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Water level controller circuit
Description.
A simple but very reliable and effective water level controller circuit diagram is shown here. The circuit uses 6 transistors, 1 NE555 timer IC, a relay and few passive components. The circuit is completely automatic which starts the pump motor when the water level in the over head tank goes below a preset level and switches OFF the pump when the water level in the over head tank goes above the full level.
Probe D is positioned at the bottom level of the tank while probes A, B and C are placed at full, half and medium levels of the tank respectively. The level sensing part of the circuit is built around transistors Q1, Q2 and Q3. When water level is below the quarter level probes A, B and C are open and the transistor Q1, Q2 and Q3 remains OFF. When the water level rises and touches the probes the corresponding transistors gets biased and switches ON. Resistors R1, R2, R3 limit the bases current of corresponding transistors while resistors R4, R5, R6 limit their collector current. LEDs D1, D2 and D3 provide a visible indication of the current water level.
When the water level goes below medium, transistor Q2 gets switches OFF and its collector goes positive. Collector of Q2 is connected to the base of transistor Q6 and as result transistor Q6 gets switched ON. Transistor Q5 will be also ON because its base in connected to the collector of Q4 which is presently OFF. As a result when the water level goes below medium relay K1 gets energized and the pump is driven. The relay is wired in the latching mode so that even if the water level goes above medium level the pump remains ON so that the tank gets completely filled. For wiring the relay in latching mode one set of N/O contacts is used. When relay is activated these contacts close which forms a short across collector and emitter of Q6. This makes the state of Q6 irrelevant to the operation of the relay and the relay remains ON as long as the transistor Q5 is ON. The only way to make the relay OFF is by switching OFF Q5 and it is done automatically when the water level reaches the full level.
Collector of transistor Q1 is connected to the trigger pin (pin2) of IC1. When the water level reaches full level the transistor Q1 gets switched ON. As a result its collector goes to ground level which triggers the IC1 which is wired as a monostable. The output of IC1 goes high for about 1S. This makes the transistor Q4 ON for the same time and transistor Q5 whose base is connected to the collector of Q4 is switched OFF cutting the supply to the relay. This makes the motor OFF and it remains OFF until the water level again goes below the medium level.
Resistor R8 is a pull up resistor for the trigger pin of the NE555. Capacitor C3 couples the collector of Q1 to the trigger pin of NE555 and facilitates edge triggering whenever the transistor Q1 goes ON. A monostable circuit can be made edge triggered by connecting the trigger signal to the trigger input pin through a capacitor. The capacitor blocks DC and passes sudden changes. The circuit used here is termed as negative edge triggered because the monostable is triggered when ever the trigger input signal falls. R10 and R12 limits the collector current of Q4 and Q5 respectively while R9 and R11 limits their base current. R13 limits the base current of Q6 while D4 is a freewheeling diode which protects the switching transistors from voltage transients.
Circuit diagram.
Water level controller circuit diagram
Probe arrangement diagram
The probes can be arranged as shown in the diagram above. Insulated Aluminium wires can be used as the probes. The probes can be binded on a plastic rod and should be erected vertically inside the tank. The length of the probes wires and the supporting plastic rod must be chosen according to the depth of the tank. Since DC is used in the level sensing section electrolysis will occur in the probes and so the probes require small maintenances in 1 or 2 month intervals. Using AC in the sensing section will completely eliminates the chance of electrolysis and I am presently working on such a circuit. You can expect it soon.
Notes.
Use 12V DC for powering the water level controller circuit.
The relay I used was a 5V/220 ohm relay and that’s why the current limits resistor R12 was added in the circuit. If you use a 12V relay then the R12 can be shorted.
Do not use a relay that consumes 500mA. Maximum collector current PN2222 can handle is 600mA.
Use insulated single strand aluminium wires for probe and they can be arranged in the tank as per the probe arrangement diagram.
Use a holder for mounting NE555.
The circuit can be assembled on a Perf board.
K1 must be a double pole relay.
The load current, voltage ratings of the relay must be selected according to the ratings of the pump motor.
The type number of the transistors used here are not very critical and you can do suitable replacements if any type number is not available.
Most of the components required for this project can be found inside your scrap box.
Power supply for this circuit.
12V DC power supply
A classic 12V regulated DC supply based on 7812 is shown above. A power ON indicator LED is also added in the circuit.Resistor R13 limits the LED current. A small aluminium heatsink can be fitted to
the 7812 for better saftey.Small Al heatsinks for TO-220 package are readily available in the market.
Electronic mosquito repeller
Description.
Here is the circuit diagram of an ultrasonic mosquito repeller.The circuit is based on the theory that insects like mosquito can be repelled by using sound frequencies in the ultrasonic (above 20KHz) range.The circuit is nothing but a PLL IC CMOS 4047 wired as an oscillator working at 22KHz.A complementary symmetry amplifier consisting of four transistor is used to amplify the sound.The piezo buzzer converts the output of amplifier to ultrasonic sound that can be heard by the insects.
Circuit diagram with Parts list.
Notes.
Assemble the circuit on a general purpose PCB.
The circuit can be powered from 12V DC.
The buzzer can be any general purpose piezo buzzer.
The IC1 must be mounted on a holder.
making a Rheostat
I have already explained in detail the working of a rheostat. To know more about the component click on the link below.
TAKE A LOOK : POTENTIOMETER AND RHEOSTAT – WORKING AND COMPARISON
Although the below explained process is not applicable for any electronic circuits, you will clearly get a clear idea on how a rheostat works.
Components
The components needed for the connection are
Flashlight bulb and socket [1]
Dry cell lantern battery/D-cell battery [2]
Wire [About 15 to 17 inches and another one 2 inches]
Spring [1]
Wire Clippers [A pair]
A typical spring can be obtained from a widow roll up. You can even get to buy one at a cheap rate.
Procedure
Connect the two Dry cell lantern/D-cell batteries tail-to-tail, so that the positive polarity of one battery is connected to the negative polarity of the other.
Using a wire cutter, cut the wire in equal lengths. One wire should be at least 8 centimetres long.
Connect the wires onto the open ends of both the batteries.
The end of one wire must be connected to the bulb socket with the bulb in it.
Connect the second wire to one end of the long spring.
Connect the free end of one wire to one terminal of the light socket.
Connect the other free wire to one end of the spring.
Take the two inch wire and connect it to the second terminal of bulb socket.
Connect the other end of the two inch wire onto the other end of the spring.
How to make a Rheostat
How to make a Rheostat
What happens?
As soon as the circuit is in closed loop, the bulb begins to glow. Although the glow intensity is less, when you move the wire through the spring onto the other end where the wire is connected, the bulb starts to glow more brightly. When both the wires are nearby the glow will be in its maximum.
The spring is mainly made of steel wire. Steel wires are not very good conductors of electricity. Thus the resistance of the circuit also increases. If the spring length is long enough you will get to see different stages of the glow. Thus you will get to see the working of a rheostat.
Wireless Power Transmission
Most of us at home maybe using multi-plug to connect all the electronic devices with power cords. You may have even got confused to get the right cord for unplugging it among the other cords that lead to the same outlet.
At last you pull one out and hope that it is the right one. This is one of the main problems with electric connections. Though it makes the life of people simpler, it can also cause more clutter in the method. It may not be a big problem for us. But think about the electric stations where hundreds of wires run from the same outlet. For them, it is a problem.
As a part of the upgrade in technology and also the above reasons, researchers have started developing methods to transmit electricity to devices wirelessly. Though the method may sound completely new, the basic idea behind this theory was first proposed by Nicola Tesla in the early 1900′s. He was also able to release a prototype by transmitting power to lights that were kept in the ground at his Colorado Springs experiment station.
Though the first prototype received wide applause, the method was not practical enough for a higher range of its application. After years of research, many theories about this matter were discussed and some prototypes were also released. Some of them were not recognized while some of them are already in use. The best example for such a device is the electric toothbrush.
There are many types of wireless data transferring mediums in this world. Some of the most common ones are infrared, radio waves, bluetooth, and so on. In all these technologies, the signals will be scattered into space before they are received by the corresponding devices. The same method cannot be used for transferring electricity as it is power consuming and dangerous.
The main principle that is used in electric toothbrush is called Inductive Coupling. The basic idea is that a magnetic field is induced when an electric current flows through a wire. The magnetic field will be circular in shape and will flow around the wire. When another coil is placed in the same magnetic field, a current will be induced in the wire. This is the same principle that is used in a transformer and also in the electric brush. A magnetic field is created inside the brush through the current that moves through the coil inside the charger. When the brush is connected to the charger, another current will be produced in another coil, due to the magnetic field. This current is supplied to the battery which is the input for the brush.
But this method is not practical when it comes to transmitting energy to longer distances. For such a method, it is necessary that the coils are close enough to each other so that the small magnetic field is produced. When it comes to longer distance transmission, a very big magnetic field is to be produced and the coil turnings should be multiple. Counter measures should be taken to save the energy wasted due to the flow of magnetic field in different directions. This is practically impossible. A much better method and its explanation are given below.
Resonance and Wireless Power
Some researchers at MIT found a better way to transmit power between coils that are kept a few metres apart. They also claimed to increase the distance between the coils by adding resonance to the equation.
Resonance can be defined as the frequency of a device when it vibrates naturally. The resonance of a device greatly depends on the size and shape of it. The frequency is called the resonant frequency. The vibration at resonant frequency can be easily obtained. But vibration at other frequencies is difficult.
Wireless Power Transmission
According to the researchers, when the magnetic fields have the same resonation around the coils, the current will be induced in a different manner. The theory was proved by placing a curved wire coil as an inductor along with a capacitance plate at each end of the coil. This plate is responsible for holding the charge. When current is passed through the coil it starts resonating. The frequency of resonation can be calculated by the equation given below.
Resonant Frequency = Inductance of the Coil x Capacitance of the Plates
Apart from the principle in a toothbrush, the electricity will be flowing through an electromagnetic wave and will move from one coil to another, until they have the same resonant frequency. For different resonating frequencies, there will not be any transmission. But transmission is also possible from one transmitter to multiple receivers as long as the former and the latter have the same resonant frequency.
The coils being far apart there is no need to worry about the fields around them colliding with each other. Their most successful prototype had a light bulb that was powered from a distance of 2 metres wirelessly. They also formulated some theories regarding wireless electrical transmission through very long distances. It is explained below.
Long Distance Wireless Power Transmission
The first experiment for long distance wireless power transmission was carried out by the Communications Research Centre in Canada during the year 1980. They designed an unmanned plane by the name Stationary High Altitude Relay Platform (SHARP). This plane could not only fly from one point to another, but could also fly in circles at a height if 21 kilometres away from the ground with a radius of 1 kilometre. It was also designed to fly without rest or battery backup for months.
Stationary High Altitude Relay Platform (SHARP)
The main idea behind the SHARP technology is a large ground-based microwave transmitter. The plane will fly only in the range of the transmitter. The signal from the transmitter will be received by a disc-shaped rectifying antenna called the rectenna, which is placed behind the wings of the plane. This signal will then be converted into DC current. The antenna is usually of the dipole type, that is, it has positive as well as negative poles. When the signal hits the antenna, they will be transferred to a series of diodes. These diodes behave like switches and allow the electrons to flow in unidirection. These electrons are then passed onto the rectenna’s circuitry. The electrons are then shifted to the other parts of the plane.
Nanoelectronics
Nanoelectronics are based on the application of nanotechnology in the field of electronics and electronic components. Although the term Nanoelectronics may generally mean all the electronic components, special attention is given in the case of transistors. These transistors have a size lesser than 100 nanometres. Visibly, they are very small that separate studies have to be made for knowing the quantum mechanical properties and inter-atomic design. As a result, though the transistors appear in the nanometre range, they are designed through nanotechnology. Their design is also very much different from the traditional transistors and usually falls in the category of one dimensional nanotubes/nanowires, hybrid molecular electronics, or advanced molecular electronics.
This technology is said to be the next future, but its practicality is near to impossible even now that they may be difficult to emerge soon.
Basic Concept of Nanoelectronics
Although a nanoelectronic device can be made fully functional, the work load it can do is restricted to its size. The basic principle is that the power of a machine will increase according to the increase in volume, but the amount of friction that the machine’s bearings hold will depend on the surface area of the machine.
For the small size of the nanoelectronic device cannot be used for the moving of heavy load like a mechanical device. If such a task is tried, it will fail as the available power will be easily overcome by the frictional forces. So, it is sure that these devices have limitations in real world applications.
Different Approaches to Nanoelectronics
Nanofabrication
This method is used to design arrays or layers of nanoelectronic device to work for a single operation. Nanoelectromechanical systems are also a part of nanofabrication.
Nanomaterials electronics
In Nanoelectronics, the transistors are packed as arrays on to a single chip. Thus they remain in a uniform manner and symmetrical in nature. Thus they are known to have a more speedy movement of electrons in the material. The dielectric constant of the device also increases and the electron or hole characteristics also become symmetrical in nature.
Some of the devices that have been developed with the help of Nanoelectronics and its future applications are listed below.
Nanoradio
Nanocomputers
The conventional computers with a big processor will be replaced with Nanocomputers with nanoprocessors that will have higher performance and speed than the conventional computers. Researchers are performing various experiments on by using nanolithographic methods to design better nanoprocessors. Experiments are also taking place by replacing the CMOS components in conventional processors with nanowires. The FET’s in the computers are replaced by carbon nanotubes.
Energy production
The devices using Nanoelectronics technology also includes solar cells that are highly efficient and cheaper than the conventional ones. If such efficient solar energy can be created it would be a revolution to the global energy needs.
Using the technology, researchers are developing a generator for energy production in vivo called bio-nano generators. Basically, the generator is an electrochemical device which is designed in nanoscale size. It works like a fuel cell which generates the power by absorbing the blood glucose in a living body. The glucose will be separated from the body with the help of an enzyme. This enzyme separates the glucose from the electrons and makes them useful for generating power.
The power generated through such a device will be only a few watts as the body itself needs some glucose for its normal functioning. This small power can be used to power up devices placed inside the body like pacemakers or sugar-fed nanorobots.
