We can convert the High voltage AC into Low voltage DC without using the Transformer. This is known as Transformerless power supply. The main component of a Transformerless power supply is Voltage dropping capacitor or X-rated capacitor, which are specially designed for AC mains. This X rated capacitor is connected in series of Phase line of AC, to drop the voltage.

Sensors are very important part of electronics, especially in Robotics and Automations. Sensors in electronic devices make our life easy by automatically sense and control the devices, without human interaction. There are many kinds of sensors like Fire sensor, humidity sensor, motion sensor, temperature sensor, IR sensor etc.

Voltage doubler is the circuit where we get the twice of the input voltage, like if we supply 5v voltage, we will get 10 volt at the output. Generally transformers are there to step-up or step-down the voltage, but sometimes transformers are not feasible because of their size and cost. So here is the quick, easy and practical solution to double the voltage, using 555 timer IC.

The integrator does just what the name implies. It integrates - in the calculus sense - the input signal to produce the output signal. There is a scaling factor and a minus sign again, but that's pretty much what happens.

As per the reader’s request, here is the making of the IR Sensor Module. An IR Sensor module is a sensor that transmits and receives infra-red rays when a surface or object is detected. It is a multipurpose sensor, which can be used in line following robot, obstacle avoiding robot, edge avoiding robot, etc.

This circuit creates a voltage inversely proportional to a variable resistance.

The Schmitt-trigger is a circuit which creates hystereses and which is useful in digitizing an analog signal into a digital signal of either high or low. The hystereses makes inputs more immune to noise. The input must surpass a low threshold voltage before the output goes low, and likewise the input must exceed a high level threshold before the output goes high.

LM386 is a low voltage audio amplifier and frequently used in battery powered music devices like radios, guitars, toys etc. The gain range is 20 to 200, gain is internally set to 20 (without using external component) but can be increased to 200 by using resistor and capacitor between PIN 1 and 8, or just with a capacitor.

H-bridge is the circuit in which voltage can be applied across the load, in either of the direction. These circuits are frequently used in robotics, especially for the DC motor. Voltage can be applied in either direction to rotate the DC motor forward or backward

This gate is mainly used in applications where there is a need for mathematical calculations. So calculators, computers and many digital applications use this gate.