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# Ldr house activity

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### Ldr house activity

1. 1. LIGHTHOUSEElectronic circuit production
2. 2. The components
3. 3. The battery clip holds the 9volt battery whichpowers the circuit. The red wire ispositive and the black is negative.Current flows through the wire muchas the flow of a river, the currentflows in one direction from the battery frompositive to negative.The battery clip
4. 4. The resistor limits the amount of currentwhich flows to the L.E.D. it “resists” theCurrent flow slowing it down.It can protect delicate components in acircuit from receiving too much voltageand slows the current flow through thecircuit. Resistors are too small to haveNumbers printed on them so they havea colour code printed in bands.Your resistor is a 100KThe resistor
5. 5. The L.E.D gives off visible light and is a commoncomponent in lots of electrical equipment such as powerindicators on televisions. It is known as an output component. It has a positive leg (long) called the anode and a negative leg (short) called the cathode and it is important to remember this when you solder this in your circuit.The wrong way round and it won’t workThe Light Emitting Diode
6. 6. The transistor can be used as an amplifieror a switch to control the flow of currentaround the circuit. It has three legs, the middle leg is thebase which activates the transistor, the positive or collectorand the negative or emitter. These need tobe soldered to the other componentscorrectly. It is semi circular in shape sothat you can tell which way round it goes. - +The transistor
7. 7. The L.D.R is the most important componentin this circuit. It works like a resistor by limiting current.Unlike a resistor which has a set value, resistance changesbased on the amount of light falling on thesurface of the LDR. This allows morevoltage to the L.E.Ds which in turn allows thelights to come on when it begins to get dark.These components are known as sensors.The Light DependentResistor
8. 8. The wire is the glue that holds the componentstogether in the circuit. There are two coloursthat match the flow of current, positive (red) andnegative (black)It is vitally important your wires are soldered inproperly in order for the circuit to work.The plastic serves as a non conductinglayer to prevent short circuits.It also helps identify positive and negative inwiring circuits.The wires
9. 9. CREATING THE CIRCUIT
10. 10. Take your two L.E.Ds andtwist the positive and negativelegs together so they are attachedas in the diagramAPPLY SOLDERStep 1
11. 11. Prepare one black length of wire and onered length of wire by stripping the endsand twisting the exposed wireAPPLY SOLDERStep 2
12. 12. Twist these wires onto the legs of the L.E.DsRemember the red wire goes on the long legand the black one on the shortAPPLY SOLDERStep 3
13. 13. Attach the resistor to the red wireon the L.E.DsAPPLY SOLDERStep 4
14. 14. Prepare two wires in the same wayfor the LDR but in this case the red andblack wire can be on either leg as thereis no positive or negative.APPLY SOLDERStep 5
15. 15. Prepare a piece of red wire and attach it the center leg of the transistor.you may need to bend the legs outslightly to do this.APPLY SOLDERStep 6
16. 16. You are now ready to solder thecircuit together. Take your time to look at thediagrams and ensureyour components are soldered toeach other in the right orderPreparation complete
17. 17. Attach the black wire from theLDR to one leg of the transistoras shown. Make sure the transistorIs the right way round.APPLY SOLDERStep 7
18. 18. Now join the black leg of theL.E.D to the remainingleg of the transistorAPPLY SOLDERStep 8
19. 19. Next join the two red wires togetherand solder them to the remaining leg of the resistorAPPLY SOLDERStep 9
20. 20. The final step is to solder the batteryclip in place.Step 1.The black wire goes to the leg of the transistorwhich is attached to the LDRStep 2. The red wire attaches to the wire leadingfrom the L.E.Ds at a point before the resistor.A FULL DIAGRAM IS ON THE NEXT SLIDEThe final step
21. 21. L.D.R BATTERY CLIPRESISTOR TRANSISTOR L.E.Ds Complete circuit
22. 22. • If you have completed the steps correctly you should have a functioning circuit.• Now all that remains is to attach the battery• If you put your hand over the LDR the L.E.Ds should light up• If this doesn’t happen;• Check your soldering• Check the components are soldered together correctly• Check the positive and negative legs are the right way roundTesting your circuit
23. 23. Building the house
24. 24. A development net is a flatshape which when foldedand assembled will become a 3D objectThe development net
25. 25. Apply details to the outsideof your house to makeit more creative.Colour in the walls and roofAnd add flowers or a designMaybe your school logoDesigning your house
26. 26. The thick black lines on thenet are cut lines, cut alongThese lines neatly with thescissors.The dotted lineson this net arefold lines. Carefully foldalong each of these pointsCut and fold
27. 27. The areas at the sides of the housere glue tabs and you should applyThe double sided tape to this areaDo not stick it together until theCircuit is installedGlue tabs
28. 28. • The LDR goes through the small hole in the roof of the net and is attached with tape• The battery will be stuck to the floor also using tapePutting in the circuit
29. 29. • Double sided sticky tape is used on the glue tabs to assemble the house• Try to be neat when folding and assemblingAssembly
30. 30. You have now created your first sensor operated circuit.There is a pack of components for you to take home or toassemble in school with your teachers.Pass on what you have learnt to your classmates and see ifyou can create your own sensor based projects.Task complete