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I am trying to make an LED strip dimmer circuit using LM2596 Buck converter, but the trimmer pot trimmer makes it difficult to change the brightness every time. Is there any way to replace the trimmer pot with a rotary pot rotary pot, if so then what wattage and resistance should I keep in mind in buying the appropriate rotary pot ?

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closed as off-topic by Bimpelrekkie, Voltage Spike, Harry Svensson, pipe, winny Nov 20 '17 at 11:13

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  • \$\begingroup\$ 1) off topic 2) it depends on how the original potmeter is used (which you do not show, there are many ways to make a dimmer with an LM2596 and a potmeter so include the actual circuit) if it can be replaced with a different potmeter. \$\endgroup\$ – Bimpelrekkie Nov 14 '17 at 8:10
  • \$\begingroup\$ @Bimpelrekkie I suspect it is one of those super-cheap units that includes TWO pots -- one for setting the voltage and one for setting the current limit. The OP doesn't say which of the two they are using to control the brightness. But for these \$12\:\textrm{V}\$ strips anyway it tends to work okay using either the current control pot or the voltage control pot. (I actually did this with an LED strip using those cheap controllers. So that's why I have a small clue.) \$\endgroup\$ – jonk Nov 14 '17 at 8:49
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    \$\begingroup\$ Those tiny multiturn pots have no power requirement to speak of. Regarding the resistance, just remove the pot and use an Ohmmeter on it. That will tell you what you need for resistance. Power won't be an issue. But if you buy one of those pictured, then it is just one turn and that may be a problem for you as too much change may occur for very minor adjustments. Perhaps you should just consider buying a larger multiturn pot with a knob. Multi-turn pot seller \$\endgroup\$ – jonk Nov 14 '17 at 8:56
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    \$\begingroup\$ Have you discounted the possibilities shown by searching for "trimmer pot knob" and looking at the images? \$\endgroup\$ – Andrew Morton Nov 14 '17 at 10:40
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    \$\begingroup\$ @UditSarkar You can get trimmer pots just like the one you show but they have a grooved shaft to add a knob example, also you can get knobs with a long shaft that you could attach to the existing pot example. Either way would avoid moving the trimpot away from the PCB which could possibly make it unstable or susceptible to noise pickup. \$\endgroup\$ – Andrew Morton Nov 14 '17 at 18:40
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If you are using POT to control the output voltage in the LM2596 standard circuit then any of them will work. The feedback pin current is in 100nA range, so, power dissipation will be very small.

You can check the datasheet and you will find the standard application circuit for this buck regulator.

enter image description here

You need to calculate and adjust the POT value may be in combination of resistor value for R1 and R2 such that for maximum and minimum value of pot, you will have a variation of around 8V to 12V or whatever you need at the output voltage.

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