Hi,I need <20mm diameter that can output 4-6V at 1.8A (powering a 1W green LD). It can be up to 5mm tall
EDIT: I want to build the circuit myself using linear regulators, so ideally the design shouldn't require too too many parts
Keep in mind that lord Styro used linear regulators in his 100W handheld. Thanks for the input Cyp! I will take a stroll thru my local FPV store to see if I can find some kind of weirdly shaped LiPo I could use for the high voltage input. Is there any other topology that a newb like me could cheaply deploy for driving 1.8A?2 problems with your test. 6 of those diodes in series is going to be about 5.5V at this current. If that's a 1ohm shunt, that's another 1.8V. So I'm estimating you're driving a 7.3V load in an attempt to emulate a 4.5V load. Also, The lm317 current source needs almost 4V of overhead to function reliably. Add in the internal resistance of the lithium cells, and you really need to have three in series for this topology to work. That's why no one uses this for high power, and I'm confused why it's still suggested. There are also several sticky threads on this, and other similar drivers.
As for resistor calculations, it's just ohm's law. If that's too hard, there are lm317 current calculators like this one. At least put some effort into google.
Apparently you did not read the description of the Survival Laser driver you gave a link to. It clearly states " capable of delivering from 220mA to as much as 1.8A of regulated current at a recommended input voltage of 4.2 to 8.4 volts, meaning either one or two batteries. A standard 3.7V li ion battery is 100% charged at 4.2V---so SL means one or two standard batteries eg. 1 x 18650 or 2X 15340 or 18350'.Aight folks, I got the thing to work but it needs a pretty high input voltage in order to output enough voltage. Idk what I'm doing really, so is there some way for me to make it so that the circuit boosts the 3.7V from a regular battery up to the correct output voltage? Or if not is there any kind of compact battery that outputs high voltage (12V+ with less than 18mm diameter and 35mm height).
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I looked at this SL driver (https://www.survivallaser.com/Survival_Laser_Fixed_Current_Driver/p556088_7425633.aspx), but the darn thing needs 2 batteries (4.2V+) to run since it has no boost circuit!
Long story short, do you know of any circular 1.8A laser drivers that can operate (without making too much heat) off of just one LiIon battery?
Please help me out here