Simple 14V SMPS Circuit

This article discusses a power supply with a 14V 1 amp output.

It is versatile circuit with wide range of uses.

This circuit gives some electrical components a second chance at life.

There is no need to go into great detail about how this new design operates because it is quite similar to a power supply that was previously created in the article that was 3.3V at 2.5 amps.

However this circuit will take everyone through the process of building a 14V/1A power supply including choosing the required components and identifying their values.

Building a switching power supply is challenging therefore it is important to carefully follow the directions to ensure both safety and proper circuit operation.

What is a 14V SMPS Circuit:

A 14V SMPS Switched Mode Power Supply circuit is made to generate a 14 volt output voltage that is constant and regulated.

In most electronic applications where efficient power conversion is required such as powering electronic devices, LED lighting systems or supplying a consistent power source for other circuits where SMPS circuits are usually used.

Circuit Diagram:

Parts List:

How to Build:

By using ohms law calculate the resistance value for R1 and the required output voltage range which should be between 8 and 18V:

R = V / I

Transformer Winding:

• Wind the first half of the primary turns 27 turns on the ferrite core using the specified wire diameter.
• Apply at least 8 layers of insulating tape.
• Wind the secondary winding using insulated wire for safety.
• Add another 8 layers of insulating tape.
• Wind the auxiliary winding 4 turns using the same wire as the primary.
• Apply another insulating layer.
• Wind the remaining 27 turns of the primary.
• Add a few more layers of insulation.

Make an Air Space:

To make a 0.2 mm air gap place two pieces of paper or insulating tape between the cores two sides.

The core assembly:

To ensure a strong connection the core parts should be properly joined.

PCB Design:

• To provide sufficient separation build the PCB layout such that it fits the main and secondary sides of the transformer.
• According to the circuit diagram solder MOSFET/IGBT half bridge drivers, resistors, capacitors and diodes.

Connect the transformer:

• The transformers primary and secondary windings should line up correctly when it is connected to the PCB.

Test and Adjust:

• After turning the circuit ON check the output voltage.
• To reach the necessary output voltage which must fall within the specified range one needs to adjust R1.

Inspections for safety:

• Check that all the parts are connected and soldered correctly.
• Verify again for any short circuits or loose connections.
• Be sure that the power source is operating within the 80 to 250V AC or 80 to 350V DC voltage range.

Final Enclosure:

• For safety and security represent the circuit correctly if needed.

Formulas:

A 14V SMPS circuit design requires additional calculations and formulas to assure safety and effectiveness similar to the 3.3V for example.

Significant knowledge is provided by the simple formulas shown below:

Duty Cycle D:

This regulates the ratio of ON and OFF time for the switching components in the same manner as in the 3.3V example.

D = V_out / V_in

where:

• 14V is the specified output voltage or Vout.
• Vin is the input voltage which ranges from 100V to 240V.

Output Resistor R:

This is another chance for current limitations and initial testing.

R = V_out / I_out

where:

• Vout is desired output voltage of 14V
• Iout is desired output current of 14V 1A

Important Safety Considerations:

• Respect safety rules when dealing with high voltage circuits.
• Put on protective clothing like insulated tools.
• Be aware of any risks and do a controlled circuit test.
• When building and testing safety should always come first.

Conclusion:

With a simple 14V SMPS circuit an adjustable 14V output is generated from a higher voltage source.

Even though there are simple formulas for selecting the circuits basic components a safe and efficient circuit requires deeper information and factors such as feedback loops for inductor selection and temperature management.