Engineering Research Publication

22/12/2018

www.erpublication.org

07/07/2016

www.erpublication.org

ER Publication stands for Engineering Research Publication is a rapidly growing academic publisher in the fields of Sciences and Engineering having full access to publication of research.

16/05/2015

Contrast Meter Circuit Diagram

One leg of the photocell (R1) is tied to the +15 volt supply and the other end is connected to ground through resistor R2, forming a voltage-divider network. The noninverting input of the 741 op amp, IC1, is tied to the junction formed by R1 and R2, while its inverting input is grounded through resistor R3. When switch S1is pressed, another divider network is formed, reducing the voltage applied to the inverting input of the op amp. When light hits the photocell its resistance begins to decrease causing a greater voltage drop across R2 and a higher voltage to be presented to the non-inverting input of IC1. This causes IC1 to output a voltage proportional to the two inputs. The circuit gives a meter reading that depends on the intensity of light hitting photocell R1; therefore, R1 should be mounted in a bottle cap so that the light must pass through a 3/16 inch hole. Potentiometer R5 is used to adjust the circuit for the negative you're working with.

16/05/2015

Logic Probe with Pulse Circuit

This is a very simple transistor circuit to provide HIGH-LOW-PULSE indication for digital circuits. It can be built for less than $5.00 on a piece of matrix board or on a small strip of copper clad board if you are using surface mount components. The probe will detect a HIGH at 3v and thus the project can be used for 3v, 5v and CMOS circuits.

16/05/2015

Alarm Clock With Day Selector Circuit Diagram

This circuit disables an alarm clock on Saturdays and Sundays when people like to sleep in but enables normal operation on Mondays to Fridays so that people rise in time for work or school. The core of the circuit is a 4017 decade counter which acts as the day counter and it is used in conjunction with a desk clock which acts the alarm and a watch module with alarm function which provides one clock pulse very day to the 4017. In operation, the watch module feeds a day pulse via transistor Q3 to the clock input of IC1. This has seven outputs connected via day switches (S1-S7) and diodes D3-D9 to Q1 which disables the alarm signal to the speaker via transistor Q2. LEDs1-7 indicate the actual day (if you forget!).
To set the system, set the desk clock for the correct time and for the desired alarm time (eg, 6’o’clock). The watch module is set to the correct time and its alarm set to midnight. The day counter, IC1, is set to the correct day, as indicated by the LEDs, by pushing switch S12 and closing switch S8 or S9. S8 is normally left open to conserve the battery by leaving the LEDs off. As shown on the circuit, switches S1-S7 are set to sound the alarm on Mondays to Fridays and disable it on Saturday and Sunday. However, you can change the days to suit your work habits.

16/05/2015

Difference Between LED and NPN Phototransistor

16/05/2015

Inside Air Conditioning Unit

Description:
1. The coils and pipes in an air conditioning unit contain refrigerant gas. The refrigerant gas enters the compressor as warm, low-pressure gas and leaves it as hot, high-pressure gas.
2. In the condenser coils, hot, compressed refrigerant gas loses heat to the outdoor air and becomes liquid while it is still warm.
3. The warm, liquid refrigerant passes through the tiny opening of the expansion valve, expands, and partly turns to gas at a low temperature.
4. In the cooling coils, the refrigerant takes up heat from the indoor air and leaves the coils as warm, low-pressure gas.
5. The indoor air gives up heat to the refrigerant in the cooling coils and also loses moisture as it is chilled. The moisture condenses on the coils and trickles down to outside drain holes.

16/05/2015

Mobile Phone SIM-card Architecture

16/05/2015

Inside MCB and How MCB works.

MCBs or Miniature Circuit Breakers are electromechanical devices which protect an electrical circuit from an overcurrent. The overcurrent, in an electrical circuit, may result from short circuit, overload or faulty design. An MCB is a better alternative to a Fuse since it does not require replacement once an overload is detected. Unlike fuse, an MCB can be easily reset and thus offers improved operational safety and greater convenience without incurring large operating cost.
The principal of operation is simple. An MCB functions by interrupting the continuity of electrical flow through the circuit once a fault is detected. In simple terms MCB is a switch which automatically turns off when the current flowing through it passes the maximum allowable limit. Generally MCB are designed to protect against over current and over temperature faults (over heating).
There are two contacts one is fixed and the other moveable. When the current exceeds the predefined limit a solenoid forces the moveable contact to open (i.e., disconnect from the fixed contact) and the MCB turns off thereby stopping the current to flow in the circuit. In order to restart the flow of current the MCB is manually turned on. This mechanism is used to protect from the faults arising due to over current or over load.
To protect against fault arising due to over heating or increase in temperature a bi-metallic strip is used. MCBs are generally designed to trip within 2.5 millisecond when an over current fault arises. In case of temperature rise or over heating it may take 2 seconds to 2 minutes for the MCB to trip.

16/05/2015

3 Point Starter and its construction

A 3 point starter in simple words is a device that helps in the starting and running of a shunt wound DC motor or compound wound DC motor. Now the question is why these types of DC motors require the assistance of the starter in the first case. The only explanation to that is given by the presence of back emf Eb, which plays a critical role in governing the operation of the motor. The back emf, develops as the motor armature starts to rotate in presence of the magnetic field, by generating action and counters the supply voltage. This also essentially means, that the back emf at the starting is zero, and develops gradually as the motor gathers speed.
Construction wise a starter is a variable resistance, integrated into number of sections as shown in the figure beside. The contact points of these sections are called studs and are shown separately as OFF, 1, 2,3,4,5, RUN. Other than that there are 3 main points, referred to as
1. 'L' Line terminal. (Connected to positive of supply.)
2. 'A' Armature terminal. (Connected to the armature winding.)
3. 'F' Field terminal. (Connected to the field winding.)
And from there it gets the name 3 point starter.
Now studying the construction of 3 point starter in further details reveals that, the point 'L' is connected to an electromagnet called overload release (OLR) as shown in the figure. The other end of 'OLR' is connected to the lower end of conducting lever of starter handle where a spring is also attached with it and the starter handle contains also a soft iron piece housed on it. This handle is free to move to the other side RUN against the force of the spring. This spring brings back the handle to its original OFF position under the influence of its own force. Another parallel path is derived from the stud '1', given to the another electromagnet called No Volt Coil (NVC) which is further connected to terminal 'F'. The starting resistance at starting is entirely in series with the armature. The OLR and NVC acts as the two protecting devices of the starter.

16/05/2015

How does a Heat Pump Water Heater work?

Major components of a heat pump water heater include a compressor, a refrigerant, two heat exchangers ( a condenser and an evaporator) and an expansion valve.
1. The operation begins with air being forced through an evaporator which contains a liquid refrigerant, with the help of a fan.
2. This refrigerant evaporates to a gas and extracts heat from the ambient air.
3. The warm gaseous refrigerant then passes through the compressor, which increases its pressure and it becomes a hot gas.
4. This hot gas enters a heat exchanger (condenser) and transfers its heat to the water flowing from a storage tank.
5. The refrigerant cools down in the condenser and becomes a warm liquid.
6. It then passes through an expansion valve and becomes a cool liquid and enters the evaporator again.
7. The cycle is then repeated in this manner.
8. Thus heat absorbed from the air is transferred to the water and the heating continues till the desired temperature is reached.
Heat pump water heaters are highly energy efficient as most of the energy for heating comes from the external environment, and only a fraction comes from electricity. Thus for 1KW electricity consumed the heat transferred will be 3KW. The amount of electrical energy needed to heat water is greatly reduced compared to a conventional electric water heater in which, for 1KW electricity consumed the heat transferred is only 1KW . Thus in heat pump water heaters the coefficient of performance (ratio of output power to input power) can be as high as 4.

16/05/2015

Catalyst for green biodiesel production from unrefined feedstock

Biodiesel is a sustainable liquid fuel originated from biomass. However, traditional liquid biodiesel catalyst generates a huge amount of waste water in the final purification procedure.

A new class of solid catalyst is developed by precise surface chemistry engineering to catalyze the biodiesel production. With excellent adaptability to low grade unrefined feedstock like waste cooking oil, the catalyst can provide complete solution to the waste water problem.
In addition, it operates at a significant lower temperature and pressure as compared with the existing solid biodiesel catalyst due to its high catalytic activity, which can reduce the energy and cost required for biodiesel production.
Special Features and Advantages:
One-step biodiesel production from low grade unrefined feedstock
No washing with fresh water required for biodiesel produced
Operates at low temperature and pressure which can reduce the cost
The catalyst demonstrates excellent reusability and robustness
Applications:
This new catalyst is designed for one-step energy saving biodiesel synthesis from low grade unrefined feedstock containing high free fatty acid and water content with no post-production washing required. Toxic methanol used can also be replaced by ethanol or propanol which makes the process more sustainable.