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Snap Circuits®

Project Manuals 2

Preface 2

PART I (All models)

Chapter 1: Basic Components& Circuits 3

1-1 Electricity 41-2 Wires 51-3 Batteries 61-4 The Switch 71-5 The Lamp 7, 81-6 The Base Grid 8-101-7 Series and Parallel Circuits 10-121-8 Short Circuits 131-9 Solder 131-10 Schematics 14Summary & Quiz 15

Chapter 2: Motors &Electricity 16

2-1 Motors 17, 182-2 Motor Circuits 18-212-3 Fuses 212-4 Your Electric Company 222-5 Static Electricity 232-6 Types of Lamps 242-7 Types of Switches 242-8 Electricians 24Summary & Quiz 25

Chapter 3: Resistance 263-1 Resistors 273-2 LEDs 27-293-3 Resistors in Series & Parallel 29, 303-4 Resistance 313-5 The Adjustable Resistor 31, 323-6 The Photo Resistor 32, 333-7 Resistance of Water 33, 343-8 Introduction to Logic 343-9 Digital Electronics 35Summary & Quiz 36

Chapter 4: Capacitors 374-1 Capacitors 38-404-2 Capacitor Circuits 40, 414-3 Capacitors in Series& Parallel 42, 43Summary & Quiz 43

Chapter 5: Transistors 445-1 More About LEDs 455-2 Transistors 465-3 Transistor Basics 47, 485-4 More Transistor Circuits 48-505-5 Human Transistor 515-6 Motor as Generator 515-7 Microphone 52Summary & Quiz 53

Chapter 6: Oscillators &Electronic Sound 54

6-1 Electronic Sound 54, 556-2 Oscillators 56, 576-3 Whistle Chip 576-4 Oscillator Circuits 58-60Summary & Quiz 60

Chapter 7:Integrated Circuits 61

7-1 The ICs in Snap Circuits® 62, 637-2 Description of all projectsusing ICs 64-66Summary & Quiz 67

Chapter 8: Electromagnetism& Radio 68

8-1 AC 698-2 Transformers 69, 708-3 Inductance & Antennas 70, 718-4 Radio 71, 728-5 Radio Circuits 72, 73Summary & Quiz 73

PART II(only used in Models SC-500R & SC-750R)

Chapter 9:Meters, Transformers& FM Radio 74

9-1 Meters 759-2 Meter Circuits 76-789-3 More About Transformers 78-809-4 Transformers in Oscillators 80-839-5 More About FM Radio 83, 849-6 When Wires are not Wires 84Summary & Quiz 85

Chapter 10:Diodes & Applications 86

10-1 More About Diodes 86-8910-2 Digital Displays 89-9110-3 Recording IC 92, 93Summary & Quiz 94

Chapter 11:Electronic Switches 95

11-1 Relays 95-9911-2 Silicon Controlled Rectifiers 99-10111-3 Voltage Dividers& Current Dividers 101, 102Summary & Quiz 102

PART III (only used in Model SC-750R)

Chapter 12:Electromagnetism 103

12-1 Magnetism 10412-2 An Electronic Magnet 10512-3 Magnetic Fields 106-10912-4 Electromagnet Oscillators 109, 11012-5 The Anti-Capacitor 110, 11112-6 More About Motors 112Summary & Quiz 113

Chapter 13: Sun Power 11413-1 Born in the Space Program 114, 11513-2 How Your Solar Cell Works 115-11713-3 More Solar Cell Circuits 117-11913-4 Our Solar Future 120Summary & Quiz 121

Chapter 14: More Circuits &New Ways to Look at Them 122

14-1 Vibration Switch 12214-2 Other Applications 125, 12614-3 The Snap Circuits®

Computer Interface 127-130Summary & Quiz 131

Summary ofComponents 132-134

Definition of Terms 135-137

For Further Reading 137

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The Snap Circuits® project manuals include lots of usefulinformation in addition to the projects themselves, aslisted below. The project manuals summarize much ofthe lesson in the Student Guide while addingtroubleshooting information.

The Model SC-300R contains two project manuals, theModel SC-500R contains three, and the Model SC-750Rcontains four. Note that the parts lists and informationabout the parts is spread across all the project manuals.The DO’s and DON’Ts of Building Circuits section of themanual with the highest numbered projects is the mostthorough.

Much of the text in all chapters is color-coded green andblue so that instructors can easily adapt the coursebased on the skills and interests of the students. Theorange boxes are more advanced material while thebrown boxes are considered additional/backgroundmaterial, either can generally be omitted without asignificant impact on the course.

First Project Manual contains:1. Parts List (partial, continued in other manuals)

2. How To Use It - brief description of how to makeconnections and understand the circuit drawings.

3. About Your Snap Circuits® Parts - brief descriptionof what each component does (partial, continued inother manuals).

4. DO’s and DON’Ts of Building Circuits - brief butimportant guidelines for building circuits (additionalguidelines are in other manuals).

5. Basic & Advanced Troubleshooting - systematictesting procedure for identifying damaged parts(continued in other manuals).

6. Project Listing

7. Projects 1-101

Other Project Manuals contain:1. Parts List (partial, continued from first manual)

2. How To Use It - brief description of how to makeconnections and understand the circuit drawings.

3. About Your Snap Circuits® Parts - brief descriptionof what each component does (partial, continuedfrom first manual).

4. DO’s and DON’Ts of Building Circuits - brief butimportant guidelines for building circuits.

5. Basic & Advanced Troubleshooting - systematictesting procedure for identifying damaged parts(continued from first manual).

6. Project Listing

7. Projects 102 and up

This booklet is an introduction to the exciting worldof electronics. Following the “Learn by Doing®”concept, electronics will be easy to understand byusing Snap Circuits® to actually build circuits as youlearn about them. This booklet emphasizes thepractical applications of electronics, withoutbogging down in mathematics. Why learn about electronics? Electronics plays animportant and increasing role in our everyday lives,

and so some basic knowledge of it is good foreveryone. Learning about it teaches how to doscientific investigation, and the projects developbasic skills needed in today's world. The first pages of the Snap Circuits® projectmanuals contain a brief description of the parts inSnap Circuits®, along with brief guidelines forbuilding circuits.

• If you have the SC-300R version, you may wish to purchase the UC-50 Upgrade Kit to continue to Part IIof this manual. The UC-70 Upgrade Kit will allow you to continue to Parts II & III of this manual.

• If you have the SC-500R version, you may wish to purchase the UC-80 Upgrade Kit to continue to Part IIIof this manual. Upgrade kits can be purchased online: www.snapcircuits.net

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What is electricity? Nobody really knows. We onlyknow how to produce it, understand its properties,and how to control it. It can be created by chemistry(batteries), magnetism (generators), light (solarcells), friction (rubbing a sweater), and pressure(piezoelectric crystals).

Electricity is energy that can be used tosave us effort (electric toothbrushes anddishwashers), heat things (electric heaters andmicrowave ovens), make light (light bulbs), andsend information (radio and television). Butelectricity can also be dangerous if abused (electricshock).

Batteries

Generator

Solar Cells

ElectricToothbrush

Dishwasher

MicrowaveOven

ElectricHeaterLight Bulb

Radio

Television

In this section you will learn about basic electricalcomponents and circuits. By building circuits usingSnap Circuits®, you will begin to understand theelectrical world. Electric Shock

Rubbing a Sweater

PiezoelectricCrystal

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In this chapter you will learn about generators andmotors. A generator uses mechanical motion tocreate electricity and a motor uses electricity tocreate mechanical motion. This statement may notseem important to you but it is actually the foundationof our present society. Nearly all of the electricityused in our world is produced at enormousgenerators driven by steam or water pressure. Wires

are used to efficiently transport thisenergy to homes and businesses where it isused. Motors convert the electricity back intomechanical form to drive machinery andappliances. The most important aspect ofelectricity in our society - more important than thebenefits of the Internet - is that it allows energy tobe easily transported over distances.

Note that “distances” includes not just largedistances but also tiny distances. Try to imagine aplumbing structure of the same complexity as thecircuitry inside a portable radio - it would have to be

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Water flowing under pressure in a pipe or a fast-moving stream can be used to turn apaddlewheel. If the paddlewheel was linked to afan blade then you could use the water pressureto turn the fan, perhaps to cool yourself on a hotday. If the water was flowing very fast due to highpressure, then you could get the fan moving fastenough it might create a strong airflow like apropeller on a plane.

A similar thing happens in a motor, with electricityinstead of water. A motor converts electricity intomechanical motion.

Snap Circuits® includes one motor, shown here with itssymbol. Snap Circuits® also includes a fan, which isused with the motor. An electric current in the motor willturn the shaft and the motor blades, and the fan bladeif it is on the motor.

How does electricity turn the shaft in the motor? The answer ismagnetism. Electricity is closely related to magnetism, and anelectric current flowing in a wire has a magnetic field similar to thatof a very, very tiny magnet. Inside the motor is a coil of wire withmany loops, if a large electric current flows through the loops themagnetic effects become concentrated enough to move a smallmagnet. The motor also has a small magnet, on a shaft. Whenelectricity moves the magnet, the shaft spins. If the fan is on themotor shaft then its blades will create airflow.

Magnet

Electromagnet

Shaft

Power Contacts

Consider this circuit (which is project 2):

When the switch is on, current flowsfrom the batteries through the motormaking it spin. The fan blades willforce air to move past the motor. Becareful not to touch the motor or fanwhen it is spinning at high speed.

Motor Symbol Motor (M1) Fan Blade

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Motors are used in all electric powered equipmentrequiring rotary motion, such as a cordless drill,electric toothbrush, and toy trains. An electricmotor is much easier to control than gas or dieselengines.

The electromagnetic effect described above alsoworks in reverse - spinning a magnet next to a coilof wire will produce an electric current in that wire.This is what happens in a generator, which usesmechanical motion to create electricity. In anelectric power plant, high-pressure water (from adam) or steam (heated by burning oil or coal) isused to spin a paddlewheel linked to magnets. Themagnets create an electric current in a coil of wire,which is used to power our cities.

In theory, you could connect your Snap Circuits®

motor directly to the 2.5V lamp and spin the fanblade with your fingers to light the lamp. In reality,it would be impossible for you to spin the motor fast

enough to produce enough current to get even aglimmer of light from the lamp.

To summarize, a generator uses mechanicalmotion to create electricity and a motor useselectricity to create mechanical motion.

MagnetCoil of Wire

Water Flow

Consider this circuit (which is project 5):

If the switch is on, the lamp will light and the fan willspin. The lamp and motor are in series, so the voltagefrom the batteries will get divided between them. Inthis circuit more of the voltage will be used at thelamp than at the motor. If the fan was not on the motor then the motorwould spin much faster but the lamp would not beas bright. The motor needs more voltage to spinfaster, so there is less voltage available to light thelamp.

Consider this circuit (which is project 6):

If the switch is on, the lamp will light and the fan willspin. This circuit has the lamp and motor inparallel, so the full voltage from the batteries wouldbe applied to both. So the fan would spin fasterthan for the circuit in project 5, which divided thebattery voltage between the lamp and motor.

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This part acts like a resistor that changes whenexposed to sound waves. This change inresistance will change the current through acircuit when sound waves apply pressure to itssurface. This action is similar to squeezing agarden hose and watching the water through itdecrease. The side with a “+” mark should alwaysbe placed toward the higher voltage.

Consider this circuit (which is project 273):

If you blow on the microphone, the LED brightnesschanges.

Consider this circuit (which is project 109):

Current flows through the 100KΩ resistor to turn onthe transistors and lamp. Blowing on themicrophone diverts current away from thetransistors and the lamp shuts off briefly.

Microphone Symbol

Microphone (X1)

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Chapter 5 Practice Problems1. In a transistor, the ____________ will have the most

current flowing through it.A. Emitter C. CollectorB. Base D. Vacuum tube

2. The following are advantages of transistors except . . .A. they can be miniaturized.B. they can amplify signals.C. their resistance can be changed by adjusting

the voltage in the circuit.D. it has zero resistance under certain operating

conditions.

3. Which circuit will light the LED?

All three.

4. Which circuit will light the lamp?

All three.

A

Answers: 1. A, 2. D, 3. B, 4. B

B

C

D

D

A B

C

Summary of Chapter 5:

1. The resistance of semiconductors may becontrolled by their operating conditions.

2. Semiconductors have a turn-on level (0.7Vfor silicon), after which the resistancebecomes very low in one direction.

3. Transistors have three connection points,called the emitter, base, and collector.

4. The transistor is a current amplifier, it usesa small amount of current to control a largeamount of current.

5. When a small current flows into the baseand out of the emitter in an NPN transistor,a larger current flows into the collector andout of the emitter. In a PNP transistor,current flows into the emitter and out of thebase and collector.

6. A microphone is a resistor that changeswhen exposed to sound. This change inresistance will change the current througha circuit when sound waves apply pressureto its surface.

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Your electronic stereo and radio are powered byelectricity and play music, so how does electricitymake sound? In this chapter you will find out. Youwill also learn about oscillator circuits, and buildsome simple ones using snap circuits.

Oscillators are used in all radios, TVs, and electroniccommunications equipment to set the transmitter orreceiver frequency. Different types of oscillators areused as timing references in computers and almostall complex electronic products. It would be hard to

count how many oscillator circuits are inyour home since there are different typesand they can be hard to identify.

Oscillators can be among the most difficultelectronic circuits to design, due to the tightrequirements placed on them by today’scommunications technology. They usually don’t usea lot of components, but the way they are arranged iscomplex and often difficult to analyze. But they arefun to learn about.

A speaker can only create sound from aCHANGING electrical signal, for unchangingelectrical signals it acts like an 8Ω resistor. (Anunchanging signal does not cause the magnet inthe speaker to move, so no sound waves arecreated).

For example, compare these two mini-circuits:

When you press or release the press switch, youhear static from the speaker. When you hold thepress switch down, the speaker is silent and thelamp is not as bright as the circuit without it.

Snap Circuits® includes a speaker:

A speaker converts electricity into sound. It doesthis by using the energy of a changing electricalsignal to create mechanical vibrations (using acoil and magnet similar to that in the motor).These vibrations create variations in air pressure,called sound waves, which travel across the room.You “hear” sound when your ears feel these airpressure variations.

Coil of WireVibrating Magnet

(voice coil)

Sound Waves

SpeakerSymbol

Speaker (SP)

Suspension

BasketDiaphragm

Spider

Voice Coil

+–

Magnet

Dust Cover

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Integrated circuits are used in most electronicproducts; there are probably more than a thousandthroughout your home. The range and uses of ICsavailable is hard to imagine.

Although Snap Circuits® contains only five ICmodules, more than half of the projects use at leastone. There are many more examples of using the

parts described in the preceding chapters, such asthe microphone and photoresistor. Here is a shortdescription of each, the project manuals explainthem in more detail:

Suggested Projects: 38, 51, 58, 61, 81, 83,119, 158, 178, 202, 237, 238, 242, 245, 250,255, 272, and 297.

Project 3: Uses the music IC with thewhistle chip as a vibrationsensor.

Project 4: Uses the music IC with thewhistle chip as a vibrationsensor.

Project 10: Combines the sound effects ofthe music and space war ICs.

Project 15: Uses the music IC as a doorbell.

Project 16: Uses the music IC as an alarm.

Project 17: Makes one of the alarm IC sirensounds.

Project 18: Makes one of the alarm IC sirensounds.

Project 19: This is the standard circuit usingthe space war IC.

Projects 20-21: This uses the photoresistor withthe space war IC.

Projects 22-26: Uses the photoresistor andmusic IC to control the alarm ICsiren sounds.

Projects 27-31: Uses the whistle chip and musicIC to control the alarm IC sirensounds.

Projects 32-33: Uses the whistle chip and musicIC to control the space war IC.

Projects 34-35: Uses the motor and music IC tocontrol the space war IC.

Projects 36-37: Uses the motor and alarm IC tocontrol the space war IC.

Projects 38-39: Uses the alarm IC to controlthe music IC. An example ofa periodic (repeating) signal.

Projects 40-44: Uses the motor and music ICto control the alarm IC sirensounds.

Project 45: Uses the photoresistor,music IC, and alarm IC tocontrol an LED.

Project 46: Makes one of the alarm ICsiren sounds.

Project 51: The alarm IC uses thephotoresistor to sensereflections from a lamp.

Project 52: The alarm IC uses thephotoresistor to sensereflections from a lamp.

Project 53: Sound and light controlled bythe alarm IC.

Project 54: Uses the alarm IC to controlthe space war IC.

Project 58: Uses the music IC to controlthe alarm IC, with additionalcontrol from the whistle chipand photoresistor. Alsoshows how some parts canbe used as wires.

Project 60: Uses the alarm and spacewar ICs to control the motor.

Projects 61-65: The alarm IC makes soundwith the whistle chip;loudness is controlled by thephotoresistor.

Project 66: Uses the space war IC in amind-reading game.

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Consider this circuit: The whistle chip makes a sound like a drippingfaucet; use the adjustable resistor to make it dripfaster or slower. Although the sound may seem tobe nearly continuous, the transistor is onlyactivating for about 1/100 second for each drip.

Other Snap Circuits® using the transformer in an oscillator: 347-351, 399-408, 419-424, 447-452, and 458-465.

In sections 8-4 and 8-5 you learned about AM (Amplitude Modulation) and FM (Frequency Modulation) radio,and built some AM radio circuits. You may want to review those sections now.

Snap Circuits® includes an FM module, whichcontains an integrated FM radio circuit. The insidelooks like this:

Its actual schematic looks like this:

This circuit is actually much more complex than itappears here, since it is built around an integratedradio circuit. A schematic of the circuitry within thispart would be too large to show here, but this blockdiagram gives a summary of it:

Its Snap Circuits® connections are like this:

The antenna ( ) is a loose wire that should alwaysbe left unconnected and spread out for best radioreception.

Antenna (A1)

Antenna Symbol

(+)OUT(–)

FM Module:(+) - power from batteries(–) - power return to batteriesT - tune upR - resetOUT - output connection

or

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Consider this circuit (which is project 307, or avariation of it):

Turn on the switch (S1) and press the R button.The R button resets the frequency to 88MHz (thebeginning of the FM band). Now press the T buttonand the FM module scans for an available radiostation.

When a station is found, it locks on to it and youhear it on the speaker. Adjust the volume using theadjustable resistor (RV). Press the T button againfor the next radio station. The module will scan upto 108MHz (the end of the FM band), and stop.

Snap Circuits® project 316 is a variant of this circuit without a volume adjustment. Project 306 is a variant ofthe AM radio circuits discussed in section 8-5.

In section 8-3 you learned that the AM antenna(Snap Circuits® part A1) has inductance due to itsmagnetic affects at AM radio frequencies, and thatat low frequencies it acts like an ordinary wire. AtFM radio frequencies (88-108MHz) a long wire hasenough inductance to become an antenna, andone is used like this on the Snap Circuits® FMmodule.

The entire FM radio circuit comes as a completemodule, instead of coming as individual parts thatyou could build and experiment with. This wasnecessary because at FM frequencies the snapwires connecting your parts on the base grid arelong enough to have enough inductance to changethe performance of the circuit. The output signal tothe power amplifier IC (U4) is at much lowerfrequency (audio, 300-3000Hz).

At microwave frequencies (>1000MHz) circuitdesign becomes very complicated since everycomponent or interconnection has some amount ofcapacitance and inductance. Components and thespaces between them must be as small aspossible for circuits to perform properly.

AM Antenna (A1)

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If you don’t have a compass, you can make oneusing metal paperclips. Slide two paperclipstogether, using their loops.

Hold the paperclips just above theelectromagnet, without them touching the ironcore rod. Press the switch and watch how thelower paperclip is attracted to the rod. It willpoint toward it like a compass.

Snap Circuits® includes some paperclips, use theelectromagnet to pick up some. Release the switchto drop them.

Use the paperclips to pick up things.

The magnetic field created by a magnet occurs ina loop. You can see this using the electromagnetand paperclips:

Materials made of iron concentrate their magneticeffects at both ends. The center of the material ismagnetically neutral because the attraction fromeach end is the same.

The magnetic field created by the electromagnetworks the same way. It is strongest at both endsbut neutral in the center. But the electromagnet ishollow - so iron at one end will be sucked into themiddle.

The 2-snaps aresnapped aroundthe paperclip.

Magnet(not included)

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Use the same simple circuit but lay theelectromagnet on its side with the iron core rodsticking out about halfway. Press the switch to seethe rod get sucked into the center.

A lighter iron object will move better. Straighten outa paperclip, and bend it in half.

Place it on one side of the electromagnet andpress the switch to see it sucked inside. Hold theswitch and gently pull it out to see how muchsuction the electromagnet has.

Try sucking in other thin iron objects, like nails.

This circuit will use electromagnetism to defygravity. Mount the electromagnet on the base gridusing this circuit (which is project 664).

Bend a paperclip as shown, and drop it into theelectromagnet. Press the switch to suspend thepaperclip in mid-air.

Add two more 1-snaps under the electromagnet tomake it higher, and try it again.

You can also make your electromagnet towershorter (one 1-snap on each side) and place theiron core rod under it. Then you can suspend therod in mid-air.

Straighten andbend paperclip

Rod

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All of the preceding circuits used electricity tocreate magnetism. But most electricity is madeusing magnetism, by steam-driven generators in

power plants operated by your electric company.These spin a magnet to create a current in a wire.

If you have a magnet available (Snap Circuits®

does not include one), consider this mini-circuit:

Set the meter (M2) to the LOW (or 10mA) settingand place the iron core rod in the electromagnet.This circuit has no batteries and won’t do anythingby itself.

Move your magnet up and down next to theelectromagnet. The meter deflects to show thatyou created an electrical current in the circuit.

Snap Circuits® will now give you a more dramaticdemonstration of how electricity can control magneticfields in ways ordinary magnets can’t. Consider thiscircuit (which is project 669 or a variation of it):

Straighten and bend a paperclip as shown, anddrop it into the electromagnet. Set the adjustableresistor (RV) control lever to the right, and thepaperclip gets sucked into the electromagnet. Setthe lever to the left and it falls. Now slowly slide thelever until you find a spot where the paperclip isbouncing up and down!

The transistors make an oscillator that turns theelectromagnet current on and off. If the oscillatorfrequency is just right, the paperclip bounces upand down.

For another demon-stration, replace the bentpaperclip with the ironcore rod. Slide twopaperclips together usingtheir loops and dangleone above the rod withouttouching it. Slide theadjustable resistor controllever around to see thelower paperclip vibrate asthe magnetic fieldchanges.

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Consider this circuit (which is project 666):

Set the meter to the LOW (or 10mA) scale anddrop a bent paperclip into the electromagnet.Move the adjustable resistor control lever to adjustthe height of the paperclip above the table. Themeter shows how the current changes as youadjust the paperclip height.

Coils of wire like those in the electromagnet,antenna, transformer, relay, and motor can storeelectricity in a magnetic field. Electricity is neededto set up the magnetic field, and is released intothe circuit when the magnetic field collapses. A coilof electricity is like a long garden hose – the waterdoesn’t start or stop immediately when you turn thewater on or off.

Coils store energy in a magnetic field whilecapacitors store energy as an electric chargeacross a material (an electric field). Coils andcapacitors have opposite effects on a circuit, but itdepends on their construction and the frequency.

Other paperclip vibration circuits: 667, 668, and 670-682.

Large hose filledwith water

Coil

Capacitorstoringelectricityacrossdielectricmaterial

Clothingstoring static

electricity

Coil storingstatic in

magnetic field

Magneticfield

Consider this circuit (which is project 683):

Connect the electromagnet to points A & B usingthe jumper wires. Hold the electromagnet oneinch above the table and drop a bent paperclip intoit. Slide the adjustable resistor control lever aroundand watch the paperclip vibrate. Covering thephotoresistor (RP) stops the vibration. You cancontrol the height and frequency of the vibration.

Replace the bent paperclip with theiron core rod. Slide two paperclipstogether using their loops anddangle one above the rod withouttouching it. Slide the adjustableresistor control lever around to seethe lower paperclip vibrate as themagnetic field changes.

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Consider this circuit (which is project 535 in most manuals):

Turn on the slide switch (S1) and the familiar sirensound is badly distorted. The distortion occursbecause the electromagnet opposes some of thesiren frequencies more than others. You can testit with and without the iron core rod.

Now push the press switch (S2) and the sirensounds more normal. The 0.1μF capacitorcounteracts the electromagnet effects.

Now use a jumper wire to connect points A & B,and test the effects using a different alarm sound.Then move the jumper wire to points B & C, thenA & D.

The electromagnet is a long wire wrapped in a coil.For constant or slowly changing voltages, itsmagnetic properties can be ignored and theresistance of the wire is about 25 ohms. Considerthis circuit (which is project 658):

The iron core rod isn’t needed, because the voltagechanges slowly. Notice how lamp L2 takes longerto get bright while lamp L1 gets bright initially butbecomes less bright as L2 turns on. Why?

Incandescent lamps like these are made with ahigh-resistance filament that gets hot enough toglow. The current is higher when a lamp is coldthan when the filament has heated up (and hasmore resistance). This is why bulbs only burn outwhen you first turn on the light.Lamps L1 and L2 have low resistance at firstbecause the filaments are cold. The resistanceincreases as the filaments heat up, and L1’sfilament heats up faster than L2’s. The resistance of the electromagnet lowers thecurrent, so the filaments don’t heat up as fast.Compare this circuit to project 152, which will turnon the lamps faster.Snap Circuits® projects 656 and 657 are variationsof project 658.

Consider this circuit (which is project 531 in most manuals):

Place the iron core rod in the electromagnet andturn the switch on and off. When the switch isturned off the energy from the electromagnet’smagnetic field discharges through the LED.

If you remove the iron core rod then the LED willnot flash as brightly, because less energy isstored in the magnetic field.

Snap Circuits® projects 530, 532, 533, and 534are similar circuits showing that the antenna,transformer, and relay store energy in magneticfields. Project 529 shows the fan blade storingenergy as mechanical motion.

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Here are some highlights from projects PC1-PC73:

Project PC1: Shows that a tone consists of onestrong frequency and many multiples of it at loweramplitudes. It also shows that adding capacitanceto an oscillator (lowering the tone of the sound)widens the spacing in oscilloscope mode andlowers the frequency spacing in FFT mode.

Projects PC4-PC7: Shows how the alarm ICmakes different siren sounds by changingcharacteristics of the signal.

Project PC10: This is an example of modulation(see section 8-4) and filtering.

Project PC12: View the voice signal from a radio.

Project PC14: Shows what your voice looks like,and some sound patterns you can make.

Use Winscope to take a closer look at this circuit(project 523, which you studied in section 10-1):

Place the fan on the motor and turn on the slideswitch (S1). As the motor spins it connects/disconnects sets of electrical contacts that keepthe magnetic field from a coil spinning the shaft.This creates an electrical disturbance whichcrosses the transformer and moves the meter. Usethe Winscope settings shown here to view thedisturbance.

Push the pressswitch (S2) toconnect the 470μFcapacitor across themotor.This filters out mostof the disturbance,as you can see withWinscope (use thesame settings).

Now change Winscope to FFT mode and changethe horizontal scale to compare the frequencyspectrum. Press the switch to add the capacitor.This filters out most of the high frequency energyfrom the disturbance.

Press switchpressed, sameWinscope settings.

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Meter To measure how much current is flowing in a circuit.1

SC-500R &SC-750R only

Transformer Inductor used to change the AC voltage withoutwasting power.

FM Module Module containing an FM receiver and amplifiercircuit.

Diode Block current flow in one direction.

Recording IC Module to record and play music or talking.

Relay An electronic component that uses magnetism toopen or close a mechanical switch.

7-Segment A group of seven LEDs that can display one letter ornumber.

SCR A controlled diode used as an electronic switch.

Solar Cell Uses light to produce a voltage that can power acircuit.

Electromagnet Inductor that acts like a magnet when a current flowsthrough it.

Vibration Switch Connect or disconnect power to a circuit whenshaken.

Two-spring Socket Easy connection of other electrical components toSnap Circuits®.

Computer Interface View the electrical signals in a circuit.

1SC-500R &

SC-750R only

1SC-500R &

SC-750R only

1SC-500R &

SC-750R only

1SC-500R &

SC-750R only

1SC-500R &

SC-750R only

1SC-500R &

SC-750R only

1SC-500R &

SC-750R only

1SC-750R only

1SC-750R only

1SC-750R only

1SC-750R only

1SC-750R only

Additional / replacement parts may be ordered at www.snapcircuits.net or bycalling Elenco® at 847-541-3800.

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AC Common abbreviation foralternating current.

Alternating Current A current that is constantlychanging.

AM Amplitude modulation. Theamplitude of the radio signal isvaried depending on theinformation being sent.

Ampere (A) The unit of measure forelectric current.

Amplify To make larger.

Amplitude Strength or level of something.

Analogy A similarity in some ways.

Anode The side of a diode thatcurrent flows into.

Antenna Inductors used for sending orreceiving radio signals.

Audio Electrical energy representingvoice or music that can beheard by human ears.

Base One of the connection pointson a transistor.

Battery A device which uses achemical reaction to create anelectric charge across amaterial.

Blackout When part of a city is cut offfrom the power plantssupplying it with electricity.

Capacitance The ability to store electriccharge.

Capacitor An electrical component thatcan store electrical pressure(voltage) for periods of time.

Cathode The side of a diode thatcurrent flows out of.

Circuit An arrangement of electricalcomponents to do something.

Clockwise In the direction in which thehands of a clock rotate.

Coil A wire that is wound in aspiral.

Collector One of the connection pointson a transistor.

Color Code A method for markingresistors using colored bands.

Conductor A material that has lowelectrical resistance.

Counter-Clockwise Opposite the direction inwhich the hands of a clockrotate.

Current A measure of how fastelectricity is flowing in a wireor how fast water is flowing ina pipe.

DC Common abbreviation fordirect current.

Diaphragm A flexible wall.

Digital Circuit A wide range of circuits inwhich all inputs and outputshave only two states, such ashigh/low.

Digital Electronics Using a series of numbers torepresent an electrical signal.

Diode An electronic device thatallows current to flow in onlyone direction.

Direct Current A current that is constant andnot changing.

Disc Capacitor A type of capacitor that haslow capacitance and is usedmostly in high frequencycircuits.

Electric Charge An electrical attraction/repulsion between materials.

Electrical Power A measure of how muchenergy is moving in a wire.

Electricity An attraction and repulsionbetween sub-atomic particleswithin a material.

Electrolytic Capacitor A type of capacitor that hashigh capacitance and is usedmostly in low frequency circuits.It has polarity markings.

Electromagnetic Involving both electrical andmagnetic effects.

Electronics The science of electricity andits applications.

Emitter One of the connection pointson a transistor.

Farad, (F) The unit of measure forcapacitance.

Feedback To adjust the input tosomething based on what itsoutput is doing.

Filament A high-resistance wire used inincandescent light bulbs.

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Basic Electricity, 736 pages, ISBN 0-7906-1041-8, Sams 61041

Basic Electricity & DC Circuits, 928 pages, ISBN 0-7906-1072-8, Sams 61072

Basic Solid-State Electronics, 944 pages, ISBN 0-7906-1042-6, Sams 61042

Beginning Electronics Through Projects, 236 pages, ISBN 0-7506-9898-5, Sams 67102

Modern Electronics Soldering Techniques, 304 pages, ISBN 0-7906-1199-6, Sams 61199

Schematic Diagrams, 196 pages, ISBN 0-7906-1059-0, Sams 61059

Pitch The musical term forfrequency.

Polarity Markings indicating whichdirection a device is positionedin, usually (+) and (–).

Printed Circuit Board A board used for mountingelectrical components.Components are connectedusing metal traces “printed” onthe board instead of wires.

Receiver The device which is receivinga message (usually withradio).

Resistance The electrical friction betweenan electric current and thematerial it is flowing through.

Resistor Components used to controlthe flow of electricity in acircuit.

Schematic A drawing of an electricalcircuit that uses symbols forall the components.

Semiconductor A material that has moreresistance than conductorsbut less than insulators. It isused to construct diodes,transistors, and integratedcircuits.

Series Circuit When electrical componentsare connected one after theother.

Short Circuit When wires from differentparts of a circuit (or differentcircuits) connect accidentally.

Silicon The chemical element mostcommonly used as asemiconductor.

Solder A tin-lead metal that becomesa liquid when heated to above500OF. It makes a strongmounting that can withstandshocks.

Speaker A device which convertselectrical energy into sound.

Static Electricity A naturally occurring build-upof electrical charge betweenmaterials, usually at highvoltage.

Switch A device to connect (“closed”or “on”) or disconnect (“open”or “off”) wires in an electriccircuit.

Transformer A device which uses coils tochange the AC voltage andcurrent (increasing one whiledecreasing the other).

Transistor An electronic device that usesa small amount of current tocontrol a large amount ofcurrent.

Transmitter The device which is sending amessage (usually with radio).

Tungsten A highly resistive materialused in light bulbs.

Tuning Capacitor A capacitor whose value isvaried by rotating conductiveplates over a dielectric.

Voltage A measure of how strong anelectric charge differencebetween materials is.

Volts (V) The unit of measure for voltage.

Watt (W) The unit measure for electricalpower.

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Elenco® Electronics, Inc.150 Carpenter AvenueWheeling, IL 60090

(847) 541-3800Website: www.elenco.com

e-mail: elenco@elenco.com

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