creating a non polar capacitor from 2 polarized capacitors?

Thread Starter

sdowney717

Joined Jul 18, 2012
706
Was reading this here. Is this true?
I was looking to put a 5uf in series with a tweeter, and I do have 10 uf polarized capacitors I can use.
They are 50v, they wont go boom?
https://www.electrocube.com/pages/capacitors-in-audio-crossover-networks-data-sheetNon-polar electrolytic capacitors
Non-polar electrolytic capacitors include two polarized capacitors of the same value placed in series with the positive terminals or negative terminals connected together. The resulting single capacitor is a non-polar capacitor equal to half the capacitance of the original capacitors [see Figure 4: Non-Polar Electrolytic Equivalent Design]. The two capacitors rectify the applied voltage and act as if they are partially bypassed by a diode.
 

Ylli

Joined Nov 13, 2015
1,060
Always wondered about this. If the series connected capacitor that would be reversed biased acts similar to a diode, then why is the capacitance C/2? I can see it being a bit less than C, but not as low a C/2.
 
Was reading this here. Is this true?
I was looking to put a 5uf in series with a tweeter, and I do have 10 uf polarized capacitors I can use.
They are 50v, they wont go boom?
https://www.electrocube.com/pages/capacitors-in-audio-crossover-networks-data-sheetNon-polar electrolytic capacitors
Non-polar electrolytic capacitors include two polarized capacitors of the same value placed in series with the positive terminals or negative terminals connected together. The resulting single capacitor is a non-polar capacitor equal to half the capacitance of the original capacitors [see Figure 4: Non-Polar Electrolytic Equivalent Design]. The two capacitors rectify the applied voltage and act as if they are partially bypassed by a diode.
You should be OK as long as you are not running high power amplification. Some of the peak voltages can be high. If the electrolytics are old, they could blow. You are better off using a film capacitor such as our 916D1B505K
 

Ylli

Joined Nov 13, 2015
1,060
From the linked data sheet "The resulting single capacitor is a non-polar capacitor equal to half the capacitance of the original capacitors. The two capacitors rectify the applied voltage and act as if they are partially bypassed by a diode. "

If the caps 'rectify' the applied voltage, then the resulting small signal capacitance will be 1/2 the original capacitance, but the large signal capacitance will be more than 1/2 the original as the cap that is reverse biased partially conducts. That makes for a very non-linear result.
 

AlbertHall

Joined Jun 4, 2014
12,187
Does this only apply if the voltage across the two capacitors does regularly reverse polarity?
If a DC voltage is applied for a period of time then I guess that the resulatant leakage current would degrade one of them and the capacitance could increase to C.
 
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