1 TEACHING RESOURCES SCHEMES OF WORK DEVELOPING A SPECIFICATION COMPONENT FACTSHEETS HOW TO SOLDER GUIDE GET IN TUNE WITH THIS FM RADIO KIT Version 2.0
2 Index of Sheets TEACHING RESOURCES Index of Sheets Introduction Schemes of Work Answers The Design Process The Design Brief Investigation / Research Developing a Specification Design Design Review (group task) Soldering in Ten Steps Resistor Values Capacitor Basics Ceramic Disc Capacitors How Does a Radio Work? Improving the Radio Tuning Instruction Manual Evaluation Packaging Design ESSENTIAL INFORMATION Build Instructions Checking Your FM Radio PCB Adding an On / Off Switch Designing the Enclosure How the FM Radio Works Online Information
3 Introduction About the project kit Both the project kit and the supporting material have been carefully designed for use in KS3 Design and Technology lessons. The project kit has been designed so that even teachers with a limited knowledge of electronics should have no trouble using it as a basis from which they can form a scheme of work. The project kits can be used in two ways: 1. As part of a larger project involving all aspects of a product design, such as designing an enclosure for the electronics to fit into. 2. On their own as a way of introducing electronics and electronic construction to students over a number of lessons. This booklet contains a wealth of material to aid the teacher in either case. Using the booklet The first few pages of this booklet contains information to aid the teacher in planning their lessons and also covers worksheet answers. The rest of the booklet is designed to be printed out as classroom handouts. In most cases all of the sheets will not be needed, hence there being no page numbers, teachers can pick and choose as they see fit. Please feel free to print any pages of this booklet to use as student handouts in conjunction with Kitronik project kits. Support and resources You can also find additional resources at There are component fact sheets, information on calculating resistor and capacitor values, puzzles and much more. Kitronik provide a next day response technical assistance service via . If you have any questions regarding this kit or even suggestions for improvements, please us at: Alternatively, phone us on
4 Schemes of Work Two schemes of work are included in this pack; the first is a complete project including the design & manufacture of an enclosure for the kit (below). The second is a much shorter focused practical task covering just the assembly of the kit (next page). Equally, feel free to use the material as you see fit to develop your own schemes. Before starting we would advise that you to build a kit yourself. This will allow you to become familiar with the project and will provide a unit to demonstrate. Complete product design project including electronics and enclosure Hour 1 Hour 2 Hour 3 Hour 4 Hour 5 Hour 6 Hour 7 Hour 8 Hour 9 Hour 10 Hour 11 Hour 12 Introduce the task using The Design Brief sheet. Demonstrate a built unit. Take students through the design process using The Design Process sheet. Homework: Collect examples of radio and audio products. List the common features of these products on the Investigation / Research sheet. Develop a specification for the project using the Developing a Specification sheet. Resource: Sample of radios and audio products. Homework: Using the internet or other search method, find out what is meant by design for manufacture. List five reasons why design for manufacture should be considered on any design project. Read Designing the Enclosure sheet. Develop a product design using the Design sheet. Homework: Complete design. Using cardboard, get the students to model their enclosure design. Allow them to make alterations to their design if the model shows any areas that need changing. Split the students into groups and get them to perform a group design review using the Design Review sheet. Using the Soldering in Ten Steps sheet, demonstrate and get students to practice soldering. Start the Resistor Value worksheet. Homework: Complete any of the remaining resistor / capacitor tasks. Build the electronic kit using the Build Instructions. Complete the build of the electronic kit. Check the completed PCB and fault find if required using the Checking Your FM Radio PCB section. Homework: Read How the FM Radio Works sheet. Build the enclosure. Build the enclosure. Build the enclosure. Using the Evaluation and Improvement sheet, get the students to evaluate their final product and state where improvements can be made. Additional Work Package design for those who complete ahead of others.
5 Electronics only Hour 1 Hour 2 Hour 3 Hour 4 Introduction to the kit demonstrating a built unit. Using the Soldering in Ten Steps sheet, practice soldering. Build the kit using the Build Instructions. Build the kit using the Build Instructions. Check the completed PCB and fault find if required using the Checking Your FM Radio PCB section. Answers Resistor questions 1st Band 2nd Band Multiplier x Value Brown Black Yellow 100,000 Ω Green Blue Brown 560 Ω Brown Grey Yellow 180,000Ω Orange White Black 39Ω Value 1st Band 2nd Band Multiplier x 180 Ω Brown Grey Brown 3,900 Ω Orange White Red 47,000 (47K) Ω Yellow Violet Orange 1,000,000 (1M) Ω Brown Black Green Capacitor Ceramic Disc values Printing on capacitor Two digit start Number of zero s Value in pf pF (2.2nF) pF (10nF) pF (33nF) pF (47nF)
6 The Design Process The design process can be short or long, but will always consist of a number of steps that are the same on every project. By splitting a project into these clearly defined steps, it becomes more structured and manageable. The steps allow clear focus on a specific task before moving to the next phase of the project. A typical design process is shown on the right. Design brief What is the purpose or aim of the project? Why is it required and who is it for? Investigation Research the background of the project. What might the requirements be? Are there competitors and what are they doing? The more information found out about the problem at this stage, the better, as it may make a big difference later in the project. Specification This is a complete list of all the requirements that the project must fulfil - no matter how small. This will allow you to focus on specifics at the design stage and to evaluate your design. Missing a key point from a specification can result in a product that does not fulfil its required task. Design Develop your ideas and produce a design that meets the requirements listed in the specification. At this stage it is often normal to prototype some of your ideas to see which work and which do not. Design Brief Investigation Specification Design Build Evaluate Improve Build Build your design based upon the design that you have developed. Evaluate Does the product meet all points listed in the specification? If not, return to the design stage and make the required changes. Does it then meet all of the requirements of the design brief? If not, return to the specification stage and make improvements to the specification that will allow the product to meet these requirements and repeat from this point. It is normal to have such iterations in design projects, though you normally aim to keep these to a minimum. Improve Do you feel the product could be improved in any way? These improvements can be added to the design.
7 The Design Brief A manufacturer has developed a circuit for an FM radio. The circuit has been developed to the point where they have a working Printed Circuit Board (PCB). The manufacturer would like ideas for how this PCB could be housed to create a final product. The manufacturer has asked you to do this for them. It is important that you make sure that the final design meets all of the requirements that you identify for an FM radio. Complete Circuit A fully built circuit is shown below.
8 Investigation / Research Using a number of different search methods, find examples of similar products that are already on the market. Use additional pages if required. Name Class
9 Developing a Specification Using your research into the target market for the product, identify the key requirements for the product and explain why each of these is important. Name Class Requirement Reason Example: It must be easy to access the Example: So that they can easily be changed when they become flat. batteries.
10 Design Develop your ideas to produce a design that meets the requirements listed in the specification. Name Class
11 Design Review (group task) Split into groups of three or four. Take it in turns to review each persons design against the requirements of their specification. Also look to see if you can spot any additional aspects of each design that may cause problems with the final product. This will allow you to ensure that you have a good design and catch any faults early in the design process. Note each point that is made and the reason behind it. Decide if you are going to accept or reject the comment made. Use these points to make improvements to your initial design. Comment Reason for comment Accept or Reject
12 FM Radio Teaching Resources Soldering in Ten Steps 1. Start with the smallest components working up to the taller components, soldering any interconnecting wires last. 2. Place the component into the board, making sure that it goes in the right way around and the part sits flush against the board. 3. Bend the leads slightly to secure the part. 4. Make sure that the soldering iron has warmed up and if necessary, use the damp sponge to clean the tip. 5. Place the soldering iron on the pad. 6. Using your free hand, feed the end of the solder onto the pad (top picture). 7. Remove the solder, then the soldering iron. 8. Leave the joint to cool for a few seconds. 9. Using a pair of cutters, trim the excess component lead (middle picture). 10. If you make a mistake heat up the joint with the soldering iron, whilst the solder is molten, place the tip of your solder extractor by the solder and push the button (bottom picture). Solder joints Good solder joint Too little solder Too much solder
13 Resistor Values A resistor is a device that opposes the flow of electrical current. The bigger the value of a resistor, the more it opposes the current flow. The value of a resistor is given in Ω (ohms) and is often referred to as its resistance. Identifying resistor values Band Colour 1st Band 2nd Band Multiplier x Tolerance Silver % Gold 10 5% Black Brown % Red % Orange Yellow ,000 Green ,000 Blue 6 6 1,000,000 Violet 7 7 Grey 8 8 White 9 9 Example: Band 1 = Red, Band 2 = Violet, Band 3 = Orange, Band 4 = Gold The value of this resistor would be: 2 (Red) 7 (Violet) x 1,000 (Orange) = 27 x 1,000 = 27,000 with a 5% tolerance (gold) = 27KΩ Too many zeros? Kilo ohms and mega ohms can be used: 1,000Ω = 1K 1,000K = 1M Resistor identification task Calculate the resistor values given by the bands shown below. The tolerance band has been ignored. 1st Band 2nd Band Multiplier x Value Brown Black Yellow Green Blue Brown Brown Grey Yellow Orange White Black
14 Calculating resistor markings Calculate what the colour bands would be for the following resistor values. Value 1st Band 2nd Band Multiplier x 180 Ω 3,900 Ω 47,000 (47K) Ω 1,000,000 (1M) Ω What does tolerance mean? Resistors always have a tolerance but what does this mean? It refers to the accuracy to which it has been manufactured. For example if you were to measure the resistance of a gold tolerance resistor you can guarantee that the value measured will be within 5% of its stated value. Tolerances are important if the accuracy of a resistors value is critical to a design s performance. Preferred values There are a number of different ranges of values for resistors. Two of the most popular are the E12 and E24. They take into account the manufacturing tolerance and are chosen such that there is a minimum overlap between the upper possible value of the first value in the series and the lowest possible value of the next. Hence there are fewer values in the 10% tolerance range. E-12 resistance tolerance (± 10%) E-24 resistance tolerance (± 5 %)
15 Capacitor Basics What is a capacitor? A capacitor is a component that can store electrical charge (electricity). In many ways, it is like a rechargeable battery. V A good way to imagine a capacitor is as a bucket, where the size of the base of the bucket is equivalent to the capacitance (C) of the capacitor and the height of the bucket is equal to its voltage rating (V). C The amount that the bucket can hold is equal to the size of its base multiplied by its height, as shown by the shaded area. Filling a capacitor with charge R R BATTERY V C BATTERY CAPACITOR When a capacitor is connected to an item such as a battery, charge will flow from the battery into it. Therefore the capacitor will begin to fill up. The flow of water in the picture above left is the equivalent of how the electrical charge will flow in the circuit shown on the right. The speed at which any given capacitor will fill depends on the resistance (R) through which the charge will have to flow to get to the capacitor. You can imagine this resistance as the size of the pipe through which the charge has to flow. The larger the resistance, the smaller the pipe and the longer it will take for the capacitor to fill. Emptying (discharging) a capacitor R Once a capacitor has been filled with an amount of charge, it will retain this charge until it is connected to something into which this charge can flow. The speed at which any given capacitor will lose its charge will, like when charging, depend on the resistance (R) of the item to which it is connected. The larger the resistance, the smaller the pipe and the longer it will take for the capacitor to empty. Maximum working voltage Capacitors also have a maximum working voltage that should not be exceeded. This will be printed on the capacitor or can be found in the catalogue the part came from. You can see that the capacitor on the right is printed with a 10V maximum working voltage.
16 Ceramic Disc Capacitors Values The value of a capacitor is measured in Farads, though a 1 Farad capacitor would be very big. Therefore we tend to use milli Farads (mf), micro Farads ( F), nano Farads (nf) and pico Farads (pf). A F is a millionth of a Farad, 1 F = 1000 nf and 1nF = 1000 pf. The larger electrolytic capacitors tend to have the value printed on the side of them along with a black band showing the negative lead of the capacitor. Other capacitors, such as the ceramic disc capacitor shown on the right, use a code. They are often smaller and may not have enough space to print the value in full, hence the use of the 3-digit code. The first 2 digits are the first part of the number and the third digit gives the number of zeros to give its value in pf. 1F 1F 1F 1F = 1,000mF = 1,000,000 F = 1,000,000,000nF = 1,000,000,000,000pF Example: 104 = (4 zero s) = 100,000 pf (which is also 0.1 F) Work out what value the four capacitors are in the table below. Printing on capacitor Two digit start Number of zero s Value in pf
17 How Does a Radio Work? For around 100 years, radio stations have been transmitting signals which people have been able to receive and listen to. Early radio transmissions were AM and were received either on simple crystal radios or radios that used vacuum tubes (valves). AM radio AM radio work by combining the audio signal which you wish to transmit with a higher frequency carrier signal. AM stands for Amplitude Modulation as it is the amplitude of the carrier signal that is used to carry the audio signal. This can be seen in the diagram to the right. The receiver is tuned into the frequency of the carrier frequency. It then removes the carrier to recover the audio signal, which you can then listen to. Audio signal Radio carrier signal Carrier signal combined with audio signal FM radio FM radio came along after AM radio and offered a much improved signal quality. FM stands for Frequency Modulation. As the name suggests, instead of altering the amplitude of the carrier signal, FM radio works by changing the frequency of the carrier signal (increasing it or decreasing it) to reflect the audio signal you wish to transmit. This can be seen in the diagram to the right. Audio signal Radio carrier signal Carrier signal combined with audio signal Transistor radios Transistors started to be used in radio during the middle of the last century. Transistors have many advantages over vacuum tubes including being cheaper, smaller and requiring less power. As a result of this, they helped bring radio ownership to the masses.
18 Improving the Radio Tuning Tuning the radio using the potentiometer can be a tricky task. This is because one turn of the potentiometer covers the whole frequency range. This means that only very small adjustments of the potentiometer are required to tune into the different stations. Large dial One way to improve the tuning mechanism is to attach a large dial to the end of the potentiometer. Look at the two dials below. As the smaller dial has a circumference six times smaller than the large dial, it would take six times the travel on the larger dial to achieve the same degree of change than if you used the smaller dial. This would therefore make fine tuning the radio six times easier. Dial / Pulley circumference = 12cm 45 degree adjustment = 1.5cm travel Dial / Pulley circumference = 2cm 45 degree adjustment = 0.25cm travel Using a pulley to give mechanical gearing Another solution is to use a pulley system to improve the tuning mechanism. Take the system shown below. In this arrangement the larger pulley would be attached to the tuning potentiometer and the smaller dial would be used to make the tuning adjustments. As the smaller dial (pulley) has a circumference six times smaller than the large pulley, it would take six full rotations of the smaller dial to give one full rotation of the larger pulley. This would therefore make fine tuning the radio six times easier than if the small pulley had been connected directly to the tuning potentiometer. Potentiometer Dial circumference = 2cm Pulley circumference = 12cm Using both a pulley system and a large dial Of course and even better solution would be to add a large dial in front of, but on the same shaft that the small pulley/dial in the above diagram is attached to. That way you would get the benefit of both systems this would give thirty six times better adjustment.
19 Instruction Manual Your FM radio is going to be supplied with some instructions. Identify four points that must be included in the instructions and give a reason why. Point to include: Point to include: Reason: Reason: Point to include: Point to include: Reason: Reason:
20 Evaluation It is always important to evaluate your design once it is complete. This will ensure that it has met all of the requirements defined in the specification. In turn, this should ensure that the design fulfils the design brief. Check that your design meets all of the points listed in your specification. Show your product to another person (in real life this person should be the kind of person at which the product is aimed). Get them to identify aspects of the design, which parts they like and aspects that they feel could be improved. Good aspects of the design Areas that could be improved Improvements Every product on the market is constantly subject to redesign and improvement. What aspects of your design do you feel you could improve? List the aspects that could be improved and where possible, draw a sketch showing the changes that you would make.
21 Packaging Design If your product was to be sold in a high street electrical retailer, what requirements would the packaging have? List these giving the reason for the requirement. Requirement Reason Develop a packaging design for your product that meets these requirements. Use additional pages if required.
22 ESSENTIAL INFORMATION BUILD INSTRUCTIONS CHECKING YOUR PCB & FAULT-FINDING MECHANICAL DETAILS HOW THE KIT WORKS GET IN TUNE WITH THIS FM RADIO KIT Version 2.0
23 FM Radio Essentials Build Instructions Before you start, take a look at the Printed Circuit Board (PCB). The components go in the side with the writing on and the solder goes on the side with the tracks and silver pads. 1 Start with the eight resistors: The text on the PCB shows where R1, R2 etc go. Ensure that you put the resistors in the right place. PCB Ref Value Colour Bands R2 & R8 10K Brown, black, orange R3 & R4 100K Brown, black, yellow R6 4.7K Yellow, purple, red R7 15K Brown, green, orange R9 100 Brown, black, brown R10 1 Brown, black, gold 2 PLACE RESISTORS SOLDER THE CERAMIC DISC CAPACITORS The ceramic disc capacitors should be soldered into the board. There are a lot of these so be careful to put them all in the correct place. The capacitors can be identified by the text printed on them (see close up image below right). It doesnt matter which way around the capacitor goes into the board. PCB Ref Value Text C1, C9, C15, C18 100nF 104 C2, C12, C19, C20 10nF 103 C3 & C5 3.3nF 332 C4, C6, C16 180pF 181 C7 39pF 39 C8 2.2nF 222 C10 330pF 331 C11 220pF 221 C13 220nF 224 C14 470pF SOLDER THE VOLTAGE REGULATOR Solder the voltage regulator (shown right) into the PCB where it is labelled IC2. Make sure that the shape of the component matches the outline on the PCB.
24 FM Radio Essentials 4 Solder the Integrated Circuit (IC) holder into IC3. When putting this into the board, be sure to get it the right way around. The notch on the IC holder should line up with the notch on the lines marked on the PCB. Once this has been done insert the 8 pin IC into this socket, making sure that the notch on the device matches the notch on the IC holder. 5 SOLER THE IC HOLDER SOLER THE ELECTROLYTIC CAPACITORS Now solder in the four electrolytic capacitors. The capacitors have text printed on the side that indicates their value. The capacitors are placed as follows. PCB Ref C21 C23 C17 and C22 Value 100 F 220 F 470 F Make sure that the capacitors are the correct way around. The capacitors have a - sign marked on them, which should match the same sign on the PCB. 6 Solder the two potentiometers into the PCB. Each potentiometer has a different value so they have to be put in the correct place. If you look at the potentiometers, you will see they are labelled with their value. The shaft of the potentiometer should point away from the PCB. PCB Ref R1 R5 SOLER THE POTENTIOMETERS Value 10K 100K Value 7 ATTACH THE BATTERY CLIP Solder the PP3 battery clip to the terminals labelled Power In. Connect the red wire to + and the black wire to - after feeding it through the strain relief hole. 8 CONNECT THE WIRES Solder the length of single core wire to the terminal labelled Antenna. You will first have to strip off a piece of the insulation to expose a short length of the wires core. Before doing this, make sure that you feed it through the strain relief hole. Once soldered, measure 750mm of wire from the point where the wire is soldered and cut any remainder off (this will make sure that the antenna is the right length to pick up the correct radio frequencies for the radio).
25 FM Radio Essentials 9 CONNECT THE SPEAKER The kit is supplied with ½ a metre of twin cable. This cable is used to connect the speaker. Cut this to the required length for your enclosure design. Take the piece of wire that you have cut off and strip the ends of the wire. Connect one end to the two terminals on the speaker (shown right) and the other end to the board marked speaker after feeding it through the strain relief hole. It does not matter which way around these connections go. Checking Your FM Radio PCB Check the following before you connect any batteries for you radio. Check the bottom of the board to ensure that: All holes (except the four large mounting holes) are filled with the lead of a component. All these leads are soldered. Pins next to each other are not soldered together. Check the top of the board to ensure that: The outline of components IC2 and IC3 match the outlines on the PCB. The negative markings on the electrolytic capacitors line up with the same markings on the PCB. The red wire on the PP3 lead is connected to the power connector labelled Red and the black wire on the PP3 lead is connected to the power connector labelled Black. Additionally check that the resistors and capacitors are in the correct place if your board does not work.
26 FM Radio Essentials Adding an On / Off Switch If you wish to add a power switch, dont solder both ends of the battery clip directly into the board, instead: 1 Solder one end of the battery clip to the PCB, either black to - or red to +. 2 Solder the other end of the battery clip to the on / off switch. 3 Using a piece of wire, solder the remaining terminal on the on / off switch to the remaining power connection on the PCB.
27 FM Radio Essentials Designing the Enclosure When you design the enclosure, you will need to consider: The size of the PCB (below left, height including components = 22mm). How big the battery (or batteries) are. How to mount the speakers (below right). 4 x 3.3mm diameter mounting holes 88 Power input Antenna Speaker All dimensions in mm. The volume and tuning potentiometer shafts can be cut to the required length and are designed to be mounted using a 7mm diameter hole. Maximum panel thickness is 4.5mm (allows 2mm for nut and washer on potentiometers). The potentiometers can be mounted off board and connected to the PCB using lengths of wire if required. Mounting the PCB to the enclosure The drawing to the left shows how a hex spacer can be used with two bolts to fix the PCB to the enclosure. Your PCB has four mounting holes designed to take M3 bolts.
28 FM Radio Essentials How the FM Radio Works To aid the description of the circuit, we have split it into two parts. The first deals with the decoding of the FM radio signal and the second deals with the audio amplification. Voltage regulator Battery (15V max) In Out Gnd C17 470uF R6 4.7K R5 100K Tune R7 15K C20 10nF R4 100K C16 180pF L1 56nH D1 C3 R2 10K C1 C2 C4 TDA7010T Mute Audio out LF V+ VCO Mix1 Mix2 Mix Out CR DM Gnd IF Mix 3 RF in IF IF C11 C10 C9 C8 C7 C6 C5 C12 10nF Aerial R1 10K Volume Audio out C19 10nF Radio decoding For the radio circuit to work, it needs a stable power supply (not one that falls as the battery becomes flat). To provide the stable power supply, a voltage regulator is used. This provides a 3V output for the circuit to run from. Capacitor C17 is to remove any unwanted noise from this 3V supply. The key component of the radio circuit is the TDA7010T chip. This chip is used to receive radio signals via an aerial and then decodes this signal to recover the audio signal that it carries. To recover the radio signal the chip needs to generate another radio signal by using a circuit called VCO (voltage controlled oscillator) which it mixes with the received radio signal to recover the desired radio station. The signal that the VCO generates can be altered, allowing radio stations on different frequencies to be recovered. The VCO uses a resonant circuit that is made up of inductor (L1), capacitor (C16) and the varicap diode (D1). A varicap diode is a diode that also has a capacitance. This capacitance varies as the voltage across the diode varies. By adjusting the potentiometer (R5), which is used to tune the circuit, the voltage that is fed to the varicap diode can be adjusted. This, in turn, changes the capacitance of the varicap diode and, therefore, the frequency of the resonant circuit (and thus the frequency to which the radio is tuned). The remaining capacitors are used by the chip to filter the recovered radio signal. Resistor R2 is used to disable the mute feature of the chip. If this is not fitted when the radio is not tuned into a radio station, the audio output is muted (silent). When it is fitted you get a hissy sound between stations. We have fitted it as it makes it easier to manually tune into stations. Potentiometer R1 is used to control the amount of the audio output signal that is fed to the amplifier circuit. By doing this, it will therefore control the overall volume that comes out of the radio.
29 FM Radio Essentials Battery voltage + - Audio input C13 220nF R8 10K C14 470pF FC Gain Input TBA820M BS Output C23 220uF Speaker 1 C22 470uF C18 100nF R3 100K R9 100R C21 100uF R10 1R C15 100nF Audio amplification The audio amplification is performed by another Integrated Circuit or IC called a TBA820M. Inside the TBA820M are lots of transistors, which are connected together to allow the small input signal to be amplified into a more powerful output that can drive a speaker. All amplifiers need to use feedback to ensure that the amount of gain stays the same. This allows the output to be an exact copy of the input, just bigger. The gain is the number of times bigger the output is compared to the input, so if an amplifier has a gain of 10 and there is 1 volt on the input, there will be 10 volts on the output. Before looking at how the feedback works, we first need to understand how a standard amplifier works. An operational amplifier has two inputs, these are called the inverting (-) and non-inverting (+) inputs. The output of the operational amplifier is the voltage on the non-inverting input, less the voltage on the inverting input, multiplied by the amplifiers gain. In theory, an operational amplifier has unlimited gain so if the non-inverting input is a fraction higher than the inverting input (there is more + than -), the output will go up to the supply voltage. Change the inputs around and the output will go to zero volts. In this format the operational amplifier is acting as a comparator: it compares the two inputs and changes the output accordingly. Input Amplifier X10 gain 90% 10% Output With an infinite gain the amplifier is no good to amplify audio, which is where the feedback comes in. By making one of the input a percentage of the output the gain can be fixed, which allows the output to be a copy of the input but bigger. Now when the two inputs are compared and the output is adjusted, instead of it going up or down until it reaches 0 volts or V+, it stops at the point when the two inputs match and the output is at the required voltage. Looking at the circuit diagram for the audio amplifier, its not obvious where the feedback is this is because inside the IC is a 6K resistor between the Output pin and the Gain setting input pin. The internal 6K resistor and the 100 resistor (R9) on the gain setting pin make up a potential divider that feeds back approximately a sixtieth of the output. This fixes the gain so that the output is about 60 times bigger than the input. The rest of the components are needed as follows: C13 removes any DC offset from the audio signal from the radio IC. R3 and R8 reduce the audio signal from the radio slightly so that when it is at full volume there is less chance of any distortion on the sound from the speaker. C18 & C22 are connected across the supply to make sure it remains stable. The other capacitors have a filtering role, either to cut out high frequency noise or get the best out of the speaker.
30 Online Information Two sets of information can be downloaded from the product page where the kit can also be reordered from. The Essential Information contains all of the information that you need to get started with the kit and the Teaching Resources contains more information on soldering, components used in the kit, educational schemes of work and so on and also includes the essentials. Download from: This kit is designed and manufactured in the UK by Kitronik Every effort has been made to ensure that these notes are correct, however Kitronik accept no responsibility for issues arising from errors / omissions in the notes. Kitronik Ltd - Any unauthorised copying / duplication of this booklet or part thereof for purposes except for use with Kitronik project kits is not allowed without Kitroniks prior consent.
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400W MONO/STEREO AMPLIFIER Universal, robust and compact are the words to describe this amplifier. Total solder points: 264 Difficulty level: beginner 1 2 3 4 5 advanced K4005B ILLUSTRATED ASSEMBLY MANUAL
H8084IP-1 VOLUME AND TONE CONTROL - PREAMPLIFIER K8084 When using one of our amplifiers (big or small), you always need a volume control and preferably also a tone control Features & specifications When
Using Your Arduino, Breadboard and Multimeter Work in teams of two! EAS 199A Fall 2012 pincer clips good for working with breadboard wiring (push these onto probes) Your Multimeter probes leads Turn knob
Assembly Notes Before you start building your kit, please take time to read the manual in full at least once to enable you to fully understand the procedures and avoid any mistakes. The following notes
RS232/DB9 An RS232 to TTL Level Converter The RS232/DB9 is designed to convert TTL level signals into RS232 level signals. This cable allows you to connect a TTL level device, such as the serial port on
Total solder points: 169 + 99 + 67 Difficulty level: beginner 1 2 3 4 5 advanced TEMPERATURE CONTROLLER K6002 Unlike a normal thermostat, this kit has two outputs, one for "high" alarm and one for "low"
THE ELECTRONIC DICE a technology project for secondary education Name: Class: Many parties were involved in making this lesson / project available for schools: This technology project was originally developed
Homebuilt HF Radios for Use Underground Paul R. Jorgenson KE7HR With the good success in using Amateur Band HF radio for underground communications, I started looking for cheaper alternatives to the $500+
SYMMETRIC 1A POWER SUPPLY K8042 Low cost universal symmetric power supply ILLUSTRATED ASSEMBLY MANUAL H8042IP-1 Features & Specifications Features low cost universal symmetric power supply just add a suitable
Total solder points: 18 Difficulty level: beginner 1 2 3 4 5 advanced UNIVERSAL POWER SUPPLY 5-14DC / 1A K2570 The easy way to power your projects. ILLUSTRATED ASSEMBLY MANUAL H2570IP-1 Features & Specifications
Module 2 AC Theory Looking at What you'll learn in Module 2: In section 2.1 Common capacitor types and their uses. Basic Circuit Symbols for. In section 2.2 Charge & Discharge How capacitors work. What
ax You Can DIY! Build a Voltage and Current Peak Detector Here is a simple portable device that can help answer the question about peak voltage and peak current requirements and whether or not your power
Total solder points: 18 Difficulty level: beginner 1 2 3 4 5 advanced UNIVERSAL POWER SUPPLY 5-14DC / 1A K2570 The easy way to power your projects. ILLUSTRATED ASSEMBLY MANUAL H2570IP-1 Features & Specifications
The Radio-Kits Digital SWR meter kit Construction and user manual Author - Steve Drury G6ALU List of contents Section Page no. 1. Features and specifications 2 2. Introduction 2. Construction 4. General
Total solder points: 57 Difficulty level: beginner 1 2 3 4 5 advanced 3 TO 30VDC / 3A POWER SUPPLY K7203 A power supply for all our kits, based on a stabilised DC voltage of 30V. ILLUSTRATED ASSEMBLY MANUAL
Introduction Building the HVPS High Voltage Power Supply Voltages higher than the LVPS provides kilovolts are needed in later experiments to get strong electric fields and to generate microwaves. The high-voltage
Build A Video Switcher Reprinted with permission from Electronics Now Magazine September 1997 issue Copyright Gernsback Publications, Inc.,1997 BUILD A VIDEO SWITCHER FRANK MONTEGARI Watch several cameras
Chapter 19 Operational Amplifiers The operational amplifier, or op-amp, is a basic building block of modern electronics. Op-amps date back to the early days of vacuum tubes, but they only became common
Teacher Notes Transistor Astable Project Introduction The aim of this 7 week (2hr lessons) project is to design and manufacture an electronic product based on the transistor astable circuit. The project
HP 8970B Option 020 Service Manual Supplement Service Manual Supplement HP 8970B Option 020 HP Part no. 08970-90115 Edition 1 May 1998 UNIX is a registered trademark of AT&T in the USA and other countries.
The national association for AMATEUR RADIO ARRL Morse Code Oscillator, How It Works By: Mark Spencer, WA8SME This supplement is intended for use with the ARRL Morse Code Oscillator kit, sold separately.
G-QRP Club components This is a service for G-QRP Club members only 6 pole crystal filter SSB 9MHz 2.2kHz 500 Ohm in/out 12 Polyvaricon capacitors 2 gang - 8 to 140pF & 6 to 60pF (tags marked A & O respectively)
CS99S Laboratory 1 Objectives: 1. Become familiar with the breadboard 2. Build a logic power supply 3. Use switches to make 1s and 0s 4. Use LEDs to observe 1s and 0s 5. Make a simple oscillator 6. Use
Introduction The detects the tones generated when numbers are dialed on your touch tone telephone and speaks the numbers that were dialed. This verifies that you dialed the correct number and is especially
Description Quasar kit No.1218 is part of a new line of constructions which combined form a full stereo system. The line consists of the following KITS Quasar kit No.1214 6 inputs stereo selector Quasar
PGA103+ Low noise, high dynamic range preamp for VHF and UHF By Sam Jewell, G4DDK and Kent Britain, WA5VJB Introduction This paper describes a low noise, high dynamic range VHF/UHF preamp that uses the
N9WB D-104 Project Revision 2 Pre Amp Modifications for higher load impedance. By Walter A. Breining, N9WB D-104 Discussion The D-104 has been around since the 30 s and is still popular today for communications.
Module 3 AC Theory What you ll learn in Module 3. Section 3.1 Electromagnetic Induction. Magnetic Fields around Conductors. The Solenoid. Section 3.2 Inductance & Back e.m.f. The Unit of Inductance. Factors
The $25 Son of a cheap timer This is not suitable for a beginner. You must have soldering skills in order to build this kit. Micro Wizard has been manufacturing Pinewood Derby timers for over 10 years.
PowerAmp Design COMPACT HIGH VOLTAGE OP AMP Rev G KEY FEATURES LOW COST SMALL SIZE 40mm SQUARE HIGH VOLTAGE 200 VOLTS HIGH OUTPUT CURRENT 10A PEAK 40 WATT DISSIPATION CAPABILITY 200V/µS SLEW RATE APPLICATIONS
Step 1 of 10: Introduction This tutorial shows you how to make an electronic circuit using Livewire and PCB Wizard 3. You should follow this tutorial to learn the basic skills you will need to use Livewire
Measurement of Capacitance Pre-Lab Questions Page Name: Class: Roster Number: Instructor:. A capacitor is used to store. 2. What is the SI unit for capacitance? 3. A capacitor basically consists of two
Using Ohm s Law to Build a Voltage Provided by TryEngineering - Lesson Focus Students will design, build, and characterize one of the basic circuits of electrical engineering, the voltage divider. These
& nstall Publication, Duplication, or Retransmission Of This Document Not Expressly Authorized n Writing By The nstall Doctor s Prohibited. Protected By U.S. Copyright Laws. 1997,1998,,2000. Factory Radio
Electronics Operational Amplifier Internal design of an operational amplifier LD Physics Leaflets Discrete assembly of an operational amplifier as a transistor circuit P188.8.131.52 Objects of the experiment
The new Velleman Projects catalogue is now available. Download your copy here: www.vellemanprojects.eu Modifications and typographical errors reserved - Velleman nv. H8098 IP 2 (rev.1.0) Velleman NV, Legen
PS 29M DUAL CHANNEL BELTPACK IN METAL CASE USER MANUAL October 2013 This product is designed and manufactured by: ASL Intercom BV Zonnebaan 42 3542 EG Utrecht The Netherlands Phone: +31 (0)30 2411901 Fax:
Lab 3 DC Circuits and Ohm s Law L3-1 Name Date Partners Lab 3 - DC Circuits and Ohm s Law OBJECTIES To learn to apply the concept of potential difference (voltage) to explain the action of a battery in
THE MclNTOSH MC 2100 SOLID STATE STEREO POWER AMPLIFIER Price $1.25 Your MC 2100 stereo amplifier will give you many years of pleasant and satisfactory performance. If you have any questions concerning
Germanium Diode AM Radio LAB 3 3.1 Introduction In this laboratory exercise you will build a germanium diode based AM (Medium Wave) radio. Earliest radios used simple diode detector circuits. The diodes
POWERBLOCK - POWER AMPLIFIER This amplifier is an ideal set-up for active speaker use. Total solder points: 383 Difficulty level: beginner 1 2 3 4 5 advanced K8081 ILLUSTRATED ASSEMBLY MANUAL H8081IP-1
BMD16N version 1.2 Feedback decoder with 16 contacts for the S88-bus Compatible with a.o. Märklin Digital, Uhlenbrock Intellibox, Fleischmann Twin-Center and LDT HSI-88 Compatible with the s88-n standard
Physics 3330 Experiment #2 Fall 1999 DC techniques, dividers, and bridges Purpose You will gain a familiarity with the circuit board and work with a variety of DC techniques, including voltage dividers,
DDS VFO CONSTRUCTION MANUAL DDS VFO Construction Manual Issue 1 Page 1 Important Please read before starting assembly STATIC PRECAUTION The DDS VFO kit contains the following components which can be damaged
T E C H N I C A L S P E C I F I C A T I O N The ATL EL-AD-151 (Resistance Output) and EL-AD-152 (Voltage Output) Fuel Level Senders are highly advanced sensors for continuously measuring the contents of
PC FUNCTION GENERATOR Create standard signal waves like e.g. sine, triangle and rectangle are available; other sine waves can be easily created with integrated software. Total solder points: 954 Difficulty
Total solder points: 167 Difficulty level: beginner 1 2 3 4 5 advanced DMX CONTROLLED RELAY K8072 Control a relay by means of the wellknown DMX512 protocol. ILLUSTRATED ASSEMBLY MANUAL H8072IP-1 Features
POWER SUPPLY MODEL XP-15 Instruction Manual ELENCO Copyright 2013 by Elenco Electronics, Inc. REV-A 753020 All rights reserved. No part of this book shall be reproduced by any means; electronic, photocopying,
AM/FM Component Stereo Receiver System (120-1470) Preparation Faxback Doc. # 18708 POWER REQUIREMENTS Connect the AC line cord into any outlet furnishing 117 volts 50-60 cycles AC current. CONNECTING SPEAKERS
VISHAY VITRAMON Multilayer Chip Capacitors Application Note GENERAL is a multilayer ceramic chip antenna designed for receiving mobile digital TV transmissions in the UHF band. The target application for
F O R T H E L O V E O F M U S I C F O R T H E L O V E O F M U S I C MODEL 2202IQ (1991-MSRP $549.00) OWNER'S MANUAL AND INSTALLATION GUIDE INTRODUCTION Congratulations on your decision to purchase a LINEAR
A Versatile Audio Amplifier...built around the TBA 810 Integrated Circuit You can build a versatile audio amplifier for your workbench or for any other of your audio projects...with the TBA 810 IC (Integrated
2014 Amplifier - 1 FREQUENCY RESPONSE OF AN AUDIO AMPLIFIER The objectives of this experiment are: To understand the concept of HI-FI audio equipment To generate a frequency response curve for an audio
Electronic Circuit Construction: Various methods are used for building electronic circuits. The method that you choose depends on a number of factors, including the resources available to you and whether