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The circuit was designed to create a spare and reserve power source with the use of batteries during the absence of power from the mains. BD139 – NPN power transistor used for driver stages in hi-fi amplifiers and television circuits because of its low voltage at 80 V maximum and high current at 1.5 A maximum. Bridge Rectifier – also known as bridge rectifier which has four diodes arranged in a bridge configuration where the output voltage has the same polarity with either polarity of the input voltage.     1N4002 – a 1.0 Amp Silicon rectifier with voltage range of 50 to 1000 Volts and possessing features such as guaranteed high temperature soldering, high current capability, diffused junction, low reverse leakage, utilizes void-free molded plastic technique for low cost construction, and carries Underwriters Laboratory Flammability Classification of 94V-0 by its plastic package. One of the main components in the construction of this circuit is the transformer which ...

This is a circuit solar charger via USB cable emergency , it is an alternative circuit that uses solar cell and LM317 to regulate and make a recharge via USB for electronic equipment that can be IPODs , cell phones, MP3 , tablets , etc. .   The simplicity of the circuit can be noted that he does not have much appeal, but it's enough to make a simple battery charge . The Solar Cell should be 12v current should be enough for loading , 10 % of the batteries .   Battery Charger Circuit using Solar Cell Circuit Diagram

This battery charger circuit is regulated and adjustable to make this circuit able to charge the mosto NiCAD battery. This adjustable regulated battery charger circuit will work for single cell or multi battery cell which connected with series/parallel connection. The maximum voltage of the batteries should be 18V maximum. Power transistors Q1 and Q2 are connected as series regulators to control the battery charger ‘s output voltage and charge-current rate. An LM-317 adjustable voltage regulator supplies the drive signal to the bases of power transistor Q1 and Q2. Potensiometer R9 sets the output-voltage level. A current sampling resistor, R8 (a 0.1 ohm/5W unit), is connected between the negative output lead and circuit ground. For each amp of charging current that flows through R8, a 100mV output is developed across it. The voltage developed across R8 is fed to one input of comparator U3. The other input of the comparator is connected to variable resistor R10. As the charging volta...

Today, the spread of rechargeable batteries, chargers and circuits that are required for them has led to the spread. Ni-Cd batteries, cell phones, battery-powered drills posal is widely used in many electronic devices and circuit.  Ni-Cd Battery Charger Circuit Diagram These types of circuits are used to charge the batteries, under constant tension, provide stable current level circuits should be pretty good. The output voltage can be set for this purpose, a charging circuit is made ​​with LM317 IC regulated. Improved standard LM317'li circuit connection, the figure was obtained charging circuit. Current limiting circuit formed by transistors, resulting high current output off, which makes the task of protecting the circuit and the batteries. Circuit, 5 Ah (Ampere-hours) of current to the battery can provide 1A'lik. LM317 integrated circuit connected to the refrigerant heating must be avoided. Output connected batteries, charging circuit output voltage value in accordance with ...

This circuit delivers an initial voltage of 2.5V per cell to rapidly charge a car battery. The charging current decreases as the battery charges and when the current drops to 180 mA the charging circuit reduces the output voltage to 2.35 V per cell, leaving the battery in a fully charged state. This lower voltage prevents the battery from overcharching, which will shorten its life. The LM301A compares the voltage drop across R1 with a 18 mV reference set by R2. The comparator’s output controls the voltage regulator, and produce the lower float voltage when the battery-charging current, passing through R1, drops bellow 180 mA. Temperature compensation helps prevent overcharging, the LM334 temperature sensor should be placed near or on the battery. Because batteries need more compensation at lower temperatures, change R5 to 30Ω for a tc of -5mV/0C per cell il this circuit will be used at temperatures below – 200C. The charger’s input voltage must be filtered dc that is at least 3V higher...

This circuit is used to monitor the battery voltage to display a dual-colored LED status of the battery to. If the LED “green”battery voltage exceeds 11.9 volts. If the yellow LED , battery voltage 11.9 to 11.5 volts. If the LED is “red” If the battery voltage below 11.5 volts. You can of course change the trigger points by the trimmer resistors and / or changing the value of the resistors in the divider.  .  Simple Car Battery Voltage Monitor Circuit Diagram . A dual op amp is used as a comparator. The green LED on the board, until the voltage exceeds 11.5 volts. The red LED illuminates when the voltage falls below 11.9 volts to the circuit. Therefore, in the 11.9 to 11.5 volts, both LEDs are on, producing a slightly yellow color. When the voltage falls below 11.5 V, the green LED , and now only the red LED flashes to indicate low voltage. Parts List R1=1K2 R2-3-4=680R R5=15K R6=10K R7-8-9-10=1K IC1=LM324 D1=5V6 /0.5W Zener D2-3-4-5=LED RV1=10K trimmer  Is recommend...

This is a simple Project of Nicad Battery Protection Circuit Diagram. If a NiCad battery is discharged to a point at which the lowest capacity cell becomes fully discharged and reverses polarity, that cell will usually short internally and become unusable.  To prevent this type of damage, this circuit detects a one-cell drop of 1.25 V and turns the load off before cell reversal can occur. Low-current zener or other voltage sensor Dl and resistors Rl and R2 establish a reference level for transistor Ql. These resistors bias the zener to a few microamperes above its `knee.` Therefore, if battery voltage falls more than 1.25 V, Ql turns off, turning off Q2, and disconnecting the load.   Nicad Battery Protection Circuit Diagram After the load is disconnected, if the battery returns to nominal voltage, the high value of resistor shunting Q2 provides enough output voltage to reset the voltage sensor and turn Q2 back on. If desirable, shunt diode D2 or the parasitic diode of the...

This  Battery Charger Electronic circuit Project   An LM317 voltage regulator is configured as a constant-current source. It is used to supply the 50 mA charging current to S01-S06, an array of AA-cell battery holders. Each of the battery holders is wired in series with an LED and its associated shunt resistor. Battery charger using LM317 Circuit Diagram: When the battery holder contains a battery, the LED glows during charging. Each battery holder/LED combination is paralleled by a 5.1-volt Zener diode. If the battery holder is empty, the Zener conducts the current around the holder. A timing circuit prevents overcharging. When power is applied to the circuit, timing is initiated by IC2, a CD4541 oscillator/programmable timer. The output of IC2 is fed to Ql. When that output is high, the transistor is on, and the charging circuit is completed. When the output is low, the transistor is off, and the path to ground is interrupted. 

Except for use as a normal Battery Charger , this circuit is perfect to 'constant-charge' a 12-Volt Lead-Acid Battery , like the one in your flight box, and keep it in optimum charged condition. This circuit is not recommended for GEL-TYPE batteries since it draws to much current. The above circuit is a precision voltage source, and contains a temperature sensor with a negative temperature coλficient. Meaning, whenever the surrounding or battery temperature increases the voltage will automatically decrease. Temperature coλficient for this circuit is -8mV per °Celcius. A normal transistor (Q1) is used as a temperature sensor. This Battery Charger is centered around the LM350 integrated, 3-amp, adjustable stabilizer IC. Output voltage can be adjusted with P1 between 13.5 and 14.5 volt. Lead Acid Battery Charger Circuit Diagram T2 was added to prevent battery discharge via R1 if no power present. P1 can adjust the output voltage between 13.5 and 14.5 volts. R4's value can be...

The design of the charger is similar to that of many commercially available chargers. The charger consists of a mains adaptor, two resistors and a light emitting diode (LED). In practical use, this kind of charger is perfectly all right. Resistor R1 serves two functions: it establishes the correct charging current and it drops sufficient voltage to light the diode. This means that the LED lights only when a charging cur-rent flows into the battery. The charging current is about 1/4 of the battery capacity, which allows a slight overcharging, and yet the charging cycle is not too long (4–5 hours). Circuit diagram : NiCd Battery Charger Circuit Diagram The value of the resistors may be calculated as follows, for which the nominal e.m.f. and the capacity of the battery must be known. Adjust the output of the mains adaptor to 1.17 times the nominal battery voltage plus 3.3 V, which is the potential across R1. Note that the adaptor must be capable of supplying a current of not less th...