Elenco PK101 w- Computer Interface User Manual

CI-22

BASIC ELECTRONIC EXPERIMENTS

with computer interface

Experiments PC1-PC8

Instruction Manual

Elenco Electronics, Inc.

Copyright © 2003 by Elenco Electronics, Inc. All rights reserved. No part of this book shall be reproduced by
any means; electronic, photocopying, or otherwise without written permission from the publisher.

Sample Controls Display

See these Oscilloscope Signals

See these Spectrum Analyzer Signals

Looking at Electronic Signals using the WINSCOPE Software:

Electronics engineers use specialized test equipment to “see” electronic signals and make perform­ance measurements.They use an oscilloscope to look at the waveform of the signal in time and use
a spectrum analyzer to look at its frequency content.This equipment is specialized and usually very
expensive.

The Winscope software simulates this equipment using your personal computer.The PC-interface
cable can be connected across any 2 points in your circuit to look at the signal.

It is usually connected to the output of a circuit, as in the circuits shown for the CI-22.Connect the
plug end of the probe to the microphone input on the back of your personal computer. Run the
Winscope application (from the CI-22 menu). It will come up in Hold mode looking like this:

Click on the On-Line button to turn it on.You should now get one of the following 2 pictures, depend­ing on whether your microphone input is properly turned on:

-2-

WARNING:

SHOCK HAZARD - NEVER connect

the probe to AC power or a wall

electricity outlet for any reason since

serious injury or damage may result.

!

!

If you get the picture on the right then your microphone input is not properly turned on, go to the
“Turning On Your Microphone Input” to tur n it on. There may also be other sound card controls on
your computer that you need to set, when your input is properly configured then you will get a pic­ture like the left one above.Touch the red and black “alligator” clips on the PC-interface cable to
each other and you should see the random pattern on the winscope screen change as you do so.
You are now ready to proceed with the first CI-22 experiment or you may investigate the Winscope
software on your own.

You may freeze a waveform on the screen by
clicking on the Hold mode button
(just to the right of the On-Line button).

WARNING:Do not “save setup” in Winscope.
Many of the buttons on Winscope control features
that this manual will not be using. If you acciden­tally place the Winscope software into an
unknown mode, you may always close and re­start Winscope. Doing so will reset all settings to
those described in this booklet unless you have
done a “save setup”.

PROJECT PC1 SHOWS HOW TO USE THE MAIN FUNCTIONS
OF WINSCOPE SO DO IT FIRST!

NOTES:

1. It is recommended that you disable or turn down the volume to the speakers on your com­puter. CI-22’s use of the microphone input port will also channel the same signal to the
speakers, and the result is often ver y annoying.

2. It is recommended that you be familiar with the PK-101 parts and assembly methods before
building any of the circuits in this manual.

-3-

IMPORTANT NOTE: The designs for the microphone input port vary throughout the computer

industry. Hence you may get waveforms different from those shown in your manual even though the
circuit is actually performing the same way. Here are some types of differences:

A.The gain of your microphone input may be significantly different from that indicated on
pages 8-10 (and similarly for the other circuits). Page 6 describes how to turn on the microphone
input and adjust its volume to about 40% of max, you may want to adjust this volume higher or lower
so that your results better match those shown.Note that having the volume set too high may “clip
off ” the top or bottom portion of a waveform.

B.The oscilloscope waveforms shown on your display may appear upside down (“inverted”)
from those shown throughout this document. For example the waveform shown on the top of page 9
would look like this:

If this is the case then swap the connections of
the red and black clips of the Winscope probe in
all circuits.

C.The shape of waveforms may appear distorted for some circuits, due to protection circuitry
that acts as a filter.For example:

This
waveform

might look
like this.

And this
waveform

might look
like this.

-4-

And this
waveform

might look
like this.

Contact Elenco Electronics if you have any questions about this.

Limitations of Winscope and its interface:

By using the microphone audio input and the flexible processing power of the personal computer,
we have created an inexpensive and easy-to-use way of looking at electronic signals. However, no
electronic oscilloscope or spectrum analyzer ever made works on all electronic signals, and simi­larly Winscope has limitations.The projects in this booklet were written to minimize those limita­tions.

Winscope can only measure changing signals (AC voltages, >20 Hz frequency) and cannot meas­ure fixed voltages (DC voltages, such as a battery), due to the design of the microphone input.
Fixed voltages are not very exciting to look at anyway. Slow-changing or transient signals (such as
when you first turn on power to a circuit) will be displayed in a distorted form.

Winscope works best on signals up to about 5 KHz, since its sampling rate is limited to 44 KHz. If
you attempt to measure signals that are higher than this then you will get wrong results due to
undersampling.This is a narrow range but it covers human voice and most (but not all) music. AM
and FM radio frequencies cannot be measured. Every measurement you make will have some
amount of random “chatter” superimposed on the signal of interest. This chatter is due to the limit­ed sampling rate and from the PC-interface cable picking up energy from other electronic instru­ments in the vicinity (including room lights and your computer), hence it cannot be avoided.

-5-

Using Winscope’s full capabilities:

Winscope has 2 input channels that can be displayed at the same time.This is commonly done by
electronic engineers using an oscilloscope, to show the relationship of one (or more) signals to
another.However use of this requires a second microphone input, which most computers do not
have. If the sound card in your computer has this then you may use all of Winscope features for 2
channels, which include X-Y and correlate modes. Use of these Winscope capabilities is beyond
the introductory level of this product, use the Help menu in Winscope for information about using
these features.

If you have any questions contact:

Elenco Electronics, Inc.

150 W. Carpenter Avenue

Wheeling, IL 60090

[phone]

http://www.elenco.com

e-mail: [e-mail]

-6-

Turning On Your Microphone

(For Windows 98, other Windows versions may be slightly different.)
If you don’t get any signal from the PC-interface cable then your microphone may be disabled on

your computer.To turn it on, follow these instructions which begin by pressing the <Start> button
on the lower-left corner:

1. Select <Start> - <Programs> - <Accessories> - <Enter tainment> (or <Multimedia>) - <Volume
Control>.

2. Select <Options>.

3. Select <Properties>.

4. Select <Recording> in the “Adjust Volume For” box.

5. In the “Show the Following Controls” box, check <Microphone>.

6. Select <OK>.

7. In the “Microphone - Volume” box, check <Select> and set volume to about 40% of max.
Your microphone should now be turned on.

WARNING:

SHOCK HAZARD - NEVER connect

the probe to AC power or a wall

electricity outlet for any reason since

serious injury or damage may result.

!

!

SPEAKER

+9V

S

P

10kΩ

3.3kΩ

473

-7-

Project # Description Page #

PC1 Pitch 7
PC2 Speaker Microphone 13
PC3 Siren PC 15
PC4 Space Gun PC 16

Project # Description Page #

PC5 Electronic Noisemaker PC 18
PC6 Noisy Blinker PC 21
PC7 Electronic Sound PC 23
PC8 Electronic Rain PC 25

PROJECT LISTINGS

Project PC1

OBJECTIVE:To look at the output signal from a transistor oscillator while
changing the pitch of the sound.

Pitch

You will now be introduced to the Winscope features, and thereby become familiar with oscilloscopes
and spectrum analyzers, and see some of the most important concepts in electronics. It is recom­mended that you already be familiar with the parts and assembly methods from the other manual.

Build the circuit shown and connect the PC-interface cable to the microphone input on your computer.
Press the switch and vary the variable resistor. The frequency or pitch of the sound is changed. Run
the Winscope software and be sure your microphone input is configured properly, as described earli­er.Winscope will be used to view the electrical signal to the speaker.

DISC CAPACITOR

473 marking = .047µF

Click on the On-Line button if Winscope is currently in Hold mode and you should get a picture simi­lar to this one:

The waveform peak is off the top of the screen because the scope gain (amplification) is set too
high.You may adjust this gain by moving the Y1 gain control around (try it).

Similarly, you may adjust the position of the waveform on the screen by moving the Y1 position con­trol around (try it).

Now click on the 1:1 button to set the gain to x1 and disable the Y1 controls.You should now have a
picture similar to this one:

Note that your picture may not
exactly match this picture due to
variances in the microphone input
gain between computers, which is
beyond software control.You may
want to adjust the volume control
of your microphone input to com­pensate, see note A on page 6
for more details.You may also dis­able 1:1 mode by clicking on its
button again and then adjust the
gain using the Y1 control.

The gain and position control features just described enable electronics engineers and technicians
to “see” the amplitude (voltage level) of a signal.By adjusting the settings on an oscilloscope, they
can look at both very large and very small voltage waveforms.

-8-

Move the variable resistor knob and watch how it changes the waveform on the computer screen.
Now click on the 0.5ms/div button to change the time scale on the display. (The button to the left of it
is for 5ms/div, the default.) Move the variable resistor knob around again.You may click on the Hold
button to freeze the waveform on the screen, then click on On-Line to re-start.

With the time scale at 0.5ms/div
and the adjustable resistor set for
middle position, you should now
have a picture similar to this one.

Your picture may appear different
due to variations in the micro­phone input designs between
computers. Although this is
beyond software control, in some
cases you may be able compen­sate externally. See notes B and
C on page 4 for details.

Notice that the waveform seems to be randomly dancing across the screen, making it hard to study.
We can fix this.Click on the “trigger positive level” button and make sure the trigger bar is in the
position shown here. Notice that a small “-” appears on the left of the display as you do so.

The small slash “-” represents the
trigger voltage, when the signal
reaches this voltage level it acti­vates the display.This makes it
easy to observe a stream of puls­es like you have now, and also to
record a single (non-repeating)
pulse.

Move the variable resistor control
and watch how it changes the
waveform on the computer
screen. Now you can see how
changing the variable resistor
changes the time between the
pulses, which changes the tone of
the sound you hear.

The waveform you see here is the voltage across the speaker, the peaks of the pulses occur when
the transistors turn on and provide current to the speaker. Changing the amplitude of the peaks
changes the loudness of the sound, changing their separation changes the tone or “pitch” of the
sound.The time scale and tr igger control features just described enable electronics engineers and
technicians to see the relationship between parts of a waveform on their oscilloscope.

-9-