Direct Current; Types And Applications

Direct current is a naturally occurring form of electricity which can be produced  from many sources like solar cells, batteries, DC dynamo, thermocouple etc. 

It is use to power integrated chips, CPUs, microcontrollers and micro electronics. 

      

Sources and generation of DC.

There are many sources of direct current from which it can be generated, most common one are listed below. 

 1. Batteries (chemical energy). 

Direct current is produced from chemical energy through batteries or cells. A cell is a device that converts chemical energy to electric current. It consists of two unsimilar conductors (usually metals) dipped into a liquid or sticky solid solution of chemicals, this conductors are called electrodes. The chemicals reacts with the electrodes to produce direct current. A battery is the combination of two or more cells to give a large amount of current. Examples of batteries are lithium-ion, lead acid batteries, li-po batteries etc. 

2. Thermocouples.

We can show that heat energy can be converted into direct current by means of  thermocouples. A thermocouple is a made of two dissimilar metals joined together in parralel. When one side of a thermocouple is heated and other side is cooled,  electrons flows from the hot side to the cold area with the hot side of negative polarity and cold side with positive polarity. Thermocouples can only produce little current in milliamps and a few volts. Mordern thermocouples known as peltier element can produce more voltage and current which then stepped up with a boost converter circuit.

3. Solar cells.

Solar cells transforms light energy into electric current.  It is very efficient and serves as a green and clean source of energy which doesn't depletes the globe. Solar cells are made from semiconductors which when exposed to light causes electrons to flow from the cathode to anode. 

Metals like ceasium and pottasium converts light into electricity, this stunning effect was discovered by Leonard in 1902, this phenomenon is called the photoelectric effect. Solar cells are slowly replacing other sources of DC but it main draw back is high cost. 

4. DC Magnetic motor.

DC can be generated from magnetic motors that operates on DC, when it shaft is rotated it produces DC current from it terminals. This works by the convention of magnetic and mechanical energy into direct current.  DC motors consists of insulated copper wire wound on a laminated soft iron core which is then supported by bearing systems between magnets. When the amature connected to a rotary shaft is rotated at high speed the magnetic field of the magnet pulls out electron from the copper winding. The resulting current which is a DC can power loads just like the normal current produced from a battery.

5. Rectified DC from AC.

Here, AC is converted to DC with diodes. Diodes are use to filter AC signals into DC as shown in the circuit above, it allows current to flow only in one direction thus blocking current when connected in  the reverse direction.