Resistor colour codes

Resistor values are encoded as colour codes . Here we are talking about 3 band resistor col0ur coding system and how to remember it easily . The colour coding system is as below

The number starts from 0 and ends at 9 . Lets take the first letter of each colour

B B R O Y G B V G W ( 0 1 2 3 4 5 6 7 8 9 )  . Here is an easy way to remember it

” B.B ROY Of Great Britain had a Very Good Wife”

Example:

The 1st and 2nd band is the number and the third one is the multiplier for 10 ( if its 3 => 10 raised to 3  or 10^3 ) . And the third band is for tolerance

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Presently we have a variety of cells or batteries to choose from; lead acid, zinc carbon, Nickel cadmium and Nickel metal hydride, lithium, silver oxide and what not!Cell is a storage form of electrical energy. When more cells are used, it is known as battery, but these words are used interchangeably. These are used where portability of the equipment is needed and some times as a back up for the mains voltage. Each these cells have their own characteristics, like cell voltage, current capability, storage capacity and rechargeability.

Good old Zinc carbon cells have 1.5 volts and if two cells are fixed in series, they show 3V. These are the most common cells powering most of the portable devices and are available in various sizes known variously as AAA, AA, BB, CC etc. This nomenclature denotes the capacity and dimensions of each cell but all these cells show a voltage of 1.5 volts. These are not normally rechargeable. Alkaline batteries last longer.

Lead acid cells are most widely used for high power applications such as in automobiles, UPS systems, emergency lighting systems where weight of the battery is no concern but the capacity required is high. Sealed lead acid batteries or maintenance free batteries are another form of the same where the electrolyte is within the moistened separators. Lead acid batteries can deliver high currents and recharge cycles are high. Each cell voltage is 2 volts and in a typical car battery, six of such cells are connected in series in a single container to give 12 V.

Nickel cadmium cells (Ni. Cad) show a voltage of 1.2 volts, which means that two cells in series show a voltage of 2.4 volts. These are rechargeable. They suffer from a memory effect. If they are recharged after only partially discharged, they tend to recharge only to that partial extent rather than to their full capacity.

Nickel metal hydride cells (Ni. Mh) also show a voltage of 1.2 volts and are rechargeable. They show certain better characteristics than nickel cadmium cells. They are environmentally friendly and do not show the memory effect ofNi-Cad cells.

Lithium ion cells are the fast emerging technologies. These have higher energy density and most of the present day cell phones, laptops; handy-cams are powered by these cells. They should be always used with protection circuit. Charge them only with specified charger. They have a cell voltage of’3.6 volts

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Ceramic, polyester, paper, mica, and electrolytic capacitors are some of the types. A detailed discussion is left out here. Each type has distinctive features and qualities and capacities. Capacitors are marked with voltages at the maximum voltage they can operate. It is a good practice to use a capacitor rated at twice the operating the voltage. Capacitors above the range ofl mfd generally are electrolytics and are used such in these circuits. Electrolytic capacitors are polarized and marked on the can. They should be connected as per the polarity. Electrolytic capacitors of 25 V rating are used in the following circuits unless otherwise specified. Capacitors rated at higher voltages can be used in any of the circuits. Capacitors with higher capacity should not be used unless the implications are understood. Other capacitors normally rated at 30V are used in the following circuits unless otherwise specified.

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