This is a power source that creates a DC voltage higher than the voltage feeding the it. It might be used to power your laptop (+18V) from a car battery (12V ~ 13.8V). It is built using very ordinary parts that should be readily available. Here are some specs:
Input voltage 9V ~ 15V
Output voltage 12V ~ 25V
Output current Max. 3A @18V
Switching frequency 20kHz – 40kHz
Efficiency 65% – 95%
If you know these circuits, please skip the following. The circuit is a step-up converter, and it’s workings can be explained by the main property of a coil: its inductance. Imagine a current flowing through a coil. The inductance will cause the current to continue running, even if the power supply that caused this current is taken away. The voltage across the coil will take any value required to keep the current running. This is why you can easily create sparks with a coil, a spark is simply a current flowing at a very high voltage.
This circuit flips between two states: ‘charging’ the coil with current, and dumping this current into the output capacitor. The frequency at which this happens is so high that only a small ripple remains at the output capacitor (10000uF). Here is the circuit.
Source:http://www.xs4all.nl/~jwasys/old/diy4.html
Thank you.
Related Links
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This entry was posted on Wednesday, February 6th, 2008 at 10:25 pm and is filed under 555, dc converter, switching power supply.
