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  • AndrewB52 commented on TueBjørn's instructable 100W LED - Flashlight5 days ago
    100W LED - Flashlight

    I believe you are right about this. LED lights and laser diodes use current regulated drivers. This is from Digikey's website:"Why do I need to use a driver for my LEDs?Choosing the right supply is key to ensuring that you get the best performance from your LED. The long lifetimes of LEDs foster the perception that the weakest link is now the power supply. Excelsys has chosen design techniques, market leading components, and thermal management techniques in order to provide solutions for customers with lifetime matching figures. We also have incorporated a number of design features that fit in nicely with LED market requirements:IP67 rated, waterproof metal casing and will probably be pottedLEDs are non-linear devices (If vs. Vf) with a forward voltage that is temperature depende...

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    I believe you are right about this. LED lights and laser diodes use current regulated drivers. This is from Digikey's website:"Why do I need to use a driver for my LEDs?Choosing the right supply is key to ensuring that you get the best performance from your LED. The long lifetimes of LEDs foster the perception that the weakest link is now the power supply. Excelsys has chosen design techniques, market leading components, and thermal management techniques in order to provide solutions for customers with lifetime matching figures. We also have incorporated a number of design features that fit in nicely with LED market requirements:IP67 rated, waterproof metal casing and will probably be pottedLEDs are non-linear devices (If vs. Vf) with a forward voltage that is temperature dependent — that is, it needs to be controlled by regulating currentLEDs are low voltage DC devices with forward voltage requirements. LEDs also require protection against damageIncandescent light bulbs are purely resistive loads, LEDs are not. Drivers are required to provide a power factor close to one over all line and load conditionsHigh efficiency (driven by lumens per watt demanded by luminaire designers)High reliabilityLong lifetime (power supplies now perceived as the weakest link in the chain), needs to be in the tens of thousands of hoursUL8750 approvedFuture designs will have the capability to communicate with the power suppliesNow I know why I need an LED driver, should I use a constant current driver or a constant voltage driver?We have stated that LEDs are current driven devices, so why do companies offer both Constant Current (CC) and Constant Voltage (CV) solutions for LED drivers?The reason for this is to give the light fixture designers a number of options in optimizing their system. If many strings of LEDs are used in series, the most efficient way to drive them is to use a constant current power supply and connect the LEDs directly across the terminals of the power supply. However, if strings of LEDs are connected in parallel, there may be an issue in trying to match the current in all the strings. A possible alternative to this would be to place an external component or active circuit to control the current. This may result in a slightly less efficient overall number of lumens per watt, but it allows the user to have full flexibility in ensuring that an identical current flows though many LED strings in parallel."

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  • Bubble-Free Resin Casts with Modified Paint Tank

    Is it possible to use the Venturi device to pull a vacuum in the pressure container...is it strong enough? Can enough vacuum be pulled?

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