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This is a circuit of SA58672 Small Class-D Audio Amplifier. This circuit is suitable for mobile device. It has maximum output power of 3.0 W for a 4ohm load and 1.7W for 8ohm load with power supply of 5V. If we uses 3.6 V power supply, the maximum output power is 900mW with 8ohm load. Here is the circuit : Using 9-bump Wafer Level Chip Scale Package (WLCSP), the SA58672UK save space in portable designs, because it measures only 1.66 x 1.71 x 0.6 mm. This circuit produces better overall audio performance because it has improved RF rectification and immunity to noise. The SA58672UK is suitable for cellular handsets or wireless and other portable audio application because it has fast start-up time of 7 ms eliminates pop-on sounds. [Source: NXP Application Note]

Although electricity is a ubiquitous and there are times when it is not possible at all to connect your equipment to an electrical outlet. The purpose of the KIWI-Powered U-passes is to provide energy to any type of mobile device. You can connect this device to any source of energy, including the car’s cigarette lighter, USB port, an outlet or even solar power through photovoltaic cells leaflets. Once loaded, it has the ability to store this energy for at least 6 months. Finally, in terms of connectors, this Swiss Army knife of the batteries can be connected to virtually any device. From phones, to MP3 players or any other gadget. In terms of capacity, the KIWI U-Powered masi can get loads of 1000 and has the ability to charge 2000mAh. The price was another pleasant surprise is which is less than $ 50 USD.

Charge Your Mobile Phone While Enjoying The Journey Here is an ideal Mobile charger using 1.5 volt pen cells to charge mobile phone while traveling. It can replenish cell phone battery three or four times in places where AC power is not available. Most of the Mobile phone batteries are rated at 3.6 V/500 mA. A single pen torch cell can provide 1.5 volts and 1.5 Amps current. So if four pen cells are connected serially, it will form a battery pack with 6 volt and 1.5 Amps current. When power is applied to the circuit through S1, transistor Q1 conducts and Green LED lights. When Q1 conducts Q2 also conducts since its base becomes negative. Charging current flows from the collector of Q1. To reduce the charging voltage to 4.7 volts, Zener diode D2 is used. The output gives 20 mA current for slow charging. If more current is required for fast charging, reduce the value of R4 to 47 ohms so that 80 mA current will be available. Output points are used to connect the charger with the mobile ph...

Using a mobile phone while driving is dangerous. It is also against the law. However, you can use your mobile phone as a powerful music player with the help of a stereo power amplifier. This does away with the need of a sophisticated in-dash car music system. Most mobile phones have a music player that offers a number of features including preset/manual sound equalisers. They have standard 3.5mm stereo sockets that allow music to be played through standard stereo headphones/sound amplifiers. Nokia 2700 classic is an example.  Circuit diagram : Mobile Car Stereo Player Circuit Diagram   A car audio amplifier with 3.5mm socket can be designed and simply connected to the mobile phone output via a shielded cable with suitable connectors/jacks (readymade 3.5mm male-to-male connector cable is a good alternative). Fig. 1 shows the circuit of car stereo player. It is built around popular single-chip audio power amplifier TDA1554Q (IC1). The TDA1554Q is an integrated class-B power amp...

Most of the mobile phone complaints are related to the power supply. This is mainly because of improper charging and use of non-recommended chargers and low-quality batteries. Depending upon the make and model, the charging time of mobile phones varies from 1 hour to 3 hours. The charging current is also different for different models. So it is better to use the charger specified by the company only. Equipment for measuring the capacity or the backup time of a battery are not readily available in the market. But by measuring the charging and discharging currents, the approximate backup time of a battery can be found out. For example, charge a battery of 4.8V, 400mA rating for 1 minute and check whether it can discharge for 1 minute through a 400mA torch bulb. If the battery is discharged fully, it would not get charged again through a normal charger. The battery would require an initial charge or  boosting. Here’s a multipurpose circuit (see Fig. 1) for battery boosting as well as ...