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DC 12V Car Battery Charger

The circuit has been designed to produce a battery charger for automobiles that are using 12V batteries only. BTY79 is a 10A Silicon controlled rectifier with an operational temperature range from 0ºC to 125ºC. C106D is a 4A sensitive gate Silicon controlled rectifier that functions as reverse blocking thyristors designed for high volume consumer applications such as light, speed control, temperature, process and remote control, and warning systems where reliability of operation is important.

Circuit Diagram:

DC 12V - Car Battery Charger Circuit Diagram

The typical car battery chargers have simple designs that produce a few amperes during its operation while charging the battery continuously. In the event that the charger is not turned OFF, overcharging will occur with due to evaporation which looses electrolyte and might cause damage to its elements. With the design of this circuit, this type of problem can be avoided by monitoring the condition of charging of the battery via the retroactive control circuit.

This is done by imposing a high current charge until the charging is complete. The LED LD2 will indicate that charging is full which will eventually deactivate the charging circuit. In creating this design, the cables that connect the transformer to the circuit should have enough cross-sectional area to prevent voltage drop when heat is produced as the current flows through. The adjustment of the circuit comes after the design, with the adjustment of TR1 to null value.

The LEDs are checked without connecting the battery initially and allowing them to turn ON. By connecting a battery, a 2A to 4A current is permitted to flow while ensuring that LD2 is turned OFF. TR1 is carefully adjusted to a few hundred milliamps until LD2 turns ON. This is done using the hydrometer technique. The correct adjustment allows LD2 to begin flickering as the battery is being charged. Connected to the battery is Q1, since it functions as a rectifier and charges the battery, which can be fired in each half cycle by R3-4 and LD2.

In case an uncharged battery is connected, a low terminal voltage is obtained. When the voltage of the battery exceeds the predetermined value, Q2 is activated by the combination of C1, TR1, R2, and D2. Q1 is deactivated with the current supply cut off as the battery terminal voltage is increased where Q2 shifts the control of Q1 gate after TR1 fixed the increased battery terminal voltage above the level. A heat sink should be mounted on the bridge rectifier GR1 and Q1 to prevent overheating. A 5A DC ammeter M1, connected in parallel, is used to measure the charge current.

The circuit’s theory of design will only be applied to batteries with rating of 12V. These batteries are mainly used in a variety of vehicles used in land, air, and water such as personal watercraft like boat, yacht, Jet Skis, and other marine applications. They are also utilized widely in automobiles and motorcycles such as quad bike, RVs, snowmobile, motor scooter, utility vehicle, and riding mower. It can also be beneficial to disabled persons by providing aid to wheelchairs and mobility scooters.

Parts:

R1= 1Kohms
R2= 1.2Kohms
R3= 470 ohms
R4= 470 ohms
R5= 10Kohms
C1= 10uF 25V
D1= 1N4001
D2= 6.8V 0.5W zener
TR1= 4.7Kohms trimmer
Q1= BTY79 or similar 6A SCR
Q2= C106D SCR
GR1= 50V 6A Bridge Rectifier
T1= 220V/17V 4A Transformer
LD1= Green LED
LD2= Red LED
M1= 0-5A DC Ampere meter
S1= 10A D/P On Off Switch
F= 5A Fuse

Adjustable 0 30V 2A Laboratory DC Power Supply circuits

Adjustable 0-30V 2A Laboratory DC Power Supply

PCB of Cheap adjustable 0-30V 2A Laboratory DC Power Supply

This 0-30V power supply is the variable voltage Regulator at 2A max, by used IC-723 for control volt stable regulated. The 2N3055 power transistor for boost up current to 2amp.
It suitable for general electronics work shop. Because it is a simple circuit and easy circuit. In addition to this has the over current protection as well.
This circuit is designed using LM723 voltage regulators IC –DIP 20pin maintain a constant voltage, and a power transistor as the way through the current to can be used up as wanted.
The circuit was designed also with overload protection or short circuit in the output. The amount of current flow will not exceed the set. Because it is monitored constantly by R4.
When the current flows through the R4, until the 0.6V voltage drop across it. Making Q3 runs short the bias voltage between the base-emitter of Q2, it stopped working. Now, the Q1 stop working because does not has the bias voltage to base pin its, The output voltage is zero or down quite a close to zero.
The potentiometer VR1 acts as adjust the voltage that enter to the LM723 for the volt output by you want. By the our circuit can adjust the voltage output from 0V to 30V.
In use real, because the properties of the transistors used and values error of each device. Therefore, if the circuit can not be supply up to 2 A. Try changing the value of R4 is a lower value, until has the maximum current desired. Should be to use transformer 3A. The Transistor to Hold Heat sink as well.

4 5V To 12V DC

This ic 4.5V to 12V boost circuit.You all can get lots of advantages through this circuit.Here I have used famous IC LM2698.

Note

# input supply voltage range is 2.2V to 17V DC and outputs ranging from 2.2V to 17V DC
# IC can deliver only up to 400mA.So dont connect lodes more than that
# Build this circuit on a PCB

How to Test DC Voltage Regulator IC

It is simple way to test DC voltage regulator. We will test a DC voltage regulator IC, the output voltage level. For example we want to do testing on a 7805 regulator. IC 7805 regulator designed provide a fixed output voltage of 5V, if the good results it will be measured at the pin (3) the amount of output voltage of 5 volts DC.

To perform the test we need a DC power supply panel equipped with a voltmeter, a DC voltmeter, regulator IC 7805 and the black and red wires as needed. Red and black wires are used as a link between positive polarity (+) and negative (-) of the voltage source to the input pin (1) and ground (2) the regulator IC. Output pin (3) and ground (2) of the 7805 IC to be connected to the positive polarity (+) and negative (-) on the voltmeter.

Diagram of DC Voltage Regulator IC Testing

Test DC Voltage Regulator 7805

The things you should know and be prepared prior to testing or measuring voltage regulator is:

A type of three-terminal regulator IC regulator will work fine if input voltage is greater than the output voltage around 3V. It should be remembered that 7805 was a positive linear type regulator which will be different pinout configurations with IC 7905.
Turn on the DC power supply and adjust the output voltage of about 8V or slightly larger. Or alternatively you can use a battery 9V-12V as voltage source. Look at the voltmeter panel when you set the voltage
Prepare a DC voltmeter readings on voltage range 50V to measure the output voltage of the IC 7805.
Perform the red and black cable connections are correct, red for positive polarity (+) and pin (1) IC, black for polarity (-) and pin (2) IC.

The test results of IC 7805 is good if the pin (3) read positive DC voltage 5V. And you can do it over and over to ensure that the condition of IC 7805 is still functioning well. Do a test for another DC voltage regulator IC..

using IRF150 build a MCU system Controller 12V DC Motor Speed and Direction circuit

This
be power motor controller 12V circuit. with a signal MCU Control be
high class voltage , about 3V. It can motor control turn advance or
walk go backwards all right. By use power mosfet number IRF150 use
apply to 100W small stump size hills. The relay 12V 2 contract , for
change electronic pole gives motor. By feed a signal Reverse Rotation
change a B pins of 2N3904 give it works to give the electric current to
the coil relay. This circuit uses voltage 12V at current about 10A.
The C1-4700uF help increase efficiency of the circuit while , feed the
fire gives motor during first. The D2 use protect the electric
current pulls sharply from motor harm with mosfet Q1-IRF150 get.
Other detail in the circuit.

Simple DC Over voltage Protector Circuit Diagram

A very simple DC over voltage protector circuit is shown below. The transistor is set to monitor the input voltage applied to it from the left, in case the voltage rises above a specified limit, the transistor conducts, providing the required current to the SCR, which instantly fires, shorting the output and thus protecting the load from the hazard. Its also called a Crowbar circuit.
The circuit shown below is very simple to understand and is quite self explanatory.
The working may be understood with the following points:
The supply DC input voltage is applied from the right hand side o the circuit across the SCR.
As long as the input voltage remains under a certain predetermined value, the transistor is unable to conduct and therefore the SCr also remains shut.
The threshold voltage is effectively set by zener diode voltage.
As long as the input voltage stays below this threshold everything goes on fine.
However in case the input crosses the above threshold level, the zener diode starts conducting so that the base of the transistor starts getting biased.
At some point of time the transistor becomes fully biased and pulls the positive voltage to its collector terminal.
The voltage at the collector instantly passes through the gate of the SCR.
The SCR immediately conducts and shorts the input to ground.
This may look a bit dangerous because the situation indicates that the SCR might get damaged as it shorts the voltage directly through it.
But the SCR remains absolutely safe because the moment the input voltage drops below the set threshold the transistor stops conducting and inhibits the SCR from going into damaging extents.
The situation is sustained and keeps the voltage from reaching above the threshold.

Electrinic and circuit