A boost converter is a type of DC-DC converter that steps up a lower input voltage to a higher output voltage. The circuit shown here is a simple 5V to 12V boost converter, designed using the versatile 555 timer IC, an inductor, and a few supporting components. This circuit is ideal for low-power applications where a stable 12V DC output is required, such as powering small electronic devices or modules from a 5V source.
The heart of this boost converter is the 555 timer IC, configured in astable mode to generate a continuous PWM signal. This signal controls the switching of a BD139 transistor, which alternately charges and discharges the inductor. The inductor plays a critical role in storing energy and releasing it at a higher voltage. A Schottky diode and Zener diode ensure efficient and stable operation, while a smoothing capacitor reduces ripples in the output voltage.
This circuit demonstrates the fundamental principles of energy storage and release in inductors, making it a practical and educational project for hobbyists and engineers alike. With a simple design and commonly available components, this boost converter effectively steps up a 5V input to a 12V output, delivering up to 300mA of current.
Component Details:
S.No
Components
Value
Qty.
1.
IC
NE555
1
2.
Transistor
BD139
1
3.
Resistor
1K, 10K
2, 1
4.
Capacitor
1uf/50uF, 560pf, 10nf
1,1,1
5.
Diode
1N5819
1
6.
Zener Diode
12V 1W
1
7.
Inductor
100uH
1
8.
Power Supply
5V DC
1
BD139 Pinout:
NE555 Pinout:
Circuit Diagram:
Circuit Explaination:
This circuit is a 5V to 12V boost converter that uses the 555 timer IC in astable mode to generate a high-frequency PWM signal. Here’s how it works:
Components and Their Roles:
555 Timer IC:
Configured in astable mode to produce a continuous square wave signal.
The frequency and duty cycle are controlled by the 1kΩ and 10kΩ resistors, and the 560pF capacitor.
Inductor (100µH):
Stores energy when current flows through it and releases it when the circuit switches off, boosting the voltage.
BD139 Transistor:
Acts as a switch controlled by the 555 timer output.
Alternates between conducting and non-conducting states based on the PWM signal.
1N5819 Schottky Diode:
Prevents reverse current and allows current to flow to the load during the off state of the transistor.
1µF Capacitor:
Smoothens the output by reducing voltage ripples.
12V Zener Diode:
Regulates the output voltage to 12V by clamping it when it exceeds the Zener voltage.
Working:
The 555 timer generates a high-frequency signal that switches the transistor on and off.
When the transistor is on, the inductor charges, storing energy as a magnetic field.
When the transistor switches off, the inductor releases its stored energy, and the combined voltage is boosted.
The Schottky diode ensures the current flows to the output capacitor and load.
The Zener diode ensures the output voltage is clamped at 12V.
Output:
The circuit boosts a 5V DC input to a regulated 12V DC output, capable of delivering up to 300mA.
