# Making a 5V DC Power Supply for Microcontroller: Possible Damage?

In summary, the maximum secondary current that can be drawn is partially defined by the turns ratio, and without safety circuitry, your power supply presents a shock and fire hazard.

i want to make a 5v dc power supply for microcontroller i know how to make it i am going to use a 220v to 15v transformer and then by using capacitor and 7805 regulator ic i will convert it to 5v my question is as in transformer pout=pinput (ideally) by decresing the voltage from 220 to 15 the secondary current will increase can it damage the circuit(microcontroller[/SIZE])?

Did you just neglect to mention the rectifer you will need between the transformer and the regulator?

Yes i forgot ofcouurse a bridge rectifier

i want to make a 5v dc power supply for microcontroller i know how to make it i am going to use a 220v to 15v transformer and then by using capacitor and 7805 regulator ic i will convert it to 5v my question is as in transformer pout=pinput (ideally) by decresing the voltage from 220 to 15 the secondary current will increase can it damage the circuit(microcontroller[/SIZE])?

The secondary current is defined by the secondary voltage and the secondary load resistance, not by the transformer turns ratio. The max secondary current that can be drawn is defined partially by the turns ratio.

BTW, you also did not mention the safety circuitry that you have included in the design and construction of your power supply. Without very specific safety measures and circuits, your power supply presents a shock and fire hazard.

Can you tell us what mandatory safety features you have included in your design?

berkeman said:
The max secondary current that can be drawn is defined partially by the turns ratio.
can you elaborate what partially means here and also what kind of safety equipment do you recommend?

can you elaborate what partially means here and also what kind of safety equipment do you recommend?

For an ideal transformer, the turns ratio and the max input primary current would dictate the max secondary current that could be drawn. For a real transformer, however, there are resistance losses in the windings and core losses that lower the potential max output current from that ideal number.

I'm not asking about safety "equipment", I'm asking about what design features are necessary in any equipment that connects to the AC mains, in order to help safeguard agains shock and fire hazards. What kinds of things would UL (in the United States) look for in your design if you submitted it for a safety approval? You need to include those things even in a hobby design, or you put yourself and other users of the power supply at risk...

## 1. What is a 5V DC power supply and why is it important for a microcontroller?

A 5V DC power supply is a type of power source that provides a constant voltage of 5 volts to electrical devices. It is important for microcontrollers because they require a stable and regulated power supply to function properly and avoid damage.

## 2. What components are needed to make a 5V DC power supply for a microcontroller?

The basic components needed for a 5V DC power supply for a microcontroller include a transformer, rectifier, smoothing capacitor, and voltage regulator. Additional components such as resistors and capacitors may also be needed for specific circuit designs.

## 3. Can using the wrong voltage for a microcontroller damage it?

Yes, using a voltage higher or lower than the recommended voltage for a microcontroller can damage it. Most microcontrollers operate at 5V, so using a higher voltage can cause overheating and potential burnout, while using a lower voltage can result in insufficient power for the microcontroller to function properly.

## 4. How can I ensure that my 5V DC power supply is safe for my microcontroller?

To ensure safety, it is important to carefully select and test all components before assembling the power supply. It is also recommended to use a voltage regulator to regulate the voltage and protect the microcontroller from any fluctuations. Additionally, following proper circuit design and using appropriate fuses can also help ensure safety.

## 5. What are some common mistakes to avoid when making a 5V DC power supply for a microcontroller?

Some common mistakes to avoid include using the wrong voltage, incorrect wiring or connections, using low-quality components, and not properly grounding the circuit. It is also important to double-check the circuit design and test the power supply before connecting it to the microcontroller.