Capacitor component

Capacitors store electrical charge from a power source. They also release that charge at a later time.

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Capacitor component common appearances schematic symbols and basic uses diagram by electronzap electronzapdotcom
Capacitor component common appearances schematic symbols and basic uses diagram by electronzap electronzapdotcom

Capacitors have 2 close conductive areas called “plates” separated by an insulator. the plates can gain an equal but unbalanced number of charges.

The more charge imbalance, the higher the voltage.

The larger the value of the capacitor, the more current it takes to change the voltage of the capacitor by a certain amount.

For quicker demonstration circuits check out:

Brief capacitor charge and discharge through LEDs circuit

Charging



Nice looking larger value capacitor kit.

Capacitor charging through resistor protected LED illustrated schematic diagram by electronzap electronzapdotcom
Capacitor charging through resistor protected LED illustrated schematic diagram by electronzap electronzapdotcom

That’s a 470 microfarad (470µF) capacitor which is almost always polarized. The side with the dashes on the physical component always needs to be more negative than the unmarked side for most capacitor. You often connect the negative side of the capacitor to the zero volt reference point ground (negative side of a singe supply power source).

Discharging



Power supply I use in my videos. One alternative to using batteries.

Capacitor discharging through resistor protected LED illustrated schematic diagram by electronzap electronzapdotcom
Capacitor discharging through resistor protected LED illustrated schematic diagram by electronzap electronzapdotcom

Used for:


Polarized and non polarized capacitor schematic symbols diagram by electronzap electronzapdotcom
Polarized and non polarized capacitor schematic symbols diagram by electronzap electronzapdotcom

C=Q/V – Capacitance equals electric charge divided by voltage.

Capacitor basic properties:
  • Conductive “plates” separated by an insulator.
  • Charges are moved off one plate while being moved onto the other when charging.
  • An electric field between the plates makes the plate imbalance possible. Atoms missing an electron can pull on an extra electron at an atom on the other side of a thin insulator.
  • A voltage builds up as the imbalance of the plate charges grows. Ultimately the charges want to return to their original place, once there’s a conductive path.
  • A stored charge/voltage can be used to power something later but nowhere near as long as a rechargeable battery. Mostly the discharge is used for timing purposes or helping to hold the voltage briefly.
  • The amount of stored charge for a voltage is determined by the capacitance in units called Farads.
  • A Farad is a large amount of capacitance. Supercapacitors are in the Farad range. Most capacitors are in the microfarad (millionths of a farad) to nanofarad (billionths of a farad) range. They even come in the picofarad (trillionths of a farad) range.

Millifarad (thousandths of a farad) capacitors are usually just written as thousands of microfarads.

For example, usually you will see 10,000 microfarad, instead of 10 millifarad. Be careful because the symbol for micro is the Greek letter mu ( µ ) and not m. The m is reserved for milli. Sellers often mistakenly write 100mF for 100 microfarad, when they should have wrote 100µF.

  • Maximum voltage is highly variable by specific component. Electrolytic and supercapacitors usually have their maximum voltage written on the component. Other capacitor maximum voltages will have to be researched. They are generally always above 25V though from my experience.
Smoothing uses

Oscilloscope trouble shooting my NE555 timer needing a smoothing capacitor for bench power supply

Basic AC diode rectification and capacitor smoothing process diagram by electronzap electronzapdotcom
Basic AC diode rectification and capacitor smoothing process diagram by electronzap electronzapdotcom

Smoothing a power supply voltage is the simplest use of a capacitor to understand. The capacitor gets charged directly from a power supply while the power supply is also powering some other load.

The capacitor and the load are connected in parallel. A large enough value capacitor will be able to hold a voltage relatively steadily during brief power supply spikes (rapid but short voltage rise) or voltage drops.

Filtering

Capacitors pass AC and block DC. Often you want to let current change direction a lot (AC) in part of a circuit, while also preventing it from going in just one direction (DC) for very long. You can easily do so by putting a non polarized capacitor, which can be charged in either direction, in series with the rest of that circuitry. Sometimes a polarized capacitor will work too.

Related topics:
More topics:

555 timer is an integrated circuit (IC). Being an IC, it has complex circuitry combined in a single package with external pins/terminals to connect to other circuitry. You can easily make all kinds of fun circuits with just a 555 timer and the components covered above, so I think it’s a good component to learn next.

Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.

Other topics:

These pages are still being compiled.

Circuits covered more quickly series:


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