Normal Electrolytic Capcitors as non-polarized (bipolar) ones in AC circuits?

I work on circuits that use electrolytic capacitors, back to back, in AC circuits.
What I discovered is that a DC voltage develops on the capacitors that prevents the AC peaks from reversing biasing the capacitors by very much. 1 volt sound right after running for a while. It seems that the capacitors work as rectifiers to some extent. I have not seen this arrangement fail so far.

This arrangement is frequently used in speaker systems.

I do this with electrolytic capacitors and tantalum capacitors.

 

I work on high voltage pulse generators and laser pulse generators.
I recently finished a project requiring to have a DC level that will go anywhere from -500 volts to 500 volts with about 200uF of filtering. I used two 470uF capacitors back to back without diodes.
From what I have seen in the lab a little bit of voltage reversal does not seem to harm a capacitor at all. And I'm afraid to place a diode across capacitors because an excess amount of current discharging the capacitor string might wipe out a diode.
So I feel safe with what I did.

 

When I connected two 470uF capacitors in series I got 235uF. I only needed 200uF to meet specifications. But I'm happy to have some overkill.

Your are right. If you discharge or that is bring the ends of the capacitor strings to the same potential, 0 volts, the diodes are not affected.
Using back to back electrolytic capacitors in a power supply is an unusual application. I did in my application because I needed to go from -500 volts to +500 volts.

About the ripple current in the datasheet I would have to see to be sure.
Now the ripple current in a series string is going to be the same in both capacitors. Nothing is going to be halved in terms of ripple.

As far as the diodes are concerned there is a surge current that is specified in the datasheet that is typically many times the average rated current.

 

Let's look at it this way.
If you have a 10 volt power supply and connect a 1 farad capacitor to it you will develop a charge of 10 volts across the capacitor and you will will have 10 coulombs of charge or electrons in the capacitor.
Now if you connect the capacitor to a 5 volt power supply you will have 5 volts and 5 coulombs of charge in the capacitor.
Now if you charge the capacitor over a time of one second you will have a current of 10 amperes and 5 amperes during that second because current in amperes is equal to the change of charge in coulombs divided by time in seconds.

Your experimentation will show you that your charge is directly proportional to your voltage on the capacitor.

Capacitance in Farads is defined as coulombs divided by volts.

Now if you have a 10 volt power supply and have two of the same value in series you will have 5 volts in each capacitor.
So just using two capacitor instead of one you are only moving half as many coulombs of electrons.
Therefore you will only have half the the capacitance or half the total Farads.

So adding capacitors in series, that is in a string, your capacitance will be decreased.
Adding capacitors in parallel you will get more capacitance. In fact the capacitance simply add up.

This is true in AC circuits and DC circuits.

When an electrolytic capacitor is reversed biased, that is charged backwards, tends to conduct and thereby prevent it from charging very much when connected is series with another capacitor. This characteristic is way I was able to connect two capacitors back to back, that is in opposing polarities, and be able to charge the string to plus or minus 500 volts. But in doing so I got less capacity.

 

I take it this is only necessary at high power levels? I've been using single electrolytics with small audio and other AC circuits for ages - and most diagrams you'll find do this.

 

Electrobrains, I don't understand your confusion. IF you mean that the capacitor conducts in one direction but not the other I can explain.
When you have two capacitor connected in series back to back and apply a voltage to the series string one capacitor charges up while the other tends to look like a short. So for this moment of time the capacitance will be greater because this is much like only one capacitor. After you are done charging both capacitors start looking like capacitors again and the capacitance of both affects the total capacitance. When you discharge the series string, that is bring the ends of the string back to zero volts relative to each other both capacitors now are charged to some voltage and the series string of capacitors assume a value of less than either capacitors. If both capacitors are 1 Farad your string will be 1/2 Farad.

It may be helpful to get a capacitor meter and try various series, parallel arrangements.