Phones, headphones and other devices are among the many devices we use in our daily basis.
Are they battery operated?
Actually they require charging.
Although many chargers are available in market but here is how to make a simple USB charger on our own.
What is a USB Battery Charger Circuit:
A USB battery charger circuit is a device that uses a USB (Universal Serial Bus) connector to take electricity in order to charge rechargeable batteries.
These circuits are often found in many different kinds of portable electronic devices such as cameras, tablets, phones and other devices that run on rechargeable batteries.
They are used to charge devices from various power sources such as USB wall chargers, PCs and power banks.
They include a standard USB connection which are compact, effective and completely functional.
Circuit Diagram:
Parts List:
| Component | Quantity |
|---|---|
| Resistors (all 1/4 watt) | |
| 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 | 1 |
How to Build:
- Gather all the mentioned circuit parts as per the above diagram
- The circuit operates by using the USB ports power source to charge a rechargeable battery.
- The anode of the Zener diode is connected to the positive terminal of the USB port
- Connect the cathode of the Zener diode to the base terminal of the switching transistor TIP35.
- The positive terminal of the rechargeable battery is connected to the collector of the transistor
- To the ground terminal of the USB port join the emitter of the transistor
- Add resistors R1 and R2 for controlling current at voltage levels.
Calculate Zener Diode Voltage (Vz):
- Select a Zener diode whose voltage rating matches to the features and needs of the mobile battery chosen to charge in order to ensure the best possible charging.
Formulas:
Below mentioned are the formulas for Simple USB Battery Charger Circuit:
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 power supply receives a DC bias from the USB port.
- Based on the selected Zener diode voltage Vz the Zener diode ZD controls the voltage.
- For charging the battery the output pin offers a regulated power source of about 4.7V.
- To start the charging process connect the smartphone or other electronic item to the circuit.
Application and Uses:
Cell phones are among the various electronic devices, gadgets and equipment that can get charged using this simple circuit for a USB battery charger.
Using the USB ports electricity increases user comfort and removes the need of extra charging equipment.
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