Simple 3V to 24V Variable Power Supply Circuit

This Simple 3V to 24V Variable Power Supply Circuit work like swiss knife for electronics.

Only one power supply but can do many thing.

We can turn a knob or change setting and voltage which will go from 3V to 24V.

This type of circuit is very good for many project and when we need a different power for different device.

No need of many power adapter just we can use this one.

Circuit Working:

Parts List:

This power supply can change voltage from 3 to 25V and can give 2 amps but can give 3 amps or more if we use smaller 0.3 ohm resistor for current.

The 2N3055 and 2N3053 transistors need to be on heat sinks and resistor for current should be 3 watt or more.

Voltage control uses half of 1558 or 1458 op-amp.

We can use 1458 instead but better to keep voltage at pin 8 under 30V.

For that we can put 6.2V Zener or 5.1k resistor on pin 8.

Max voltage for 1458 is 36V and for 1558 is 44V.

The transformer must give enough current and voltage at least 4V more than output voltage.

But not too much or op-amp will get too much voltage when load is low.

The transformer here is center tap 25.2V AC 2 amp which gives:

• 24V at 0.7 amp
• 15V at 2 amp
• 6V at 3 amp

To get 3 amp output we should use center tap and set switch to 18V.

We can buy all parts from radio shack only 1558 op-amp may not be there.

How to Build:

To build a Simple 3V to 24V Variable Power Supply Circuit we need to follow the below mentioned connection steps:

Mount the Transistors:

• Put 2N3055 and 2N3053 transistors on good heat sinks.

Connect Current Resistor:

• Join 0.3 ohm resistor like in circuit diagram but this is for current sense.

Set Voltage Control:

• Use half of op-amp 1458 or 1558 for voltage control.
• Be sure voltage to pin 8 should not be more than 30V and use 6.2V Zener diode or 5.1k resistor with pin 8.

Use Power Transformer:

• Use 25.2V AC and 2A center tap transformer.
• To get 3A use center tap and put switch to 18V.

Connect All Parts:

• Connect all parts same like circuit diagram and make wires safe and strong.

Test Circuit:

• Put all parts in place and test.
• Change voltage and current to see if its working good.

Final Fix:

• If needed change part values or connections to make power supply work better.

Note:

• Be careful when working with electronics and solder in air flow place there should be no short circuit.

Conclusion:

To conclude Simple 3V to 24V Variable Power Supply Circuit is very useful circuit.

It can give different voltage from 3V up to 24V.

People use this in many electronics project where there is need of changeable power.

References:

Design and Construction of a DC Variable Power Supply

Datasheet IC LM1558

Datasheet 2N3055

Datasheet 2N3053

Datasheet 2N3904