Circuit book free

Showing posts with label 12v. Show all posts

Monday, December 23, 2013

12V Touch Switch Exciter

This circuit is designed to generate a 20KHz pseudo sine wave signal that can power about 50 remote touch activated switch circuits. It can support a cable length of about 2500 feet. A typical remote switch circuit is also shown as well as a receiver circuit for those switches.

Source: DiscoverCircuits

ReadMore..

Saturday, October 5, 2013

12V Speed Controller Dimmer

This handy circuit can be used as a speed controller for a 12V motor rated up to 5A (continuous) or as a dimmer for a 12V halogen or standard incandescent lamp rated up to 50W. It varies the power to the load (motor or lamp) using pulse width modulation (PWM) at a pulse frequency of around 220Hz.

SILICON CHIP has produced a number of DC speed controllers over the years, the most recent being our high-power 24V 40A design featured in the March & April 2008 issues. Another very popular design is our 12V/24V 20A design featured in the June 1997 issue and we have also featured a number of reversible 12V designs.

Circuit looks like:

For many applications though, most of these designs are over-kill and a much simpler circuit will suffice. Which is why we are presenting this basic design which uses a 7555 timer IC, a Mosfet and not much else. Being a simple design, it does not monitor motor back-EMF to provide improved speed regulation and nor does it have any fancy overload protection apart from a fuse. However, it is a very efficient circuit and the kit cost is quite low.

Parts layout:

Connection diagram:

There are many applications for this circuit which will all be based on 12V motors, fans or lamps. You can use it in cars, boats, and recreational vehicles, in model boats and model railways and so on. Want to control a 12V fan in a car, caravan or computer? This circuit will do it for you.

Circuit diagram:

The circuit uses a 7555 timer (IC1) to generate variable width pulses at about 210Hz. This drives Mosfet Q3 (via transistors Q1 & Q2) to control the speed of a motor or to dim an incandescent lamp.
Halogen lamps:
While the circuit can dim 12V halogen lamps, we should point out that dimming halogen lamps is very wasteful. In situations where you need dimmable 12V lamps, you will be much better off substituting 12V LED lamps which are now readily available in standard bayonet, miniature Edison screw (MES) and MR16 halogen bases. Not only are these LED replacement lamps much more efficient than halogen lamps, they do not get anywhere near as hot and will also last a great deal longer.

Source: Silicon Chip 15 November 2008

ReadMore..

Sunday, August 4, 2013

Build a LT3582 12 DC 5V to 12V DC Converter

Using LT3582-12 dual channel DC DC converter integrated circuit, manufactured by Linear Technology, can be designed a very simple step up dc converter. This 5 to 12V c converter electronic project provide both positive and negative outputs required in many biasing applications such as active matrix OLED (organic light-emitting diode)displays as well as CCD (charge coupled device) applications.

The LT3582 offer an I2C interface that can dynamically program output voltages, power sequencing and output voltage ramps as the application requires. The LT3582’s positive output voltage can be set between 3.2V and 12.775 in 25mV steps, whereas the negative output can be set between -1.2V and -13.95V in 50mV steps. The LT3582-12 is preconfigured with ±12V output, requiring no future programming.

ReadMore..

Monday, July 8, 2013

12V DC Switch Mode Power Supply Rise

Basic Of Switch Mode Power Supply

In recent years, the use of switch mode power supply (SMPS) has become more comon as more applications demand for greater power eficiency. It makes use of semiconductor (mostly MOSFET) fast switches to switch DC input that has been rectified at high frequency. The advantages of high frequency switching are that it reduces the size of inductor, capacitors & transformer used. Other advantages of switching power supply over linear power supply are :

1) High Efficiency (up to 90% and above for nice design).

2) Output can be higher than input.
3) Able to operate over a variety of input power supply.
4) Able to have over output.

The setback of using SMPS compared to linear power supply is that it generates electrical noise which contributes to electromagnetic compatibility design issues & more part count.

Buck Converter SMPS

The SMPS circuit below from Power Integration makes use of LNK304 as its high frequency switch. Take note that this circuit is non isolated type which means that the output is not electrically isolated from the input & all testing ought to be completed using an isolation transformer to provide the AC line input to the board.

Make positive that you have electrical safety knowledge & experience before you embark on doing this project.

The features of this project is as summarized below.

Input : 85-265 VAC
Output : 12 V, 120 mA, 1.44 Watt
Low Cost : Only 16 components are needed
No-load power consumption : < 0.2 Watt

ReadMore..

Saturday, April 13, 2013

500W Low Cost 12V to 220V Inverter

Note :This Circuit is using high voltage that is lethal. Please take appropriate precautions

Using this circuit that you could convert the 12V dc in to the 220V Ac. In this circuit 4047 is use to generate the sq. wave of 50hz and enlarge the current and then enlarge the voltage by means of the use of the step transformer. How to calculate transformer rating

$\"500w_220v_inverter_corrected\"$
The basic formula is P=VI and between input output of the transformer we've Power input = Power output
For example if we wish a 220W output at 220V then we want 1A at the output. Then on the input we should have at the least 18.3V at 12V because: 12V*18.3 = 220v*1

So you should wind the step up transformer 12v to 220v but input winding should be able to endure 20A.

http://www.ecircuitslab.com

ReadMore..

Saturday, April 6, 2013

12V Stroboscope Circuit

Usually many stoboscope circuit work directly from mains voltage, but this circuit uses 12V DC instead on mains AC. The circuit has some special functions compared to other stroboscope circuits found electronics books. First the there is a switch for selecting the flash power: with C3 you can get very fast flash rates (over 50 Hz), C2 is most suitable for normal operation and using C1 directly you get very bright single flashes. This is the figure of the circuit;

The stoboscope tube needs about 250-400V DC to operate. This high voltage is generated using simple voltage step up circuit built from transistors Q1,Q2 and transformer T1. This circuit gives out about 230V AC voltage which is then rectified with rectifying bridge U1 (must have at least 400V voltage rating) and stored to the main capacitor C1. This approach gave me nice flash tube with reflector, trigger transformer and some of the capacitors (for example C1). Other parts were the one luying around.

ReadMore..