About Capacitor Polarity Marking. Tech enthusiasts understand that a capacitor is an important electronic component, like a diode or resistor.
Generally, a capacitor is a two-terminal passive component that stores charge in a circuit. Surprisingly, we can categorize capacitors into polarized and non-polarized capacitors.
However, our interest today is in polarized capacitors with definite positive and negative terminals. This is to help you easily fit them into your circuit during development.
Unfortunately, not many people understand how capacitor polarity marking works. We have written this article specifically for you if you fall under such a category.
Table of Contents
- What Are Capacitor Polarity Markings?
- How To Identify Capacitor Polarity
- Do All Capacitors Have Polarity Markings?
- Electrolytic Capacitor Polarity
- What Happens When You Reverse Capacitor Polarity?
What Are Capacitor Polarity Markings?
(A polarized capacitor symbol)
A capacitor is a two-terminal passive component that stores a small charge in a circuit. Surprisingly we have two types of capacitors: polarized and non-polarized capacitors.
A non-polarized capacitor lacks definite polarities, while a polarized capacitor comes with definite positive and negative terminals.
Therefore, you must connect your polarized capacitor in the direction of your circuit polarity.
The positive (+) and negative (-) capacitor polarity symbols on your component are what we refer to as capacitor polarity markings.
Generally, the positive terminal indicates the anode, while the negative one indicates the cathode.
By checking the arrow representation, you can also determine capacitor polarity from the positive and negative symbols. Here, the arrow points toward the negative terminal.
Finally, you’ll notice an NP marking on a non-polarized capacity which stands for Non-polarized. Therefore we represent radial and axial non-polarized as NPR and NPA, respectively.
How To Identify Capacitor Polarity
We have two main methods of identifying capacitor polarity:
- Visual identification
- Using a multimeter
Sometimes, all you need to identify capacitor polarity is a keen observation. Check out three common scenarios under this option below:
Radial Electrolytic capacitors Polarity
These capacitors come with two pins and are black-gray or green-black. Therefore, you can use the color and pin length to identify polarity. Generally, the longer pin represents the anode, while the shorter one is the cathode.
For the case of color, the green in the green-black or black in the black-gray combination represents the anode. Also, the black and gray in the green-black and black-gray combination represent the cathode.
Tantalum Capacitors Polarity
These components are yellow; you can surface mount them on your PCB. When you check on the housing surface, an end marked in-dash represents the anode. Therefore, it automatically makes the cathode the other end.
Aluminum Electrolytic Capacitors Polarity
Most aluminum electrolytic capacitors have a grey color. Moreover, they have a geometric configuration with right-angle and trapezoidal corners.
The gray-colored side represents the positive pole (anode), and the black part indicates the negative pole or the cathode.
With this, the pin corresponding to the right-angle base edge refers to the cathode, and the pin corresponding to the trapezoidal edge refers to the anode.
Use of Multimeter
(A digital multimeter)
Not many people can identify the polarity of capacity by checking its visual appearance. And this is where a multimeter comes in handy. Surprisingly, a multimeter is known for offering precise and accurate results.
Connecting your capacitor’s anode and cathode to the power supply’s positive and negative poles, it’ll experience a large leakage resistance. Consequently, a small current will pass through the capacitor. Otherwise, the capacitor will have a low leakage resistance and high leakage current.
Follow the below steps to use a multimeter:
- To begin with, connect one pin to your multimeter’s black pen and the other to the red pen.
- Capture the reading at which the multimeter pointer stops. We recommend setting the reading at R*1K or R*100.
- Next, discharge your capacitor and exchange the multimeter pens.
- One test will have the pointer stopping on the multimeter’s left side. In this case, the pole on the black pen represents the capacitor anode.
Do All Capacitors Have Polarity Markings?
(A non-polarized capacitor symbol)
As we mentioned, we have polarized and non-polarized capacitors. Polarized capacitors have negative and positive poles.
For polarized capacitors to work, their positive pole should be in contact with the anode of the power supply. However, non-polarized capacitors don’t have definite positive and negative poles.
Therefore, you can place them on your PCB without caring about the anode or cathode.
Generally, polarized capacitors work only in circuits where current flows in a single direction. Moreover, non-polarized works well with AC power.
And since polarity isn’t an issue for non-polarized capacitors, you can use them to replace polarized ones and not vice-versa.
Some common non-polarized capacitors include
- Ceramic capacitors
- Glass capacitors
- Mica silver capacitors
- Polyester capacitors
- Ceramic capacitors
- Film capacitors
Comparison Between Polarized and Non-polarized Capacitors
There is no denying that these capacitors work with the same principle of storing charge. However, they have some differences, as we’ll explore below.
Polarized capacitors have electrolytes that provide a high capacitance. Generally, the electrolytes determine the capacitance and voltage your capacitor can hold. On the contrary, non-polarized capacitors have a metal oxide layer.
Polar capacitors are perfect for coupling, filtering, and decoupling applications. However, non-polar capacitors have good high-frequency characteristics, thus perfect for resonance, current limitation, and frequency selection.
If we take a polar and non-polar capacitor of equal size, the polar one will offer a higher capacitance.
Electrolytic Capacitor Polarity
This is a polarized capacitor with a positive and negative pole. Here, the positive pole, the anode, is a metal that will ionize to form a dielectric. The negative pole, the cathode, is a solid or liquid surrounding the anode.
Generally, electrolytic capacitors find application in low-frequency applications. Moreover, they store a larger charge.
These capacitors come in two types:
- Tantalum capacitors
- Aluminum capacitors
Advantages of Electrolytic Capacitors
- Smaller size but higher capacitance than non-polarized capacitors
- They support low-frequency applications
- These capacitors consume low power
Disadvantages of Electrolytic Capacitors
- The capacitor will damage if you supply more voltage than its capacitance
- It would be best if you connected it in the polarity direction
Applications of Electrolytic Capacitors
The application of electrolytic capacitors includes:
- LED and on-board power supply
- Used in inverters, circuit boards, and chargers
- Smoothing and filtering AC power and components
- Buffering and interim storage for DC supplies
- Storing energy flash devices
- Cross over in loudspeakers
- Motor starters
- Pulse width modulation smoothing
What Happens When You Reverse Capacitor Polarity?
(A damaged capacitor)
It would be best to always connect your capacitor’s positive and negative terminals to the power source’s positive and negative terminals. Otherwise, the following will happen:
- The capacitor might explode thanks to the leakage current
- The capacitor might blast thanks to the hydrogen ion theory
- The resistivity of the capacitor reduces
- Your capacitor functions as a short circuit
Is there a difference between polarized and non-polarized capacitors?
Yes! Polarized capacitors have positive and negative poles or terminals.
Therefore, they work only when the current flows in one direction. However, non-polarized ones have no definite pole and thus work well when the current flow in any direction.
Why does capacitor polarity matter?
Capacitor polarity determines how you connect your capacitor to a circuit.
For the case of polarized capacitors, you’ll have to connect the positive and negative poles to the power source’s positive and negative terminals, respectively.
However, the non-polarized options allow you to connect in any way without observing polarity rules.
When working with capacitors, you should understand polarity and how it affects your circuit connection.
In summary, a polarized capacitor has positive and negative poles. Therefore, you’ll have to connect the positive and negative poles to the power source’s positive and negative terminals.
However, non-polarized capacitors don’t have poles, thus allowing connection without following polarity rules.
Overall, a polarized capacitor offers a higher capacitance than a non-polarized option of equal size.