Transformer DIY Assembled and Tested Kits Power Supply

A good regulated AC to DC power supply circuit is essential for any electronic products. Microcontrollers require a 5V DC supply, so the AC 230V needs to be converted into 5V DC using the step-down converter in their power supply circuit.

Circuit consists of 4 parts: Step down transformer, bridge rectifier, capacitor filter and voltage regulator IC. The transformer step downs the high voltage AC to a low voltage AC. W10 (Bridge rectifier) internally consists of four diodes which are connected in the form a bridge. We know that the diode is an uncontrolled rectifier which will conduct only forward bias and will not conduct during the reverse bias. Output of the W10 will get 15v DC. 15V DC can be regulated into 5V DC using 7805 IC, but before this, it is required to obtain pure DC power. The output of the W10 bridge rectifier is a DC consisting of ripples also called as pulsating DC. This pulsating DC can be filtered using a capacitor filter for removing the ripples. The Capacitor input increases from zero to a peak value and, while the supply voltage decreases from peak value to zero, capacitor starts discharging. This charging and discharging of the capacitor will make the pulsating DC into pure DC.

    7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear voltage regulator ICs. Which restricts the voltage output to 5V. It comes with provision to add heatsink.The maximum value for input to the voltage regulator is 35V. It can provide a constant steady voltage flow of 5V for higher voltage input till the threshold limit of 35V. Again Filter circuit is added to eliminate remaining ripples. When Output 5v is came, LED will glow. This circuit can connect any of power supply sections if regulated 5v is needed.