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Capacitor & types: ceramic, electrolytic, film

Capacitor is an analog memory. Ceramic capacitors are meant for maintaining a certain timing, where as electrolytic capacitors are meant for maintaining a certain voltage across them & timing as well.

Digits

Multiplier, 10( )

10 * 104 * 10-12 M= 10-7 = .1uF/100nF

Moreover, a ceramic capacitor has no polarity with respect to terminals.

Cathode(-) is a bit short compared to anode(+). Electrolytic shows its polarity, cathode marked as (-)

Film capacitors on the other hand have no polarity like ceramic and can withstand higher voltage than electrolytic, in the range of Kilo Volts.

They have less series resistance & self inductance in contrast to other capacitors.

Inductor & types: air, iron, tapped

A wire wound to cause EMI (Electro Magnetic Induction) when some voltage is applied to it makes an inductor.

(An Iron core inductor in a mobile charger circuit )

(A Toroidal core inductor in a SMPS )

Iron core/Ferro magnetic inductors are made for high inductance but they are limited to usage of low frequency circuits, where as toroidal

core inductors have less losses (eddy & hysteresis) & they are used in power amplifiers & SMPS (Switching Mode Power Supply).

(A tap inductor in a antenna tuner/rxr board)

Tap inductors are used in applications where the inductance must be varied for tuning.

(An air core inductor in a FM receiver )

Air core inductors on the other hand offer less inductance & they are used in simple tuning circuits like an FM radio.

Resistor & types: carbon, ceramic, wire wound, LDR

Wire wound resistors are meant to be used for tens of watts, but suffer from EMI at higher frequencies & hence they are confined to low frequencies.

Pots or Potentiometers are meant for low power & they make a voltage divider

One of the extremes should be supply & the other, ground. The middle one is the required voltage.

Resistor purpose is to limit the current flow in to a particular component/lead/pin/terminal/line. They dissipate (waste) energy in the form of heat. Higher resistance means, it’s made of material that has less percentage of free electrons.

Carbon or metal resistor color code:

Black Brown Red Orange Yellow Green Blue Grey White

B B R O Y G B G W

0 1 2 3 4 5 6 7 8

BBROY of Great Britain has Grey Wolf

Digits

Multiplier, 10( )

Brown (1), Black (0) Orange (3) -> 103

10 *103 = 10KΩ

Thermistor Vs Sensistor:

Thermistor finds its application in medical field like myocardiogram & esophageal monitoring

(myocardial probes)

Like some electronic components with different representations for different standards of the world, thermistor do has different symbolics

(Japanese representation) (European representation)

PTC (positive temperature coefficient) or NTC are available in many forms (disc type to mountable/SMT).

Force sensitive resistor or simply sensistor is used in cricoid cartilage probes, sore monitors & head drapes.

FSR (Force Sensitive Resistor) works similar to an LED, its resistance varies from mega ohms to hundreds/tens of ohms depending upon the force applied on it.

Switch & types:

Switches are electromechanical meant to control/allow current only when needed. Switches are like gates for current flow.

Micro switch/reset switch mainly used in control panels

Slide switch mainly used as a power button in radios

Wall switch used as domestic household power button

DPST used in switching supplies

Based on the number of inner contacts (referred as poles) & number of human-manual contact (referred as throws), they are of 4 types: SPST, DPST, SPDT, DPDT.

Diodes (signal, rectifier, photodiode, Zener, schottky, LED):

(Zener diode) (signal/switching diode) (schottky diode)

1N4730 1N4814 1N5819

(Light Emitting Diode) (rectifier) (photodiode)

1N4007

Switching/signal diode Vs Rectifier diode:

Switching/signal diodes have less forward current (repetitive & non-repetitive) & low power dissipation than rectifier diodes.

Current Ratings:

(as specified in 1N4148 high speed signal diode datasheet)

(as specified in 1N4007 rectifier diode datasheet)

Power Rating:



Switching/signal diodes are faster (less reverse recovery time) than rectifier diodes.

Reverse recovery time:



Schottky diode Vs Rectifier diode:

Schottky diodes have better reverse characteristics & less forward voltage compared to rectifier diodes.

Reverse characteristics:

(as specified in 1N5819 schottky barrier diode datasheet)


Forward voltage drop:

(as specified in 1N5819 schottky barrier diode datasheet)


Based on the reverse characteristics for converting domestic AC (50 to 60Hz) to DC, rectifier diodes are preferred than schottky barrier diodes.

For applications where less cut-in and where speed is crucial (saturation has to be prevented), schottky diodes are preferred

Forward voltage measurement:

1. Move multimeter's dial to diode test ( )2. Connect the black lead to cathode (-) & red to positive (+)3. DMM displays nominal forward voltage drop

Some commercially available diodes:Rectifier -->1N400X

Signal/switching -->1N4X48

Schottky barrier-->1N581XZener-->1N473X

In cell phone chargers, 1N4007 (rectifier diode) & 1N4730 (zener diode) are commonly used.

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