paralleled .22uF Wima film for AC coupling in THAT 1512 with servo

[intergalactic]

Is paralleling smaller film caps for AC coupling ok (I have perhaps 100 .22uF 100V parts)? I don't want to start a war here, and the meta-meta link for cap selection is broken.

I also have a very few 160v, 4.7uF and 10.0uF box caps from WIMA too, from my switchmode power supply design days.

P.S. Demo board with servo is 2.2uF coupling value?

 

[abbey road d enfer]

There's nothing wrong with paralleling caps in order to get the right value (or using an existing stock). Notice that the stray capacitance may increase and may introduce unwanted capacitive coupling if too close to other sensitive components or tracks.

 

[intergalactic]

ok, as another question, electrolytics as AC coupling seems weird (I have only ever built motor drives and stuff that needed DC supplies, so please bear with me) as I know what happens to common electrolytics when reverse polarity is applied, (or when they are charged from a near zero impedance source... bang). Apparently they aren't damaged with these small signals? Or my understanding is incorrect (that much is certain).

 

[abbey road d enfer]

As long as they are really used as coupling capacitors, their operation is safe. What I mean is, in coupling, the value of the cap is such that its impedance is negligible at all useful frequencies, so no real voltage develops across them.
That would not be true if they were used as filters in power applications (e.g. loudspeaker crossover).

 

[intergalactic]

As long as they are really used as coupling capacitors, their operation is safe. What I mean is, in coupling, the value of the cap is such that its impedance is negligible at all useful frequencies, so no real voltage develops across them.
That would not be true if they were used as filters in power applications (e.g. loudspeaker crossover).

OK, that makes more sense. Thanks!