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I'm building an Arduino-based midi fader controller, and want to also add an audio VU / Level Meter to the enclosure.

The Arduino is USB-powered.

I bought a standalone audio level meter on AliExpress, though, that is rated as needing between 7-12 vdc.

It won't be attached to the Arduino, and it just has a stereo audio-input and power terminals, and I'm feeding it audio that is coming from a recording console output.

I'm trying to figure out how to power it?

I am trying to keep the enclosure light and portable, and also I'm not really too proficient with electronics, just a beginner.

Since the Arduino USB is 3.5 / 5.5 vdc powered, do I need to buy a separate power-supply or wall-wart just to power the meter?

Much appreciated!!!

enter image description here

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  • \$\begingroup\$ Be sure buying a DC-DC boost convertor with the "same" ground at input/output ... \$\endgroup\$
    – Antonio51
    Mar 15 at 18:51
  • \$\begingroup\$ 7-12 sounds like the input voltage requirments for a 7805 regulator, find it, and bypass it, power from usb. \$\endgroup\$ Mar 15 at 23:50

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You need a what's called a boost convertor. You are looking for a module that will take in 5V and output 9V nominal. What happens is the Arduino get's powered directly from the USB power GND and 5V+ and the boost converter also gets powered from the USB. Then, The VU meter gets powered from the boost convertor.

schematic

simulate this circuit – Schematic created using CircuitLab

The exact connections will depend on you convertor, but the concept will be the same. You might also need some capacitors for stabilizing the power rails. And possibly resistors for setting the boost convertor output. But 9 volts is such a super popular output, you can easily find a fixed 9V version, no adjustment resistors required.

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  • \$\begingroup\$ Thanks so much! That sounds prefect, and also simple enough for me to do myself. Thanks again! \$\endgroup\$
    – jimj31
    Mar 15 at 18:03
  • \$\begingroup\$ If I am going to power everything from a small mini powered USB hub in the enclosure, could I use something like this? Thanks! \$\endgroup\$
    – jimj31
    Mar 15 at 18:07
  • \$\begingroup\$ aliexpress.us/item/… \$\endgroup\$
    – jimj31
    Mar 15 at 18:07
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    \$\begingroup\$ @jimj31 This is one of the problems of buying from places like aliexpress, there is usually little if any documentation. The meter says it takes over 100mA, is that 101mA or 800mA? You don’t know, ‘more than’ is useless when specifying current. I didn’t see any current rating on the converter, is it enough? Flip a coin and take your chances. Whatever current the meter draws from the converter, the converter will draw that much multiplied by the voltage ratio divided by the efficiency so for 12V@100mA 80% eff. it’s 100mA*(12V/5V)/0.8=300mA from the USB port. \$\endgroup\$
    – GodJihyo
    Mar 15 at 18:59
  • \$\begingroup\$ Hi thanks once again! I will have to try to figure out if that will work. On the other point, I have to say you are right. I really have had mixed luck with AliExpress, but ordering from Mouser and the like is so expensive. Then again, ordering my faders from Ali was a mistake, so I ended up paying again to get some accuracy. But that said, thanks again so much for your help! \$\endgroup\$
    – jimj31
    Mar 15 at 19:26

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