Elenco Radio Controlled Car Soldering User Manual

RADIO CONTROLLED CAR KIT

MODEL RCC-7K

ight © 2005, 2001 b

yr

Cop

t of this book shall be reproduced b

No par

Instruction & Assembly Manual

Elenco®Electronics, Inc.

y Elenco

®

Electronics

y means;

y an

, Inc.

electronic

ights reser

All r

, photocopying, or otherwise without written permission from the publisher.

ved. Revised 2005 REV-I 753288-I

PARTS LIST

C

ontact Elenco

as they will not be able to help you.

®

E

lectronicsif any parts are missing or damaged. DONO

T c

ontact your place of purchase

CARD 1 - RESISTORS (in Bag 2)

Qty. Symbol Value Marking Part #

1 R11 68Ω 5% 1/4W blue-gray-black-gold 126800
5 R12, R17, R18, R19, R20 100Ω 5% 1/4W brown-black-brown-gold 131000
1 R5 200Ω 5% 1/4W red-black-brown-gold 132000
2 R1, R21 560Ω 5% 1/4W green-blue-brown-gold 135600
2 R13, R14 1kΩ 5% 1/4W brown-black-red-gold 141000
2 R15, R16 1.5kΩ 5% 1/4W brown-green-red-gold 141500
1 R10 2.7kΩ 5% 1/4W red-violet-red-gold 142700
2 R4, R8 3.3kΩ 5% 1/4W orange-orange-red-gold 143300
2 R2, R3 22kΩ 5% 1/4W red-red-orange-gold 152200
1 R9 200kΩ 5% 1/4W red-black-yellow-gold 162000
2 R6, R7 3.9MΩ 5% 1/4W orange-white-green-gold 173900

CARD 2 - CAPACITORS (in Bag 2)

Qty. Symbol Type Value Marking Part #

1 C1
2 C2, C3 Ceramic 27pF 27 213010
1 C8 Ceramic 500pF 501 225080
1 C11
1 C4 Ceramic or Mylar 3300pF 332 233310
2 C9, C10 Ceramic or Mylar 0.01µF 103 241031
1 C7
1 C5 Electrolytic 4.7µF 50V 4.7µF 264747
4 C6, C12, Electrolytic 220µF 10V 220µF 282244

C13, C14

Ceramic 10pF 10 211011

Ceramic or Mylar

Ceramic or Mylar 0.1

2200pF 222 232217

µF 104

251017

CARD 2 - INDUCTORS & DIODES

. Symbol Type Value Part #

Qty

1 L2 Inductor 8.2µH (gray-red-gold-silver) 6RCC7K02E

D1 or D2 Zener Diode 3.0V (usually marked 3.0B2 or 3.6B1) 6RCC7K41

1

BAG 1 - PCB & SEMICONDUCTORS (6RCC7KB1E)

Qty. Symbol Description Part #

1 IC1 IC SCRX2BC 6RCC7K01E
1 IC1 IC socket, 16-pin 664016
1 T1 9 Turn inductor 6RCC7K03E

ransistor S8050, NPN 6RCC7K04

Q7, Q8, Q13, Q14

4
4 Q5, Q6, Q11, Q12 Transistor S8550, PNP 6RCC7K05
4 Q2, Q3, Q9, Q10 Transistor 9014, NPN 6RCC7K06E
1 Q1 Transistor C945, NPN 6RCC7K07E
1 - Printed Circuit Board 6RCC7K10E

T

-1-

BAG 3 - SCREWS (6AK870B1E)

Qty. Description Part #

5 Screws 0.4” x 0.1” (10mm x 2.6mm) 640101
4 Screws 0.3” x 0.1” (8mm x 2.6mm), 0.15” head 640102
3 Screws 0.3” x 0.1” (8mm x 2.6mm), 0.2” head 640102E

ou may have been given different screws from

Y
those specified here (and usually some spares).

ontact Elenco

C

®

f it is not clear which to use.

i

BAG 4 - HARDWARE (6RCC7KB4E)

Qty. Description Part #

2 Rear Springs 680023
1 Front Spring 680024
2 Shock Absorber Springs 680025
1 Rear Rod 0.8” x 0.075” 610808

(20mm x 2mm)
1 Steering Alignment Wire/Spring 6RCC7K11
2 Front Wheel Bars 6RCC7K12E
1 Battery Contact, + 6RCC7K13E
1 Battery Contact, – 6RCC7K14E
2 Battery Contact, + – 6RCC7K15E
1 Battery Contact, – + 6RCC7K16E
1 Switch, on/off 6RCC7K18E
1 Rear Axle 662019E1
1 Transmitter Antenna 484010E

BAG 5 - WIRES (6RCC7KB5E)

Qty. Description Part #

1 Light Bulb, with wires attached 6RCC7K21
1 4” wire

, red
1 4” wire, blue 6RCC7K23
1 4” wire, black 6RCC7K24

, green

1 4”

wire
1 4” wire, yellow 6RCC7K26
1 4” wire, orange 6RCC7K27

, white 6RCC7K29

1 4”

wire
1 Solder Roll 6RCC7K30

6RCC7K22

6RCC7K25

BAG 7 - GEARS (6RCC7KB7E)

Qty. Description Part #

2 Locators for Rear Wheels 626019E3
2 Turning Posts for Front Wheels 6RCC7K34E
1 Steering Alignment Post 6RCC7K36E
1 Gear, Rear Wheels Axle 626019E4
1 Steering Motor Bracket 626018E2
1 Gear, middle of rear section 610809

BAG 8 - MOTORS (6RCC7KB8E)

Qty. Description Part #

1 Driving Motor (larger) 6RCC7K39
1 Steering Motor (smaller) 6RCC7K40E
1 0.01µF Disc Capacitors 241031
1 0.1µF Disc Capacitors 251010
2 Motor Gear 6RCC7K37

PACKAGED SEPARATELY

Qty. Description Part #

1 Bottom Frame 6RCC7K42E
1 Top Frame 6AK870TFE
1 Car Antenna 484011E
1 Remote Control Transmitter, 6AK870TAE

Assembled Except for Antenna

1 Decorative Decals (1 Sheet) 720063E

BAG 6 - COVERS (6RCC7KB6E)

Qty. Description Part #

1 Front Section Cover 626018E1
1 Rear Section Cover 626019E

Steering Bar 626023E

1
1 Battery Cover 6RCC7K31E
2 Front Wheels 6RCC7K43E
2 Rear Wheels 626019E2
1 Top Light Bulb Cover 626022

standard (carbon-zinc), or rechargeable (nickel-cadmium) batteries.

Caution:

Do not mix alkaline

,

-2-

Important Note:

There is only one operating frequency for this kit
(27MHz). If you have several units then each
transmitter can control every car. You may
purchase a conversion kit to change the

ating frequency to 49MHz, use the order

oper

orm on page 34. This conversion requires

f
replacing 14 par
comes pre-assembled here) and 7 part
substitutions on the car circuit board (that you
will assemble here).

ts in the transmitter (which

INTRODUCTION

The RCC-7K is a radio-controlled car that you put together. It has 7 control functions: forward, forward-left,
forward-right, backward, backward-left, backward-right, and stop. The remote control operates at a frequency
of 27.9MHz. It uses 4 AA batteries and one 9V battery (not included). It takes about 7 hours to build.

Assembly of the RCC-7K will prove to be an exciting project and give much satisfaction and personal
achievement. If you have experience in soldering and wiring technique, you should have no problems. For the
beginner, care must be taken in identifying the proper components and in good soldering habits. Above all, take
your time and follow the easy step-by-step instructions. Remember, “An ounce of prevention is worth a pound
of cure”.

THEORY OF OPERATION

Remote Control Transmitter: (refer to the schematics and block diagram on p.31 as needed)

When the levers in the Remote Control Unit are pushed electrical contacts are made connecting the 9V battery
power to the transmitter and indicating which commands the user wants sent to the car. Forwards/Backwards
and Left/Right commands are controlled by different levers and use different sets of electrical contacts that are
used to encode a sequence of electrical pulses; the number of pulses depends on which command is being
sent. On some models Left/Right commands are only sent if Forwards/Backwards commands are also being
sent, since there is too much friction to turn the wheels unless the car is moving.

An electrical circuit that is tuned to a frequency of 27.9MHz creates a signal that is sent to the antenna when
the pulses are activ
energy bursts, which travel through the air to be picked up by and understood by the radio receiver in the car.
The frequency of 27.9MHz was selected for RCC-7K with the approval of the FCC (the US government) to
minimize radio interf

e. The antenna converts this electrical energy into radio energy, creating a stream of radio

erence between this product and all other electrical products.

Transmit Signals

Pulse Sequence

•••

27.9MHz Signal

•••

Transmitted Signal

•••

Characteristics of Radio Reception:

y factors affect the ability of the RCC-7K to receive commands from its Remote Control Transmitter. A weak

Man
battery in the Transmitter will result in a weaker transmitted signal; if the battery is very weak then the Transmitter
may not function at all. The Transmitter’s ability to convert electrical energy to radio energy is best when its
antenna is fully extended and degrades as the antenna length is reduced; the same thing also applies to the car
antenna’s ability to convert the radio signal back into electrical energy for the receiver. The Transmitter’s
antenna tr
received at the car. When operated with strong batteries and in an open area the range will be at least 40 ft.
Obstacles such as walls, furniture, and trees will degrade the radio signal’s ability to travel through air and
reduce operating range, but will never block it completely. In some cases more radio energy may travel from
the Transmitter to the car by going around obstacles than by going through them. In the car, weak batteries will

•

•

•

4 synchronization bursts each
~

~ 1.8ms long with ~ 600µs
spacing.

ansmits energy in all directions so as the r

{

~

Burst sequence, each ~ 600µs long with
~

~ 600µs spacing.
10 bursts for forward; 34 bursts for forward-left;

ursts f

28 b
46 bursts for backward-left; 52 bursts for backward-right.

Note: some models use different sequence lengths

~

orward-right; 40 bursts for backward;

or f

ange betw

een it and the car is increased less energy is

{

Sequence

Repeats

{

-3-

reduce power to the Motor and degrade the receiver’s ability to filter, amplify, and decode commands from the
Transmitter.

Radio Receiver: (refer to the schematics and block diagram on p.31 as needed)
The car antenna collects radio energy and converts it back into electrical energy; the energy here will always
be much less than the energy originally applied to the transmitting antenna. If the car is turned on then the radio
receiver in the car is continuously monitoring the electrical energy from its antenna. The first stage of the
receiver is basically a filter which is tuned to amplify any energy around 27.9MHz and block energy the antenna
picks up outside this region. If the Remote Control Transmitter is sending commands then its radio signal will
be picked up by the receiver and converted back into the original pulse sequence. Decoding circuitry then
determines which commands were sent by measuring the number of received pulses in the sequence. Signals
are then sent to the motors to execute the commands.

Take a closer look at the receiver schematic. The sub-circuit centered around transistor Q1 filters the antenna
output, if an RCC-7K transmitter is operating nearby then the 27.9MHz burst signal may be visible at its
collector. Inductor L1 is tuned so that the circuit amplifies around 27.9MHz while rejecting all other frequencies.
But we really want the pulse sequence that is hidden in the 27.9MHz signal, so then C10 is used to filter out the

27.9MHz from the burst signal we received. This result is applied to pin 14 of the SCRX2BC integrated circuit.

Inside SCRX2BC the signal is amplified and filtered in two stages between pins 14, 15, 16, 1, and 3. Pin 3 (DI)
is the output pulse sequence that was picked up by the receiver; this is used as the input to the decoder. The
SCRX2BC scans for the 4 long (synchronization) pulses and then counts the number of short pulses after them
to determine which command was sent by the transmitter. The gain of the SCRX2BC stages is high enough to
produce a pulse sequence at pin 3 even if no signal from a tr
but the resulting sequence will seldom be identified as one of the transmitter commands. Note from above that
there are 4 long pulses and 10 - 52 short pulses for each command, less pulses could have been used but then
the car is more likely to activ

ate on random noise.

ansmitter is present (it amplifies random noise),

Pins 4 and 5 of SCRX2BC are a 100 kHz (±30%) oscillator that is used as a reference by the decoder

Car Steering Mechanism: (refer to the schematics on p.31 as needed)
When a command is received to turn left, the SCRX2BC creates a voltage at pin 7 which turns on transistor Q9.
This then tur
motor, and then through Q14 to ground. This current through the Motor creates a magnetic field. Inside the
motor is a small magnet which is connected to the gear you see on the outside of the motor. The magnetic field
turns the magnet in the motor, which tur
to one side. Since the Front Wheels are connected to the Steering Bar, the car will turn.

To turn right, the SCRX2BC creates a voltage at pin 6 instead of pin 7. This turns on Q10, Q12, and Q13, and
current flows through the steering motor in the opposite direction. In turn this causes the steering gear, the
steering bar, and the car to turn in the opposite direction.

Car Drive Mechanism: (refer to the schematics as needed)
The Dr

orwards the SCRX2BC creates a voltage at pin 11 which turns on Q2. This then turns on Q5 and Q8 and

f
current flows from the batteries through Q5, then through the driving motor, and then through Q8 to ground.
Similarly to go backwards the voltage is created at pin 10, and Q3, Q6, and Q7 are turned on. The small gear
on the Motor drives the Middle Gear, which drives the gear on the rear wheels axle, making the wheels move.
Note that the gears on the Motor and the rear wheels axle rotate f

e the car f

iv

to dr
the Motor gear and the Middle Gear and again betw
number of “teeth” is increased by 4:1 and 5:1 respectively, for 20:1 overall. The Motor must rotate 20 times to
rotate the rear wheels once. The reason for this is that if the Motor were to drive the wheels directly then the
RCC-7K would be very hard to control.

ns on Q11 and Q14 and current flows from the batter

ns the gear. The “teeth” on the gear grab the Steering Bar and pull it

ks the same as the Steering Mechanism. When a command is received to go

iving Mechanism w

orward, this is because interlocking gears spin in opposite directions. Also notice that between

or

een the Middle Gear and the Rear Wheels axle gear, the

ies through Q11, then through the steering

orward and the Middle Gear rotates backward

.

-4-

CONSTRUCTION

Introduction

Assembly of your RCC-7K R/C Car Kit will prove to be an exciting project and give you much satisfaction and personal achievement. If
you have experience in soldering and wiring techniques, then you should have no problem with the assembly of this kit. Care must be
given to identifying the proper components and in good soldering habits. Above all, take your time and follow these easy step-by-step
instructions. Remember, “An ounce of prevention is worth a pound of cure”. Avoid making mistakes and no problems will occur.

CAUTION: WEAR SAFETY GLASSES WHEN ASSEMBLING THIS KIT.
Assemble Components

In all of the following assembly steps, the components must be installed on the top side of the PC board unless otherwise indicated. The
top legend shows where each component goes. The leads pass through the corresponding holes and the board is turned to solder the
component leads on the foil side. Solder immediately unless the pad is adjacent to another hole which will interfere with the placement
of the other component. Cut excessive leads with a diagonal cutter. Then, place a check mark in the box provided next to each step to
indicate that the step is completed. Be sure to save the extra leads for use as jumper wires if needed.

Foil Side

Rx - 100Ω 5% 1/4W Resistor

(brown-black-brown-gold)

Mount Part

Bend Leads to Hold Part Solder and Cut Off Leads

Soldering

The most important factor in assembling your R/C Car is good soldering techniques. Using the proper soldering iron is of prime
importance. A small pencil type soldering iron of 25 - 40 watts is recommended. The tip of the iron must be kept clean at all times
and well tinned. Many areas on the PC board are close together and care must be given not to form solder shorts. Size and care of
the tip will eliminate problems.

For a good soldering job, the areas being soldered must be heated sufficiently so that the solder flows freely. Apply the solder
simultaneously to the component lead and the component pad on the PC board so that good solder flow will occur. Be sure that the
lead extends through the solder smoothly indicating a good solder joint. Use only rosin core solder of 60/40 alloy.

DO NOT USE ACID CORE SOLDER!

1. Solder all components from
the copper foil side only.
Push the soldering iron tip
against both the lead and the
circuit board foil.

2. First apply a small amount of
solder to the iron tip. This
allows the heat to leave the
iron and onto the foil.
Immediately apply solder to
the opposite side of the
connection, away from the
iron. Allow the heated
component and the circuit
foil to melt the solder.

Do not blob the solder over the lead because this can result in a cold solder joint.

Soldering Iron

Component Lead

Foil

Circuit Board

Soldering Iron

Solder

4. Here is what a good solder
connection looks like. Cut
off excess leads.

Example 1

Poor solder connections occur
when the lead is not heated
sufficiently. The solder will not
flow onto the lead as shown.To
correct. reheat the connection

Solder does not flow onto the
lead. A hard rosin bead
surrounds and insulates the
connection.

oor solder

P
connection

and, if necessary, apply a small

Foil

amount of additional solder to
obtain a good connection.

Soldering iron
positioned incorrectly

Example 2

.

3. Allow the solder to flow
around the connection.
Then, remo

ve the solder and
the iron and let the
connection cool.

e flo

should ha

v

The solder

ed smoothly

w
and not lump around the wire
lead.

Solder

oil

F

Soldering Iron

A solder br
solder r

idge occurs when

uns betw
paths and creates a shor
circuit.

y using too m

b
correct this
solder

This is usually caused

uch solder. To

, simply dr

ing iron across the

solder bridge as shown.

-5-

een circuit

t

ag your

IDENTIFYING CAPACITOR VALUES

Capacitors will be identified by their capacitance value in pF (picofarads) or µF (microfarads). Most capacitors
will have their actual value printed on them. Some capacitors may have their value printed in the following
manner.

Second Digit

First Digit

Multiplier
Tolerance

The above value is 10 x 1,000 = 10,000pF or .01µF
The letter K indicates a tolerance of +
The letter J indicates a tolerance of +5%

Multiplier

For the No.01234589
Multiply By 1 10 100 1k 10k 100k .01 0.1

Note: The letter “R” may be used at times to

10%

signify a decimal point; as in 3R3 = 3.3

IDENTIFYING RESISTOR VALUES

Use the following information as a guide in properly identifying the value of resistors.

BAND 1

1st Digit

Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green

5
Blue 6
Violet 7
Gray 8
White 9

BAND 2

2nd Digit

Color Digit
Black 0
Brown 1
Red 2
Orange 3
Yellow 4
Green
Blue 6
Violet 7
Gray 8
White 9

PART IDENTIFICATION CARDS

To help identify the resistors and diodes used in the construction of your car we have
mounted the resistors, capacitors, diodes, and an inductor onto cards. The card will

ou find the parts quickly. THE PARTS WILL NOT NECESSARILY BE LISTED IN

help y
THE ORDER SHO
PROCEDURE.

Multiplier

Color Multiplier
Black 1
Brown 10
Red 100
Orange 1,000
Yellow 10,000

5

Green

100,000
Blue 1,000,000
Silver 0.01

Resistance

Tolerance

Color Tolerance
Silver +
Gold +5%
Brown +1%
Red +2%
Orange +3%
Green
Blue +
Violet +.1%

Gold 0.1

Multiplier

1

2

Tolerance

WN IN THE PARTS LIST SECTION OR IN THE ASSEMBLY

10%

+

.5%

.25%

When you are ready to assemble the car kit, follow the procedure shown. For an

xample refer to page 16. The first resistor called for is R13, 1k

e

Ω resistor (bro

wn­black-red-gold). Locate it on the card ( ), verify that it is the correct value. Some
resistors may be mounted backwards on the card so you must be certain that you are
reading the resistors correctly
then will y

ou mount it into its correct position on the PC board.

When the correct v

.

alue has been established, only

-6-

ASSEMBLY INSTRUCTIONS

Inspection of Parts: Take a look at each of the parts bags and compare to the Parts List (on pages 1 &

1

2

). Be sure that nothing was damaged during shipment and handling. Contact Elenco

have any problems (phone number is on the back of this manual).

®

E

lectronics if you

2

9V Battery Slot

(Alkaline recommended)

Battery Contact,

Battery Cover

Snap In Tab

Note: Screw in tight.

Battery Contact, +

Battery Contact, +

emote Control Transmitter

R

Transmitter Antenna

Switch Placement

Insert the switch onto the posts. Then,
secure by melting the plastic posts with
a soldering iron.

Switch

Posts

Back of

Bottom Frame

NOTE: Slide

the contacts into

the slots and then

fold back the tabs on

the top side to hold

in place.

Battery Contacts

+ ,

Red

Wire

White

Wire

Black Wire

-7-

3

Driving Motor

the larger motor; Yellow

(

wire goes to tab next to

⊕ marking in plastic)

0.1µF Capacitor

(marked 104):

Solder leads to motor

tabs, one lead is also

soldered to motor

shell.

You cannot get good connections
soldering to the motor shell unless
you first file or scrape away a
small area of the outer coating.

Green Wire

Yellow Wire

NOTE: If you

have a problem

putting the gear on

the shaft of the motor,

then gently tap the

gear on with a hard

object.

bend tab back

180Oand solder

to motor shell

Driving Motor

Motor Gear

Side Tab:

⊕

Interior Tab:
Bend Tab 90O,
but don’t short
to motor shell.

⊕

Interior Tab

Side

Ta b

Test:

k

Quic

1.5V battery across the
motor wires with y
hands. The motor should

spin.

Connect a

our

Bottom Fr

-8-

ame

4

Rear Wheels

Locators

NOTE: The

next 3 steps will be

much easier if you

elevate the car about

1” using a small

object.

Rear Axle:

the “grip” near the

middle should be

toward the left

Gear for rear axle:
slide on until it is
firmly in the
“grips” on the axle

Hard

surface

Note: You ma

y want to use the
method illustrated above to slide the
gear onto the rear axle. Warm the axle
and gear with a heat gun or hairdryer,
then press the gear on carefully using
both thumbs.

-9-

Locator Slots

5

NOTE: Put some

Vaseline or grease into

the slots for the rod and

some on the teeth of all the

gears (motor gear, middle

gear, and the rear axle

gear). This will make the

car go faster.

Gear, Middle of rear section

Rear Rod

Check the alignment of the
gears. The middle gear
must not be able to slide
out of alignment with the

Adjust the

other gears

.
positions of the gears on
the motor and rear axle if

.

necessar

y

-10-

Quick Test: All 3 gears

should be lined up and
turning one of them by hand
should also tur

n the others

.