Electronic Circuits and Diagram-Electronics Projects and Design

Description. This is the circuit diagram of a 3 LED bar graph type battery monitor circuit that is ideal for monitoring the voltage level of an automobile battery.When battery voltage is 11.5V or less transistor Q1 will be On and the LED D1 will be glowing.When battery voltage is between 11.5 and 13.5V, the transistor Q2 will be On and the LED D2 will be glowing.When battery voltage is above 13.5V the transistor Q3 will be On and the LED D7 will be glowing. Circuit diagram with Parts list. Notes. Assemble the circuit on a general purpose PCB. The battery…

Description. Here is a simple circuit using IC LM 350, which can be used for charging 12V lead acid batteries. This circuit is perfect for “constant charging” 12V lead acid batteries. The circuit is designed as a constant voltage source with a negative temperature coefficient. The transistor Q1 (BD 140) is used as the temperature sensor. The transistor Q2 is used to prevent the battery from discharging through R1 when the mains power is not available. The circuit is designed based on the voltage regulator IC LM350.The output voltage of the charger can be adjusted between 13-15 V by varying…

 Description. A simple battery charger based on SCR is shown here.Here the SCR rectifies the AC mains voltage to charge the battery.When the battery connected to the charger gets discharged the battery voltage gets dropped.This inhibits the forward biasing voltage from reaching the base of the transistor Q1 through R4 and D2.This switches off the transistor.When the transistor is turned OFF,the gate of SCR (H1) gets the triggering voltage via R1 & D3.This makes the SCR to conduct and it starts to rectify the AC input voltage.The rectified voltage is given to the battery through the resistor R6(5W).This starts charging…

 Description. A very simple battery charger circuit having reverse polarity indication is shown here.The circuit is based on IC L200 . L200 is a five pin variable voltage voltage regulator IC.The charging circuit can be fed by the DC voltage from a bridge rectifier or center tapped rectifier.Here the IC L200 keeps the charging voltage constant.The charging current is controlled by the parallel combination of the resistors R2 & R3.The POT P1 can be used to adjust the charging current.This circuit is designed to charge a 12 V lead acid battery.The transistor t1,diode D3 and LED are used to make…

Description. Here is a simple but effective battery charger circuit using IC LM 317.The circuit can be used to charge 12Vlead acid batteries.The circuit is very simple and can be easily assembled on a general purpose PCB.   The heart of the circuit is IC LM 317 ,which is an adjustable voltage regulator IC.The pin 1 of the IC is the control pin which is used to control the charging voltage.The pin 2 is the output pin at which the charging voltage appears.The pin 3 is the input pin to which the regulated DC supply is given.   The charging…

Description. This circuit will produce a visual as well as audible alert whenever the connection between the charger circuit and the battery being charged.What ever be the situation whether it be a  loose contact or breakage the circuit will give you the alarm.Such a circuit can be very handy in the fail safe charging of the batteries in some applications , like as in burglar alarms etc.This circuit can be easily assebled from the components in your electronic junk box. As long as there is a little current flows from the charger to battery the diodes D1 and D2 will conduct.This forward voltage drop…

Description. Here is a simple charger circuit for charging SMF(sealed maintenance free ) batteries.The charger circuit being curernt and voltage regulated,can be safely used to charge SMF batteries of 1.2 AH rating.This circuit was actually designed in response to a request from a reader.With slight modifications you can use it for charging any sort of SMF batteries. The first part of the circuit is the power supply made of transformer T1 and diodes D1&D2.The capacitor C1 filters the rectifier output .The next part is the section comprising of IC1 and Q1 which provides the necessary volatge and current regulation.The diode…

Description . Here is the circuit diagram of a simple and straight forward 12 V battery charger circuit with diagram. This circuit can be used to charge all type of 12V rechargeable batteries including car batteries. The circuit is nothing but a 12V DC power supply with an ammeter for monitoring the charging current. The two diodes forms a centre tapped full wave rectifier. The capacitor filters the rectifier output to produce a clean 12V output. Circuit diagram with Parts list.  Notes.  At initial stages of charging the ammeter will read about 1 to 3 amperes. As the battery is…

Description. Here is  the circuit diagram of an effective and super fast Ni-Cd battery charger circuit.The circuit is based on the IC MAX 712. The circuit is designed to fast charge a Ni-Cd battery at 3oomA. After the fast charging is completed the circuit charges the battery in trickle charging mode at 15 mA. Here the instant to end fast charging and start trickle charging is sensed by dv/dt method as per the data sheet. This method of charging increases the charging speed as well as the battery life. The circuit is designed strictly as per the data sheet from…

Simple Battery Level Indicator Description Here is a easy to build low battery level indicator circuit that produces a visible indication by flashing a LED when the battery voltage drops below a predetermined voltage.The circuit is based on Panasonic’s  IC MN13811G   and a efficient flasher based on transistors Q1&Q2.Here when the battery voltage drops below 2.4  V the output of the IC is activated and the flasher starts flashing.This circuit here is an ideal one for monitoring the level of all types of 3V batteries.The circuit is power efficient with a  idle current drawing as less as 1 uA  ,…