Elenco Surface Mount Technology Kit User Manual

SMT - TRAINING COURSE

MODEL SM-200K

Assembly and Instruction Manual

Surface Mount Technology Kit

Copyright © 2013, 2000 Elenco®Electronics, Inc. Revised 2013 REV-O 753200

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

ELENCO

®

Qty. Description Part #

! 1 PC Board 517008
! 1 Dimple switch 546101
! 1 Battery snap 590098
! 1 Buzzer 595201
! 1 Filter red 621424

Qty. Description Part #

! 1 Spacer 7/32” 624008
! 1” Tape double sided 748127
! 1” Cushion tape 790006
! 1” Wire red #22 solid 814220
! 1 Solder Lead-free 9LF99

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 Marking Part #

! 6 J1,J2, P1-P4 0Ω 0 / 000 196101
! 2 R7,R8 470Ω 5% 1/8W 471 196344
! 1 R5 10kΩ 5% 1/8W 103 196514
! 1 R1 15kΩ 5% 1/8W 153 / 1502 196518
! 1 R4 56kΩ 5% 1/8W 563 196556
! 1 R3 100kΩ 5% 1/8W 104 196614
! 2 R2,R6 1.5MΩ 5% 1/8W 155 / 1504 196758

CAPACITORS

Qty. Symbol Value Description Part #

! 1 C2 .0039µF 10% 50V Cap. chip 233997
! 1 C1 .015µF 10% 50V Cap. chip 241597
! 1 C4 2.2µF 20% 10V Electrolytic (Lytic) 262220
! 1 C3 100µF 20% 10V Electrolytic (Lytic) 281020

SEMICONDUCTORS

Qty. Symbol Value Description Part #

! 1 D1 1N4148 SM Diode RA6J, A6, A2, or 5H 31BA16
! 1 Q1 3904 Transistor RIA, 1A, N71, 1AM, KINC, or ZC 32SM04
! 1 IC1 4011 4011 Integrated Circuit (IC) 33SM11
! 1 IC2 4017 4017 Integrated Circuit (IC) 33SM17
! 6 LED1-LED6 LTL907 Light Emitting Diode (LED) 350907

MISCELLANEOUS

-1-

Transistor LED

Capacitors

PARTS IDENTIFICATION

Dimple Switch

Diode

Resistor

471

Battery Snap

Buzzer

Integrated Circuit

Spacer

Chip

Electrolytic Chip

INTRODUCTION

Need help in making up your mind? Just ask the SM-200K Decision Maker. Press the ask button and the right
answer will be given to your question. The Decision Maker has six light emitting diodes (LEDs) that are driven
ON and OFF one at a time in sequence. When the ASK button is pushed the LEDs will flash and the buzzer will
sound. After a brief period of time only one LED will remain lit. Above the lit LED is the answer to the question
asked. In a minute or two the LED will get dim and gradually go out.
The SM-200K uses very small surface mounted components. By building this kit you will obtain an interesting
electronic device and also gain valuable experience in surface mount technology.

THEORY OF OPERATION

Figure 1 shows the block diagram of
the Decision Maker circuit. It consists
of 6 LEDs driven by a decimal counter
and two oscillators. One oscillator
drives the decimal counter and the
other drives a buzzer. The counter and
the oscillators are controlled by two
timers. We shall proceed to study the
circuit in detail.

DECADE COUNTER

The 4017 IC is a 5 stage divide by 10 counter. Figure 2 shows a
diagram of the IC. The IC has 10 outputs and a clear input. Only
one of the 10 outputs will be high at any given time. The other 9 will
be low. Let us assume that output 1 is high. If a pulse is fed to the
clock input, output 1 will go low and output 2 will go high. Each
clock pulse will move the output one position. If we connect an LED
to the output, it will light only when the output goes high. It is
obvious that when the clock is running, the LEDs will flash ON and
OFF with the speed of the clock. When the clock stops only one
LED will be lit.
In this design, 6 LEDs are used per IC. However, the counter has
10 outputs. If the clock stops at an output without an LED, nothing
will light. To prevent this the 4017 IC is preset after hitting the 6th
output. This is done by tying the 7th output to the clear pin (pin 5 and pin 15 shorted together).

LIGHT EMITTING DIODES (LED)

The operation of the LED is very simple. When current flows through the LED it will emit light. Note that the LED
is connected between an IC output and ground through a resistor. When the IC output goes high the LED will
light. The resistor limits the current so that the LED will not be damaged.

-2-

Figure 1

Figure 2

Timer 1

Osc 1

Decade
Counter

Osc 2

Timer 2

Button

Ask

B+

Buzzer

LEDs

Block Diagram

Clock

Clock
Enable

Reset

Q0
Q1

Q2
Q3

Q4
Q5

Q6
Q7

Q8
Q9

COUT

3
2

4
7

10
1

5
8

9
11

12

14

13

15

VDD = Pin 16

VSS = Pin 8

-3-

OSCILLATORS

The SM-200K uses two oscillators. The first oscillator produces
a frequency of about 2000 hertz (cycles per second) and the
other produces a frequency of about 20 hertz. Figure 3 shows
the basic oscillator circuit.nThe 4011 integrated circuit (IC)
contains four-two input NAND gates. Two of these NAND gates
are needed to form an oscillator. Feedback for this oscillator is
via capacitor C1 and resistors R1 and R2. These elements
determine the frequency of oscillation. Both ICs act as inverters,
that is when the input is low the output is high. As long as pin 1
of IC is high the circuit will oscillate. If pin 1 is brought low, the
circuit will stop oscillating.

The second oscillator is similar to the one described except for a difference in its frequency controlling
components, capacitor C2 and resistors R3 and R4. C2 and R4 are smaller values causing the oscillator to
oscillate at a much higher frequency. Pin 8 of the first NAND gate is brought high at a 20 cycle rate. This causes
the second oscillation to be chopped up at the first oscillation frequency rate as shown in Figure 4. This
combination produces the unusual sound heard from the buzzer.

BUZZER

The SM-200K buzzer consists of a piezoelectric material on a metal base. When a voltage is applied to a
piezoelectric material its dimensions change. The buzzer is connected to the 2,000 Hz oscillator. When the
oscillator runs, the changing dimensions of the piezoelectric buzzer act like the cone of a speaker to set up
sound waves.

TIMERS

Timer 1 is made up of capacitor C4 and resistor R6. Timer 2 is made up of capacitor C3 and resistor R5 (see
schematic diagram). When switch S1 is pushed both capacitors charge up to 9 volts and the oscillators run.
When the switch is released, capacitor C4 discharges through resistor R6 and capacitor C3 discharges through
resistor R5 and the base of Q1.

Note that C4 is tied to pin 1 of the 4011 IC. Thus, when capacitor C4 loses its charge, the circuit stops oscillating.
The buzzer stops and a single LED remains lit. After a minute or two, C3 loses its charge and removes the base
current from Q1. Q1 is in the ground return path of the LEDs and both ICs. Thus, when Q1 is turned off, the
LED goes out. Only a very small leakage current is then drawn from the battery. This current is so small that no
ON/OFF switch is required.

Figure 3

Figure 4