position and connect an ohmmeter to S9-1
and S9-2. The ohmmeter should read 0 Ω. When the switch is brought to the down
position, an open circuit should be indicated. Move the ohmmeter lead from S9-1 to
S9-3 and observe a short circuit with S9 down, and an open with S9 up. These steps
can be repeated on S10 to test its functions.
To test the logic probe, connect a wire from Vcc to +5 terminal. Set mem/pulse
switch to pulse and TTL/CMOS switch to TTL. Connect a wire from input to +V
terminal. Connect the multimeter between GND and +V. Turn the +V pot fully counter-
clockwise, read approx. 1.2V on the meter. Slowly turn the +V pot until the HI LED
lights. Read approx. 2.4V on the meter. Set pulse/mem switch to mem. Touch input

globalspecialties.com
Global Specialties
19
lead to ground. Observe low LED lighting and pulse LED lighting and staying on.
Move pulse/ mem switch to pulse and observe pulse LED going out. Move TTL/
CMOS switch to CMOS, reconnect input lead to the +V terminal. With the +V pot fully
counter clockwise, slowly turn the +V pot clockwise until the low LED goes out. Read
approx. 1.6 volts on the DMM. Continue turning the +V pot until the HI LED lights
read approx. 3.5 volts on the DMM.
To test the BCD to 7 segment displays, jumper together pins 1A, 1B, and 1C.
Connect a jumper wire from these points to ground. Connect a second jumper wire
from position 1D to +5V. Observe a number 8 showing on the display.

20
Global Specialties
globalspecialties.com
451-054-000_rA
Breadboarding Techniques
This section contains information which may prove useful when constructing circuits
using the PB-505A. While there are no hard and fast rules for breadboarding, the
following tips may save time and trouble.
Unless a circuit is being prepared for a demonstration or display, avoid cutting
component leads very short. While short wires and leads may look neat, the clipped
components will only t into a limited “span” of connector sockets, limiting the use
of the component. It is perfectly permissible to use untrimmed components while
exploring dierent circuit possibilities. The only time short leads may be necessary
is when operating at higher frequencies and experiencing mysterious malfunctions.
Sometimes the only way to correct high frequency circuit problems is to shorten all
circuit connections.
Be cautious when using components which have been removed from a tape reel
used in automatic insertion equipment. Suppliers of surplus components often sell
components which are taped together in small batches. Removing the components
from the tape does not always remove the adhesive from the leads of the
components. Placing a formerly taped component into a socket connector may result
in a poor electrical connection and, worse still, leave tape adhesive in the socket.
Avoid this problem by either carefully cleaning taped component leads, clipping the
taped portion of the lead o, or avoiding the use of taped components altogether.
Be especially careful when inserting integrated circuits into the breadboard sockets.
Unless the IC pins are straight, it is very easy to crush the pin into a zigzag shape or
fold the pins underneath the body of the IC. Either way the result is a bad connection
or no connection at all.
Always use solid wire for breadboard connections. When stripping the wire ends, be
careful not to strip more than about three-eighths of an inch of insulation from the
wire. Too much bare wire may result in unintentional connections near the wire end.
After you have built up a few circuits, you will have a good collection of pre-stripped
jumper wires. Save them. By reusing these wires, you can save even more time and
eort in assembling future circuits. Pre-formed wires in various sizes are also avail-
able from Global Specialties (please visit web site for available options and accesso-
ries).