Polarized capacitors must be connect correct way otherwise, will be damage if connected wrongly. At least one of their leads (terminals) is mark either “+” or “−”. Examples of these capacitors are (with brief descriptions):
Electrolytic capacitors may be found in these two different forms; AXIAL (where the leads are built to each end) and RADIAL (where both the leads are built in the same end). Axial electrolytic capacitors stand or soldered horizontally on the circuit board while Radial upright (vertically).
Electrolytic capacitors are printed with the value of their capacitance as well as their voltage rating on them, their negative side terminal is shaded white with a mark (–) while the positive side isn’t shaded or marked.
The voltage rating can be quite low and it is very important to check when selecting. If for an instance the voltage is not specify for a capacitor in a list of parts for a project, choose a capacitor with rating which is greater than the project’s power supply e.g. 25V as it is a sensible minimum for most battery circuits.
Tantalum Bead capacitors
Tantalum bead capacitors are also polarized and have low voltage ratings like electrolytic capacitors. They are used where a large capacitance is needed and in a small size because they are usually small when compared to the electrolytic type.
These days, tantalum bead capacitors are printed with their capacitance, voltage rating, and polarity in full. However, older ones are colour-code used system which has two stripes (for two digits) and a spot of colour for the number of zeros to give the value in microfarad (µF).
The standard colour-code system is used just as resistor colour code, but for the spot, grey is used to mean “×0.01” and white “×0.1” so that values of less than 10µF can be shown. A third colour stripe near the leads show the voltage.
- Yellow = 6.3V
- Black = 10V
- Green = 16V
- Blue = 20V
- Grey = 25V
- White = 30V
- Pink = 35V
The positive (+) lead is to the right when the spot is facing you directly.
METHOD OF DETERMINING TANTALUM BEAD CAPACITOR’S CAPACITANCE VALUE
Method of determining this type of capacitor’s capacitance value is just as using resistor colour code but, the spot colour is the multiplier. Grey spot means ×10 and White spot means ×0.1.
Examples below show capacitors colour codes and their values.
- Blue, Grey, Black spot = 68µF
- Blue, Grey, White spot = 6.8µF
- Brown, Black, Brown spot = 100µF
- Blue, Grey, Grey spot = 0.68µF
- Red, Red, Brown spot = 220µF