LIGHTBULB WITH SWITCH
Beginner
A basic build that demonstrates how the electronic circuit in principle
works. The switch acts as a circuit breaker, the bulb generates light and
the jumpers close the circuit so that electric current can flow through
it. The battery is an integral part of the circuit and serves as a source of
energy for the light bulb.
LED WITH SWITCH
Beginner
A basic build with an LED as a light source. LEDs are not adjusted to the
soupply voltage of a battery, therefore is necessary to add a serial resistor
to the build.
SWITCH VS. BUTTON
Beginner
The basic components in the circuit include switches and buttons that
control the current flow. The switch has two stable positions (OFF and ON)
and the current flows only in the ON position. The current flows through
the button only when it is pressed.
SERIAL CONNECTION OF LEDS
Beginner
The objective is to test that by connecting 3 LEDs in series, none of
them will light up because the voltage drop across each of the diodes
is in total greater than the supply voltage of the batteries, which is 6V.
SWITCHING WITH BUTTON I.
Beginner
In this circuit, a red and a white LED are connected in parallel with a common resistor. When the switch is closed, the white
LED lights up. If you press the button, you connect the red LED to the white LED in parallel.
LED LIGHTS UP IN ONE DIRECTION
Beginner
A LED is a semiconductor device (made up of two transitions called
P and N) that conducts an electric current in only one forward direction
(from the cathode (N) to the anode (P)).
HIGH LUMINOSITY WITH 100Ω RESISTANCE
Beginner
The LED light intensity is determined by the amount of current flowing
through the circuit. A resistor included in the circuit blocks the current
from flowing, and this allows you to adjust its magnitude.
HIGH LUMINOSITY WITH RESISTOR CONNECTED IN PARALLEL
Beginner
You can find the resistor as a component in the package in several values, and it is possible to connect them in parallel
(next to one another) or in series (in a row).
CONTROLLING BY PHOTORESISTOR
Beginner
There are electronic components that respond to light. One of them is
a photoresistor – its resistance changes with the intensity of incoming
light. When you cover the photoresistor with your finger, its resistance
increases.This reduces the current flowing through the circuit, which in
turn decreases in the LED light intensity
CONTROLLING BY MICROPHONE
Beginner
A microphone is a component that converts sound into an electrical
signal. As a rule, the sound is converted into a diaphragm vibration,
which is further evaluated as a change in resistance or capacitance.
BULB CONTROLLED BY A MAGNET
Beginner
The electrical switch does not need to be just a manually operated
component. A magnetic reed switch can serve as an alternative.
LED CONTROLLED BY A MAGNET
Beginner
The magnetic reed switch can be used to directly switch a wide range
of appliances. However, it is not suitable for large appliances with
high current consumption as the contacts may slowly get burned or
lose flexibility due to overheating.
SWITCHING LEDS
Beginner
The changeover switch is a variant of the on-off switch that has both positions of the switching contact available. When the changeover switch is operated, the contact interrupts the current flow in one part of the circuit and, at the same time, closes another part of the circuit.
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CHANGING THE CURRENT BY LED
Beginner
We do not have to change the LED light brightness by means of altering the current flowing through it by physically changing a component. We can use a changeover switch to change the ballast resistance for the LED. We have a choice of two values of the current that can flow through the LED, i.e. 2 variants of brightness.
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CONNECTING A LIGHT BULB AND LED IN SERIES
Beginner
Connecting multiple appliances in a row. The same current flows through both appliances, but the battery voltage is divided between the two appliances. In our circuit, it is reflected in a low brightness of the bulb. In practice, a connection in series is used for the same appliances with the same consumption.
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CONNECTING A LIGHT BULB AND LED IN PARALLEL
Beginner
Connecting multiple appliances side by side. The total current drawn
from the source is a sum of the partial currents taken. The voltage on
both appliances is the same. If one appliance is disconnected from
the circuit, it will not affect the rest, only the value of the current flowing
through the circuit will decrease.
LED BYPASS
Beginner
A button connected in parallel to the LED. When the button is not pressed, i.e. it is open, the LED light is on. If you press the button, you short-circuit the LED diode and it goes out. It stays off as long as the button is pressed and lights up again when the button is released. The ballast resistor not only protects the LED from excessive current, but also ensures that the button does not short-circuit the battery directly. The resistor thus limits the short-circuit current and protects the battery as well as the button from excessive current.
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POLARITY INDICATOR
Beginner
Two anti-parallel LEDs indicate the polarity of the power supply. The LEDs
light up alternately depending on the battery orientation.Try connecting
the battery the other way – you will see that the second LED lights up.
HOW A SEMICONDUCTOR DIODE WORKS IN THE FORWARD DIRECTION
Beginner
Insert a semiconductor diode into the basic circuit with a switch and a light bulb. The bulb only lights up when the switch is closed and the diode is oriented in the forward direction.
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HOW A SEMICONDUCTOR DIODE WORKS IN THE REVERSE DIRECTION
Beginner
If the diode is oriented in the reverse direction, no electric current can
flow through the circuit and the bulb cannot light up even when the
switch is closed.
CHANGING BRIGHTNESS SMOOTHLY I.
Beginner
If you want to change the LED current continuously and without step changes, you can use a variable resistor, also called a potentiometer, for which the resistance corresponds to the angle of rotation of the small shaft.
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SMOOTH BRIGHTNESS CHANGE II.
Expert
Two LEDs in series with a potentiometer connected in parallel. Use the slider to set the voltage between the LEDs.
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CONDUCTIVITY DETECTOR I.
Beginner
If the object is conductive, the circuit will be closed and the LED
will light up. In this case, the object has a similar function like a switch.
HUMAN BODY CONDUCTIVITY DETECTOR
Beginner
You can use a simple electrical circuit to test the conductivity of your
body. The human body is made up mostly of water; however, the human
skin is dry and poses high resistance to electrical current. The resistance
of the skin decreases when the skin is moist.
CONDUCTIVITY DETECTOR II.
Advanced
In addition to the human body, which has a high water content, you
can test the conductivity of other water-containing things, such as
various fruits and vegetables.
WATER DETECTOR
Advanced
Test that pure water, tea, or any other liquid is conductive enough to
light up the LED in the circuit.
LIGHT ALARM
Expert
At rest, the base of the transistor is short-circuited by a conductor to
ground. No current flows into the base and the transistor is closed.
INTENSIVE LIGHT ALARM
Expert
By replacing the LED with a white LED with a different resistance, you will
obtain an intensive light alarm.
NPN AMPLIFIER WITH LED
Advanced
The circuit demonstrates the ability of a transistor to amplify an electric current.
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NPN AMPLIFIER WITH LED IN REVERSE DIRECTION
Advanced
This build uses the same circuit as the previous one, just with the LED connected in the reverse direction.
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AMPLIFIER WITH LED
Advanced
The circuit demonstrates the ability of a transistor to amplify an electric
current.
SWITCHING WITH BUTTON II.
Advanced
To switch between the red and the white LEDs, we used significantly
different properties of both LEDs (different lighting voltages). However,
if you want to switch similar or the same LEDs, you need to choose
a different solution.
ADJUSTABLE POWER SWITCH
Advanced
By combining a switch and a potentiometer, you can build a circuit
where the switch can be used to select a constant brightness, or
continuous LED brightness control with a potentiometer.
SAFETY BUTTON
Beginner
Two buttons connected in series close the circuit only if both buttons
are pressed. The circuit closure is indicated by the LED.
CARBON BUTTON
Advanced
You can create a button using a graphite painting - a set of two separate conductive parts that you connect with the touch of a finger.
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CARBON POTENTIOMETER
Advanced
The material from which the resistance layer of the potentiometer is made is graphite. It is the same material that forms the ordinary pencil lead. If you draw a thick line on paper with a pencil, a resistance path is created that you can then connect to the conductors in the circuit.
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CE PNP AMPLIFIER WITH A LED AND BULB
Advanced
Functionally, it is the same circuit as the NPN amplifier with LED (page 40), just with a transistor of opposite conductivity.
The base current flows in the opposite direction; therefore, it is necessary to modify the base circuit accordingly.
PNP AMPLIFIER WITH LED IN REVERSE DIRECTION
Advanced
Use a potentiometer to control the current flowing through a LED diode to the transistor base.
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EMITTER FOLLOWER WITH NPN
Advanced
This build basically replicates the connection of the potentiometer slider
directly to the bulb against the ground.
CE AMPLIFIER WITH NPN AND LEDS
Advanced
The circuit demonstrates the ability of a transistor to amplify an electric
current.
CE AMPLIFIER WITH PNP AND BULB
Advanced
By changing the low current to the transistor base, you can control
the high current flowing through the bulb since opening and closing
the transistor causes the voltage on the bulb to change.
EMITTER FOLLOWER WITH PNP
Advanced
Functionally, it is the same circuit as the emitter follower with NPN, just with
a transistor of opposite conductivity.
RAISING CURRENT BY BASE WITH CC AMPLIFIER WITH PNP
Advanced
Changing the base resistor to a low value of 100 Ω will increase the current
flowing to the transistor base, but the bulb brightness remains almost
constant.
CE AMPLIFIER WITH NPN AND BULB
Advanced
By changing the low current to the transistor base, you can control the
high current flowing through the bulb since opening and closing the
transistor causes the voltage on the bulb to change. We use an NPN
transistor in this case.
BRIGHTNESS CONTROL
Advanced
With the potentiometer you can directly control the current flowing
through the LED diode and thus change its brightness.
TWO-FINGER TOUCH LAMP
Advanced
In addition to the graphite potentiometer, you can use your own fingers
to turn on the transistor.
CONTROLLING NPN TRANSISTOR BY LIGHT I.
Advanced
The more the photoresistor is illuminated, the more light the bulb emits since the transistor opens.
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CONTROLLING NPN TRANSISTOR BY LIGHT II.
Advanced
The photoresistor together with the resistor form a voltage divider, the output voltage of which depends inversely on the degree of illumination.
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CONTROLLING PNP TRANSISTOR BY LIGHT I.
Advanced
Functionally, this is the same build as L470, but with a transistor of opposite conductivity.
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CONTROLLING PNP TRANSISTOR BY LIGHT II.
Advanced
Functionally, this is the same build as L480 but with a transistor of opposite conductivity.
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STANDARD TRANSISTOR CIRCUIT
Expert
We use a potentiometer to control the current flowing to the base, which changes the current flowing through the collector and, thus, also changes the LED brightness because the voltage on the LED changes.
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FLASHING LIGHT BULB
Expert
An astable flip-flop can also be built using two amplifiers consisting of transistors of opposite conductivity.
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NIGHT LIGHT AUTOMATIC SWITCH-OFF I.
Expert
When the switch is turned in the ON position, the capacitor starts charging. As the capacitor charges, the current flowing through it decreases.
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NIGHT LIGHT AUTOMATIC SWITCH-OFF II.
Expert
The light dimming time can be extended by adding another capacitor in parallel with the previous one.
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NIGHT LIGHT AUTOMATIC SWITCH-OFF III.
Expert
You can also shorten the lighting time. You can use a capacitor with a smaller capacitance, but a more practical variant is to replace the resistor between the transistor base and the ground with a smaller one.
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SCHMITT CIRCUIT
Expert
A special type of two-stage amplifier. Unlike simple amplifiers that allowed the LED brightness to be adjusted continuously using the potentiometer, here the brightness changes in steps.
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NIGHT LIGHT AUTOMATIC SWITCH-OFF IV.
Expert
With the Schmitt circuit, you can improve the familiar switching off of the night light, which has the disadvantage that switch-off is not abrupt – the brightness slowly fades. The Schmitt circuit solves this with its step change, causing the light bulb to be either fully lit up or go out.
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NIGHT LIGHT AUTOMATIC SWITCH-OFF V.
Expert
A simplified version without the Schmitt circuit. The circuit works similarly to L570 however, in the absence of a Schmitt circuit, it causes an undesirably slow dimming of the light.
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RAIL CROSSING
Expert
If you connect two separate transistor amplifiers in series and connect the output again to the input, we get an astable flip-flop. This circuit has no stable state and constantly flips. Similar to L530 the transistor opening time is determined by the charging of the capacitor, with the difference being that the capacitor does not remain charged but begins to discharge again.
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TWILIGHT SWITCH
Expert
You can also use the Schmitt circuit to detect darkness. A voltage divider of the resistor and the photoresistor evaluates the Schmitt circuit, which turns on the bulb through the PNP transistor. If the photoresistor is well lit, the bulb will not light up.
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MULTIPLE-TONE GENERATOR I.
Advanced
This build demonstrates a change in tone of a simple buzzer depending on the capacitor. We will use a buzzer as the first place for the capacitor. Its membrane acts as a capacitor and has its own capacitance. The capacitance is relatively small and, therefore, the tone of the buzzer is high. The oscillation is so fast that we do not see the LED flashing and perceive it as constantly lit up.
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MULTIPLE-TONE GENERATOR II.
Advanced
We replace the buzzer with a capacitor with a capacitance of 100 nF. The capacitance is higher, and the tone pitch decreases. Again, the LED only appears to be constantly lit, but the brightness has changed.
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MULTIPLE-TONE GENERATOR III.
Advanced
Replace the capacitor with a capacitance of 100 nF with a capacitor with a capacitance of 10 µF. This capacitance is many times higher, and the continuous tone falls apart into mere clicking.
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ENGINE SOUND
Expert
A sound generator can also be built using two amplifiers consisting of transistors of opposite conductivity. The circuit is simplified a bit, but the stability of the circuit is worse, which is reflected in a spontaneous change of tone.
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VOICE-CONTROLLED LIGHT
Expert
By connecting a microphone and a transistor amplifier, you can control the LED brightness with sound.
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APPLAUSE LED
Expert
This is a modification of the S50 manual. We charge the capacitor
with an amplified current from the microphone. The capacitor
slowly discharges into the base of the second transistor. It is actually
a similar circuit as L530, only differently connected. The LED lights up
quickly with a sound and then slowly goes out.
BUZZING IN THE DARK
Expert
We can equip the astable flip-flop circuit not only with a photoresistor to change the pitch, as was the case in the L100 build, but with a suitable arrangement of components we can completely prevent the circuit from oscillating.
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ADJUSTABLE TONE GENERATOR
Expert
By suitably selecting components, we can force the L590 circuit to flip so rapidly that the change in electric current is able to cause the buzzer diaphragm to vibrate so fast that we hear a tone.
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PHOTOSENSITIVE ELECTRONIC ORGAN
Expert
You can connect a photoresistor instead of a potentiometer so the pitch will be directly proportional to the degree of illumination of the photoresistor.
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CAPACITORS CONNECTED IN SERIES
Advanced
This build makes it possible to supply power to the LED diode from one capacitor (with the switch closed) or from two
capacitors connected in series (with the switch open).
CAPACITORS CONNECTED IN PARALLEL
Advanced
The build allows to supply power to the LED diode from two parallel capacitors (with the switch closed) or from one capacitor (with the switch open).
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YOUR OWN BATTERY I.
Advanced
This circuit demonstrates the ability of the capacitor to accumulate an
electric charge.
YOUR OWN BATTERY II.
Advanced
This build is identical to the previous version but contains two capacitors
connected in parallel.
YOUR OWN BATTERY III.
Advanced
If you increase the current passing through the LED by reducing the
value of the ballast resistor from 1 kΩ to 100 Ω, the current flowing
through the LED diode will increase 10 times.
YOUR OWN BATTERY IV.
Advanced
Increasing the value of the ballast resistor to the LED will decrease the
brightness and reduce the discharge current. The LED will last longer.
CHARGING AND DISCHARGING THE CAPACITOR I.
Advanced
Charging and discharging the capacitor is controlled by two buttons and indicated by two LEDs. A fully charged capacitor is
indicated after pressing the button with the green LED flashing. Once the capacitor has fully been charged, no current flows
into the capacitor (the green LED is off) because the voltage on the capacitor is the same as on the battery.
CHARGING AND DISCHARGING THE CAPACITOR II.
Advanced
By connecting the second capacitor in parallel, you will double the capacitance of the capacitor bank.
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COMPRESSION METER
Expert
As we know from the L240 build, our skin is conductive, especially when wet. If you replace the resistor in the simple buzzer described under S20 with conductors, then the resistance between the conductors will depend on the degree of compression between them.
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VOLTAGE METER
Expert
Each electrical device is powered by electrical energy, which can come from a battery or a power generator. In both cases, the source supplies an electric current of a certain voltage to the circuit. For batteries it is 1.5V, 9V or other voltage. As the battery discharges over time, its voltage also decreases. With this circuit, you can measure whether you can still use the battery or not.
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LOW CURRENT MEASUREMENT
Expert
The flow of electric current through the circuit through the resistor causes the component to heat up, which represents an output power loss on the appliance. In order to determine the output power loss, it is first necessary to know the current flowing through the circuit, which is digitally measured as a voltage drop across a very small resistance.
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DIODE FORWARD DIRECTION MEASUREMENT
Expert
By connecting a diode to the circuit in the forward direction, you can determine its voltage drop and then also the output power loss during the passage of current.
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LED FORWARD DIRECTION MEASUREMENT
Expert
You can use the same circuit as in the previous build, just connect a light-emitting diode instead of a diode.
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LUMINANCE LEVEL MEASUREMENT
Expert
You can test the conversion of a non-electric quantity into its digital representation in this task, where you create a resistive voltage divider and connect a ballast resistor in one part and a photoresistor in the other as an element responding to the intensity of illumination.
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Fast reflexes
Advanced
A circuit for measuring how fast your reflexes are (reaction times to an optical stimulus). It is a fun and yet a practical build.
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PLATFORM GAME WITH BOFFIN
Advanced
Make your own game console with a microcomputer, buttons and joystick.
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PING PONG MULTIPLAYER
Advanced
In the previous project, you learned how to build a game console using Boffin Magnetic. Now it is time to play a game against a friend.
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TETRIS
Advanced
In previous projects, you learned how to assemble a game console using Boffin Magnetic. The connected circuit is the same as in the previous builds.
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ROXY CATCHES DICE
Advanced
In previous projects, you learned how to build a game console using Boffin Magnetic. This build remains almost the same as in the previous projects, just remove the two buttons and leave the joystick.
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PING PONG SINGLE PLAYER
Advanced
In the previous project, you learned how to build a game console with a joystick only. Because there is not always an opponent at hand, you can play against a micro computer that will be more than an equal opponent.
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SHOOTING DOWN THE DICE
Advanced
In this project you will be able to build a console that you will use for racing games and shooters. We replaced the joystick with a potentiometer, which changes its internal resistance by turning and can thus be used for direct control. You can attach a steering wheel to the potentiometer which will give you a more realistic experience.
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SPACE SHOOTER
Advanced
In this project you will be able to build a console that you will use for racing games and shooters. The circuit remains the same as in the previous project. Now you can go on a space mission and save the whole world.
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RACING GAME I.
Advanced
Build a racing simulator. You can steer using a potentiometer (it changes its internal resistance by turning and can thus be used for direct control) on which you place a plastic steering wheel.
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RACING GAME II.
Advanced
Build a racing simulator. You can steer using a potentiometer (it changes its internal resistance by turning and can thus be used for direct control) on which you place a plastic steering wheel.
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SNAKE
Advanced
Build a simple game console. You only have two buttons, but as usual, that is enough to control most funny games, such as the classic snake. In this game you have only one task, and that is to achieve the highest possible score.
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JUMPING WITH BOFFIN
Advanced
Build a simple game console. You only have two buttons, but as usual, that is enough to control most funny games. This game has been personally prepared for you by the Boffin figure, and your task is to bring the figure to the end of a thorny path along which you will run, having to jump over specific obstacles.
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LOGIC GAME WITH BOFFIN
Advanced
Build a simple game console. You only have two buttons, but as usual, that is enough to control most funny games. This game is mainly about your knowledge. Boffin will ask you tricky questions and it is up to you how fast you answer them and how far you progress in this game.
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KITCHEN TIMER
Advanced
Make your mother or partner happy and put a kitchen timer in her kitchen so that she can bake something good for you.
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CLOCK
Advanced
There are many things you can do with a microcomputer, but how about doing something to help you get up for school or work? Build a simple clock with an alarm function. As soon as you set the alarm, put it as far away from your bed as possible so that you can be sure that you will not destroy the connection in the morning and that you will get up.
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PASS COUNTER
Advanced
Assemble a pass counter using a LED and a photoresistor. The whole principle is simple – if an object or person gets between the diode and the photoresistor, the LED light does not shine on the photoresistor, which is interpreted as a circuit interruption. You can place this circuit, for example, on the door of a refrigerator and find out how many times a day it has opened. I believe that the number will surprise you.
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