ELECTRONICS:
JUNE UPDATE
14 BRAND NEW PRODUCTS INSIDE!
NEW SELF-ASSEMBLY LASER CUT AMPLIFIER CASE
www.kitronik.co.uk/quicklinks/ampcase Our high power stereo amp kit sounds really good, but to sound amazing it needs to be mounted, and what better case to use than the Kitronik self-assembly case? The kit of parts includes the pre-cut Perspex sheets, nuts & bolts, feet, knob, LED bezel & switch. When built it makes this really nice case for our high power stereo amplifier (the amplifier kit needs to be purchased separately). Designing the case has been a challenging task and the curved sections on the corners are actually cut from a flat sheet of Perspex. Developer Aaron had this to say about the design process, “It’s been interesting to see what can be made using acrylic when you put a bit of thought into the design”. If you would like a different colour to the orange case shown, you can customise your case by picking a colour for the front and back and a different colour for the sides. Check out the product page on the Kitronik website for full details of colour choices. Description
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Laser cut high power amplifier case
See website
£25.00
USING A SERVO WITH A PICAXE CHIP A servo is a type of motor that is often used in robotics as the position of the servo arm can be precisely controlled. Unlike a standard motor, a servo requires a signal to tell the motor how far to turn in addition to the power lines. The signal that controls the servo is a series of pulses, with the length of the pulses determining the angle that the servo will move to (see diagram). If the signal is stopped the servo will lose its position.
SERVO ARM POSITION
INPUT SIGNAL
1st Step 0°
2nd Step 90°
3rd Step 180°
A simple way to get your servo working is to connect it to a PICAXE microcontroller using the Kitronik PIC development board. The servo should be connected to the board as shown in the picture, it is important to use a separate supply for the servo and PICAXE as the servo is electrically noisy. START
Finally a flowchart needs to be written to control the servo. The PICAXE system has a command to drive servos which outputs the required pulse pattern to a given pin. The sample program (shown to the right) moves it through 180 degrees in three steps.
SERVO 0,65 WAIT 3 SERVO 0 ,155
WAIT 3
A full four page explanation can be downloaded from the website.
SERVO 0 ,250
www.kitronik.co.uk/quicklinks/servo
WAIT 3
FUTABA S3003 SERVO The Futaba S3003 Standard Servo is designed for use in remote controlled cars & boats, but can also be used in other applications and can be driven by a PICAXE chip or other microcontroller system. The S3003 superceeds the following servos, S138,S148,S22,S38 and S12. Description
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Futaba S3003 Servo
2542
£8.24
£6.50
MINI PROTOTYPE BOARD A board for prototyping circuits. Components and wires can be placed into the board and the circuit built and tested without soldering. Multiple boards can be interconnected. This board has170 tie points. www.kitronik.co.uk/quicklinks/miniproto Components not included
Description
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Mini prototype board
2446
£2.23
£1.89
LET US MAKE YOUR PCBS FOR YOU If you have ever had to make hundreds of the same PCB then you won’t need to be told it is time consuming and can be frustrating. By using the Kitronik custom PCB service your schools PCBs can be made, cut into single boards, drilled, will also benefit from a component
identification layer on the top and a solder resist layer on the bottom (which only allows solder to be applied to the pads). With prices starting at 3p per square centimetre the service offers great value on small school project boards.
Order by the 19th July and your PCBs will be ready for the new academic year. MORE INFORMATION Details on how to export the manufacturing data and a price calculator can be found online:
www.kitronik.co.uk/services/custom-pcbs
MAKE YOUR BUDGET GO FURTHER As people start to finalise what projects they will be doing in the new academic year and working out how far the budget will go it’s worth noting that we do a discount for bulk buying of kits. Order 200+ kits and get a 5% discount on the kits, or order 300+ kits and get a 10% discount on the kits. The kits can be mixed and matched to make the total, the discount only applies to project kits not the whole order and only Kitronik manufacture kits are eligible for the discount. www.kitronik.co.uk/quicklinks/bulkkits
USING THE LED PICTURE FRAME KIT WHAT DOES THE KIT DO? Simple lighting projects are often done within D&T and allow students to get familiar with using LEDs. This project allows students to take it a stage further and add a number of LEDs to a picture frame or mirror. The project lights the LEDs for a period of time every time the start button is pressed. The picture frame kit is easy to build and is a good project for most secondary D&T students. A wide range of LEDs are available separately giving students the opportunity to choose what size, type & colour LEDs they would like to use in their design. Adding one or two LEDs into each edge of the picture frame gives a good result. The board is able to drive about 10 LEDs, however this will vary depending upon the type of LEDs used. Both the PCB & AA battery holder are fairly small in size (PCB: 58 x 28mm, holder: 57 x 64mm) and are around 16mm deep. This means the frame needs to be of a slightly deeper design to hide the board and batteries around the back.
HOW TO SELECT AND CONNECT LEDS TO THE KIT The PCB has a terminal block to which the LEDs are connected. The LEDs are likely to require a current limit resistor. This is because the output terminals have about 4.5 Volts on them when the button is pressed and most LEDs require a lower voltage than this. In theory every LED should have its own current limit resistor, however in practice if the same type of LEDs are being used it is possible to share one current limit resistor between a number of LEDs. When doing this the resistor value will be smaller than the resistor that is used with a single LED. If a red LED and a white LED are going to be positioned in each corner of a picture frame, then the four red LEDs would be connected in parallel and the four white LEDs in parallel. Each colour LED then shares a current limit resistor. The picture (left) shows these connections. Flat edge of LED connected to (-) This example is connected to make it easy to see how to do the connections; in reality longer wires would be needed. The value of the resistor depends on the type and number of LEDs used. Whilst you can calculate this we have an online calculator* that works out the values for you. Alternatively this table gives the resistor required for various LEDs when using four in parallel. * See next page for quick links
Current limit resistor for four LEDS 3504 3505 3506 3542 3543 3507 3524 3537
Standard red Standard green Standard yellow Standard white Standard blue Ultra bright red Ultra bright white Ultra bright blue
33Ω 33Ω 33Ω 22Ω 22Ω 33Ω 68Ω 68Ω
HOW THE CIRCUIT WORKS When the switch is pressed the capacitor C1 is charged up. Upon release it slowly discharges through the variable resistor (R3). Provided there is sufficient voltage across the capacitor the Field Effect Transistor (FET) is turned on and so are the LEDs. Although FETs have a much sharper response than standard transistors they still gradually turn on and the second FET is present to make sure different types of LEDs turn off together. R3 10MΩ
C1 220µF R2 10KΩ
OUTPUT TO LEDs Q2
R1 10KΩ Q1
SWITCH
QUICK LINKS Resistor Calculator: www.kitronik.co.uk/quicklinks/ledcalc/ Product Information: www.kitronik.co.uk/quicklinks/pictureframe/ Free Samples: www.kitronik.co.uk/services/samples/
LED PICTURE FRAME KIT This kit allows you to illuminate the edge of a picture frame using a number of LEDs. This happens for a period of time when the button is pressed. The duration is set using a trimmer potentiometer and can be anything from a few seconds to 30 minutes. The student can choose which LEDs they would like to use. These are connected to the terminal block (along with a current limit resistor). The board can drive 200mA, which is enough for about 10 high brightness LEDs. Description
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LED picture frame kit
2146
£2.95
£2.20
£1.90
NEW ENCLOSURE PROJECT BOXES Sometimes you just need a nice looking box to mount your electronics in. If you don’t want to make your own we are sure that one of the enclosures in our new range will do the job. There are standard ABS boxes in black, white or grey, but if you want to show off your electronics then you should go for a translucent box. These are available in either in blue or red. If your students will be working on an external electronics project there is even a range of boxes that are watertight. There are too many types and sizes to describe them all so we’ve picked out a few examples. The whole range is available online. www.kitronik.co.uk/quicklinks/boxes
HAMMOND 1591 TRANSLUCENT BOXES PRICES FROM: £3.25
MINIATURE TWO-PART BOXES PRICES FROM: £1.33
WATERTIGHT ABS ENCLOSURES PRICES FROM: £6.75
TWO-PART MODULE BOXES PRICES FROM: £2.53
NEW LEDs The LED range continues to grow. The most recent additions are a selection of colours of Super flux LEDs which are really bright and wide angle. The square format makes them ideally suited for using multiple LEDs in a matrix. We have also added a white flashing LED to the existing four colours of flashing LEDs. If you’re on a tight budget and counting the pennies we have added a slightly cheaper, dimmer LED to our colour changing LED range.
5MM SUPER FLUX LED Description
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White 5mm super flux LED - 10 pack
3597-10
£2.20
Blue 5mm super flux LED - 10 pack
3596-10
£2.20
Yellow 5mm super flux LED - 10 pack
3594-10
£2.20
Green 5mm super flux LED - 10 pack
3595-10
£2.20
Red 5mm super flux LED - 10 pack
3593-10
£2.20
Description
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White flashing 5mm LED - 25 pack
3592-25
£3.80
www.kitronik.co.uk/quicklinks/fluxled
WHITE FLASHING 5MM LED
www.kitronik.co.uk/quicklinks/whiteflash
5MM ROUND COLOUR CHANGING LED This LED slowly cycles through various colours, making it ideal for mood lighting, toys or ornaments. Typical brighness = 500mCd. Description
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5mm round colour changing LED
3591
£0.46
£0.37
£0.30
www.kitronik.co.uk/quicklinks/colourled
10% DISCOUNT ON ALL ANTEX PRODUCTS Stretch your budget a little further with this great offer on all Antex products. We have taken 10% off the already low catalogue price on all Antex products. Get your order in now as the offer closes at the end of July 2013. Kitronik stock over 20 Antex products and all are discounted, here are just a few examples. www.kitronik.co.uk/quicklinks/antex
MAINS SOLDERING IRON - 18W Description
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Mains soldering iron - 18W
2609
£15.60 £14.04
Description
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Antex soldering iron stand
2611
£4.50
Description
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Antex soldering tool set
2661
£45.79 £41.21
Description
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Gem Master Tool
2644
£21.50 £19.35
ANTEX SOLDERING IRON STAND £4.05
ANTEX SOLDERING TOOL SET
GEM MASTER TOOL
FREE SAMPLES Request your free sample Kitronik project kit by phone, email or online at:
www.kitronik.co.uk/services/samples/
The samples service is available for any self assembly electronic kit which is marked as exclusive to Kitronik (except for the motor controller, FM radio & high power amp)
All prices shown are exclusive of VAT, delivery charge may be applicable.
T: 0845 8380781 A: Kitronik Unit 3a, Shipstones Business Centre, North Gate, Nottingham, NG7 7FN W: www.kitronik.co.uk E: sales@kitronik.co.uk
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