3
\$\begingroup\$

Due to size constraints on a custom PCB, I have opted out for using the smallest type of electrolytic capacitors (3 mm diameter.) However, capacitors in such a small diameter are almost impossible to find.

If I remember my high school books correctly , tantalum caps are actually a type of electrolytic capacitors just with different purpose and their size to capacitance ratio is much better than the electrolytic ones.

I know that they have other advantages, but my biggest concern is is it possible to just use tantalum capacitors instead of ordinary electrolytic capacitors? The circuit in mind is just an ordinary amplifier for an electret microphone using a simple LM386.

Edit : Here is the schematic, I am asking for all the electrolytic capacitors. enter image description here

\$\endgroup\$
6
  • 3
    \$\begingroup\$ Note that tantalum capacitors are electrolytic capacitors. This is a bit of a pet peeve of mine; both aluminum and tantalum capacitors (and niobium ones too, though those are rare) are electrolytic, but people tend to talk about aluminum electrolytics as though they're the only type of electrolytic capacitor out there. \$\endgroup\$
    – Hearth
    Commented Apr 5, 2019 at 2:21
  • \$\begingroup\$ Read this and tell us from there what you don't understand and what factor that might be negatively impact your system including your environment usage requirements, so that we can provide a solution to prevent it. \$\endgroup\$
    – Unknown123
    Commented Apr 5, 2019 at 2:26
  • \$\begingroup\$ The 0.1uF and 0.047uF can be replaced with ceramic (COG or NPO) caps or tantalum. The 100uF cap can be replaced with tantalum. I am not really sure what C10 is for. It possibly could be ceramic, too (X7R or X5R) but since I don't know what it is doing, I am not positive. \$\endgroup\$
    – user57037
    Commented Apr 5, 2019 at 2:53
  • 1
    \$\begingroup\$ @Unknown123 I went to search for my Q&A on the subject and then saw that you had beaten me to it :-) . Hopefully TommyD will in fact read that and get the point. \$\endgroup\$
    – Russell McMahon ♦
    Commented Apr 5, 2019 at 5:24
  • 1
    \$\begingroup\$ @mkeith Curiously, the C10+R1 combination is included on every example circuit in the datasheet but never mentioned or explained. \$\endgroup\$
    – pipe
    Commented Apr 5, 2019 at 8:56

4 Answers 4

Reset to default
2
\$\begingroup\$

Yes, you can change it for Tantalum capacitors. The zobel capacitor can be ceramic or nylon. C7 probably you can't find any of this value 0.1uF but you can change it to 1.0uF this will give some aditional bass to your amplifier; however if you use any ceramic capacitor won't have any problem. I've have made this preamplifiers for my projects with success handling tones for hifi amplifiers.

For hobby purposes you can find this kind of assortments inside an old car stereo, any old VCR, any obsolete FTA, etc.

\$\endgroup\$
2
  • \$\begingroup\$ Nylon capacitor are hard to find :^) \$\endgroup\$
    – Robert Endl
    Commented Apr 5, 2019 at 8:01
  • \$\begingroup\$ Yup, changed C7 to 1uF, and used tantalum for the others, thank you for the help. \$\endgroup\$
    – Tommy D
    Commented Apr 5, 2019 at 17:01
1
\$\begingroup\$

Yes you can use tantalum capacitors for the 10uF and 100uF. The .1 uF and .047 caps can be X7R or even Z5U. If space is very tight and this is not an amp for a radio you can omit R1 and the .047 cap. This zobel network is not essential.

\$\endgroup\$
8
  • \$\begingroup\$ not essential? Yet every example shows the Zobel filter or the ferrite bead filter \$\endgroup\$
    – Tony Stewart EE75
    Commented Apr 5, 2019 at 4:24
  • \$\begingroup\$ Yes,every circuit you see today includes the zobel. But my Nat Semi Audio/Radio Handbook says that they are not required only recommended for use in AM radios. I have used the IC without and not seen any instability. I will let the OP decide whether he wants to risk it or not. \$\endgroup\$
    – EinarA
    Commented Apr 5, 2019 at 4:36
  • 3
    \$\begingroup\$ C7 better be not ceramic. Ceramic caps usually have piezoelectric effect, and the amplifier might produce some unwanted noises. \$\endgroup\$
    – Ale..chenski
    Commented Apr 5, 2019 at 5:25
  • \$\begingroup\$ You are correct. I would use a film cap here but assumed that Tommy D wasn't that particular since he seems to be focused on component size. I have used ceramic caps in audio circuits and never noticed piezoelectric effects. Except for one cap that turned into some kind of avalanche oscillator. \$\endgroup\$
    – EinarA
    Commented Apr 5, 2019 at 6:22
  • \$\begingroup\$ Class 1 NP0/C0G MLCC cap could also be used here instead of film. \$\endgroup\$
    – Unknown123
    Commented Apr 5, 2019 at 6:33
1
\$\begingroup\$

Yes you can, but you are far better off using the TPA321D that occupies far less space and has no need for large caps as it is a bridge (differential) driver.

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

Tantalum capacitors should not be used for audio coupling capacitors in high performance audio circuits, as their capacitance value can vary within audio range based upon bias voltage and current. This can be a source of distortion. Solid aluminum electrolytics generally have less of this effect. There is little advantage delivered by tantalum capacitors in audio circuits that would justify the higher cost of tantalum capactors.

\$\endgroup\$
2
  • 1
    \$\begingroup\$ This is incorrect, and sounds like it was written about ceramic rather than tantalum capacitors. Was this AI generated? \$\endgroup\$
    – Tim Williams
    Commented Oct 9, 2023 at 22:06
  • 1
    \$\begingroup\$ Not so, as I used to design audio gear (many moons ago) Tantalums get very nasty when they have only a small bias voltage. Here is someone elses opinion: "Metalized plastic film capacitors have the lowest distortion. Tantalum and electrolytic coupling capacitors change value with voltage so the low frequencies will have even-harmonics distortion. If the signal across a tantalum capacitor causes reversed polarity then the capacitor is a rectifier producing severe distortion." \$\endgroup\$
    – Ted
    Commented Oct 12, 2023 at 21:32

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