Coupling Capacitors

[dlad87]

Hi,

I noticed in a couple designs that electrolytic caps are used as stage coupling caps. Are these ok to replace with film caps? I always thought film caps were supposed top be better for coupling purposes where electrolytic caps are more for power supply filtering where larger values are needed.

Thanks

[antonis]

Hi & Welcome..

Generaly, well said..

[danfrank]

 Yes, plastic film caps are generally better for coupling caps. The problem becomes one of size... That's why electrolytics are used for coupling, because they require much less space. BUT, if you have the space, go plastic!
Again, because of size constraints, plastic caps are also better as power supply filtering caps, but you rarely see them used as such. Their ESR is generally much less than electrolytics, which is a good thing. Solen caps come to mind when thinking of high capacity plastic caps. They aren't small though!