Topic 5. Sources of Power
All electronic projects need a source of electrical power. This supplies the charged electrons which make electronic circuits work.
There are four main sources:
Portable equipment, such as mobile phones and iPods, needs a portable power source. Topic 3 describes many types of chemical cells and batteries, which are ideal portable power sources for portable equipment. The most portable of these are the small button cells, often used in pocket calculators and hearing aids.