6
\$\begingroup\$

Attached schematic for the e-Paper driver HAT.

The meaning of the yellow marked part is not clear to me.

enter image description here

Does this mean I can replace 105 (1 μF) with 4.7 μF and use either as available?

The entire schematic can be found here.

\$\endgroup\$
6
  • 1
    \$\begingroup\$ You might want to ask from who made the schematics. Or just look at what the e-paper display requires. It can't be deciphered what is meant here with that notation. \$\endgroup\$
    – Justme
    Aug 12, 2022 at 11:47
  • \$\begingroup\$ @Justme Its from waveshare, I didn't find any forum there to ask it. But I'll try again. \$\endgroup\$ Aug 12, 2022 at 11:57
  • 1
    \$\begingroup\$ It's 105 and it means 1uF. 150 would mean 15pF, unreasonably low value. \$\endgroup\$
    – Justme
    Aug 12, 2022 at 12:00
  • 2
    \$\begingroup\$ Yes I know what you mean and it can't be answered because we don't know why the caps are marked weirdly and we don't know if the e-paper display module you will use requires 1uF or 4.7uF capacitors to work or even if it makes any difference. But it is possible that it makes a difference. \$\endgroup\$
    – Justme
    Aug 12, 2022 at 12:10
  • 4
    \$\begingroup\$ Could it mean a 105 (1uF) in parallel with a 4.7uF? \$\endgroup\$
    – GodJihyo
    Aug 12, 2022 at 13:42

2 Answers 2

6
\$\begingroup\$

Does this mean I can replace 105 (1 μF) with 4.7 μF and use either as available?

In this specific case yes, though this isn't a standard marking as others have mentioned. It seems to be an artifact of the history of these documents, as I found out. It is NOT a "caps-in-parallel" mark, as JRE's answer suggests.

I've actually been working on miniaturizing this very board recently. Waveshare's documentation is rather confusing, so to figure out what I needed, I consulted:

  • the actual breakout "hat" schematic, including the history of that document on their wiki
  • various versions of eink manuals from their site, including the history of those documents on their wiki
  • Adafruit breakout schematic & Open source design
  • CrystalFontz breakout schmatics

Comparing those, I found that Waveshare has recently bumped up the size of the caps to 4.7µF, but have historically been smaller at 1µF. I'm unimpressed with their document skills.

Here is a snippet of the relevant part of the table that I extracted from these resources when I was trying to decipher this myself, showing marked values and voltage rating:

name eink v3 eink v2 newer hat older hat Adafruit CrystalFontz CF-rating
VSH 4.7/25 105/50 105/50 105/50 1u/25 1u/25 10V~17V
PreVGH 4.7/25 105/50 105/50 105/50 1u/25 1u/50 ~22V
VSL 4.7/25 105/50 105/50 105/50 1u/25 1u/25 -17V~ -10V
PreVGL 4.7/25 105/50 105/50 105/50 1u/25 1u/50 ~ -20V

As you can see, it looks like the newest hat is a mix of eink v3 and the "newer hat" version.

As for me, I ended up using 105/50 (1.0µF 50V rating) as that fit the rest of the project (and I had on hand) and it is working fine for me today.

\$\endgroup\$
0
0
\$\begingroup\$

What does a capacitor marked "105 | 47 μF" mean?

"105 | 47 μF" - a 47 μF electrolytic capacitor with a maximum operating temperature of 105° C.

"105 / 50 V" - a 1 μF 50 V ceramic capacitor.

\$\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.