Damn Simple LED Flasher Circuit

Introduction:

 Led flashers or blinking led lights find a lot of applications in electronics. Power indicator lights in battery powered devices have led's that flash to conserve power. Here is an extremely simple circuit to do just that.

Some of the applications:

• Battery charging indicator
• Fake burglar alarm indicator inside the car.
• Warning lights and hazard flashers
• Decorative lighting
• Hobby projects
• Solar powered flashers

The credit goes to Leo Easki and his research on the negative resistance in transistors. The following circuit is based on this principle. 

Components:

1 - 1K Resistor

1 - NPN transistor [ bd139 , 2n2222 or the like ]

1 - 10 ohm resistor

1 -330 uf Capacitor [ Any value between 330 uf and 1000 uf is ok]

1 - led

Circuit Diagram:

The input power is 12V DC. The positive is connected to a 1K resistor. The other end of the resistor is connected to the positive side of the capacitor and the emitter of the transistor.The negative side of the capacitor is connected to the negative/ground.

The collector of the transistor is connected to the 100 ohm resistor which is then connected to the positive of the led. The negative of the led is connected to the negative of the capacitor.

Here is the circuit in action:

Modern Organic Farming Without Soil [Part1]

Introduction:

Farming or agriculture has been an integral part of the human race since time immemorial. Years went by and  population grew. The basic human nature to live in clusters or groups saw the concentration of the major chuck of population in specific geographical locations, forming cities and towns. Most of the modern day cities have very little vegetation and very little fertile soil. No one is to be blamed, but when one population increases it takes up the space of another, sadly it is the trees and vegetation that we chop down starting a chain reaction. I have no intention to bring out any melodrama here so let me cut to the chase.

The best way to put forth the topic would be through a series of question and answers, and here it goes.

Q: Is soil absolutely necessary for cultivation ?
Now, that sounds like a stupid question. The plain and simple answer is NO, cultivation can be done without the use of soil.

Q: How is it possible ?
The answer is not in the soil,the answer is in the plants. Just like humans adapt to varying dwelling conditions, so do plants. The more comfortable the living conditions, the happier the plants. To understand this further, let us look as what the plants need for a healthy growth.

Q: What do plants need ?
Lets keep this very simple. Plants need food to grow and this is taken in through the roots, the leaves use sunlight and process the food. The stem as we know helps in transportation and also in giving form to the plant.

Coming back to the soil, it is a variable mixture which changes from region to region. Soil primarily contains substances such as silica (silicon dioxide), rock powder, minerals and organic and inorganic substances. It has two primary functions as far as the plants are concerned,  firstly it provides the nutrients and secondly it helps build a foundation so that the plant can stand upright.

Both these functions are made possible by the plant roots. Which brings us to the next question...

Q: What do the roots need ?
The root is a very interesting part of the plant. Silently working underground, cut off from out naked eye this intricate labyrinth decides whether the plant should live or die. It would be quite apt to say that the roots are the heart of the plant. If the leaves or stem are under attack they resist quite well and they are quite hardy to environmental changes. In the case of roots, too much water can rot the roots and too little can kill the roots. Once either happens it is very difficult to revive the plant because the whole system shuts down. The more complex the plant the more complex the situation. The roots also need aeration in healthy quantities.

Q: What is the ideal condition for the root?
Roots need nutrients, a strong foot hold to keep the plant upright, moisture and air. If we provide a condition congenial to this then we have a healthy plant.

If we can provide such a condition without using soil and if we use only organic nutrients, then we have a perfect and healthy plant. In part two we will see how this can be achieved so that we can grow our vegetables on our balconies or terraces.

Damn Simple - Mobile Charging Circuit | USB Power Supply

Introduction:

Most of the mobile phones these days can be charged from a USB port with an output of 5 v DC. There are a variety of devices that run by taking power from a USB port. My idea was to construct a 5 v constant voltage circuit using readily available components, keep it as simple as possible and with the least number of components [ 4 components ] . Here is the result, feel free to try it out and pass it on to any one who you think would find it useful.

Applications:

• USB mobile charger construction.
• Mobile car charger from the cigarette lighter plug.
• 5v source for electronic projects and IC's.
• Solar powered mobile phone chargers. 
• Solar powered battery charger.
• Constant power output from a variable source like a dynamo/generator. 

and many many more.... :)

Construction:

Here is a picture of the positive and negative terminal connection of the USB.

The components we will use are:

• One -  LM7805 
• Two - 1μf Capacitor
• One - 5 Ω 3 Watt Resistor 

LM7805:

The LM 7805 is a three pin voltage regulator.It takes in a voltage of 7 to 30 volts and regulates it down to 4.8 ~ 5.2 volts:  it can provide up to 1.5 Amps of current. The first pin is the input [+] pin, the second [ middle ] pin is the negative pin and the third the output pin. The first capacitor takes out any ripple coming from the source so that the 7805 is receiving a smooth input voltage, and the second capacitor acts as a load balancer to ensure consistent output from the 7805. A resistor is added in series to the output to reduce the output current and this also helps prevent the over heating of the 7805.

The circuit is very simple and can be soldered very quickly on a small general purpose PCB. The components from left to right are, 7805 , 5.4 ohm resistor and two 1uf capacitors. It would be ideal to use a heat sink on the 7805 to prevent it from overheating.

I have sketched the layout along with the 7805's pin configuration. It is a fairly simple and straight forward circuit. The positive input is connected to both the pin one  of the 7805 and the positive of the first capacitor . The pin three is connected to the positive of the capacitor and one end of the resistor, this forms the positive 5 v output. This completes our positive side. For the negative we connect all the negatives together - the negative in, negative out, negative of the first capacitor, negative of the second capacitor and pin 2 of the 7805.

The output can be taken as a wired output or a USB port can be directly mounted on to the PCB. Here you see the completed board. I have drilled two holes to secure the port later. The red and the black wires are the input wires.

p.s: By varying the resistance of the resistor between 5 and 15 ohms the output current can be reduced or increased as per requirement. While doing this ensure that the resistor you use is rated at 3 watts or above and that the 7805 has a very good heat sink and that it doesn't overheat. A small amount of heat however is quite normal.

Below is a video of the circuit in action:

Solar Energy : Photo Voltaic Basics [ Part1 ]

Introduction:

Here are some facts on solar power generation using photo voltaic cells and how to put it to practical use. Just the right amount of information you need when you set up your own or buy a solar powered system. I will keep it as simple as possible :)

Ohms Law:
This law helps us do our simple math. This is just for reference.
Voltage (E) = Current (I) * Resistance (R) 
Power (watts) = Voltage (E) * Current (I)


The main components in our system are:

• Solar Panel.
• Charge Controller.
• Battery 
• Inverter

Solar Panel:

A PV [Photo Voltaic] panel converts incident light into electrical DC voltage. The term " Photo Voltaic " comes from "Photon" for light particle and "Voltaic" for voltage. The panels are rated at their "Watts" . You might have hear people say 100 watt panel, 250 watt panel and so on. The output wattage of the solar panel remains the same across the voltages. For example a 100 watt panel produces 100 watts whether it is rated at 6V or 12V or 24V , the current [ Amp ] however varies.

eg:
6 V 100 Watt panel gives 16.7 Amps at 6 V [ 100/6=16.7 as per Ohms Law]
12 V 100 Watt panel gives 8.3 Amps at 12 V
24 V 100 Watt panel gives 4.2 Amps at 24 V
and so on......

Charge Controller:

A circuit that sits between the PV panel and the battery, the charge controller is a crucial component in the system. The efficiency of the system can largely depend on the type of charge controller used. It has the following functions:

• Ensures optimal charging of the battery using different charging patterns .
• Prevents over charging of the battery.
• Prevents discharge of battery below critical value.
• Conditions battery to ensure prolonged life.
• Visual information display on battery condition [ some models ]

There are different types of charge controllers the most popular being PWM [ Pulse Width Modulation ] and MPPT [ Maximum Power Point Tracking ]. MPPT is more efficient and costlier than PWM. We will go into the differences of the two in a later post.

Battery:

This is our storage tank where we store the DC energy produced by the PV panel. We see certain values written on a battery, say 12 V 100 Ah. Let us take a quick look at these values.

The "12V" indicates that the battery voltage is 12 V. The 100 Ah stands for the amount of storage. "Ah" stands for "Ampere Hour". This means that, if we draw 100 Amps from this battery it will last for 1 hour. If we draw say, 50 Amps from the battery it will last for 2 hours and so on.

Since most of the appliances and devices have a wattage rating lets calculate the batteries wattage output. A 12 V 100 Ah battery produces 1200 Watts for one hour [ 12x100 = 1200 ]. If we use a 120 watt appliance it will run for 10 hours [ 120x10=1200].

Direct Current [DC] Vs Alternating Current [AC]: 

When we plot a DC output it produces a straight line. The AC however produces a wave and this is called a Sine wave. The trick in converting DC to AC is to take the DC source and convert it into AC source as close as possible to the Sine wave. This process is done in the inverter.

Inverter:
The inverter converts and steps up the DC voltage into the rated AC mains voltage, based on your regions standard voltage specification. This is done by a process of pulsing the DC voltage and modifying the output wave as required. The three common types of inverters are Square Wave, Modified Sine Wave and Pure Sine Wave. The square wave inverter is the most economical inverter and the pure sine wave is the most expensive type of the three. If you plan to connect sensitive electronic equipment to your inverter a sine wave is highly recommended.

Note: Another term that you might comes across is the term "Offline" and "Online" . This is generally used in relation to the UPS [ Uninterrupted Power Supply ] connected to the AC mains. Both these charge the battery from the mains and maintain it at full charge. In  the case of the "offline" ups the battery power is used only when the main power goes down, while in the "online" ups, the output is always coming from the battery which is constantly topped up from the mains.

Connecting Components:

Solar Panel [DC]  >> Charge Controller [DC]  >> Battery [DC]  >> Inverter >> AC Out

The PV panel output is fed to the charge controller and the output from the charge controller goes to the battery. The battery output is taken by the inverter which converts the DC into usable AC mains voltage. Many of the modern day solar inverters have a built in charge controller, letting the PV panel output to be plugged directly to it.


This concludes part one.

Ford Ecosport Peak

Ford Ecosport

Here is a sneak peek at the Ford Ecosport: