Solar Charger Circuit

This is a design circuit for a solar charger circuit to charge Lead Acid or Ni-Cd batteries using solar energy. The circuit harvests solar energy to charge a 6 volt 4.5 Ah rechargeable battery for various applications. The charger has Voltage and Current regulation and Over voltage cut off facilities. This is the figure of the circuit;

The circuit uses a 12 volt solar panel and a variable voltage regulator IC LM 317. The solar panel consists of solar cells each rated at 1.2 volts. 12 volt DC is available from the panel to charge the battery. Charging current passes through D1 to the voltage regulator IC LM 317. By adjusting its Adjust pin, output voltage and current can be regulated. VR is placed between the adjust pin and ground to provide an output voltage of 9 volts to the battery. Resistor R3 Restrict the charging current and diode D2 prevents discharge of current from the battery. Transistor T1 and Zener diode ZD act as a cut off switch when the battery is full. Normally T1 is off and battery gets charging current. When the terminal voltage of the battery rises above 6.8 volts, Zener conducts and provides base current to T1. It then turns on grounding the output of LM 317 to stop charging. [Circuit schematic source: D. Mohankumar Notes].

Voltage Doubler For Solar Battery Charger

This is a circuit for PV Solar Panels have typical voltages of 3, 6, 12, 24 Volts. This circuit can be built which will increase the voltage output from a solar panel so it can be used to directly power a device or to charge batteries. This is the figure of the circuit;


It is comprised of some very easy to source components. The key component is the NE555 timer IC - one of the most popular integrated circuits (ICs) of all time. In this circuit it is used to generate short pulses of DC electricity which are passed through a couple of diodes and capacitors which act to multiply the voltage. The maximum output current of a 555 timer is typically 200 mA and it can dissipate up to 600mW of power. Exceed these specifications and the chip may be destroyed. Click here for full typical NE555 Specifications.

USB Devices Charger Circuit

If you are in the traveling, you may be need this device to charge your gadget along the way, since it is much cheaper to buy some standard AA batteries for backup than buying several rechargeable batteries of your gadget type. Below is a charger that more efficient than linear regulator like the “7805″ while you are on the go. The most important component on this device is the “LT1301″. This is a small step up converter for to build switching mode power supply with only a few external components. This is the figure of the circuit;


To build this device, you need a LT1301 and a ic socket (8DIP), 2 electrolyte caps WITH! low ESR (6,3V 100uF), one inductor with a very LOW! DCR (around 0,03R) with 10uH should be able to handle switching currents at about 1,5 Amperes, one schottky rectifier like “SB130″ or “1N5817″ (important if you can’t get one of the two proposed rectifiers: low forward voltage drop, fast switching capability and it should be able to handle currents of 1 Ampere.), and A switch(on/off), an USB connector, a circuit board, a LED with resistor (limit led current to 2mA!, don’t loose your mA by pumping them through the LED) and don’t forget the battery holder.

FM Radio Receiver Circuit for Battery Supply

This is a schematic for radio receiver circuit. This circuit is based on the TDA7088T that can be used in mono portable and pocket radios. This is a bipolar integrated circuit. This is the figure of the circuit;


When a minimum of peripheral components (of small dimensions and low cost) is important, we can use TDA7088T. Frequency-locked -loop (FLL) system with an Intermediate Frequency (IF) of about 70 KHz is built on this circuit. By active RC-filters, selectivity is achieved. De-tuning related to the IF and the mute circuit is suppress too week input signals. [Schematic circuit source: NXP Semiconductor Application Notes]

Lead Acid Battery Charger Circuit Using MAXIM Chip

This is battery charger circuit that is use a fly back converter topology, and implements a current-limited power supply to charge lead-acid batteries. This circuit is control by MAX471 and MAX733 IC. This is the figure of the circuit.


The flyback transformer provide isolation and voltage input range flexibility, event at supply voltage lower that the battery voltage. Monitoring the charging current is done by sensing the output using MAX471 IC current sense amplifier. The result of the output current monitoring is then used to give a feedback to a threshold detector, to detect if the value falls below the predetermined threshold. This detection is used to switch the charger into trickle mode, when a lower voltage is applied for lower charging current. [Schematic source: Maxim Integrated Products Application Notes]