1、 Go to: 101 - 200 CircuitsSee TALKING ELECTRONICS WEBSITEemail Colin Mitchell: .auINTRODUCTIONThis e-book contains 100 transistor circuits. The second part of this e-book will contain a further 100 circuits. Most of them can be made with components from your “junk box“ and hopefully you can put them
2、 together in less than an hour. The idea of this book is to get you into the fun of putting things together and theres nothing more rewarding than seeing something work.Its amazing what you can do with a few transistors and some connecting components. And this is the place to start. Most of the circ
3、uits are “stand-alone“ and produce a result with as little as 5 components. We have even provided a simple way to produce your own speaker transformer by winding turns on a piece of ferrite rod. Many components can be obtained from transistor radios, toys and other pieces of discarded equipment you
4、will find all over the place. To save space we have not provided lengthy explanations of how the circuits work. This has already been covered in TALKING ELECTRONICS Basic Electronics Course, and can be obtained on a CD for $10.00 (posted to anywhere in the world) See Talking Electronics website for
5、more details: http:/Transistor data is at the back of this book and a transistor tester circuit is also provided. There are lots of categories and I am sure many of the circuits will be new to you, because some of them have been designed recently by me. Basically there are two types of transistor: P
6、NP and NPN. All you have to do is identify the leads of an unknown device and you can build almost anything. You have a choice of building a circuit “in the air,“ or using an experimenter board (solderless breadboard) or a matrix board or even a homemade printed circuit board. The choice is up to yo
7、u but the idea is to keep the cost to a minimum - so dont buy anything expensive.If you take parts from old equipment it will be best to solder them together “in the air“ (as they will not be suitable for placing on a solderless breadboard as the leads will be bent and very short). This way they can
8、 be re-used again and again. No matter what you do, I know you will be keen to hear some of the “noisy“ circuits in operation. Before you start, the home-made Speaker Transformer project and Transistor Tester are the first things you should look at. If you are starting in electronics, see the Worlds
9、 Simplest Circuit. It shows how a transistor works and three transistors in the 6 Million Gain project will detect microscopic levels of static electricity! You can look through the Index but the names of the projects dont give you a full description of what they do. You need to look at everything.
10、And I am sure you will.KIT OF PARTSTalking Electronics supplies a kit of parts that can be used to build the majority of the circuits in this book. The kit costs $15.00 plus postage.In many cases, a resistor or capacitor not in the kit, can be created by putting two resistors or capacitors in series
11、 or parallel or the next higher or lower value can be used. Dont think transistor technology is obsolete. Many complex circuits have one or more transistors to act as buffers, amplifiers or to connect one block to another. It is absolutely essential to understand this area of electronics if you want
12、 to carry out design-work or build a simple circuit to carry out a task.CONTENTSAmmeter 0-1A Automatic Garden LightAutomatic LightBench Power SupplyResistor Colour CodeRobo RollerRobotRobot Man - Multivibrator Boom Gate LightsBoxesBuck Converter for LEDs 48mABuck Converter for LEDs 170mABuck Convert
13、er for LEDs 210mACable TracerClock - Make Time FlyColpitts OscillatorConstant Current SourceContinuity TesterDancing FlowerDoor-Knob AlarmDynamic Microphone AmplifierElectronic DrumsFog HornFRED PhotopopperGold DetectorGuitar FuzzHartley OscillatorHeads or TailsHearing Aid Constant VolumeHearing Aid
14、 Push-Pull OutputHearing Aid 1.5v SupplyHee Haw SirenIC RadioLED Detects LightLED Flasher 1-TransistorLED Torch with Adj BrightnessLED Torch with 1.5v SupplyLie DetectorLight Alarm-1Light Alarm-2Light Alarm-3Light Extender for CarsListener - phone amplifierLogic Probe - SimpleLogic Probe with PulseM
15、ake Time Fly!Making 0-1A AmmeterMetal DetectorMicrophone Pre-amplifierMotor Speed ControllerMovement DetectorMultimeter - Voltage of Bench SupplySchmitt TriggerSCR with TransistorsSecond Simplest CircuitSignal by-passSignal InjectorSimple Logic ProbeSiren Solar EngineSolar Engine Type-3Solar Photovo
16、reSound to LightSound Triggered LEDSpeaker TransformerSpy AmplifierStrength TesterSun Eater-1Sun Eater-1ASuper EarTicking BombTouch SwitchTrain ThrottleTransistor PinoutsTransistor Tester-1Transistor Tester-2Trickle Charger 12vWalkie TalkieWalkie Talkie with LM386 Walkie Talkie - 5 Tr - circuit 1Wal
17、kie Talkie - 5 Tr- circuit 2Worlds Simplest CircuitWhite LED FlasherWhite LED with Adj BrightnessWhite Line FollowerZener Diode (making)0-1A Ammeter1.5v to 9v Inverter5 LED Chaser5 Transistor Radio6 Million Gain 6 to 12 watt Fluoro Inverter12v Relay on 6v12v Trickle Charger20watt Fluoro Inverter27MH
18、z Door PhoneMusic to Colour On-Off via push ButtonsPhaser Gun Phone AlertPhone Tape-1Phone Tape-2Phone Transmitter-1Phone Transmitter-2Phase-shift Oscillator27MHz Transmitter27MHz Transmitter - no Xtal27MHz Transmitter-Sq Wave27MHz Transmitter-2 Ch27MHz Transmitter-4 Ch27MHz Receiver27MHz Receiver-2
19、303MHz TransmitterRESISTOR COLOUR CODESee resistors from 0.22ohm to 22M in full colour at end of book and another resistor table A two-worm reduction gearbox producing a reduction of 12:1 and 12:1 = 144:1 The gears are in the correct positions to produce the reduction.BOXES FOR PROJECTSOne of the mo
20、st difficult things to find is a box for a project. Look in your local “junk“ shop, $2.00 shop, fishing shop, and toy shop. And in the medical section, for handy boxes. Its surprising where you will find an ideal box. The photo shows a suitable box for a Logic Probe or other design. It is a toothbru
21、sh box. The egg shaped box holds “Tic Tac“ mouth sweeteners and the two worm reduction twists a “Chuppa Chub.“ It cost less than $4.00 and the equivalent reduction in a hobby shop costs up to $16.00! to IndexThe speaker transformer is made by winding 50 turns of 0.25mm wire on a small length of 10mm
22、 dia ferrite rod. The size and length of the rod does not matter - it is just the number of turns that makes the transformer work. This is called the secondary winding. The primary winding is made by winding 300 turns of 0.01mm wire (this is very fine wire) over the secondary and ending with a loop
23、of wire we call the centre tap. Wind another 300 turns and this completes the transformer.It does not matter which end of the secondary is connected to the top of the speaker. It does not matter which end of the primary is connected to the collector of the transistor in the circuits in this book.to
24、IndexSUPER EARThis circuit is a very sensitive 3-transistor amplifier using a speaker transformer. This can be wound on a short length of ferrite rod as show above or 150 turns on a 10mH choke. The biasing of the middle transistor is set for 3v supply. The second and third transistors are not turned
25、 on during idle conditions and the quiescent current is just 5mA. The project is ideal for listening to conversations or TV etc in another room with long leads connecting the microphone to the amplifier.to IndexTRANSISTOR TESTER-1CIRCUITThe 10mH choke with 150 turns for the secondaryTRANSISTOR TESTE
26、R - 1Transistor Tester - 1 project will test all types of transistors including Darlington and power. The circuit is set to test NPN types. To test PNP types, connect the 9v battery around the other way at points A and B. The transformer in the photo is a 10mH choke with 150 turns of 0.01mm wire wou
27、nd over the 10mH winding. The two original pins (with the red and black leads) go to the primary winding and the fine wires are called the Sec. Connect the transformer either way in the circuit and if it does not work, reverse either the primary or secondary (but not both).Almost any transformer wil
28、l work and any speaker will be suitable.If you use the speaker transformer described in theHome Made Speaker Transformer article, use one-side of the primary.to IndexTRANSISTOR TESTER - 2Here is another transistor tester.This is basically a high gain amplifier with feedback that causes the LED to fl
29、ash at a rate determined by the 10u and 330k resistor. Remove one of the transistors and insert the unknown transistor. When it is NPN with the pins as shown in the photo, the LED will flash. To turn the unit off, remove one of the transistors.to IndexWORLDS SIMPLEST CIRCUITThis is the simplest circ
30、uit you can get. Any NPN transistor can be used. Connect the LED, 220 ohm resistor and transistor as shown in the photo. Touch the top point with two fingers of one hand and the lower point withfingers of the other hand and squeeze. The LED will turn on brighter when you squeeze harder. Your body ha
31、s resistance and when a voltage is present, current will flow though your body (fingers). The transistor is amplifying the current through your fingers about 200 times and this is enough to illuminate the LED.to IndexSECOND SIMPLEST CIRCUITThis the second simplest circuit in the world. A second tran
32、sistor has been added in place of your fingers. This transistor has a gain of about 200 and when you touch the points shown on the diagram, the LED will illuminate with the slightest touch. The transistor has amplified the current (through your fingers) about 200 times.to Index6 MILLION GAIN!This ci
33、rcuit is so sensitive it will detect “mains hum.“ Simply move it across any wall and it will detect where the mains cable is located. It has a gain of about 200 x 200 x 200 = 6,000,000 and will also detect static electricity and the presence of your hand without any direct contact. You will be amaze
34、d what it detects! There is static electricity EVERYWHERE! The input of this circuit is classified as very high impedance.to IndexThe circuit uses a flashing LED to flash a super-bright 20,000mcd white LEDLED FLASHER WITH ONE TRANSISTOR!This is a novel flasher circuit using a single driver transisto
35、r that takes its flash-rate from a flashing LED. The flasher in the photo is 3mm. An ordinary LED will not work. The flash rate cannot be altered by the brightness of the high-bright white LED can be adjusted by altering the 1k resistor across the 100u electrolytic to 4k7 or 10k. The 1k resistor dis
36、charges the 100u so that when the transistor turns on, the charging current into the 100u illuminates the white LED. If a 10k discharge resistor is used, the 100u is not fully discharged and the LED does not flash as bright. All the parts in the photo are in the same places as in the circuit diagram
37、 to make it easy to see how the parts are connected. to IndexDANCING FLOWERThis circuit was taken from a dancing flower. A motor at the base of the flower had a shaft up the stem and when the microphone detected music, the bent shaft made the flower wiggle and move. The circuit will respond to a whi
38、stle, music or noise. to IndexWHITE LINE FOLLOWERThis circuit can be used for a toy car to follow a white line. The motor is either a 3v type with gearing to steer the car or a rotary actuator or a servo motor.When equal light is detected by the photo resistors the voltage on the base of the first t
39、ransistor will be mid rail and the circuit is adjusted via the 2k2 pot so the motor does not receive any voltage. When one of the LDRs receives more (or less) light, the motor is activated. And the same thing happens when the other LDR receives less or more light.to IndexLED DETECTS LIGHTAll LEDs gi
40、ve off light of a particular colour but some LEDs are also able to detect light. Obviously they are not as good as a device that has been specially made to detect light; such as solar cell, photocell, photo resistor, light dependent resistor, photo transistor, photo diode and other photo sensitive d
41、evices. A green LED will detect light and a high-bright red LED will respond about 100 times better than a green LED, but the LED in this position in the circuit is classified as very high impedance and it requires a considerable amount of amplification to turn the detection into a worthwhile curren
42、t-source. All other LEDs respond very poorly and are not worth trying. The accompanying circuit amplifies the output of the LED and enables it to be used for a number of applications. The LED only responds when the light enters the end of the LED and this makes it ideal for solar trackers and any ti
43、me there is a large difference between the dark and light conditions. It will not detect the light in a room unless the lamp is very close.to Index12v RELAY ON 6V SUPPLY This circuit allows a 12v relay to operate on a 6v or 9v supply. Most 12v relays need about 12v to “pull-in“ but will “hold“ on ab
44、out 6v. The 220u charges via the 2k2 and bottom diode. When an input above 1.5v is applied to the input of the circuit, both transistors are turned ON and the 5v across the electrolytic causes the negative end of the electro to go below the 0v rail by about 4.5v and this puts about 10v across the re
45、lay.to IndexMAKE TIME FLY!Connect this circuit to an old electronic clock mechanism and speed up the motor 100 times! The “motor“ is a simple “stepper-motor“ that performs a half-rotation each time the electromagnet is energised. It normally takes 2 seconds for one revolution. But our circuit is con
46、nected directly to the winding and the frequency can be adjusted via the pot. Take the mechanism apart, remove the 32kHz crystal and cut one track to the electromagnet. Connect the circuit below via wires and re-assemble the clock. As you adjust the pot, the “seconds hand“ will move clockwise or ant
47、iclockwise and you can watch the hours “fly by“ or make “time go backwards.“The multivibrator section needs strong buffering to drive the 2,800 ohm inductive winding of the motor and thats why push-pull outputs have been used. The flip-flop circuit cannot drive the highly inductive load directly (it
48、 upsets the waveform enormously). From a 6v supply, the motor only gets about 4v due to the voltage drops across the transistors. Consumption is about 5mA.HOW THE MOTOR WORKSThe rotor is a magnet with the north pole shown with the red mark and the south pole opposite. The electromagnet actually prod
49、uces poles. A strong North near the end of the electromagnet, and a weak North at the bottom. A strong South at the top left and weak South at bottom left. The rotor rests with its poles being attracted to the 4 pole-pieces equally.Voltage must be applied to the electromagnet around the correct way so that repulsion occurs. Since the rotor is sitting equally between the North poles, for example, it will see a strong pushing force from the pole near the electromagnet and this is how the motor direction is determined. A reversal of voltage will
