Full-wave Rectifier
Since I am posting the results of my chemistry project, it occurred to me that I might also post what I did in physics. The work in this project is already complete and ready to be posted.
This is one of the simplest physics projects one can do. A device to convert household supply of Alternating Current (220V, as available in India) to Direct Current, of significantly lower voltage. It is basically a full-wave rectifier. It can be used as a battery and it supplies almost a constant voltage with a very low amount of fluctuation.
Basic Materials
- Transformer (220V to 12V)
- Capacitor
- Diode
- Soldering iron and soldering wire
- Switch
- Connecting wires
- AC wire
- Eliminator box (optional, but recommended)
- LED (optional, but recommended)
- Crocodile clips (optional)
Circuit
The LED is not shown in the circuit. It may be connected in parallel, attached with a resistance, with the capacitor, and may serve as an indication of the current supply in the DC output region.
The Finished Product
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| The top view of the eliminator, set in an eliminator box. The transformer, capacitor, AC wire, connecting wires, crocodile clips are visible clearly. |
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| View without power supply. |
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| With power supply (notice the glowing LED). |
Points to be Noted
The diodes in the circuit ensures the flow of unidirectional current in the output. But the DC thus generated is variable, since the output voltage varies as a function of time. Thus, if we plot voltage vs time graph, the equation will be:
V=V0|sin(t)|, where V0 is the peak voltage (12V in this case).
But, this output is barely valuable. To filter the output, a capacitor is added in parallel (check the circuit diagram), which, by the process of charging and discharging, maintains almost a uniform voltage in the output. Thus, with the capacitor connected, the voltage vs time graph is almost similar to the graph of the equation:
V=V0, where V0 is the peak voltage.
So, the capacitor basically acts as a filter, which maintains a fairly uniform output voltage, which is independent of time.
