This content attempts to figure out an approach by which any SMPS might be created into a variable power supply for obtaining any preferred voltage level from 0 to maximum.
SMPS symbolizes switch mode power supply, as the name indicates this power supply concept makes use of high frequency switching pulses for transforming mains AC voltages to a specific specific low voltage DC for example 12V or 24V.
I have discussed this quite thoroughly in one of my earlier articles how you can recognize SMPS circuits
The SMPS idea today possesses almost totally changed the traditional iron core transformers as well as have converted these types of units into a much compact, light weight and economical power adaptor options.
Nevertheless considering that SMPS units are typically offered as fixed voltage components accomplishing a favored voltage according to the users application requirements turns into very difficult.
For instance for charging a 12V battery one can require an output voltage of around 14.5V, however this value being quite odd and nonstandard we might find it stressful to obtain an SMPS rated using these specifications available in the market.
Even though variable SMPS circuits are available in the market, these types of might be more expensive compared to the ordinary fixed voltage variants, consequently choosing an approach of transforming an existing fixed voltage SMPS into a variable type appearance a lot more fascinating and suitable.
By considering the idea slightly I was in a position to discover a very easy procedure for applying the same, let's discover ways to perform this modification.
You will discover one popular 12V 1amp SMPS circuit within my blog which really possesses an in built variable voltage aspect.
We come across that it uses a shunt regulator circuit stage for performing the variable voltage aspect in the design.
An additional fascinating feature is that this shunt regulator device performs the function by regulating the input of the opto coupler of the circuit.
Right now since a opinions opto coupler stage is constantly found in all SMPS circuits, by presenting a shunt regulator one can very easily enhance a fixed SMPS into a adjustable counterpart.
The fact is one can also make a variable SMPS circuit utilizing the same principle as described above.
You might want to find out more about what's a shunt regulator and the way it goes.
Steps to make a Variable SMPS circuit
Talking about the following instance circuit, you can easily discover the precise location of the shunt regulator and its configuration information:
Refer to the bottom right side of the diagram labeled with red dotted lines, it demonstrates the variable portion of the circuit we have been excited about. This part turns into accountable for the meant voltage regulation measures.
Here the resistor R6 could be replaced with a 22K pot for creating the design variable.
Magnifying this section offers a much better view of the required information:
In case you have a fixed voltage SMPS circuit, open it and just be aware of the optocoupler in the design, it might be mainly found just around the central ferrite transformer, as might be observed in the following image:
When you have discovered the opto-coupler, clean up by removing all the components connected on the output side of of the opto, which means across the pins which can be towards the output side of the SMPS PCB.
And link or integrate these pins of the opto with the assembled circuit utilizing the TL431, demonstrated in the earlier diagram.
You possibly can assemble the TL431 section on a small piece of general purpose PCB and glue it on the main SMPS board.
If your SMPS circuit is lacking in an output filter coil, you could simply short the two positives of the TL431 circuit and join the termination to the cathode of the SMPS output diode.
On the other hand assume your SMPS already contains the TL431 circuit with the opto coupler then simply find the position of the R6 resistor and replace it with a pot (see R6 location in the first diagram above).
Don't forget to add a 220 ohms or 470 ohm resistor in series with the POT otherwise while adjusting the pot to the upper most level could immediately harm the TL431 shunt device.
That's it, now you understand precisely how to convert or make a variable voltage SMPS circuit utilizing the above described measures.
For those who have any additional issues concerning the design or the justification, feel free to communicate by means of your feedback.
SMPS symbolizes switch mode power supply, as the name indicates this power supply concept makes use of high frequency switching pulses for transforming mains AC voltages to a specific specific low voltage DC for example 12V or 24V.
I have discussed this quite thoroughly in one of my earlier articles how you can recognize SMPS circuits
The SMPS idea today possesses almost totally changed the traditional iron core transformers as well as have converted these types of units into a much compact, light weight and economical power adaptor options.
Nevertheless considering that SMPS units are typically offered as fixed voltage components accomplishing a favored voltage according to the users application requirements turns into very difficult.
For instance for charging a 12V battery one can require an output voltage of around 14.5V, however this value being quite odd and nonstandard we might find it stressful to obtain an SMPS rated using these specifications available in the market.
Even though variable SMPS circuits are available in the market, these types of might be more expensive compared to the ordinary fixed voltage variants, consequently choosing an approach of transforming an existing fixed voltage SMPS into a variable type appearance a lot more fascinating and suitable.
By considering the idea slightly I was in a position to discover a very easy procedure for applying the same, let's discover ways to perform this modification.
You will discover one popular 12V 1amp SMPS circuit within my blog which really possesses an in built variable voltage aspect.
We come across that it uses a shunt regulator circuit stage for performing the variable voltage aspect in the design.
An additional fascinating feature is that this shunt regulator device performs the function by regulating the input of the opto coupler of the circuit.
Right now since a opinions opto coupler stage is constantly found in all SMPS circuits, by presenting a shunt regulator one can very easily enhance a fixed SMPS into a adjustable counterpart.
The fact is one can also make a variable SMPS circuit utilizing the same principle as described above.
You might want to find out more about what's a shunt regulator and the way it goes.
Steps to make a Variable SMPS circuit
Talking about the following instance circuit, you can easily discover the precise location of the shunt regulator and its configuration information:
Refer to the bottom right side of the diagram labeled with red dotted lines, it demonstrates the variable portion of the circuit we have been excited about. This part turns into accountable for the meant voltage regulation measures.
Here the resistor R6 could be replaced with a 22K pot for creating the design variable.
Magnifying this section offers a much better view of the required information:
In case you have a fixed voltage SMPS circuit, open it and just be aware of the optocoupler in the design, it might be mainly found just around the central ferrite transformer, as might be observed in the following image:
When you have discovered the opto-coupler, clean up by removing all the components connected on the output side of of the opto, which means across the pins which can be towards the output side of the SMPS PCB.
And link or integrate these pins of the opto with the assembled circuit utilizing the TL431, demonstrated in the earlier diagram.
You possibly can assemble the TL431 section on a small piece of general purpose PCB and glue it on the main SMPS board.
If your SMPS circuit is lacking in an output filter coil, you could simply short the two positives of the TL431 circuit and join the termination to the cathode of the SMPS output diode.
On the other hand assume your SMPS already contains the TL431 circuit with the opto coupler then simply find the position of the R6 resistor and replace it with a pot (see R6 location in the first diagram above).
Don't forget to add a 220 ohms or 470 ohm resistor in series with the POT otherwise while adjusting the pot to the upper most level could immediately harm the TL431 shunt device.
That's it, now you understand precisely how to convert or make a variable voltage SMPS circuit utilizing the above described measures.
For those who have any additional issues concerning the design or the justification, feel free to communicate by means of your feedback.
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