Simple High Current 12V Voltage Regulator Circuit using Transistor

Voltage regulators play a crucial role in power supply circuits because they ensure the output voltage remains constant, even if the input voltage changes or the load shifts.

The voltage regulator circuit we are focusing on can provide a steady 12V output with a maximum current of 3A.

It can also handle situations where the current demand exceeds 3A for proper regulation.

The Simple High Current 12V Voltage Regulator Circuit using transistor ensures a reliable 12V output while managing high current requirements.

This makes it perfect for various applications including power amplifiers, battery chargers and electronic devices in vehicles.

Circuit Working:

Parts List:

This circuit is made to control a strong 12V output using a Q1 power transistor as its key part.

A 12V Zener diode D3 helps keep the voltage steady.

First the circuit changes the 230V AC input down to 15V AC with the help of a transformer.

Then a 5A bridge rectifier called D1 changes the AC into direct current, which is smoothed by a big capacitor C1 to get rid of any voltage bumps.

The D2 1N4007 diode enhances the circuits stability and safety.

It stops reverse leakage from the Zener diode, which helps maintain better regulation.

The Zener diode D3 is very important because it gives a steady 12V reference voltage.

This reference helps control the base of the transistor 2N3055 Q1 through a 680Ω resistor R1.

When the voltage goes over 12V the transistor starts to work, helping to keep the output voltage steady.

Also, a 0.01µF capacitor C2 is included in the circuit to filter out noise and make everything more stable.

Formulas with Calculations:

Below are the formulas with calculations for Simple High Current 12V Voltage Regulator Circuit using Transistor:

Transformer Output Voltage Calculation:

Transformer secondary voltage is chosen as 15V AC to ensure enough headroom for rectification and regulation.

After rectification:

VDC = VAC × 1.414

where,

• VDC is the rectified DC voltage after the bridge rectifier and capacitor filter.
• VAC is the AC voltage from the transformer secondary winding.
• 1.414 is the square root of 2 (√2), which accounts for the peak voltage conversion in a full wave rectifier.

VDC = VAC × 1.414

VDC = 15V × 1.414 = 21.21V

This 21V DC is filtered and provided to the regulator circuit.

This formula calculates the DC output voltage from the AC input after rectification.

Transistor Base Current Calculation:

Assuming the output current requirement is 5A and the current gain β of 2N3055 is approximately 20:

IB = IC ÷ β

where,

• IB is the base current of the transistor.
• IC is the collector current (or load current) flowing through the transistor.
• β (Beta) is the current gain of the transistor (how much the base current is amplified to produce collector current).

IB = IC ÷ β

IB = 5A ÷ 20 = 0.25A

The base resistor R1is 680Ω limits the current and ensures stable operation.

This formula calculates the required base current to drive a transistor with a given collector current.

How to Build:

To build a Simple High Current 12V Voltage Regulator Circuit using Transistor follow the steps mentioned below:

• Gather all the components as mentioned in the above circuit diagram
• Connect the base of transistor Q1 to the junction of resistor R1 and anode of D2 and cathode of D3 Zener diode and GND.
• Connect the emitter of transistor Q1 to Vout output
• Connect the collector of transistor Q1 to one terminal of resistor R1
• Connect the transformer primary side to 230V AC mains and secondary side of 15V AC output connect to two end of bridge rectifier
• Connect one terminal of bridge rectifier to positive of capacitor C1 and other terminal of bridge rectifier connect to GND
• Connect capacitor C2 one terminal between emitter of transistor Q1 and Vout and other terminal of capacitor connect to GND

Conclusion:

This Simple High Current 12V Voltage Regulator Circuit using Transistor delivers a steady 12V output and can handle a lot of current.

The 2N3055 transistor helps keep the voltage stable and the Zener diode ensures accuracy.

This circuit is a great option for projects that need a lot of power, stability and dependability.

References:

Using Linear Voltage regulators in parallel for a high current load