TELECOMMUNICATION ELECTRONICS
USE OF SOLDERLESS BREADBOARDS
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Using solderless breadboards
This document describes how to use the solderless breadboards available in the experimental
didactic lab (LED, previously LADISPE) of Politecnico di Torino.
1 Setting up the circuit
Each student team must come into the lab with the completed design of the circuit to be tested.
That includes schematic diagram, part list, and sequence of measurements. After verifying the
workbench arrangment, one person for each team must pick from the lab store all the devices
required for the circuit.
Warnings:
- Parts placement can be wrong; verify the value of passive devices and the type of active
devices (colr codes, labels, ….);
- faulty devices, or with wires too short, twisted, are not good for the boards and should
not be used; they must be returned to lab personel;
- the wires (and device pins) inserted in the solderless boards must have 0,5-0,7 mm
diameter (small resistors and capacitors); large wires damage the board contact
springs.
When the exercise is completed, all parts must be placed back in the correct store place. Faulty
ones must be returned to lab personel.
Passive devices available in the lab store:
•
•
•
•
•
•
carbon or metal fim resistors ¼ W, 5 %, according to E12 sequence;
various types of capacitors in the range 10 pF-1 µF (ceramic, multilayer ceramic, plastic film),
with tolerance 10 or 20 %, according to E6 sequence (with some value from E12);
electrolytic capacitors from 1 to 200 µF, tolerance 20 or 40 %;
variable resistors and potentiometers of more common values (range 100 ohm – 1 Mohm)
switches and LEDs (including a small PCB with 8 switch-LED pairs), for logic states sensing
and forcing;
active devices as required by specific experiments.
The design must uses passive device as above.
E6 (6 values/decade):
1, 1.5, 2.2, 3.3, 4.7, 6.8,
E12 (12 values/decade):
1, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2
All the components here described are with lead, since they must be used on the lab solderless
breadboards. Modern PCBs use extensively leadless Surface Mount Devices, not described
here, and not available in the lab.
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TELECOMMUNICATION ELECTRONICS
USE OF SOLDERLESS BREADBOARDS
Page 2 of 9
Reading the value of passive devices
The value of passive devices (resistor, capacitor) is expressed by printed numbers or colorcoded strips.
First digit
Second digit
RESISTOR
473
First digit
Decimal
multiplier
Tolerance
Second digit
Decimal
multiplier
CAPACITOR
The color strips or the printed digits represent, from left in the drawing
•
•
•
•
•
first significan digit
second significant digit
(third significant digit – only for high precision devices, with 5 strips)
multiplier (power of 10)
tolerance (resistors and a few capacitors)
Capacitor often carry also other information, such as voltage rating and dielectric type.
Value of resistors is in ohm, for capacitors can be pF or nF
Color Code:
black
brown
red
orange
yellow
green
blue
violet
grey
white
0
1
2
3
4
5
6
7
8
9
for the tolerance strip:
nothing
silver
gold
red
black
20%
10%
5%
2%
1%
other colors represent more tight tolerances (not used in the lab)
Warning:
it is not possible to “build” nonstandard values with parallel of series of two or more devices.
Tolerances make the total uncertainty as wide as the difference betweed adjacent values.
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USE OF SOLDERLESS BREADBOARDS
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The various types of capacitors have different features and behavior. The proper capacitor type
must be selected for each application; some hints are in the following. To provide information on
size, each photo shows a ruler with marks at 1 mm intervals.
Multilayer ceramic capacitors
the value is specified by three digits, with
meaning similar to color bands. These capacitors
have small size and good performance at high
frequency (if the leads are kept short !), but poor
precision (20 % for higher values). Best for
power supply bypass. With proper dielectric,
good also for RF circuits.
Plastic film capacitors
They have good precision, but should be used only
in low frequency circuits (up to a few MHz).
Electrolytic capacitors
The dielectric is a thin chemical layer, which is created by proper biasing; therefore these
capacitors require applied voltage (DC+AC) to have a specific sign. High values with small size,
but quite low precision (+50 - 20 %); used in power supply and audio frequency.
examples of tantalium capacitors
(good also at high frequency)
Examples of aluminium electrolytic capacitors
Remember alto that any capacitor has a maximum working voltage. The value use in lab
experiments are well tolerated by ceramic and plastic film devices, but must be verified for
electrolytic capacitors.
Warning:
an electrolytic capacitor with inverted polarization heats quickly and may explode.
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TELECOMMUNICATION ELECTRONICS
USE OF SOLDERLESS BREADBOARDS
Page 4 of 9
2 Setup of the solderless wiring breadboards
Solderless boards
The boards for
circuit assembly
include:
•
single-wire
conncetions
(banana), to
be used for
power supply
or other DC.
•
coaxial
connectrs
(BNC), to be
used for AC
signals.
Single-wire
connection
(banana plugs)
Coaxial
connections
(BNC)
Wiring posts
connectrd to
BNCs
BNCs are connected to wiring post connection, Black is the Ground, and Red the signal. Some
boards have three BNC connector, and a different connection scheme to wiring posts. Verify the
acual wiring on the bottom side of the board.
3 Solderless boards connections.
Interconnections inside the board use cantiliver springs contacts inside each hole of the
breadboard (shown by horizontal or vertical dashed lines in the drawing).
Any wire plugged in the hole is automatically connected with the other ones inserted in holes
connected by the dashed lines in the drawing.
To avoid fake contacts and othe malfunctoning, always check the wire segmant plugged into the
board: it must be straigth, clean, and of proper length (5 to 10 mm). Do not use oxidized, twisted,
or too large wires; in such cases cut the wire and use a new segmant.
Avoid also too thin wires, and be carefull to avoid insertion of insulated segments (remove at
least 10mm of insulator at each end of wires).
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USE OF SOLDERLESS BREADBOARDS
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4 Map of internal boad connections
Preferred position
for supply voltages
Conduction break
in orizontal bars
+ 12/15 V
+5V
Conduction
break
in vertical
bars
GND
- 12/15
The drawing shows the connections among wire inserting holes. These connection can be
grouped as:
•
•
four orizontal bus bars (with a break at the center), suitable for power and ground;
two groups of vertical bars, suitable for mounting various type of devices.
5 Dual-in-line packages
Most active devices (ICs) available in the lab use Dual-In-Line (DIL or DIP) package, with pin
numbering as in the drawing.
Package (plastic)
Dot or mark
Reference
tab
pin N
2
N-1
3
pin 1
Pin 1 is marked by a
dot or a tab on the
package
Looking at the device from top, numbering runs counterclockwise.
In metal case transistors (TO5 and TO18) the package tab indicates Emitter.
For any other information, refer to device data sheet.
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USE OF SOLDERLESS BREADBOARDS
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6 Circuit assembly
Preferred position
for supply voltages
Conduction break
in orizontal bars
+ 12/15 V
+5V
GND
- 12/15 V
Analyze the circuit assembly, and place parts to reflect, to a reasonable extent, the positions in
the electric diagram.
To ease assembly and verification, all IC must be placed in the same direction (e.g. with pin 1
towards bottom left). For Op. Amp. use single-amplifier 8-pin Ics (more easy to assembly than
dual and quad devices).
For complex circuits build and test separate stages or parts, then connect each other.
For high-frequency and/or high speed circuits, place bypass capacitors between supply and
ground: 10-100 nF (ceramic multilayer), place as close as possible to Vcc/GND pins.
7 Connections
Preferred position
for supply voltages
Jumpers to bring +5 V and
GND to the right side bus
bars.
+ 12/15 V
+5V
GND
- 12/15 V
•
•
•
Use only the wires provided with the board.
Connections should be direct and short.
To power circuits in the right part of the board, place jumpers on the orizontal bars.
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TELECOMMUNICATION ELECTRONICS
USE OF SOLDERLESS BREADBOARDS
Page 7 of 9
The photo shows an example of really good wiring:
The same circuit here is still acceptable (wires are slightly longer, components are not
shortened).
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USE OF SOLDERLESS BREADBOARDS
Page 8 of 9
8 What you should avoid
Missing 5V connection
to the right side
Supply voltages in
wrong position
- 12 V
+5V
GND
+ 12/15 V
Multiple chain
connection
Long
wires
Devices mounted across the
same bus bar (short circuited).
Use the horizontal connections only for power supply or ground (no signal); keep the polarity
assignement proposed in the drawings.
Do not use multiple jumps (chain connection), and keep wires short. This applies expecially for
high frequency connections, for wires carrying low-leve signals, for high impedance nets (e.g.
Op Amp input pins), ground and power supply.
The following illustration is a collection of what not to do: long and crossed wires, chain
connections on ground and power, …
The very high impedance of CMOS inputs brings open (input) pins to an unpredictable voltage
level, depending from external electric fields. Besides wrong operation, this may cause damage
to ICs (digital inputs are forced in the linear region, with high power dissipation).
Therefore, never leave CMOS input pins open.
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TELECOMMUNICATION ELECTRONICS
USE OF SOLDERLESS BREADBOARDS
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