A 12V to 24V DC Boost Converter is a compact and efficient circuit designed to step up a 12V DC input voltage to a stable 24V DC output. These converters are widely used in applications where a higher voltage is required than what the input source provides, such as in portable devices, battery-operated systems, automotive electronics, and industrial control circuits.
This boost converter uses a simple and cost-effective design centered around a 555 Timer IC configured in astable mode, an inductor, and a switching transistor. The 555 Timer generates a high-frequency PWM signal that drives the transistor to alternately store and release energy in the inductor. A Schottky diode ensures efficient transfer of this energy to the output, while a Zener diode stabilizes the voltage at 24V. This circuit can deliver up to 300mA of current, making it ideal for low-power devices.
By employing minimal components and leveraging the principles of inductive energy storage, this circuit provides a practical and reliable solution for DC voltage boosting.
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
24V 1W
1
7.
Inductor
100uH
1
8.
Power Supply
12V DC
1
NE555 Pinout:
NE555 Pinout
Pin 1 (GND):
Ground pin. Connect this to the negative terminal of the power supply.
Pin 2 (TRIG – Trigger):
The input pin that starts the timing cycle.
When the voltage on this pin drops below 1/3 of the supply voltage (VCC), it triggers the output to go high.
Pin 3 (OUT – Output):
Outputs the timer’s signal.
This pin provides the output signal, either high (VCC) or low (0V), depending on the timer’s state.
Pin 4 (RST – Reset):
Resets the timer.
Active low. Connecting this pin to ground resets the output, overriding other functions. If not used, connect it to VCC.
Pin 5 (CV – Control Voltage):
Adjusts the internal threshold voltage.
Typically connected to ground through a small capacitor (10nF) to stabilize operation.
Pin 6 (THR – Threshold):
Monitors the voltage across the capacitor.
When the voltage on this pin exceeds 2/3 of VCC, the timing cycle ends, and the output goes low.
Pin 7 (DIS – Discharge):
Provides a discharge path for the timing capacitor.
Connects to the open collector of an internal transistor.
Pin 8 (VCC):
Supply voltage.
Connect to the positive terminal of the power supply (typically 5V to 15V, but some variants support up to 18V).
Circuit Diagram:
This is a circuit diagram for a 12V to 24V DC boost converter.
Components and Operation:
IC 555 Timer:
Configured as an astable multivibrator.
Generates a pulse-width-modulated (PWM) signal at the output (pin 3).
The frequency is determined by the resistors (1k, 10k) and the 560 pF capacitor.
BD149 Transistor:
Acts as a switch, driven by the 555 timer’s output.
Amplifies the current to drive the inductor.
Inductor (100 µH, 2A/3A):
Stores energy during the ON time of the transistor.
Releases energy during the OFF time to step up the voltage.
Schottky Diode (1N5819):
Prevents backflow of current.
Directs the stored energy from the inductor to the capacitor and load.
Capacitor (1 µF / 50V):
Smoothens the output by filtering the pulsating DC.
24V Zener Diode (1W):
Regulates the output voltage to 24V.
Protects the load from overvoltage.
Output:
Provides 24V DC at up to 300mA, sufficient for low-power devices.
How it Boosts the Voltage:
The 555 timer generates a square wave, turning the BD149 transistor ON and OFF.
During the ON state, current builds up in the inductor.
When the transistor turns OFF, the inductor releases the stored energy, causing a voltage boost.
The Schottky diode directs this boosted voltage to the output capacitor, which stabilizes it at 24V with the help of the Zener diode.
