Conrad 1365868 Operation Manual
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Preface
Over the past years, our Electronics Advent Calendar featuring 24 experiments – one for each day of December including Christmas Eve - has become increasingly popular. This year’s issue focuses on sensors. And as usual, there’s
lots to look forward to. Moreover, many exciting experiments are based on very basic circuit diagrams. Means, using
the kit is not only fun, you’ll also broaden your knowledge of electronics.
The Electronics Science Kit Advent Calendar has been designed for children and parents setting up the experiments
together, thereby introducing the youngsters to electronics fundamentals in a playful way. Children under the age of
14 should not assemble circuits and carry out experiment unsupervised. Ensure your children use tools safely. As a
rule, keep supply voltage to levels below 24 V DC. And make your children aware of potential safety hazards related
to working with electronics.
Although many of the experiments are easy to set up, getting to grips with the underlying science might not always
be that straightforward. At the outset, the descriptions are kept simple, and mainly aimed at getting you going. If you
want to learn a little bit more about the technical principles behind the experiments, just read on. Also, there’s a lot
of room for you to modify or expand the respective experimental setup. Be creative!
Merry Christmas, everyone!
Contents
1 Green Light-emitting Diode (LED) .................................. 4
2 Touch Current .................................................4
3 Steady Electrical Connections ....................................5
4 Basic Switch .................................................. 5
5 Resistor ......................................................6
6 Tilt Sensor/Motion Detector ......................................6
7 Vibration Sensor ............................................... 7
8 Transistor as a Switch ........................................... 7
9 Alarm System .................................................8
10 Touch Button ..................................................8
11 Light Sensor ..................................................9
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12 Dimmer ......................................................9
13 Temperature Sensor ........................................... 10
14 Temperature Twin Sensor ....................................... 10
15 Electric Field Sensing ...........................................11
16 Electrostatic Motion Detector .....................................11
17 LED Thermometer ..............................................12
18 Temperature Switch ............................................12
19 Flashing Temperature Display ....................................13
20 25-Degrees Celsius Thermometer ..................................13
21 Lie detector ...................................................14
22 Electrosmog Detector ...........................................15
23 Electric Spark/Static Discharge Detector ........................... 16
24 Multifunctional Sensor ..........................................17
Appendix: List of Components ................................... 18
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1 Green Light-Emitting Diode (LED)
Day 1
Green LED
Opening the first door reveals a very special electronic component: a green LED with a built-in resistor. The LED case
of this diode is shorter than that of a standard LED without a resistor, to prevent confusion. Never directly connect
a standard LED to a battery or power supply. Standard LEDs always need a resistor connected in series to protect
them. No worries with this one – it comes with an built-in resistor in the form of a little cube visible on the (+) connector. What looks like a little goblet on top of the (-) pin is called the anvil.
The (+) pin of an LED is also referred to as the anode (A), the (-) pin is called the cathode (K). The lower rim of the
case has a flat spot on the side of the cathode. Also, the cathode pin is always the shorter one of the two. Means
there’s lots of help to distinguish between the two poles of an LED. Connecting an LED to a battery requires connecting the anode to battery (+) and the cathode to battery (-). An LED is basically a little electronic valve that conducts
electricity in only one direction, and lights only when conducting electricity.
Connect the LED to the battery poles and the green light flashes up. Caution: do not look into the emitted light at
close distance. And make sure you don’t short-circuit the battery poles by connecting them directly to each other.
This causes the battery to heat up which may result in an explosion if the battery is short-circuited for an extended
period of time. Moreover, short-circuiting reduces battery life significantly.
Electronic circuits are explained by circuit diagrams. Each electronic component has its own symbol. LED are represented by a triangle symbolising the anode and a line standing for the cathode. Two arrows symbolise light emission. The resistor is represented by a rectangular box. Each resistor has a characteristic value indicated next to the
box. In our case, the LED comes with an 1000 Ω resistor = 1 kiloohm =1kΩ = 1k. Despite our LED and resistor come
as a single physical entity, the diagram treats them as separate components.
The circuit diagram shown on the left constitutes a series circuit. Current passes from the battery through the LED
and the resistor back to the battery. The job of the resistor is to limit the current to a safe level. The higher the resistance, the less current can pass through.
Day 2
Again, never connect a standard LED directly to a battery without putting a resistor in place as well. Without the
resistor, the current passing through the LED is too high, damaging the component in the process. The only reason
we were able to do this here is because our LED features a built-in in resistor as indicated by the LED’s smaller case
size (see left).
2 Touch Current
Door No. 2 hides a battery clip for a 9 V PP3 battery. Change the setup of the Day 1 now using the clip. The black
lead connects to battery (+), the red lead to battery (-). Avoid short-circuiting the battery by bringing the black lead
into contact with the red one. Keeping the tow lead ends in contact with the LED poles might need a little bit of
practice. You can switch on and off the LED as you wish.
Now try this: bring the LED cathode into contact with the black battery lead whilst bridging the red lead and the LED
anode with a finger. The LED will still light up but with very low intensity (best to carry out this experiment in a
darkened room which will help you detect the glow much easier). Using the finger as a bridge allows a low current
to pass through that makes the LED glow.
+
–
The circuit diagram shows an circuit interruption that needs to be bridged using your finger. Basically, your finger
acts as a resistor with a resistance value that’s about 1000x higher than the built-in resistor of the LED. This means
that the light emitted by the LED is about 1000x weaker. The light intensity also depends on the moisture of your
skin, and on the pressure you apply to the contacts when touching them. If you moisten your finger a bit, the LED
light brightens. This experiments illustrates how a basic touch sensor works. We’ll revisit today’s topic again a couple
of days down the line, improving the design.
Green LED
3 Steady Electrical Connections
5
Opening the third door reveals a mini breadboard. Breadboards make circuit assembly easier. This one comes with
a total of 170 contacts, arranged in groups of five vertically interconnected slots. The board enables push-connecting
components which requires a certain amount of force and may result in the lead ends being bent in the process. To
prevent this, insert the wire ends in the slots approaching the board from a direction exactly perpendicular to the
board surface. Use tweezer or small pliers, grab the lead close to its end, and push it into the slot. This allows connecting sensitive leads such as tin-coated battery clips without damaging them. The LED lighting up means all your
connections are live.
Red
Black
Day 3
Green LED
4 Basic Switch
Today’s component is a copper wire with a red insulation. The wire can be used to built a basic switch, consisting
of two bits of stripped wire brought into contact by manual force i.e. applied by using your finger. Use a wire cutter
(or an old pair of scissors) to cut off bits of wire (about 2 cm long). Strip them. Bend the wires in a way that they are
close but don’t touch each other. Use your finger to bring them into contact, switching the LED on.
Moreover, and to protect the sensitive battery leads we use another bit of wire as a strain-relief for the clip. Also,
the clip should stay attached to the board to avoid tear and wear of the contacts. Cut off a bit of wire (approx. 2 cm
long) and strip the piece at both ends (about 7 mm at each end is fine). To strip the wire/ends, use a sharp knife,
score a circle around the cable jacket but try not to nick or slice the wire underneath as your connection might break
as a result.
Alternatively, bend the two wires forming your switch in a way that they make steady contact (aka normally closed).
Slide a small piece of paper between them and connect the paper to a thin string. Attach the string to a door or
window. If someone (e.g. a home intruder) forces the door or window open, the paper is pulled out from between
the wires, the circuit is closed, and the LED is switched on. In short, you’ve just assembled a basic burglar alarm.
Switch
Red
Day 4
Green LED
Black
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5 Resistor
Day 5
Green LED
Day 5 means you get another resistor. The resistance values of resistors are indicated by a colour-code printed on the
resistor enclosure. The brown ring stands for (1), the black ring symbolises (0), and the orange-coloured ring encodes
(000), adding up to 10.000 Ohm = 10 kiloohm = 10kΩ. The golden ring represents component accuracy (95 %). The
high resistance value reduces the current passing through the LED. Lower current means less light intensity and,
thus, increased battery life. LEDs are very efficient devices and the emitted light is sufficient for a wide range of uses.
But see for yourself.
The circuit now has a total resistance of 11kΩ. Assuming the voltage across the LED is 2V results in 7 V across the
resistors, and a current of 0.65 mA. The capacity of a standard 9 V battery is 500 mAh, sufficient to supply a current
of 0.65 mA for a month. When carrying out the experiments make sure you save as much battery life as possible, to
ensure the battery has still enough juice to power your Christmas Eve experiment.
Red
Black
Day 6
Green LED
S
6 Tilt Sensor/Motion Detector
Opening door No. 6 reveals one of the key components of this calendar: a tilt sensor. It consists of an open contact
that will be close by a little metal bead as soon as the sensor is orientated in an upright position. When you tilt
the sensors, the metal bead slides off the contact and breaks the circuit. Vibrations cause the bead to jump up and
down, making and breaking electrical contact in an alternating manner. If you listen closely you can actually hear
the bead moving inside the sensor enclosure.
Add the tilt sensor to the circuit. Test whether the sensor works by slowly tilting the breadboard. Afterwards, shake
the board a bit, to make the LED flash.
Red
S
Black
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