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I'm designing a buck boost converter for a simple variable power supply by connecting a boost(LM2577) converter circuit and a buck(LM2596) converter circuit in series. They each have a potentiometer to control the feedback pin. Is there anyway where I can combine both the potentiometers into one? Plus, I do not want to get a buck-boost converter module because from where I from its really expensive.

Edit: The 3 euros buck boost converter has low power and after conversion rate in my country it's not worth it since I have the individual modules already. Regarding the power rating, the input will be 12V and have an output range of 1-28V 3A.

enter image description here enter image description here These are the images of the buck boost converters respectively.

Thank you!

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    \$\begingroup\$ What are the required input and output voltage ranges? \$\endgroup\$
    – Bruce Abbott
    Aug 28, 2016 at 17:37
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    \$\begingroup\$ (1) Why do you need 2 potentiometers in the first place? Keep the boost (first stage) at fixed output voltage. Control the buck with one potentiometer. (2) Post your schematic, please. \$\endgroup\$
    – Nick Alexeev
    Aug 28, 2016 at 17:38
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    \$\begingroup\$ really expensive Hmm, less than 3 Euros a piece including shipment from China: ebay.nl/itm/… I wonder what you call expensive. \$\endgroup\$
    – Bimpelrekkie
    Aug 28, 2016 at 17:45
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    \$\begingroup\$ If you really want to do it this way (almost certainly not), get a "dual-gang" potentiometer, which is two potentiometers on one shaft. \$\endgroup\$
    – pjc50
    Aug 29, 2016 at 10:14

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I doubt that you really need 2 potentiometers in the first place. Keep the boost (first stage) at fixed output voltage. Control the buck (second stage) with one potentiometer.

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  • \$\begingroup\$ I thought of that but that would increase the energy loss and I would prefer to avoid that \$\endgroup\$
    – Max
    Aug 29, 2016 at 3:13
  • \$\begingroup\$ @Max: Increased output voltage on the first (boost) converter would not by itself increase energy loss and in fact may improve efficiency slightly. The buck converter, like all switching converters, will take just the energy it needs from its source to maintain its output voltage and current. \$\endgroup\$
    – scanny
    Aug 29, 2016 at 6:22

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