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I bought one of these cheapo Ebay toys from China. It's a buck converter with a Constant Current function. I plan on using to drive LEDs from an 18.5v 18650 li-ion battery pack.

One of the potentiometers adjusts the voltage of the output, and another limits the current.

My limited understanding of these devices is that the potentiometer controlling the voltage acts as a voltage divider. Scouring the forums tells me that most of the pots are 2K ohms.

The buck converter is based on the LM2596, for which the datasheet is here

Is it okay to replace the one voltage potentiometer with three 2K ohm potentiometers like this: with the blue pot in series controlling the maximum voltage and the blue pot in parallel controlling the minimum voltage, so that the brown pot controls the voltage within the ranges set by the two blue pots?

enter image description here

Merry Christmas!

EDIT: I forgot to add that I know controlling the current is the best way to dim an LED, however, I don't know how the current limiting feature works. Does anybody care to explain please?

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    \$\begingroup\$ Can be done ✅ or X , but poor way to regulate LED brightness when you can limit current \$\endgroup\$ – Sunnyskyguy EE75 Dec 23 '17 at 0:32
  • \$\begingroup\$ I forgot to add: I forgot to add that I know controlling the current is the best way to dim an LED, however, I don't know how the current limiting feature works. Does anybody care to explain please? \$\endgroup\$ – Che0063 Dec 24 '17 at 2:25
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    \$\begingroup\$ Link to product doesn't work, says "0 results. You may also like..." (lots of suggestions with no Constant Current function). Have you traced the circuit to find out how the pots are connected to the 'LM2596', and have you measured their values? \$\endgroup\$ – Bruce Abbott Dec 24 '17 at 4:48
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You do not need to do any modifications, only to choose the required output voltage and series resistance to create a 1V drop to prevent thermal runaway and easily check current in case you have not provided proper cooling to your LED string.

You start with the voltage setting with a pot that has a control range of 5 to 10 turns ( by appearances)

Then increase till desired brightness and temperature rise that is not too hot to touch.

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