RF CIRCUITS TSC Department UPC

Evolutionary

Breadboard A Portable Electronics Lab

A portable electronics lab is presented.It is built around an EVOLUTIONARY PROTOBOARD powered from a computer

USB port.This protoboard is mounted over a plastic plane wich facilitates the setup of experimental circuits

1

EVOLUTIONARY BREADBOARD:

A Mobile and Portable Electronic Laboratory

José M. Miguel

RF ELECTRONICS LAB

TSC-UPC CAMPUS NORD

BARCELONA SPAIN

jmiguel@tsc.upc.edu

Abstract: A portable electronics lab is presented.It is built around an evolutionary protoboard powered from a computer

USB port.The protoboard is mounted over a ground plane which facilitates the setup of experiments

Keywords: Portable lab,Electronics lab,Protoboard,Virtual instrumentation

1.Introduction

There`s growing momentum and interest in increasing the

number of students focused on science and information

technology.This kind of students along with radio and elec-

tronics amateurs need hands-on circuitry labs.A conven-

tionally equipped electronic lab is costly and sometimes

only can be used during school hour or session.It is well

known that the real amateur needs his lab available 24 hours

a day.

In this paper,we present a different approach with what we

called a “Portable lab” a complete electronics lab that`s

low cost,minimalist and flexible.It consists of a “Evolu-

tionary breadboard” ,a tester and a laptop or a PC which

provides 5V DC power supply from its USB ports and

virtual instruments like function generators or frequency

meters that run around the sound card of the laptop.

With this lab every student or electronics amateur gets his

setup and tackes individual projects.

2. The classical breadboard

Solderless breadboard are great units for making tempo-

rary circuits and prototyping.Another common use is test-

ing out new parts such as Integrated Circuits

(ICs).Electronic engineers and others scientific people love

breadboards because ease carry out the proof of concept.In

this way they can verify that some circuit idea has the

potential to being used in their designs.

Figure 1. Classical breadboard [1]

A classical breadboard it is shown in figure 1.It consists

of a metallic plate,some binding posts and the most im-

portant, a solderless plastic unit that it is bonded to the plate

by using some screws.The solderless has sets of holes into

which wires can be inserted.Inside each hole,invisible to

you,is a metallic socket appropriate for snugly receiving a

wire pushed into the hole.

Sets of sockets,arranged in rows and columns,are con-

nected together internally as it is shown in figure 2.

Figure 2.Electrical connections in rows and columns of a solderless boar

You plug the wire leads of the components into the

holes to connect them to one another without soldering

2 José M. Miguel

them.The metal plate is painted and therefore the binding

posts are electrically isolated.They are used to connect the

benchtop power supply from two banana cables as it is

shown in Figure 2.Another option is just plug the wires

from a barrel jack or from a 9V battery holder as it is

shown in Figure 3.

Figure 3. A breadboard being powered trough the binding posts from

banana cable [1]

Figure 4.The jack is soldered to two wires that shares the same holes on

the binding pots as the wires going to the power rails of the breadboard[1]

3. The evolutionary breadboard

Figure 5.The evolutionary breadboard

In this section we are going to present an evolutionary

breadboard with better usability than the classical one.In

fact,it can be considered as a portable electronic laboratory

when it is used in conjunction with a multimeter and PC

sound card based virtual instruments.

The new breadboard as it is shown in figure 4. Uses a

PCB as a support plate and incorporates a USB socket that

pulls 5V DC from your computer’s USB port or from an

USB wall charger like the shown in figure 6..Alternatively

you can use the barrel jack or the two female banana con-

nectors to DC supply yours circuits with 9 or 12 volts

The metal side of the PCB plays an important role in the

operation mode of this protoboard.It is used as

ground.The -5V negative terminal of the USB socket,the

sleeves of the female BNC connectors,the black binding

post, the metal case of the audio jacks and the negative

terminal of the external DC power jack are all of them sol-

dered to that ground plane

Figure 6. USB wall charger

One of the botton rails of the solderless board is also con-

nected to ground.Finally the two top rails of the solderless

board are connected to +5V and +external DC respective-

ly.This arrangement gives a lot of easy access to power and

ground in the prototyping space.

The red and black binding pots located at the top right

cornet are used to connect the test leads of a voltmeter.The

red pot is rear connected to a litle black post which is glued

to the solderless board.You can insert a wire in that post

and measure any voltage in the circuit as it is shown in

figure 7.

3

Figure 7. How to measure a voltage using a tester

The assembled circuit is a LED and a series cur-

rent-limiting resistor connected from +5v to ground.It is

important to quote that you don`t need an extra wire con-

necting the black banana plug to the ground of the cir-

cui.That is the function carried out by the rear ground plane

of this evolutionary breadboard.

There are two audio jacks in the breadboard.One of

them that can be used to pull a voltage from the headphone

output of the sound card to the circuit that you are test-

ing.The other audio jack is used to establish connection

from the breadboard to the line input of the sound

card.Standart PC multimedia audio facilities offer much

under-utilised potential for scientific and amateur pro-

jects.In Ref`[2] W.A.Steer presents a ready- to- run sound

card- based software frequency-counter, a real–time spec-

trum analyser and a sinewave signal generator,all for use at

frequencies up to 20KHz.(See figures 8,9 and10)

Figure 8. A sound card based frequency meter

Figure 9.A FFT based spectrum analyzer

That voltage can be produced by means a software that

Figure 10.A sound card based generator

It is not advisable to use oscilloscopes based on the

sound card because they have its inputs ac coupled.So any

DC component of the voltage input can`t be displayed.

If you need to test your circuit with an oscilloscope,an

interesting option is the Educational PC Oscilloscope Kit

from Velleman [3].It costs less than 40€,has a bandwidth

from DC to 200KHz and an input range from 100mV to

5V/Div.It needs a USB port and runs under Windows.In

figure 11 you can see this equipment that also works as

transient recorder and spectrum analyzer.

4 José M. Miguel

Figure 11.Educational PC Oscilloscope Kit from Velleman

Model EDU09

If you need a better oscilloscope,Picotech [4] has a great

variety.One of the Picoscope 2000 series can be an excel-

lent option.The evolutionary breadboard has two BNC

sockets to push the signals to the Picoscope inputs as you

can see in figure 12.

Figure 12. The Portable Lab with a PicoScope 2204 and the virtual signal

generator “Generatosaur”

Figure 13.Testing a breadboarded circuit with BasicDSP [5]

4.The Portable Lab

The portable lab provides all you need to set up elec-

tronic circuits.It can be used anywhere and only needs a PC

or laptop with USB connection.

The list of items required consists of:

1-An evolutionary protoboard (see figure 5)

2-A multimeter

3-A little box with compartments for store electronics

devices,resistors,capacitors,ICs,wire jumpers etc.

4-A case for storing tools

5-A case for storing cables (Banana-Banana,Audio)

6-A USB wall charger if you work without PC

7-An oscilloscope like Vellemam EDU09 (Kit)

The complete portable lab it is shown in figure 14.

Figure14. The complete portable lab

5

The portable lab can be carried easily inside a briefcase

or iven better inside a cool shoulder bag or a backpack.

Figure 15. The portable lab in a shoulder bag

REFERENCES

[1] How to use a breadboard.

Tutorial Sparkfunk

[2] Sound Card Audio Tools

W.A. Steer

[3] Velleman EDU09

Educational PC oscilloscope

[4] Pico Technology

[5] BasicDSP

[6] COPYBIT

6 José M. Miguel