Electrolytic or Tantalum ?

[@xi@g@me]

Hi all !
The question has already been posted in the topic about my current electronics project, but I guess it is large enough to end here too (to the moderators: please correct me if I'm wrong or violating any forum rule)

So, I was wondering : which is for you the best to chose between an aluminum electrolytic or a tantalum capacitor to put together with a ceramic capacitor for decoupling purposes ?

As said in the project log, I'd prefer the electrolytic capacitor, because it is for me less dangerous for the circuit, my house and myself if something goes wrong with it than with a tantalum capacitor. On the other hand I have to admit that tantalum capacitors use way less space on a circuit board than an electrolytic one.

Your thoughts ?

 

[kellys_eye]

Space shouldn't be an issue these days given the smaller packaged devices you can get - SMD if you're really pushed.

Tantalums would normally be used for timing accuracy purposes or areas where low ESR was a particular requirement. Their 'historical' issues surrounding 'explosions' etc don't tend to be found these days but there is no real reason to use tantalum versions with the vast array of alternatives now available.

 

[Arouse1973]

Hello. I rarely use electrolytic capacitors now, I prefer MLCCs . I won't use Tants out of principle because of where Tantalum is predominantly mined. I guess if I had to choose between the two it would have to be electrolytic type.
Thanks
Adam

 

[@xi@g@me]

Thanks for your replies seems like tantalum capacitors are more secured now. But Arouse1973 have a good argument against their use, I have to admit

I had a look to what MLCC meant, and if I'm not wrong this must stand for "Multi-layer ceramic capacitor", but if that's the case then these capacitors are not polarized. Shall one not use both a non polarized and a polarized capacitor for decoupling? For the non-polarized one I already use an SMD MLCC.

For the space I'm not really tight (especially when I use 9 female-type SCART sockets on my board...), but I'd prefer to use the SMD components for 2 reasons (which may really not sound to be good reasons, indeed, but I do not intend to make this as an industrially produced board) :
- That will make me practice the soldering of SMD components;
- I intend to put the PCB in a transparent case, so I want it to be...well...presentable.
That is why space is not really an issue for me.

 

[Arouse1973]

You don't have to use a polarized capacitors so at the end of the day it's up to you. Have a look a the characteristics of both MLCC and electrolytic, see which one is best suited to your design.
Thanks
Adam

 

[BobK]

A non-polarized capacitor can always replace a polarized one, but not the other way around.

Bob

 

[@xi@g@me]

OK. I also chose the polarized / non-polarized pair because this was suggested to be so by the 4051 datasheet, but what you say makes sense. I'll go back to a pair of MLCCs then. I don't really care about the ESR (equivalent resistance of the capacitor, right ?) here because there ain't much current flowing "through" them & because the frequency of the signals the 4051 will handle will not be so high (composite video / RGB data)