The sources of direct current (cd) have a unidirectional load flow, that is, in only one direction. These dc voltage sources are divided into 3 main categories:
1.- Batteries (Chemical action)
2.- Generators (electromechanical action)
3.-Power supplies (Rectified)
Batteries
Batteries are the most common sources of cd, these are made up of two or more similar cells, one of the two being the fundamental source of electrical energy developed through the conversion of chemical energy or solar energy. All batteries can be divided into primary or secondary types, which are the secondary type are rechargeable as your smartphone has while the primary ones are not (the conventional battery would say I).
The batteries have a nominal value of their capacity which is given in Ampere-Hora, hence the time that a battery can last according to the load that we are demanding.
Generator
The generator is very different from a battery, in its way of operating as if in construction. When the rotor of the generator is in nominal rotation, as a consequence of the applied torque of some mechanical force, such as a combustion engine, turbine, etc ...
In general, the voltages used in generators are greater than those used in batteries.
Power supplies
These sources of cd, we find them more frequently in the laboratory, this uses processes of rectification and filtering as means to obtain a continuous voltage of cd. Most of these sources have a regulated adjustable voltage output with three available terminals.
