Showing posts with label capacitors. Show all posts
Showing posts with label capacitors. Show all posts

Thursday, March 10, 2016

Electric double layer capacitor an eFlywheel

The Electric double layer capacitor has the main use of a Charge Reservoir. That means a large amount of electrical charge in a small footprint.

These charge/discharge quickly unlike the battery, There is no Electrical Energy to Chemical Energy Transformation and back, like in batteries. It may need caution in design and usage as they may carry a lot of punch.

Electric double layer capacitor an eFlywheel

Also known as Ultracap, Goldcap, Supercap - Electric double layer capacitor, In Farads, like batteries, Energy Reservoirs or eFlywheel.

In Product Safety terms; The Battery has a Internal Resistance, but a Supercap does not. When used in Values like 100F and is fully charged, an Internal or External Breakdown of Insulation or Short Circuit may Occur. The Heat Generated is Enormous. Murphy's Law says such things happen..

Supercap at Wikipedia

Electric Double Layer Capacitor (EDLC) or SuperCapacitor

DLCAP - Electric Double Layer Capacitor - Nippon

They have a range of Supercapacitors upto 2500F at 2.5V and Modules like 400F and 15V. There are two types Prismatic and Cylindrical. In comparison to batteries - multi-million cycles of charge-discharge is possible.

EverCAP - Double Layer Capacitors - Nichicon

They have two types, High Power Density for a large current discharge. High Energy Density for a long backup time. Over a million Charge/Discharge cycles. High Efficiency. Capable of fully discharging to zero volts.

Some things to note for a design engineer. The EDLC or Electric Double Layer Capacitors ...
  • Specified Endurance and end of life.
  • Excess Vibration can alter Specs.
  • Caution - The maximum temperature.
  • Specs are dependent on Temperature.
  • Maintain Low ripple current on Charge/Discharge.
  • It is Polarized like a Electrolytic cap.
  • Not Hot parts or Heatsink near cap.
The Double Layer Capacitors developed by WIMA are storage capacitors with highest capacitance values in the Farad range.

GTO Capacitors - WIMA

They are among others suited to serve as batteries, can deliver considerably higher currents for a short time, however, and are maintenance free.

SuperCapacitors - WIMA - These EDLC supercap has one-tenth of energy, but delivers over 10 times of power due to ultra low ESR. In Comparison with a Battery. A Lifetime of over 500,000 cycles.

Xelled Supercapacitor - Vinatech

Some Specs
  • Rating 2.5V / 2.7V
  • High power density (low internal resistance)
  • High electrical current, instant power back-up applied

Saturday, January 17, 2015

Types of Capacitors

Capacitors ares like reservoirs of charge. In the Water Analogy they are like your Overhead Tank or Sump. It can be like a Lake or Pond, when water is the charge.

Ceramic capacitors are the most economic in the lower values like pf and nf, Electrolytic Capacitors which have polarities that should strictly be observed, are used above 1uf. Plastic caps have temperature and environment stability and are more in use in Instrumentation and Industrial Electronics in place of ceramic, mica or paper caps. Mica and Paper caps have become rare today.

Ultracaps and supercaps are the new innovation for the years 2000+. They have values in farads but quite small in size. Electrolytic caps become too big in size beyond 10,000 uF, hence supercaps have a future.Tantalum electrolytic caps are used in Instrumentation and computers, a bit expensive but much smaller.

Types of capacitors

Capacitors Samples
Ceramic Mica Plastic Plastic
10pf-1uF
Leaks a Little.
Temperature Sensitive.
Unpolarized.
Ceramic Dielectric.
NPO stable.
Radial.
Unpolarized.
Mica Dielectric.
Costly.
Stable.
~100pF
Negligible Leakage.
Temperature Tolerant.
Unpolarized.
Plastic Dielectric.
1nf-10uF.
Radial.
Axial.
Plastic Dielectric.
Unpolarized.
1nf-10uF.
63V-2KV.
Inductive.
Capacitors Samples
Trimmer Trimmer Tantalum Surface Mount
Air Dielectric.
Very Low Values.
Unpolarized.
1-10pf.
Variable.
Stable.
Plastic Dielectric.
Unpolarized.
10-50pF.
Crystal Trim.
Variable.
AF-HF.
1uF -100uF.
Low Leakage.
Long Shelf Life.
Low Power.
Polarized.
Small Footprint.
Most Types.
Small Footprint.
Low Power.
Low Cost.
Multilayer too.
Tantalum too.
Capacitors Samples
Tuner Air Tuner Plastic Power Electrolytic Electrolytic
Air Dielectric.
Unpolarized.
100-200pf.
Antique.
Dust Sensitive.
Humidity Sensitive.
100-500pf.
Plastic.
Unpolarized.
Tuners.
RF-AF.
Low Cost.
470uF- 20,000uF.
High Ripple Current.
High Voltage.
More Leakage.
Shelf Life Low.
Polarized.
1uF-4700uF.
Filters.
Low Power.
Polarized.
Electrolytic.
Low Shelf Life.

Read More-

Caps Electronics Club -- What Exactly Is A Capacitor - - Capacitance And Capacitors

Important Point to note before circuit design
  • Voltage Rating is the most important to ensure long operational life and reliability, overrate 1.5 times. If max voltage capacitor will face is 15V then use 25V rating capacitor.
  • SMPS-ESR means Equivalent series Resistance at high SMPS frequency, the capacitor adds a inductance by the way it is constructed. So use Caps in Parallel for Lower ESR.
  • For Oscillators and A-D Converters choose Plastic Multilayer Caps as they leak less and have low temperature sensitivity.
  • Ceramic and Elcap are for Filtering and decoupling and are low priced too.
  • Electrolytic Caps back2back in series can make non-polar caps for Low current AC like AF, as used in a cross-over network of loud speaker of stereo system.
  • NPO "negative-positive-zero" caps and most plastic caps can be used for Oscillators as the negative and positive temperature coefficients are very less.
  • Most Plastic Caps are wound, so have inductance, which makes them unsuitable for filtering RF.
  • X and Y caps are special EMI-RFI filter caps, suppress interference and are safe at high voltage.

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