In electronic clocks calculators measuring instruments and some other scientific instruments LED are used to display the numerical digits.  Read more about Seven Segment Display

In this method the speed of squirrel gauge induction motor control  by varying the stator voltage, which is possible with the help of three sets of SCR’s connected back to back(parallel but opposite in direction ) with  each phase of input supply as shown  in figure  below. Read more about Three Phase motor control using SCR

The speed of  DC motor  can be control by using  SCR  in AC circuit  as shown in the below figure. Read more about SCR DC Motor control

Zener diodes are used to maintain a fixed voltage. They are designed to 'breakdown' in a reliable and non-destructive way so that they can be used in reverse Read more about Zener diodes

The diagram of magnetic amp or magnetic amplifier is shown in figure below, only silicon diodes are added in series with each winding of the saturate reactor.

LVDT consist of one primary winding and two secondary windings, which are placed at either side of the primary winding on the same magnetic core as shown in figure

Inverter is a device which converts the DC power into A.C and desired voltage and frequency.

Gluco-meter stands for Glucose meter. This instrument is used to check the % value of sugar in the blood of a human body. Read more about Gluco Meter

As shown in the below diagram, the direct coupled amplifier (DC) is consist of two transistors Q1 and Q2 , a voltage divider base bias resistor network (R1, R2) which is provided on the transistor Q1 base two collector resistors Rc1and Rc2, Read more about Direct Coupled Amplifier