Automatic Battery Charger

Normally, chargers available in the market do not have any sort of control except for a ro-tary switch that can select different tap-pings on a rheostat, to vary the charging current. This type of control is not adequate because of the irregular fluctuations in the mains supply, rendering the control ineffective.  A simple circuit intended for automatic charging of lead-acid batteries is presented here. It is flexible enough to be used for large capacity inverter batteries. Only the rating of transformer and power transistor needs to be increased.

Automatic Battery Charger Circuit Diagram

The circuit has been basically designed for a car battery (about 40 Ah rating), which could be used for lighting two 40W tube lights. The circuit includes Schmitt trigger relay driver,float charger,and battery voltage monitor sections.  The Schmitt trigger is incorporated to avoid relay chattering. It is designed for a window of about 1V. During charging, when the battery voltage increases be-yond 13.64V, the relay cuts off and the float charging section continues to work. When battery voltage goes below 11.66V, the relay is turned on and direct (fast) charging of the battery takes place at around 3A.  In the Schmitt trigger circuit, resistors R1 and R2 are used as a simple voltage divider (divide-by-2) to provide battery voltage sample to the inverting input terminal of IC1. The non-invert-ing input terminal of IC1 is used for reference input derived from the output of IC2 (7806), using the potentiometer arrangement of resistors R3 (18 kilo-ohm) and R4 (1 kilo-ohm).

LED1 is connected across relay to indicate fast charging mode. Diodes D3 and D6 in the common leads of IC2 and IC3 respectively provide added protecion to the regulators.  The float charging section, comprising regulator 7812, transistors T3 and T4, and few other discrete components, becomes active when the battery volt-age goes above 13.64V (such that the relay RL1 is deenergised). In the energised state of the relay, the emitter and collector of transistor T4 remain shorted, and hence the float charger is ineffective and direct charging of battery takes place.

The reference terminal of regulator (IC3) is kept at 3.9V using LED2, LED3, and diode D6 in the common lead of IC3 to obtain the required regulated output (15.9V), in excess of its rated output, which is needed for proper operation of the circuit. This output voltage is fed to the base of transistor T3 (BC548), which along with transistor T4 (2N3055) forms a Darlington pair. You get 14.5V output at the emitter of transistor T4, but because of a drop in diode D7 you effectively get 13.8V at the positive terminal of the battery. When Schmitt trigger switches ‘on’ relay RL1, charging is at high current rate (boost mode). The fast charging path, starting from transformer X2, comprises diode D5, N/O contacts of relay RL1, and diode D7.

The circuit built around IC4 and IC5 is the voltage monitoring section that provides visual display of battery voltage level in bar graph like fashion. Regulator 7805 is used for generating reference voltage. Preset VR1 (20 kilo-ohm) can be used to adjust voltage levels as indicated in the circuit. Here also a pot meter arrangement using resistors R7, R8, and R9 is used as ‘divide by 3’ circuit to sample the battery voltage. When voltage is below 10V, the buzzer sounds to indicate that the safe dis-charge limit has been exceeded.

Source: http://www.ecircuitslab.com/2011/11/normally-chargers-available-in-market.html

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Automatic Water Level Controller

Water-level controllers are common nowadays. The one described here is built around timer NE555 and inverter buffer CMOS IC CD4049. It uses readily-available, low-cost components, and is easy to build and install on the over-head tank (OHT) to prevent wastage of water. The circuit works off a 12V battery or 230V AC mains using a 12V adaptor. The three sensors built from non-corrosive metal are fitted to the OHT as shown in Fig. 2 and connected to the circuit (Fig. 1) at appropriate terminals.

Automatic Water-Level Controller Circuit Diagram

Power supply terminal Vcc is at the bottom of the tank, sensor terminal L is just above the bottom of the tank and sensor terminal H is at the top of the tank. After you have properly installed the sensors in the OHT and connected the power supply, the circuit is ready to use. Since Vcc terminal is at the bottom of the tank, when the water level falls below sensor L, timer IC2 is triggered at pin 2 via inverters N1 and N2 and its output goes high. As a result, the output of timer IC2 goes high. Relay RL1 energises and the motor starts filling water in the tank.

Automatic Water-Level Controller

The motor remains ‘on’ even when the water level crosses sensor L. As water in the tank rises to touch sensor H, timer IC2 is retriggered at pin 6 via inverters N3 and N4 and as a result, its output goes low. The relay de-energises and the motor stops filling water in the tank. The motor remains ‘off’ even when the water level falls below sensor H. As water is consumed and its level falls below sensor L, the motor restarts. Thereafter, the cycle repeats. You can also manually start and stop the motor using switch S1.

• Source
• ElectronicsForU

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Automatic Switch for Batteries

Nowadays the batteries are gaining more and more power, being the only components that fail to provide energy for portable electronic devices. The evolution is rapid, leading manufacturers electronic equipment to attempt to minimize the consumption of their products so that they can operate for several hours using simple batteries trade. In spite of the efforts of manufacturers, the device will absorb a zero power not yet invented. Thus, both small and if the current device is mathematically certain that at some point, after a few hours, days or ethdomades, the battery-drain .

 Automatic Switch for Batteries  Circuit diagram

The purpose of the circuit will describe below, is to keep alive batteries for the maximum time, minimizing unnecessary consumption. Taking a brief look at the circuit, you notice that the few parts that are can be integrated into any device powered by a battery of 9 V. The main trait is that allows current to flow to the load for a minute, since you pressed the switch S1. After this time automatically cuts off the battery connection. The peak current during switching is 20 mA, price satisfactory for most devices that work with batteries, this nominal voltage.

The heart of the construction is a Darlington type transistor PNP (T1), which is driven in a state of conduction through the pressing switch S1. The small current thaoio, which is due to the high rate of aid, makes able to remain in this condition even for relatively small values ??of the capacity of capacitor C 1 (Around 100 MF). The resistance A3 limits the charge current of the capacitor, thus ensuring long life pressing the switch.

Resistance A1 and A2, in conjunction with the capacitor C 1, determine the period allowed to flow, flow to the load. After this time, the T1 is driven in the state cutoff, a condition ensured by R1. In this design, the placement of a diode to protect from any reverse polarity would be an unnecessary luxury, since the maximum reverse voltage that can accept darlington between thasis and emitter (UBE) is equal to 10 V.

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Automatic room light controller

This
circuit is called the auto circuit which can use any electronic device
to operate it automatically. To make this circuit the cost is very low.
Any interested student can make it very easily. The main component of
this circuit is transistor. Its operation is very easy. 

The
main purpose of this is to operate a charger fan where need 6volt
battery. This circuit is mainly needed when the main power is OFF. That
is called load shedding. Because at the time of  load shedding , 6volt
battery operate the fan automatically. You don’t have need to ON the
switch of the fan or OFF the fan switch. Only relay work this as a
switch. The charging system is also automatically. On the other big
matter is that no over charge is occurred of the battery. So the life
time of the battery is increased.

Component:

1.      Transistor ( npn ) – 2N2222, BC547

2.      Zener Diode - 6.8V

3.      Diode

4.       Relay - 6V

5.      Resistor – 1K, 100Ω

6.      Rechargeable Battery - 6V

7.      Bulb - 6V

8.      Power supply - 6V

Operation:

This
circuit is three section, input section and output section. 2N2222
transistor is used to control relay. BC547 transistor is used to control
output section using relay. Zener diode and a diode connect with BC547
transistor base as a series connection. Zener diode always controls
battery charge. It zener voltage is 6.8V which can’t overcome battery
voltage.

When
power supply voltage is applied to the 2N2222 transistor base the
transistor is on. So the relay is ON relatively the output circuit is
OFF. Inverse will occurs when power supply voltage is OFF. When 2N2222
transistor is ON then relay active only battery charging, relay
deactivate the fan. Zener diode always keeps battery voltage full
(6volt).

Advantages:

1.      Need not switch ON/OFF.

2.      It depends on AC power supply come or gone.

3.      This circuit is used when you are sleeping.

4.      Easy to make

5.      Cost is very low

6.      Components are few.

7.      Battery can’t over charge.

8.      Overall efficiency is 78%.

9.      Not you, only relay can do your work.

10.  The circuit is a small project for all students.

 

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Automatic Battery Charger

Normally, chargers available in the market do not have any sort of control except for a ro-tary switch that can select different tap-pings on a rheostat, to vary the charging current. This type of control is not adequate because of the irregular fluctuations in the mains supply, rendering the control ineffective.  A simple circuit intended for automatic charging of lead-acid batteries is presented here. It is flexible enough to be used for large capacity inverter batteries. Only the rating of transformer and power transistor needs to be increased.

Circuit diagram :

Automatic Battery Charger Circuit Diagram

 

The circuit has been basically designed for a car battery (about 40 Ah rating), which could be used for lighting two 40W tube lights. The circuit includes Schmitt trigger relay driver,float charger,and battery voltage monitor sections.  The Schmitt trigger is incorporated to avoid relay chattering. It is designed for a window of about 1V. During charging, when the battery voltage increases be-yond 13.64V, the relay cuts off and the float charging section continues to work. When battery voltage goes below 11.66V, the relay is turned on and direct (fast) charging of the battery takes place at around 3A.  In the Schmitt trigger circuit, resistors R1 and R2 are used as a simple voltage divider (divide-by-2) to provide battery voltage sample to the inverting input terminal of IC1. The non-invert-ing input terminal of IC1 is used for reference input derived from the output of IC2 (7806), using the potentiometer arrangement of resistors R3 (18 kilo-ohm) and R4 (1 kilo-ohm). 

LED1 is connected across relay to indicate fast charging mode. Diodes D3 and D6 in the common leads of IC2 and IC3 respectively provide added protecion to the regulators.  The float charging section, comprising regulator 7812, transistors T3 and T4, and few other discrete components, becomes active when the battery volt-age goes above 13.64V (such that the relay RL1 is deenergised). In the energised state of the relay, the emitter and collector of transistor T4 remain shorted, and hence the float charger is ineffective and direct charging of battery takes place. 

The reference terminal of regulator (IC3) is kept at 3.9V using LED2, LED3, and diode D6 in the common lead of IC3 to obtain the required regulated output (15.9V), in excess of its rated output, which is needed for proper operation of the circuit. This output voltage is fed to the base of transistor T3 (BC548), which along with transistor T4 (2N3055) forms a Darlington pair. You get 14.5V output at the emitter of transistor T4, but because of a drop in diode D7 you effectively get 13.8V at the positive terminal of the battery. When Schmitt trigger switches ‘on’ relay RL1, charging is at high current rate (boost mode). The fast charging path, starting from transformer X2, comprises diode D5, N/O contacts of relay RL1, and diode D7. 

The circuit built around IC4 and IC5 is the voltage monitoring section that provides visual display of battery voltage level in bar graph like fashion. Regulator 7805 is used for generating reference voltage. Preset VR1 (20 kilo-ohm) can be used to adjust voltage levels as indicated in the circuit. Here also a pot meter arrangement using resistors R7, R8, and R9 is used as ‘divide by 3’ circuit to sample the battery voltage. When voltage is below 10V, the buzzer sounds to indicate that the safe dis-charge limit has been exceeded.

Author : Yash Deep - Copyright : EFY Mag

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