Mobile Phone Circuit Diagrams

Mobile Phone Battery Charger with Emergency Light

This circuit serves as a versatile power supply and charger for mobile phone battery. It proves valuable not only during power outages but can also function as a primary power source. It’s particularly useful for assessing and testing your electronic projects in a workshop setting. Additionally, this circuit can effectively charge mobile phone batteries and can even serve as an emergency lighting solution in case of power failures.


  • Mobile Phone Battery Charger Circuit Diagram:
    • Circuit Components:
    • Working of Mobile Phone Battery Charger Circuit:

Mobile Phone Battery Charger Circuit Diagram:

Mobile Phone Battery

Circuit Components:

  • LM317 – 1
  • Resistor
  • R1 (220E) – 1
  • R2-R12 (220E) – 11
  • R13 (470E)
  • VR1 (100K) – 1
  • C1 (100uF) – 1
  • C2 (.1uF) – 1
  • D1-D4 (1N4007) – 4
  • S1-S5 (on/off switch) – 5
  • LED1-LED12 – 12
  • Transformer – 1
  • Battery – 1
  • Zener diode (3.3) – 1

Components Description:

1. LM317:

It is a variable voltage supplier. This device with three terminals. It works on voltage range of 1.25 V to 37 V at a current of 1.5 amps.

2. Resistor:

The flow of current in any of the circuit is being controlled by the resistor. It is basically a passive device. There are two types of resistor available i.e

    1. Fixed Resistor – whose value of resistance is fixed
    2. Variable Resistor – whose value of resistance can vary

3. Capacitor:

It is used to store the electrical charges. It is also a passive device and are available in the market in two types i.e.

    1. Polarized Capacitor – Capacitors with polarity i.e. have + and – terminal eg electrolytic capacitor
    2. Non-Polarized Capacitor – Capacitor without any polarity e.g. ceramic and paper capacitor.

4. Diode:

It is mainly used to allow the single directional flow of current. It is a passive device with two terminals.

5. Switches:

In its literal sense, a switch is described as an alteration of the state. In the realm of electrical logic, there exist two states: ON and OFF, and switches play a pivotal role in transitioning the state of an electrical device from ON to OFF, or vice versa. To rephrase it differently, a switch doesn’t directly power the device on or off; rather, it establishes or interrupts contact.

6. LED (light-emitting diode):

A semiconductor component that generates various light emissions at its output. When a p-n junction is electrically biased in the forward state, it emits a limited range of light wavelengths. LEDs are easily accessible in a range of colors, encompassing red, yellow, green, white, orange, and more.

7. Transformer:

A transformer is a device employed to convert electric current from one circuit to another, altering the properties of an AC signal during this conversion. For instance, it can convert low voltage AC into high voltage AC, and vice versa. The operation of a transformer relies on the generation of a magnetic field around a conductor when an electric current flows through it, a phenomenon known as electromagnetic mutual induction. Transformers typically consist of two coils of wire wound around a central core.

8. Battery:

A battery is essentially a grouping of one or more electrochemical cells where chemical energy undergoes conversion into electrical energy. The core principles governing its operation have remained consistent since the era of Alessandro Volta. Within each cell of the battery, two halves are linked in series via an electrolytic solution. While the anode and cathode together constitute one-third of the cell, positive ions originating from the anode migrate through the electrolyte to reach the cathode.

10. Zener Diode:

This diode operates in reverse bias mode and begins to conduct when the voltage reaches the break point. All you need is a resistor and a capacitor to get a constant voltage.

Working of Mobile Phone Battery Charger Circuit:

You can obtain various circuit outputs by manipulating the different switches (S3, S4, and S5) according to your specific requirements. To obtain a variable power supply output, simply activate switch S3. The circuit employs the LM317, a three-terminal positive voltage regulator, to deliver variable power. The LM317 offers an output voltage range spanning from 1.2 V to 37V. Adjusting the desired voltage is straightforward by manipulating the variable resistor provided in the circuit and monitoring the output with a multimeter.

For charging Li-ion batteries, commonly found in mobile phones, you can engage the S5 switch provided in the circuit, using your mobile connectors. Resistor R13 allows you to fine-tune the charging current within the circuit. To activate the emergency light function, switch to S5. If you wish to enhance the light’s intensity, you can incorporate reflectors into the circuit.

S1 and S2 are the two switches within the circuit that grant you the flexibility to power your circuit either directly from the AC supply or via a battery source. To utilize an AC power source, toggle switch S1, whereas activating switch S2 enables the use of a battery power source. Solar panels can also be employed in lieu of AC power, with rechargeable batteries serving as storage for the charge. This approach not only aids in cost savings on your energy bill but also proves highly beneficial in the event of a power outage.


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