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:
| Category | Component | Quantity |
|---|---|---|
| Resistors | 10Ω 1W MFR | 1 |
| 1M 1W MFR | 1 | |
| 390Ω 1W MFR | 1 | |
| 100Ω 1W MFR | 1 | |
| 150Ω 1/4 W MFR | 1 | |
| 4.7k 1/4 W MFR | 1 | |
| 1k 1/4 W MFR | 1 | |
| Capacitors | Electrolytic 10μF 400V | 1 |
| Electrolytic 2200μF 25V | 1 | |
| PPC 2.2nF 100V | 1 | |
| PPC 220pF 1kV | 1 | |
| PPC 100nF 400V | 1 | |
| Semiconductors | Diode 1N4007 | 4 |
| Diode 1N4148 | 1 | |
| Schottky Diode BA159 | 1 | |
| IC TL431 | 1 | |
| Optocoupler 4N35 | 1 | |
| Transistor MJE13005 | 1 | |
| Ferrite core EE (pair) | 1 |
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 = Vout / Vin
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 = Vout / Iout
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.