555 Timer Practical.

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555 Timer Practical                                                     Verinder Channa

Scenario: A chef requires an egg timer which sounds a buzzer. The buzzer needs to have an adjustable timer, so that different times can be set for the egg to boil.

 

Method: To make an egg timer I will need to make a 555 timer with a variable resistor to adjust the time set for the egg to boil

In order to do this experiment, I will need the following components to make the timer:

  • 9 volt battery
  • Battery Snap
  • Switch (s.p.s.t)
  • 2x 10kΩ Resistor
  • 0.1μF Capacitor
  • 1mΩ Potentiometer
  • 220μF Capacitor
  • 680Ω Resistor
  • Light Emitting Diode
  • Buzzer
  • PCB Board (Printed Circuit Board)
  • Connector Wires – Red and Black
  • 555 Timer + Holder

The tools I will require while making the timer are a soldering iron and solder, a mini-pillar drill, and a sucker while making the Timer. I will also need 2 different sized drill-bits according to the size of the holes that I need to drill for the components to fit in.

After I have collected my components, I will follow the following procedure:

Making the PCB Board

I will firstly remove the protective covering from the PCB Board. I will then lay the master circuit film onto the U.V Light box, aligning the PCB Boards on top. I will then close the U.V Box and leave it for 3 and a half minutes.

After this I will place the PCB board on into a developer. The developer contains a developing solution which removes the silver underneath the copper, which radiation has been previously projected on.  The developing solution will loosen the silver and copper underneath the layer of the PCB board, which radiation has not been projected on by the U.V Light Box.

After this, I will wash the PCB Board in water, to make sure the solution is removed from the PCB Board.

I will then place the PCB Board in a etching tank containing ferryc chloride solution for 30 minutes. The PCB Boards are placed in an etching tank to take off the excess photoresist on the PCB Boards. When the solution is fresh, it takes 15 minutes for the excess copper to etch away. However as you put more PCB Boards in the tank the solution becomes saturated with copper and slows down. I will be doing several PCB Boards together so in this case it will take 30mins.

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I will then take the PCB Boards out of the etching tank and rinse them in water to remove any ferryc chloride solution left on the PCB Boards.

Components

After the PCB Board has been etched and the circuit is clearly shown on the PCB Board, I will drill the hole for where the components need to be soldered.

I will refer to my circuit diagram in order to do this. I will need to look at the different sizes for different components.

I will use a mini-pillar drill to drill the ...

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