3
\$\begingroup\$

I need to replace an SD card that came with a piece of electronic equipment (specifically, a sequencer for a Eurorack modular synthesizer). The SD card that came with the module is 1GB, and is a no-name brand. I have an extra "SanDisk 32GB Extreme" card (which looks like this one). Eurorack modular synthesizers run on relatively low current, and every milliamp counts in order to not overload the power supply.

I've been told that SD cards these days all draw about the same current, regardless of how large they are, and regardless of brand. I saw this thread, though, which seemed to indicate some doubt about that ("...cards are allowed to draw more current than that, but only after they've notified the host that they want more current, and the host has assented to it..."). I'm not an electrical engineer, so wasn't sure how to interpret that in my situation.

Is there any way to determine how much current the SanDisk card mentioned above draws? I couldn't find the specs. And for any currently available card?

Any info/guidance appreciated!

\$\endgroup\$
7
  • \$\begingroup\$ The comment you are referring to means that module which the SD card is plugged into would have to approve the SD card to draw more current, before it would be allowed to draw more current. \$\endgroup\$
    – user253751
    Nov 5, 2022 at 19:43
  • 1
    \$\begingroup\$ Have you considered measuring it? \$\endgroup\$
    – user253751
    Nov 5, 2022 at 19:43
  • 3
    \$\begingroup\$ Unless the device is constantly writing to the card (which will destroy it), current will be negligible. \$\endgroup\$
    – user1850479
    Nov 5, 2022 at 20:05
  • 3
    \$\begingroup\$ Here's some tests someone did. They got about 24mA average, 90mA peak. That was while constantly writing to the card. It's a lot less (1.25mA) when the card is plugged in but not doing anything. Your synthesizer probably just reads the samples into RAM when you change the samples or turn it on. \$\endgroup\$
    – user253751
    Nov 5, 2022 at 20:09
  • 1
    \$\begingroup\$ I can't say I've ever heard of SD card current consumption being a problem at all. \$\endgroup\$
    – user253751
    Nov 5, 2022 at 20:10

1 Answer 1

Reset to default
5
\$\begingroup\$

What I would do if I really want to estimate the SD card current draw using only consumer-friendly gear:

  1. Get an USB SD card reader. Simpler is better even if it is not up to the SD card specs - e.g. USB 2.0 one even if the card is capable of higher speeds than USB 2.0 can do (this is about 40 MBytes/s)

  2. Get an USB power meter like one of these

  3. Plug the SD card in the reader, the reader in the power meter and the power meter in the computer USB port.

  4. Do some prolonged data transfers and note the miliamperes drawn.

These values, of course, are somewhat inaccurate. They include the power used by the card reader and the power lost in the voltage converter inside the reader (USB power is 5 volt and SD cards use like 3.3 volt so some unknown, but likely small amount of power is lost in the conversion).

On the other hand, you can pretty much compare the two cards. Chances are that your somewhat dated 1GB SD card (I think these are not made anymore) draws more power than a brand-name modern one.

I would not think twice to insert a different SD card in a slot made for an SD card. After all, this is what the standards and mating interfaces are made for. If it plugs, it has to work or at least not break. If it doesn't work - let be it, but chances of a catastrophic failure (burning something) are pretty much low.

What else could go wrong, on the other hand?

  1. The SD card interface. SD cards changed the data protocol somewhat at the 2GB or 4GB boundary. The new cards with more GB are called SDHC and some older devices are known not to work with SDHC cards. (There are even bigger cards that are called SDXC, but the change happened at much higher capacities.)
  2. The SD card data format. Your device may or may not be capable of handling a filesystem this big. This requires more memory inside the device dedicated to filesystem handling. You may be able to use more than 1GB, but less than 32GB. This may require fiddling with the partition or filesystem parameters or may require using a smaller than 32GB card after all.
  3. The vendor may have locked the device to use only cards supplied by them at a premium price.

Your mileage may vary.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.