Wiring Diagram Remote Control

Friday, October 24, 2014

Build a Voltage Regulator 12v to 24v using 7812

How to build a voltage regulator 12v to 24v using 7812. What many people do not know is it possible for a voltage regulator IC to provide an output voltage higher than its actual value. One method to achieve this is by connecting the "common" terminal to the middle point of a potential divider, but the problem with this method is that the regulators IC has a small quiescent current (~ 10 mA) flowing out the common terminal to ground.

The circuit presented here avoids the problems of using the IC regulator to raise the voltage via the transistor Q1 to generate a low impedance to the common terminal video controller during the transfer of the voltage divider from a resistor divider network relatively high. The value of R3 is not critical, but should be low enough to accept the higher quiescent current without causing problems for T1.

Voltage Regulator 12v to 24v Circuit Diagram

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.

Project Image :

12V Speed Controller/Dimmer Project Image

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. 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.

Circuit diagram :

12V Speed Controller/Dimmer Circuit Diagram

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

Simple Circuit 12V to 120V DC DC Converter

Its a simple circuit of 12V DC to 120V DC converter. The circuit consists of two phases first phase of the investor base and then a rectifier and filter stage. IC1 NE555 is wired as an astable multivibrator operating at a frequency of 100 Hz and can be adjusted to the preset R1. IC1 output is coupled to the clock input of IC2 is a dual CMOS D flip-flop. IC2 divides the pulse train of 100 Hz IC1 2 50 Hz pulse trains that are 180 degrees out of the party and offered on the pin 1 and 2 of IC2.

When pin 1 is high transistor Q1 conducts and current flows through the upper half of T1 primary winding. When pin 2 is the transistor Q2 conducts and high current flows through the lower half of the primary coil T1. As a result of a voltage of 120 V AC are induced in the secondary of T1. This voltage is rectified with bridge D1 to provide a 120V DC output. Capacitor C2 is the DC input filter, while C3, C4 are the output filters.

Notes.

The circuit can be assembled on a vero board.
Q1 and Q2 require heat sink.
Output power of this dc dc converter is around 100 watts.
IC1 and IC2 are to be mounted on holders.
An optional 5A fuse can be added in series to the 12V supply line.
T1 can be a 9-0-9V /250V/3A mains transformer.
If 3A bridge is not available make one using 1N5408 diodes.
Out of the two Flip-Flops inside CD4013 only one is used here.
Output of IC1 must be set to 100Hz by adjusting preset R1