Which of the following is the corect/better way to connect two electrolytic cap to make it non-polarized?
1. neg-neg
2. pos-pos
3. neg-pos
1. neg-neg
2. pos-pos
3. neg-pos
Depends on whether or not dc is present..
1 & 2 work fine with most polar caps when no dc is present or it is small relative to the cap voltage rating.
3 only works with new caps - as the caps age and esr increases you will eventually get to the point where the cap exhibits issues with reverse breakdown. There must be absolutely NO dc present. Truthfully I have never seen it done this way in commercial kit.
Frankly it would be better to use a non polar cap in the first place if a suitable value can be procured. Film caps are practical at low values, and much better performers.
Incidentally you should not use anything but a film cap or non polar EL in a speaker cross-over because of the currents involved. Nothing ruins your day quicker than an exploding EL non polar made this way - particularly when it takes that expensive vintage driver with it.
1 & 2 work fine with most polar caps when no dc is present or it is small relative to the cap voltage rating.
3 only works with new caps - as the caps age and esr increases you will eventually get to the point where the cap exhibits issues with reverse breakdown. There must be absolutely NO dc present. Truthfully I have never seen it done this way in commercial kit.
Frankly it would be better to use a non polar cap in the first place if a suitable value can be procured. Film caps are practical at low values, and much better performers.
Incidentally you should not use anything but a film cap or non polar EL in a speaker cross-over because of the currents involved. Nothing ruins your day quicker than an exploding EL non polar made this way - particularly when it takes that expensive vintage driver with it.
You can connect two identical electrolytics in series, with either both negative leads connected to each other, or, both positive leads connected to each other. Either way should give you a non-polarized cap that has half of the capacitance value of either of the two identical caps.
kevinkr said:
I have seen two polarised electrolytics used for DC blocking,(connected parallel nec-pos). In CD player outputs etc. Is this also bad practise ?
Thanks
Hi pikkujöpö,
Yeah, I would consider that to be bad practice, but I am assuming there was no dc voltage present at the output.
Here it is pretty common practice unfortunately to use just a single polar cap in such a situation, and that is not the best practice long term either if you want low distortion..
Any way you look at it, it's a cheap way out - I'd use a modestly priced non polar in all such cases.
Polar and non polar caps suffer dielectric degradation over time with no dc voltage impressed across them - this imo makes them unsuitable in my mind for any high quality application.
Yeah, I would consider that to be bad practice, but I am assuming there was no dc voltage present at the output.
Here it is pretty common practice unfortunately to use just a single polar cap in such a situation, and that is not the best practice long term either if you want low distortion..
Any way you look at it, it's a cheap way out - I'd use a modestly priced non polar in all such cases.
Polar and non polar caps suffer dielectric degradation over time with no dc voltage impressed across them - this imo makes them unsuitable in my mind for any high quality application.
Quote:
You can connect two identical electrolytics in series, with either both negative leads connected to each other, or, both positive leads connected to each other. Either way should give you a non-polarized cap that has half of the capacitance value of either of the two identical caps.
Text book correct answer.
You can connect two identical electrolytics in series, with either both negative leads connected to each other, or, both positive leads connected to each other. Either way should give you a non-polarized cap that has half of the capacitance value of either of the two identical caps.
Text book correct answer.
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