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Can anyone assist me to make a power supply whose output voltage will be controlled by an Arduino, with the latest voltage setting automatically saved in non volatile memory?

I am in an OJT (On the Job Training Scheme). I was given a task to make a Arduino controlled voltage variable power supply whose outputs can be switched between several preset values using pushbutton control. It's like switching between two different outputs when a designated button is being pushed.

Here is what I have done so far. I made an LM317 based power supply with the output voltage controlled by a potentiometer. I followed this youtube tutorial. It works well but I was ask to upgrade it.

Instead of using a potentiometer to adjust the voltage, I wish to use switching buttons to choose between two or more preset voltage levels. Each switch buttons have their corresponding voltages.

This link may also be relevant. Code is given below the circuit diagram. ARDUINO AS A POWER SOURCE ALTERNATOR

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    \$\begingroup\$ You need to add significantly more detail to your question. Is this an automobile alternator? What voltage? How much current does the field winding require? \$\endgroup\$
    – Dwayne Reid
    May 5, 2015 at 5:17
  • \$\begingroup\$ @DwayneReid No, It's not an automobile alternator. It's a simple adjustable power supply and I've made one. I followed this youtube tutorial [link] (youtube.com/watch?v=F-ahtojVl4M). It works well but I was ask to upgrade it, instead of using a potentiometer in adjusting the voltage, he suggest to have a swicthing buttons which I can swap two or more power sources automatically. Each buttons must have their corresponding voltage outputs. Can you help me figure out how to apply it maybe by using an arduino? \$\endgroup\$
    – April Cyra
    May 5, 2015 at 14:38
  • \$\begingroup\$ Why do people need arduino for every single electronics project? Use the push-buttons to switch between different resistors for the LM317 and you will achieve what you want. \$\endgroup\$
    – v.m.
    May 6, 2015 at 6:21
  • \$\begingroup\$ @v.m. Can you give me a circuit diagram of what you have suggested? \$\endgroup\$
    – April Cyra
    May 6, 2015 at 6:55
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    \$\begingroup\$ Based on what you have done so far, you can replace your potentiometer with a digital potentiometer chip and use the Arduino to control it. \$\endgroup\$
    – Maxthon Chan
    May 6, 2015 at 7:20

2 Answers 2

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If a adjustable LDO is enough, you could put different discrete resistors in the place of the poti and switch between the resistors with NFET Transistors controlled by the arduino.

Second, there are digital controlled potentiometers out there, but they are expensive and I have never worked with them.

EDIT: Below is a really fast and not verified sketch what I think of. Please use with caution. In the end you have to understand yourself what you are doing.

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ This is what the application note (ti.com/lit/ds/symlink/lm117.pdf) figure 57 proposes. Note to April: it's usually a good idea to look at the datasheet and application notes. I learned tons of stuff only from those sources. \$\endgroup\$
    – 0x6d64
    May 6, 2015 at 6:17
  • \$\begingroup\$ Okay thanks, can you assist me in doing the circuit diagram? \$\endgroup\$
    – April Cyra
    May 6, 2015 at 6:17
  • \$\begingroup\$ @0x6d64 Thanks. Yes I will make a review for those sources. \$\endgroup\$
    – April Cyra
    May 6, 2015 at 6:25
  • \$\begingroup\$ You can go with a d-pot at the adjust pin of LM317, and have your Arduino adjust it upon command. \$\endgroup\$
    – Maxthon Chan
    May 6, 2015 at 7:07
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Just throw it out here, in case you like it switch mode (using a boost converter for example, if you need lower voltages go for a buck topology):

schematic

simulate this circuit – Schematic created using CircuitLab

Just use a MOSFET with low enough \$R_{ds(on)}\$

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