Conrad 10197 Operation Manual

Foreword

As in recent years, Conrad Electronics again has a new calendar in 2016, also, with 24 experiments for
December 1 through 24. The topic is digital electronics. The experiments deal with digital counters with
the CMOS chip 4060. This IC contains 14 digital divider flip-flops as well as a clock oscillator with
multifaceted uses. It enables very different and very versatile applications that are not only educational
but also fun. At the end there is a circuit that can be hung on the Christmas tree to represent a wood
fire and falling stars.

There are various ways to use the electronics calendar. One person might simply wish to build
everything exactly according to plan and enjoy the success; another wants to understand it exactly. The
experiment descriptions should satisfy both. For this reason, the construction and the function are
always described only as briefly as necessary for the successful construction. Afterwards, the technical
background is explained in brief. Thus one finds the key ways with which one can also go on to look
for more information. In any case, the experiments provide the greatest pleasure when one works on
them with others. Parents and grandparents can perhaps pass on valuable experience and pique the
interest of children and youths.

Using the available parts, one can also build significantly more circuits than can be shown here.
Someone who works through the presented experiments with interest will quickly find further circuit
variants and similar applications. And completely new circuits can also be developed. No limits are
placed on your ingenuity!

We wish you great fun and a happy Christmastide!

1 The LED test

The first test in Advent should cause an LED to light up. An LED must never be connected directly to a
power source; one always needs a series resistor as well. Without this resistance, the LED would be
destroyed by too much current! The LED must be installed in the correct direction. It has two different
connections. The short wire is the negative terminal (cathode C); the longer wire is the positive terminal
(anode A). The wider lower edge is flattened on the cathode side. Also, on all LEDs in this calendar, the
larger bracket inside the LED is connected to the cathode.

Behind the first door, you will find a red LED and a resistor that matches it. You will also need a 9-V
block battery. The first test must be carried out especially carefully. Attention: avoid looking directly
into a lighted LED from short distances of less than one meter. Bright LEDs can cause retinal damage.
Avoid having both LED contacts ever touch the battery terminals at the same time! The resistor must
always be connected in series; otherwise, the LED burns through. Hold both components to the battery
as shown in the diagram. The LED lights up brightly.

One presents electronic circuits clearly in circuit diagrams. There is a symbol for each component. The
LED consists of a triangle for the anode and a straight line for the cathode. That signifies the current
direction. Two short arrows pointing outward stand for the light that is emitted. The resistor is shown
as a rectangular box. Every resistor has a specific resistance value. In this case, it is 10,000ohms = 10

kilo-ohms (10 kΩ, in the circuit diagram 10k for short). The actual component is marked with coloured

bands (brown, black, orange for 10,000 and gold for potential deviations up to +/-5%).

The circuit diagram shows a series circuit. The current runs through the battery, resistor and LED. In this
case, the resistor has the task of limiting the amperage to a useful value. The higher the resistance, the

smaller the amperage. At 10 kΩ, the LED is in fact operated far below its maximum permitted current,
but it already lights up sufficiently brightly.

2 Battery connection

The second door hides a battery clip for the 9-V battery. Rebuild the test from the first day, but
somewhat differently. Use the battery clip and make sure that the black connection wire is the negative
terminal and the red the positive terminal. It is imperative that you avoid short-circuiting the battery,
that is, creating a direct connection between the two terminals. In the case of a short, the battery could
become very hot, and if the short lasts for a longer time, in extreme cases the battery could even
explode. Plus, short circuits reduce the lifespan of the battery.

The resistance 10 kΩ determines the current through the LED. In this case, one can assume that about
2V are applied to the LED, thus another 7V at the resistor. The result is a current of only 0.7mA. For
comparison: LEDs are mostly designed for currents of 20mA. This red LED, however, begins to generate
significantly visible light even with less than 1 mA.

3 Plug design

Open the third door and take a breadboard out of the compartment. This device makes it easier to
design complicated circuits. The breadboard, with a total of 270 contacts in the 2.54-mm grid (0.1 in),
provides a secure connection of the components.

The plug field has 230 contacts in the middle area, each of which is connected conductively through
vertical strips with five contacts. In addition, there are 40 at the edge for the power supply; these
consist of two horizontal contact spring strips with 20 contacts each. The plug field thus has two
independent supply rails, which are used here for the positive and negative terminals of the battery.

Inserting components requires a relatively large amount of strength. The connection wires thus bend
over easily. It is important that the wires be inserted exactly from above. A pair of tweezers or a small
pair of pliers helps in this process. A wire is grasped as short a distance above the breadboard as
possible and pushed downward vertically. In this way, even sensitive connection wires like the tin­plated ends of the battery clip can be inserted without bending.

Construct the circuit from the first test yet again on the breadboard. Again, you are building a series
circuit with resistance and LED. The circuit diagram shows the precise circuitry, but with a slightly
different arrangement of the components, which is as similar as possible to the actual test.

4 Lamp switch

Behind the fourth door, you will find the wire necessary for all following tests. Build an LED lamp with
switch contact. Cut a suitable piece of wire, 4cm in length, and strip the insulation from the ends to a
length of about 5mm. This wire should be installed as connection to the LED. A shorter wire, 2cm
long, is installed as strain relief to protect the weak connection wires. The battery clip should always
remain connected so that the connections do not wear down too much.

The simple switch consists of two bare pieces of wire that touch together only when pushed together
with the finger. For this purpose, cut two pieces of wire, 2 cm long, and remove the insulation
completely.

5 A protective diode

You will find another red LED behind Door Number 5. Install this second LED in the circuit. The
direction must be correct for this; otherwise, no current will flow. If everything has been put together
correctly, both LEDs light up. And although two LEDs are now in series, the brightness of the first LED
remains practically the same.

The new LED has an important function for the following tests. It serves as a protective diode and
should prevent an incorrect polarity of the battery. The component to be installed tomorrow, in
particular, reacts very sensitively to an incorrect polarity and should be protected against potential
faults. At the same time, the LED is a simple current indicator, with which one can recognize the correct
function of a circuit.

6 Digital circuit

Open Door Number 6. Behind it you will find the most important part of this calendar, the CMOS-IC

4060. This IC with 16 pins contains a total of 14 divider flip-flops and a multifaceted oscillator circuit.
The connections 1 and 16 are on the left side and are marked with a groove. An additional note is
offered by the label, which one can read on the lower row (Pin 1 to Pin 8). Before the first use of the IC,
the connections must be aligned to be parallel because they still stand a bit too far to the outside after
the production. Push all pins on one side at the same time on a hard table surface to align them
sufficiently. Then place the IC correctly on the breadboard. Attention: if it is inserted the wrong way
round, the connections 8 (GND, negative) and 16 (VCC, positive) are switched, so that the operating
voltage is connected with the wrong polarity and the IC is destroyed. In this case, even the protective
diode at the positive terminal does not help, since it protects only against a battery that is connected
the wrong way round.

The first test uses a portion of the oscillator circuit at the connections 10 and 11. The input OSC1 is placed at
GND (negative terminal, logical zero). At the output OSC2 is the LED with its series resistor. If everything has
been assembled correctly, the LED lights up. The IC thus has the voltage switched on at the output (logical
one) and thereby inverts the input status. For most of the tests with the 4060, the reset input (RES) must
also be attached at GND. The red LED at the VCC connection indicates the operating current and protects

the IC. If everything is correct, both LEDs light up with the same brightness.

7 An open input

Open the seventh door and take out a resistor. It has 22 MΩ (22 mega-ohms, red, red, blue) and is
repeatedly used in the following tests in the oscillator circuit. The resistor is connected at the input OSC1
only on one side. One thus has an "open input". It is undefined whether one or zero is present; the LED is
either on or off. The result is random and can be affected by bringing your finger close to it. Even at a
distance of a few centimetres, the status of the gate can change. Static charges and the electrical fields
connected with them are responsible for this change.

You can turn the output on or off by tapping briefly on the input with your finger. If it is switched on, both
LEDs light up; if it is switched off, both LEDs can be off. The IC then consumes virtually no power.
However, there can be circumstances in which the output is indeed still switched off, but the IC
nevertheless consumes a certain amount of power. That is the case when the input voltage is neither
exactly zero nor exactly at the operating voltage but is somehow between these voltages. As long as the
input is touched, a half brightness can also be adjusted, whereby the LEDs actually flash very rapidly.
This lies in the 50-Hz AC fields of the electrical grid, which have the effect that your own body conducts a
small alternating current.

8 Feedback

Behind Door Number 8 you will find a 10 kΩ resistor (brown, black, orange). This time, it is used as
protective resistance at the input of the IC. The 22-MΩ resistor connects the second output to the input of

the oscillator circuit. The LED is either on or off; the result is unpredictable. An existing status lasts for a
random length of time. You can change the status, however, if you hold the free connection at the input
once at the positive and once at the negative. Beyond that, you can with some luck switch the LED on or
off if you simply tap the resistor with your finger or touch it with a piece of wire that you hold in your
hand.

In this circuit, two inverters are placed in series. An input zero state becomes a one state after the first
inverter and goes back to zero after the second inverter. Through the feedback, therefore, the zero state
is maintained at the input as well. Conversely, a one status at the output appears as one again and
persists. However, if the input is brought to the other state even very briefly, the circuit turns over. A
random impulse often suffices for this purpose, which occurs when you touch it because you are
electrically charged.This kind of circuit is also called a trigger circuit or a flip-flop. At the same time,
therefore, the circuit is also a digital memory with a storage size of 1 bit. If you take the right LED at the
output OSC3 out of the circuit, the circuit is practically de-energized even in the one state. The left LED
is thus permanently off regardless. Only in the switch-over moment does current flow. If you touch the
input, the left LED can light up.