Wednesday, 19 December 2012
Sunday, 18 November 2012
"Electronics Symbols"
Circuit Symbols
Wires and connections | ||
| Component | Circuit Symbol | Function of Component |
| Wire |  | To pass current very easily from one part of a circuit to another. |
| Wires joined |  | A 'blob' should be drawn where wires are connected (joined), but it is sometimes omitted. Wires connected at 'crossroads' should be staggered slightly to form two T-junctions, as shown on the right. |
| Wires not joined |  | In complex diagrams it is often necessary to draw wires crossing even though they are not connected. I prefer the 'bridge' symbol shown on the right because the simple crossing on the left may be misread as a join where you have forgotten to add a 'blob'! |
Power Supplies | ||
| Component | Circuit Symbol | Function of Component |
| Cell |  | Supplies electrical energy. The larger terminal (on the left) is positive (+). A single cell is often called a battery, but strictly a battery is two or more cells joined together. |
| Battery |  | Supplies electrical energy. A battery is more than one cell. The larger terminal (on the left) is positive (+). |
| DC supply |  | Supplies electrical energy. DC = Direct Current, always flowing in one direction. |
| AC supply |  | Supplies electrical energy. AC = Alternating Current, continually changing direction. |
| Fuse |  | A safety device which will 'blow' (melt) if the current flowing through it exceeds a specified value. |
| Transformer |  | Two coils of wire linked by an iron core. Transformers are used to step up (increase) and step down (decrease) AC voltages. Energy is transferred between the coils by the magnetic field in the core. There is no electrical connection between the coils. |
| Earth (Ground) |  | A connection to earth. For many electronic circuits this is the 0V (zero volts) of the power supply, but for mains electricity and some radio circuits it really means the earth. It is also known as ground. |
Tuesday, 30 October 2012
"HOW A CAPACITOR WORKS"
When the circuit is switched on, the LED emits light and the
capacitor charges up. When the switch is turned off the LED stills emits a
light for a few seconds because the electricity stored in the capacitor is
slowly discharged. When it has fully discharged it's electricity the LED no
longer emits light. If a resistor is introduced to the circuit the capacitor
charges up more slowly but also discharges more slowly. What will happen to the
light ?
