In the diagram for an amp that I'm building, it calls for both polarized and non polarized capacitors. What exactly is the difference between the two? And can I use a polarized cap where it calls for non polarized or vise versa?
I'm kind new to this and trying to learn. Thanks for your help!!
I'm kind new to this and trying to learn. Thanks for your help!!
A polarised cap is a normal electroylitic. In use it is important that the cap sees no reverse bias voltage which would damage it.
A non polarised cap is polarity independent and can be used where the DC voltage on the cap could go one way and then another. They are commonly used in speaker crossovers too. You can make a non polarised cap by connecting two identical eletrolytics in series with either plus to plus or minus to minus (doesn't matter). You would chose each cap to have a value twice that of the intended part. So a 47uf non polarised could be made from two 100uf in series (giving 50uf).
Sometimes a non polar cap is specified on the grounds they might be better sonically... if you post the circuit using them then we can advise whether they need be non polarised or not.
A non polarised cap is polarity independent and can be used where the DC voltage on the cap could go one way and then another. They are commonly used in speaker crossovers too. You can make a non polarised cap by connecting two identical eletrolytics in series with either plus to plus or minus to minus (doesn't matter). You would chose each cap to have a value twice that of the intended part. So a 47uf non polarised could be made from two 100uf in series (giving 50uf).
Sometimes a non polar cap is specified on the grounds they might be better sonically... if you post the circuit using them then we can advise whether they need be non polarised or not.
no each only block 50 V in one direction, the combo should withstand +/-50V less some derating factor
except they may not like large DC component due to DC leakage flowing "backwards" across the reverse oriented cap eventually degrading its oxide
"back-to-back" polar electrolytic caps are a poor alternative to a actual purpose built nonpolar electrolytic where full thickness oxide is grown on both foil electrodes
except they may not like large DC component due to DC leakage flowing "backwards" across the reverse oriented cap eventually degrading its oxide
"back-to-back" polar electrolytic caps are a poor alternative to a actual purpose built nonpolar electrolytic where full thickness oxide is grown on both foil electrodes
No that's 94uF/50V.
To increase the voltage rating connect in series, but also add equal value resistors in parallel with each cap to swamp the leakage current in order to assure that the voltage shares evenly across the two capacitors. For a given required value when placed in series double the value of the individual capacitors used. (Say you need 100uF, two 220uF caps in series will give you 110uF)
Placing caps in series to increase voltage rating really only makes sense when you reach voltage levels where single caps with the required voltage rating are either too expensive or not available.
To increase the voltage rating connect in series, but also add equal value resistors in parallel with each cap to swamp the leakage current in order to assure that the voltage shares evenly across the two capacitors. For a given required value when placed in series double the value of the individual capacitors used. (Say you need 100uF, two 220uF caps in series will give you 110uF)
Placing caps in series to increase voltage rating really only makes sense when you reach voltage levels where single caps with the required voltage rating are either too expensive or not available.
I was wrong, sorry ... Kevinkr is write ... I mean, in parallel you will double the capacitance ... in series you will double the voltage but half capacitance ...
For example: 2 x 40uf / 50v, in parallel you will get 80uf / 50v, in series you will get 20uf / 100v.
I have a question regard a polarized / non polarized cap but i will elaborate it better and post here!
For example: 2 x 40uf / 50v, in parallel you will get 80uf / 50v, in series you will get 20uf / 100v.
I have a question regard a polarized / non polarized cap but i will elaborate it better and post here!
Can you elaborate on how to choose the resistance? Wouldn't it need to be 'really high' if the resulting non-polarized cap is used in a crossover? (specifically to use Elna RFS back-to-back)
Molly wrote this on first post
A non polarised cap is polarity independent and can be used where the DC voltage on the cap could go one way and then another. They are commonly used in speaker crossovers too. You can make a non polarised cap by connecting two identical eletrolytics in series with either plus to plus or minus to minus (doesn't matter). You would chose each cap to have a value twice that of the intended part. So a 47uf non polarised could be made from two 100uf in series (giving 50uf).
A non polarised cap is polarity independent and can be used where the DC voltage on the cap could go one way and then another. They are commonly used in speaker crossovers too. You can make a non polarised cap by connecting two identical eletrolytics in series with either plus to plus or minus to minus (doesn't matter). You would chose each cap to have a value twice that of the intended part. So a 47uf non polarised could be made from two 100uf in series (giving 50uf).
Series connection will work, but an actual non-polar type is best, if available in the uF/voltage needed.
Only with several caveats. Firstly the variation in electrolytics is large, +/-20% is pretty good spec for an electrolytic. So you won't get equal sharing, so perhaps two 50V caps can handle 85V safely, and then only with the leakage-swamping resistor chain present.
When the caps age one may fail before the other, leading to the explosive destruction of the other.
So don't do it unless you have to (very high voltage supplies need to do this).
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