Wednesday, 27 October 2010

So I'm back...

I have decided to restart my blog with another new learning curve. I started my PGCE at Nottingham Trent University way back in September and it is intense but I am really enjoying it. The subjects that I will be teaching are Resistant Materials (my strong point, thanks to my Crafts Degree!) and Electronics (my very weak point. I am about to start my block placement for the first phase in a school, which is exciting yet scary!

The first assignment, due in November is based on our weak subject specific areas. From the subject audit I identified that I needed to improve on:
  • KS3 circuit symbols, circuit diagrams, systems diagrams, units of electricity, use of resistors and other circuit components.
  • Working with plastics and smart materials: Tensile strength, ductility, malleability, ease of moulding, micro arrangement of particles and fibres.
  • Electronics terminology and key words: Micro controller (PIC), inputs, outputs, potential divider circuits, transistor used as a switch, truth tables.
  • Designing: Formal drawing techniques, construction details, dimensions.
  • Computer Aided Design, Computer Aided Modelling, 3D computer rendered images, working drawings, extrusion and revolving, sectional views.
From these weak areas in my subject audit, I needed to create a scheme of work for 6 lessons, suitable for teaching in schools.

The project:

I found some tutorials on instructables ( on very simple projects based around the 90's game 'Operation.' The projects included a very simple circuit (LED, buzzer, battery) and the materials were simple everyday materials.
So I decided to challenge myself to designing and adapting this very simple project to suit school based criteria for electronics and resistant materials. 

The project would be suitable for year 8/9 and involves a number of processes and skills that will satisfy criteria on the National Curriculum, as well as being a fun project which the children would enjoy.

So here's how I started...

I acquired a copy of circuit wizard and made a personal tutorial for future reference, showing how the PCB for the game is designed and made:

This is the circuit design, showing all the components and below that is a circuit diagram. The circuit includes:
-10K Resistor
-1K Resistor
-2 pin Terminal Block
-2.2K Resistor
-33K Resistor
-Printed Circuit Board
-400 Farad Electrolytic Capacitor
-50K Variable Resistor
-560 Resistor
-C106M Thyristor
-Push-to-make switch

-SPST Switch

I then drew out the components circuit on Circuit Wizard:

When the main SPST Switch is on, the power flows and one LED illuminates.

When the Push-to-make switch is activated, the buzzer sounds and both LED's are illuminated. The buzzer and LED's stay on until the main SPST Switch is turned off.

I then had to draw out the Printed Circuit Board (PCB) ready for etching:

1.       -Draw 2”x2” Border (start small- can be stretched).
-Draw pad.

-Adjust pad size:  
-Set size to:

 -Draw copper track to link pads.

2.       -Adjust track width:
-Width: 0.7in Gap: 0.7in

3.       Duplicate pads and arrange in circuit according to component positions

4.       Draw in linking tracks and adjust sizes accordingly.

 5. Adjust track sizes either at the end or as you go along.

 6. Stretch 2"x2" border so that all pads and tracks can fit on.

 7. Keep tweaking the design so that the pads/tracks are not too close together and not too far apart (thus wasting PCB).

8. Add text to the board so it can be easily identified.

9. The final PCB design. This is then printed out and exposed onto the PCB using Ultra Violet light. The PCB then goes into the etching tank which leaves the copper tracks and pads.

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