• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

EEs help! How do you wire a voltage regulator?

M

mercanucaribe

Banned
I got a +5v voltage regular from Radioshack that I'm using to regulate voltage to a Luxeon 1W LED... But I don't know how to wire it. THe diagram on the back of the package shows the pins as Input, Output, and Ground, but no wiring instructions. Does ground go to the + pole of both the battery and the LED, input to - on battery, and output to - on the LED?

Also, does a fixed voltage regulator work like the LM317? With the LM317, excess voltage is dissipated as heat, which is no good for a flashlight.
 
umm.. input is whatever voltage you want to regulate (must be greater than the specified regulated output voltage), output is the +5V or whatever the regulated voltage is specified to be, and ground is ground. Depending on how much greater the input voltage is over the regulated voltage, you may need a heatsink on the regulator.

Im not sure I understand what you are trying to do though. What voltage is the battery? Are you using the regulator to get 5V out of a battery that is greater than 5V?

If your battery is your input source, then connect the + terminal to input, the - terminal to ground, and then wire the LED over the output. You will probably need a current limiting resistor with the LED (not sure what kind of current would be drawn)
 
Originally posted by: mercanucaribe
I got a +5v voltage regular from Radioshack that I'm using to regulate voltage to a Luxeon 1W LED... But I don't know how to wire it. THe diagram on the back of the package shows the pins as Input, Output, and Ground, but no wiring instructions. Does ground go to the + pole of both the battery and the LED, input to - on battery, and output to - on the LED?

Also, does a fixed voltage regulator work like the LM317? With the LM317, excess voltage is dissipated as heat, which is no good for a flashlight.
Click to expand...

7805s are standard regulators, so just download a LM7805 or 78XX datasheet from any of the big semiconductor manufacturers ( national/fairchild/stmicroelectronics ). The specs should be the same across the board. A LM317 works the same way i believe as fixed regulators, just that the 317's output voltage can be adjusted though external feedback with resistors.

Usually you wire it up like this:

BATTERY + -> INPUT of 7805
BATTERY - -> GROUND of 7805
OUTPUT of 7805 is +5 to Resistor to LED to ground.

Power efficiency in linear regulators like these is fairly poor, with dissipation as heat as Pdissipatedasheat = ( Voltage in - Voltage Out )*Current Out

You would do alot better with a switching regulator like a boost or buck converter.

Maybe one from Maxim-IC?

http://www.maxim-ic.com/solutions/white_led_drivers/index.mvp

Or Linear Technology?
 
Linear regulators drop voltage by disappating the excess power. They're simple, (and often quiet in the RF sense) but that's thier major down side.
 
I'm just going to use a resistor instead. In other news, I modded my Dorcy 3D luxeon flashlight with a rheostat from an old Coolermaster 80mm case fan... But I keep getting shorts 😱. When it works though, it works great. I bet it would last a few days at the lower brightness settings.
 
You must log in or register to reply here.

TRENDING THREADS

Back
Top