Elenco AutoScan Fm Radio Kit User Manual

AUTO-SCAN FM RADIO KIT

MODEL FM-88K

Assembly and Instruction Manual

ELENCO

®

Copyright © 2011 by ELENCO®All rights reserved. 753050

No part of this book shall be reproduced by any means; electronic, photocopying, or otherwise without written permission from the publisher.

ELENCO

®

150 Carpenter Avenue

Wheeling, IL 60090

[phone]

Website: www.elenco.com

e-mail: [e-mail]

To see our complete line of Educational Products

go to WWW.ELENCO.COM

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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

®

(address/phone/e-mail 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 Value Color Code Part #

r 1 R5 10Ω 5% 1/4W brown-black-black-gold 121000
r 1 R1 680Ω 5% 1/4W blue-gray-brown-gold 136800
r 1 R3 5.6kΩ 5% 1/4W green-blue-red-gold 145600
r 1 R4 10kΩ 5% 1/4W brown-black-orange-gold 151000
r 1 R2 18kΩ 5% 1/4W brown-gray-orange-gold 151800
r 1 R6/S3 Potentiometer 50kΩ & switch w/ nut & washer 192522

CAPACITORS

Qty. Symbol Value Description Part #

r 1 C6 33pF Discap (33) 213317
r 1 C7 82pF Discap (82) 218210
r 1 C10 180pF Discap (181 or 180) 221810
r 1 C5 220pF Discap (221 or 220) 222210
r 1 C8 330pF Discap (331 or 330) 223317
r 1 C4 470pF Discap (471 or 470) 224717
r 1 C13 680pF Discap (681 or 680) 226880
r 1 C23 1500pF Discap (152) 231516
r 2 C11, C12 3300pF Discap (332) 233310
r 1 C15 0.033μF Discap (333) 243318
r 1 C19 0.047μF Discap (473) 244780
r 6 C3, C9, C14, C16, C17, C* 0.1μF Discap (104) 251010
r 2 C21, C22 10μF Electrolytic radial 271044
r 1 C20 22μF Electrolytic radial 272244
r 1 C1 100μF Electrolytic radial 281044
r 2 C2, C18 220μF Electrolytic radial 282244

COILS

Qty. Symbol Value Description Part #

r 1 L2 Coil 4-turn 430150
r 1 L1 Coil 6-turn 430160

SEMICONDUCTORS

Qty. Symbol Value Description Part #

r 1 D1 BB909/BB910 Varactor 310909
r 1 D2 1N4001 Semiconductor silicon diode 314001
r 1 D3 Red LED 3mm 350003
r 1 U2 LM-386 or identical Low voltage audio power amplifier 330386
r 1 U1 TDA7088T or identical FM receiver SM installed on PC board

MISCELLANEOUS

Qty. Description Part #

r 1 Antenna FM 484005
r 1

PC board w/ installed U1 (TDA7088T)

517038

r 2 Push button switch 12mm 540005
r 1 Battery holder 590096
r 1 Speaker 8Ω 590102
r 1 Cap push button switch yellow 622001
r 1 Cap push button switch red 622007
r 1 Knob pot / switch 622050

Qty. Description Part #

r 1 Screw M1.8 x 7.5mm 641100
r 2 Antenna screw M2 x 5mm 643148
r 1 Nut M1.8 644210
r 1 Socket IC 8-pin 664008
r 1 Speaker pad 780128
r 3” Wire 22 ga. solid 834012
r 1 Solder Lead-free 9LF99

RF Radio Frequency.

Sensitivity The ability of a receiver to pick

up low-amplitude signals.

Speaker An electronic device that turn

electric impulses into sound.

Surface-mount A method of using special
Technology components that are soldered

to the PC board’s surface.

Trimmer An adjustable fine-tuning

resistor, capacitor, or inductor of
small values.

Transistor A semiconductor component

that can be used to amplify
signals, or as electronic
switches.

Varactor A diode optimized to vary its

internal capacitance with a
change in its reverse bias
voltage.

Voltage Electrical potential difference

measured in volts.

Voltage Regulator A circuit that holds the DC

voltage.

GLOSSARY (Continued)

QUIZ

INSTRUCTIONS: Complete the following examination, check your answers carefully.

1. The number of cycles produced per second by a source
of sound is called the . . .

r A) amplitude.
r B) vibration.
r C) sound wave.
r D) frequency.

2. The frequency of the modulating signal determines the
. . .

r A) number of times the frequency of the carrier

changes per second.

r B) maximum deviation of the FM carrier.
r C) maximum frequency swing of the FM carrier.
r D) amount of amplitude change of the FM

carrier.

3. The FM broadcast band is . . .

r A) 550 – 1,600kHz.
r B) 10.7MHz.
r C) 88 – 108MHz.
r D) 98.7 – 118.7MHz.

4. The AFC circuit is used to . . .

r A) automatically hold the local oscillator on

frequency.

r B) maintain constant gain in the receiver to

prevent such things as fading.

r C) prevent amplitude variations of the FM

carrier.

r D) automatically control the audio frequencies

in the receiver.

5. The device most often used for changing the local
oscillator frequency with the AFC voltage is a . . .

r A) feedthrough capacitor.
r B) variable inductor.
r C) varactor.
r D) trimmer capacitor.

6. The capacitance of the varactor is determined by . . .

r A) the voltage level.
r B) the amount of current in the circuit.
r C) the signal strength of the RF carrier.
r D) the amount of resistance in the circuit.

7. The ability to select a specific band of frequencies,
while rejecting others, is called . . .

r A) selectivity.
r B) sensitivity.
r C) demodulation.
r D) none of the above.

8. The process of mixing two signals to produce a third
signal is called . . .

r A) filtering.
r B) detecting.
r C) rectification.
r D) heterodyning.

9. The circuit designed to supply substantial power output
into low impedance load is called . . .

r A) power supply.
r B) pre-amplifier.
r C) power amplifier.
r D) detector.

10.The gain of the LM-386 amplifier can be set in range
from . . .

r A) 1 to 20.
r B) 20 to 200.
r C) 0 to 200.
r D) 50 to 100.

Answers: 1. D, 2. A, 3. C, 4. A, 5. C, 6. A, 7. C, 8. D, 9. C, 10. B

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1. One of the most frequently occurring problems is
poor solder connections.

r a) Tug slightly on all parts to make sure that

they are indeed soldered.

r b) All solder connections should be shiny.

Resolder any that are not.

r c) Solder should flow into a smooth puddle

rather than a round ball. Resolder any
connection that has formed into a ball.

r 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.

2. Use a fresh 9V battery.

3. Make sure that all of the parts are placed in their
correct positions. Check if the IC, diode and lytic
orientations are correct.

AGC Automatic Gain Control.

AF Audio Frequency

AM Amplitude Modulation

Amplifier Converts input signal to output.

Anode The positive terminal of a diode.

Antenna Any device that either radiates

a signal or pulls in a signal.

Baffle Used to ensure positive airflow.

Bandwidth

The amount of frequency
spectrum, in hertz, utilized by a
filter or channel.

Bypass Capacitor

A capacitor used to shunt AC
around a component.

Capacitor An electronic component that

has ability to store a charge and
block DC current.

Cathode The negative terminal of a

diode.

Coil A component with inductive

reactance.

Current Transport of electrons

throughout a conductor and
measured in amps.

Detector Circuit Receiver circuit that recovers

the modulated portion of the
signal impressed on the RF
carrier wave.

Diode An electronic component that

changes alternating current to
direct current.

FM Frequency Modulation.

Frequency Wave or pulse repetition rate.

Gain Signal multiplication.

IC Integrated Circuit.

LED Light Emitting Diode. A

semiconductor device that
emits light when voltage and
current are passed through it.

PC Board Printed Circuit Board.

Potentiometer Three-terminal variable resistor,

volume control.

Power Supply An electronic circuit that

produces the necessary power
for another circuit.

Resistor An electronic component that

obstructs (resists) the flow of
electricity.

GLOSSARY

TROUBLESHOOTING

Contact ELENCO®if you have any problems. DO NOT contact your place of purchase as they will not be able
to help you.

PARTS IDENTIFICATION

SEMICONDUCTORS

FM antenna

50kΩ Potentiometer

and switch

Discap

Electrolytic

radial

Battery holder

Screw

M1.8 x 7.5mm

Speaker pad

CAPACITORS

LED

RESISTORS

LM-386

IC Socket

Diode

MISCELLANEOUS

Resistor

COILS

Speaker

PC board

Knob (pot / switch)

Cap push button

switch

Push button switch

Screw

M2 x 5mm

Nut M1.8

6-turn

4-turn

Varactor

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