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

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Car battery charger

Given below, is a very simple circuit that can be used for charging car batteries. In this circuit there is facility for monitoring the charging current and voltage.The circuit is based on the IC MC78T12ABT from Freescale.The IC is nothing but a 7812 in TO-3 package with 3A capacity. The transformer T1 steps the mains voltage to 15V AC and diodes D1&D2 does the job of rectification. Capacitor C1 does the filtering and C2 acts as a decoupling capacitor. The ground terminal of IC1 is lifted to 2.1V using the diodes D3 , D4 and D5 . So the output from the IC1 will be a regulated 14.1V (12+2.1).The battery is charged via diode D6.The D6 blocks reverse flow of current from battery to charging circuit when the mains power is not available. Meter M1 shows the charging current and M2 shows the charging voltage.

Notes.

* The transformer T1 can be a 230V primary; 15-0-15V, 3A secondary step down transformer.
* The meter M1 can be a 3A ammeter.
* Meter M2 can be a 20V volt meter.
* Fuse F1 can be a 1A fuse.

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Solar Charger Circuit Project Using Transistors

A very simple solar charger circuit project can be designed using few external electronic parts . This simple solar charger circuit is capable of handling charge currents of up to 1A. Alternate component values are given in the figure for lower current applications.

Solar Charger Circuit Project Using Transistors circuit diagram :

The only adjustment is the voltage trip point when the current is shunted through the transistor and load resistor. This should be set with a fully charged battery. As the transistor and R3 have the entire panel’s output across them when the battery is fully charged, all of the current from the panel will be going through R3 and the Darlington transistor TIP112, so these must be well heat sunk. Adjust R1 for the trip point, usually 14.4 V – 15 V for a 12 V SLA or a 12 V Ni-Cd battery.

Source : http://www.ecircuitslab.com/2011/06/solar-charger-circuit-project-using.html

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Using Cell Phone Charger For Making a LED Tube Light

Using Cell Phone Charger For Making a LED Tube Light

Posted by hitman

A plug in wall lamp can be built at home by using a few white LEDs and by powering it through a cell phone charger. The power from cell phone charger is around 6 volts at 500 mA approximately. The power may be well suited and can be tried for powering white LED lights. The application includes some important types like a LED tube light, LED wall lamp, LED porch light, LED table lamp etc. to name a few.

A discarded, spare cell phone charger and a few inexpensive LEDs are all that you want you make a simple yet powerful LED tube light. The cell phone charger can also be used for making a porch light, a bed room wall light or a table lamp. Full circuit schematic is enclosed here in.

A nice little wall mounted cool lamp can be built using a few number of white LEDs and s discarded AC mobile charger adapter. The use of a cell phone charger makes the entire unit very compact and perfectly mountable on wall sockets.

Cell phone chargers are not new to us and nowadays we all seem to have a couple of in spare with us. This may be mainly due to the reason that whenever a new cell phone is procured a charger comes free within the package with the handset. This units are so long-lasting and rugged that most of the time chargers last more than the cell phones.

These spare cell phone chargers often lie idle and at some point of time we tend to dispose them off or simply discard them from our house. For a lay man these units may be a piece of junk, but a technical individual might make a complete gem out of it. Especially a person who may be an electronic hobbyist will very well know how valuable a cell phone charger can be even when it’s not being used for its actual intended purpose.

What are Cell Phone Chargers and How do they Function

We all have seen a cell phone charger working or rather being used for charging cell phones. Therefore we definitely know that it’s something to do with the supplying of some sort of power output.

That’s correct, these are actually a form of AC to DC adapters, however they are incredibly efficient as compared to an ordinary adapter which may employ a transformer for the required conversions.

Cell phone chargers are able to provide a nice six volts at a massive 800 mA of current. That’s quite big considering the size and the weight of these units.

Basically a cell phone charger is a high-grade SMPS power supply at the above rated level. Fortunately a white LED also works at potentials which quite matches with the above specs.

This prompted me to think of using a spare cell phone charger to be used as a plug-in type wall lamp. Mind you one charger can provide enough power to support at least 30 odd numbers of high power high-efficiency white LEDs. It simply means that the lights can be used as a compact LED tube light which can comfortably replace a common CFL light and generate light quite as good.

At no loads, a cell phone charger may provide outputs up to 10 volts, which can easily power a couple of LEDs in series. The series will consume a minimum of 20 mA, however since the charger can supply a good 500 ma plus current we can add 15 more such series in parallel, making the total accommodation close to 30 or more LEDs.

Parts Required

You will require the following parts for constructing the proposed project:

Series Resistors - All 68 Ohms, 1/4 Watt

An ordinary spare cell phone charger – 1no.

White LEDs – 30 nos. for making a small tube light or 10 LEDs for making a wall mounted bedroom lamp etc. (see text)

PCB – General purpose type or as per the project specifications.

Construction Clues

Constructing this LED wall lamp is not difficult as it only requires the LEDs to be fixed in rows and columns correctly as shown in the diagram. You may use the power from the cell phone to light any number if LEDs depending upon the requirement.

For example if you want to make a porch light for illuminating your house veranda, then probably you would need to assemble not more than 6 LEDs.

For making a cool bedroom room lamp a single LED would suffice, instead of sitting in complete darkness, this light may be used or switched ON while watching TVs or videos.

For making a table lamp for reading purposes, a group of 10 LEDs would provide enough light for the purpose. 

And as discussed above, a descent LED tube light can also be built by assembling some 30 + LEDs in conjunction with a cell phone charger power supply. 

For all the above applications, the basic mode of soldering and fixing the LEDs remains the same. Fix and solder a series of two LEDs with a series current limiting resister and now go on repeating this series as many times as you want, depending upon the type of lamp you are trying to build. Once you finish assembling this layout, you may go joining all the free ends of the resistors which becomes one of the supply terminals, similarly join all the remaining free ends of the LEDs, which becomes the other supply terminal of the unit. These supply inputs now just needs to be connected with the cell phone charger supply.

The LEDs should immediately come ON and produce illumination just as desired by you.

The assembly now needs to be housed appropriately inside a suitable plastic enclosure as per individual specification and liking.

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USB Battery Charger Circuit Rise

In recent years, the use of USB or Universal Serial Bus as a reliable communications interface in plenty of electronic devices have increased due to its increased speed, size and flexibility. It fundamentally consists of terminals VBUS(+5V supply), GROUND, D+ and D-. As plenty of of the devices run on rechargeable battery, it is now the trend to design the charging circuit that makes use of the power supply from the USB port to charge the rechargeable battery. This feature will make the devices more convenient to the users as the devices will get their power from the bus and requires no outside plug or cables.

USB Bus Powered Functions

Theres fundamentally three classes of USB functions on power that can be derived from the port.

  High-Power Bus The high power bus powered functions derived all its power from the VBUS and cannt draw over 100mA until its been configured. One time configured, it can draw up to five unit loads(500mA) by requesting it in its descriptor. At full load, it must be able to work between the VBUS voltage of four.75V and five.25V.

  Low-Power Bus The low power bus powered functions derived all its power from the VBUS and must not draw over one unit load (100mA) according to the USB standard. It must even be able to work between the VBUS voltage of four.40V and five.25V.

  Self-Power Self power functions can draw up to 100mA from the VBUS and the rest from its outside source. This is the most simplest to design.

USB Port Powered Battery Charger

This application circuit makes use of the MCP73853/MCP73855 linear charge management controllers for cost sensitive applications. They are specially designed for USB applications and adhere to all the USB specifications governing the USB power bus. The circuit below makes use of the MCP73855 to design a USB powered Lithium Ion/Lithium Polymer battery charger by deriving the power from the USB port.

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