Can I Use Electrolytics or Tantalum Caps in Place of Film Caps?

Caldo71

Active member
Probably a silly newb question, but I ask because of film caps having no polarity versus the tantalum or electrilytics having a positive and negative lead.

Is it doable?
 
Probably a silly newb question, but I ask because of film caps having no polarity versus the tantalum or electrilytics having a positive and negative lead.

Is it doable?
It's doable, but you need to know what's going on in that part of the circuit. A polar cap needs a voltage across it in the right orientation to work (that's really all that makes it polar). Once it has that potential, it acts like any other cap.
 
It's doable, but you need to know what's going on in that part of the circuit. A polar cap needs a voltage across it in the right orientation to work (that's really all that makes it polar). Once it has that potential, it acts like any other cap.
…in other words I need to align the positive/negative leads in the correct direction for the voltage flow of the circuit, right? I can’t just drop it in place of a non-polarized cap willy-nilly?
 
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…in other words I need to align the positive/negative leads in the correct direction for the voltage flow of the circuit, right? I can’t just drop it in place of a non-polarized cap willy-nilly?
Sort of, for example, a lot of times your signal is riding on top of a DC voltage. When this is the case you can orient the cap to that DC voltage and it will effect you signal like a a regular cap, say as part of a filter. But if there is no DC voltage, a polar cap won't work, so, you can't sub them everywhere.
 
I’ve yet to experience it, but I’ve read that when oriented incorrectly, tantalums’ magic-smoke smells pretty bad.

Yeah, electrolytics reverse biased get fat and don't do no work no more. Probably taste bitter too. Wouldn't know from experience.

Tants explode and short. Basically, if I'm not happy then nobody can be happy.

Only talking about caps here. Not at all thinking about people I encounter at work
 
Another question related to capacitors, does it matter whether you use Poly Film vs Poly Box vs Ceramic Disc?

In the schematic all it shows is the "double box" but on the PCB there are smaller boxes where the caps go, and larger boxes where the caps go. My thoughts are use Poly film for the smaller boxes and poly film box for the larger ones. Am I correct in my thinking, or does it really even matter?
 
Use what fits on the board, use good quality parts.
Disk ceramic caps are generally shit; they can be noisy, microphonic & unreliable. The only place I will use them is to debounce the footswitch on a relay switching circuit. Everything else is silver mica, film, tantalum or for power supply bypass, aluminum.

Crankshaft board 02 - disk cap.jpg
 
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