We use many electronic devices every day, like phones and headphones.
These devices need batteries to work.
Batteries need chargers to be recharged.
There are many chargers but this guide will show you how to build a simple USB charger circuit.
What is a USB Battery Charger Circuit:
A USB battery charger circuit is an electronic circuit designed to charge rechargeable batteries using the power from a USB (Universal Serial Bus) port.
These circuits are commonly used in various portable electronic devices, such as smartphones, tablets, cameras and other gadgets that utilize rechargeable batteries.
USB battery charger circuits are designed to be compact, efficient, and compatible with the standard USB interface, making them convenient for charging devices from a variety of power sources, including USB wall chargers, computers, and power banks.
Circuit Construction:
Constructions of the circuit, complete with necessary formulas mentioned below.
Parts List:
| Component | Description | Quantity |
|---|---|---|
| Resistors (all 1/4 W CFR) | ||
| 1k | 1 | |
| 560Ω | 1 | |
| Capacitors | ||
| Electrolytic 100µF | 16V | 2 |
| Semiconductors | ||
| Zener Diode | 4.7V / 400mW | 1 |
| Rectifier Diode | 1N4007 | 1 |
| Transistor | TIP35C | 1 |
| LEDs | ||
| Red LED | 5mm, 20mA | 1 |
- Gather the components as per the diagram
- The circuit operates by utilizing the USB ports power source to charge a rechargeable battery.
- Connect the positive terminal of the USB port to the anode of the Zener diode ZD.
- Link the cathode of the Zener diode to the base terminal of the switching transistor TIP35C.
- Connect the collector of the transistor to the positive terminal of the rechargeable battery.
- Join the emitter of the transistor to the ground terminal of the USB port.
- Introduce resistors R1, R2 for controlling current and voltage levels.
- Employ capacitors C1, C2 for filtering and stabilizing the output.
Calculate Zener Diode Voltage (Vz):
- To ensure optimal charging, select a Zener diode with a voltage rating that aligns with the specifications and requirements of the mobile battery you intend to charge.
Formulas:
Vz = Vbattery + Vdrop
where:
- Vz is the Zener diode voltage.
- Vbattery is the desired battery voltage.
- Vdrop is the voltage drop across the diode.
Working Explanation:
- The USB port supplies a DC bias to the power supply.
- The Zener diode ZD regulates the voltage based on the chosen Zener diode voltage Vz.
- The output pin provides a controlled power supply of approximately 4.7V, ideal for charging the battery.
- Connect your mobile phone or electronic device to the circuit to initiate the charging process.
Application and Uses
This Simple USB Battery Charger Circuit is designed for the purpose of charging various electronic equipment, devices, and gadgets, including mobile phones with ease and efficiency.
It harnesses the power of the USB port reducing the need for additional charging equipment and enhancing user convenience.
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