DC to DC Boost Converter Circuit Using 555 Timer

This article aims to demonstrate a basic and compact DC-to-DC boost converter circuit with a 555 Timer IC. A boost converter is a DC-to-DC power converter that takes a specific amount of input voltage and uses it to raise the voltage to a fixed level. This type of exchanged mode power supply has one energy storage component, such as a capacitor, an inductor, or both in the same combination, and two semiconductors, such as a diode and a transistor, at any rate. Filters are typically added to the input terminal and output of such a converter in order to reduce voltage ripple.


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Circuit Schematic

Dc to dc boost converter using 555 timer


NE555 Timer IC
LM317 Regulator IC
BD139 NPN Transistor
10 KΩ Potentiometer (x2)
100uH/2A Inductor
1N5819 Zener Diode
39V/1W Zener Diode
1N4007 PN Diode
Ceramic Capacitor (10nF, 560pF)
Electrolytic Capacitor (1uF/25v, 10uF/35V, 100uF/35V)
Resistor (1KΩ, 220Ω)
DC Power Supply

Circuit Connection

A 555 timer IC is first taken. Pin 1 is then directly linked to ground, and pins 4 and 8 are connected directly to the VCC. Additionally, Pin 5 is connected to ground via a 10nF capacitor.

Pins 2 and 6 are linked to one another. Pin 2 is additionally linked to ground via a ceramic capacitor with a 560 pF value.

A 10KΩ potentiometer is connected to pins 6 and 8, and pin 7 of the IC is linked to its middle terminal.

Pin 3, the output of the integrated circuit, is connected via a 1KΩ resistor to the base of the NPN transistor BD139. Its collector terminal is connected to Vcc via a 100uH inductor, while its emitter terminal is connected straight to ground.

Between the BD139 collector terminal and the inductor’s input terminal on the LM317 regulator integrated circuit, a forward-biased 1N5819 Zener is attached.

The adjustment terminal of the LM317 regulator is connected to one side of a 10KΩ potentiometer, which is grounded. The ground is linked to the middle terminal.

Lastly, a 100uF/35V capacitor in parallel and a 220Ω resistor in series are connected to the LM317 regulator’s output wire.

Working Principle of DC to DC Boost Converter

The DC-to-DC flexible advanced step-up power converter circuit is shown in this boost converter project. The circuit’s output current, which ranges from 100 mA to 300 mA depending on the input power voltage, can be balanced between 1.2 V and 37 V DC. For example, at 6 V, the maximum output current is approximately 100 mA, at 9 V, it is approximately 150 mA to 200 mA, and at 12 V, it is approximately 250 mA to 300 mA. The transistor BD139 will radiate heat when operating at 12V, hence a suitable heatsink was needed. With the 5 KΩ variable resistor, the circuit’s output voltage can be adjusted.

The boost converter circuit is divided into two independent portions. The first part is a step-up converter circuit that converts DC to DC and is based on a 555 timer integrated circuit, allowing an input voltage of up to 50V. A regulator and the LM317 adjustable voltage controller integrated circuit (IC) form the second segment of the boost converter circuit. The voltage coming from the booster converter circuit is stepped down by the 39V Zener diode to bring it below the 40V DC maximum input voltage breaking point of the LM317 IC.

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