Next we have the circuit from an actual LED flashlight. This circuit is so small that it fits inside the “bulb base” behind the reflector in a 2C cell flashlight. All of the parts are surface mount except the LEDs, the 2N3904 and the coil. The LED in the schematic is actually 8 5mm ultra bright white LEDs. Unfortunately, once again we have an unmarked surface mount capacitor.
Instead of a CdS cell, a flashlight of course has a switch. In our walkway marker circuit, one of the transistors took the place of the switch, so the oscillator section was really 2 coils and a transistor. Now instead, this oscillator has one coil and two transistors. The coil is also different. It is a larger wire wound I core instead of the type that resembles a resistor. A larger coil and transistor means more power since it has to drive 8 LEDs instead of just one. Plus the white LEDs have a 4v voltage drop instead the 3v drop of the amber one from the walkway marker.
Source:http://silenceisdefeat.org/~lgtngstk/Sites/tls.html
Related Links
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This entry was posted on Saturday, April 5th, 2008 at 8:41 am and is filed under Lighting.
