Fan Control Circuit

LM56 is a monolithic thermostat designed for simple temperature control. The chip has two programmable threshold that can be used to drive a fan and or alarm. Here is the schematic diagram of the fan control circuit:

The circuit will turn on the fan when the temperature rise above 50 Celsius degree, and this threshold is set by the voltage at VT1. When the temperature rise above 70 Celsius degree then the OUT2 will go high. This signal then can be used to trigger system shutdown or just to turn on a warning LED. This threshold is set by voltage at VT2. [Schematic diagram source: National Semiconductor's Temperature Sensor Handbook]

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voltage regulator

The following circuit is designed for filtering 15 volt supplies like those typically found in instrumentation. The shunt will greatly reduce white noise, spurious signals, and line-related signals on the power supply; the attenuation can exceed 40 dB with careful construction. The values are not critical except that the gain of the amplifier should be very near the ratio of the transistor emitter resistor to the series shunt resistor. In this case the gain is 15/0.05 = 300. Actually the gain is 301 with the indicated values so a 299k resistor would be theoretically better but the resistor tolerances and the actual resistance in the 0.05 ohm shunt path will cause more variation. One of the gain resistors may be made variable to allow the performance to be tweaked for the deepest null, if desired. Choose a low noise metal foil or wirewound potentiometer for best results. Standard fixed values will give excellent noise reduction sufficient for most applications. The LM833 is an excellent choice but many other low noise op-amps will work well. Choose an op-amp with a high bandwidth and low input noise voltage. A higher value shunt resistor may be used if the voltage drop can be tolerated; adjust the gain of the amplifier to match as described above. The LM833 is a dual op-amp so two shunts may be implemented with the one package for filtering two different supplies or for cascading two shunts for additional line rejection and noise reduction. The noise shunt provides no load rejection beyond the rejection provided by the source regulator through the 0.05 ohm resistor.

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convert: 6vdc to12vdc

If you are in tour, camping, picnic it is helpful for you. you can conver 6VDC to 12VDC.Here is the circuit diagram of 6VDC to 12VDC Converter. With this circuit, you can doubled the input voltage of 6V DC to become 12V DC output voltage.

Parts:
R1, R4 = 2.2K
R2, R3 = 4.7K
R5 = 1K
R6 = 1.5K
R7 = 33K
R8 = 10K
C1,C2 = 0.1uF C3 = 470uF/25V
D1 = 1N914
D2 = 1N4004
D3 = 12V 400mW Zener Diode
Q1, Q2, Q4 = BC547
Q3 = BD679

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MAD BAND

The Mad Band - Brief Band Description and

Biographies

MAD BAND MAD BAND
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circuit diagram:12dc to 220ac converter

You want to convert 12vdc to 220vac, 300w. Then this schematic diagram will helps you. It can be used for home appliances, lamps, electric radio, mobile charger etc.

Part Total Qty.Description

C1, C22 = 68 uf, 25 V Tantalum Capacitor


R1, R22 =10 Ohm, 5 Watt Resistor


R3, R42 =180 Ohm, 1 Watt Resistor


D1, D22 =HEP 154 Silicon Diode


Q1, Q22 =2N3055 NPN Transistor (see "Notes")


T11 =24V, Center Tapped Transformer (see "Notes")


MISC1 =Wire, Case, Receptical (For Output)

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loadshedding routine of electricity: Nepal

Nepal Electricity Authority has hiked load-shedding 10 hours a day.Download latest loadshedding Schedule Effective from 2068/01/25 .

"Use CFL and save Electricity"

To download Click here...

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B.E Preparation

SOME PRACTICE MODEL QUESTIONS
Sub:Physics F.M.:100 Time: 2hr
Useful physical constants and symbols:
Speed of light, C=3*108m/s Permittivity of vacuum=8.86*10-12F/m
Planks constant, h=6.6*10-34JS Charge of an electron, e=1.6*10-19C
Mass of an electron, m=9.1*10-31kg Mass of proton, M=1.67*10-27kg
Density of water, p=1000kg/m3 Density of sea water, d=1030kg/m3
Gravitational Constant, G=6.67*10-11Nm2/kg2
Stefan’s constant, =5.685*10-8Wm-2K-4
GROUP-A
Tick ( ) on the correct answer.
1. The dimensional formula for gravitational constant is
a) M-2L3T-2 b) M-1L-3T 2 c) M-1L3T-2 d) ML3T-2
2. THE RATIO of K.E. to P.E. Of an orbiting satellite is (in magnitude)
a)2 b)4 c)1:4 d)1:2
3. A driver in the water can see sun setting when the angle of refraction is
a) 42° b) 60° c)90° d)49°
4. Coefficient of viscosity of most liquids, on increasing the temperature
a) Increase b)becomes zero c)remain same d)decreases
5. The latent heat of a substance is zero at
a) Its boiling point b) its melting point c) at critical temperature d)its freezing point
6. Radiation from hot body at a temperature T is proportional to
a)T-2 b)T2 c)T4 d)T-4
7. Any substance having more specific heat
a) Gets heated slowly and stores long time b) gets heated quickly and stores long time
c) Gets heated slowly and stores short time c) gets heated quickly and stores short time.
8. Which of the following gases has maximum rms speed at a given temperature?
a)CO2 b) N 2 c)H2 d)O2
9. Focal length of a equiconvex lens (μ=1.5) is
a) Equal to radius b) half the radius c) twice the radius d) infinity
10. Which is used in searchlights?
a) Concave parabolic mirror b) convex mirror c) plane mirror d) infinity.
11. A convex lens can give vertical image of a real object when the object is
a) At the focus b) at infinity c) at a distance less than focal length
d) At a distance greater than the focal length
12. A person suffering from prebiopia should use:
a)cylindrical lens b) bifocal lens c) wavelength d) none
13. In vacuum, the speed of light wave depends on:
a) frequency kb) speed of source and observer c)wavelength d) none
14. Capacitance of parallel plate capacitor decreases when
a) Distance between plates is increased
b) Area between plates is increased
c) Distance between plates is decreased
d) Both a& b
15. Sound waves in the is are
a) Transverse waves b) longitudinal waves
c) May be both type d) none of the above
16. The quality of a musical sound depends upon
a) The number of overtones b) the distance from the source
c) The fundamental frequency d) intensity of sound
17. Sounds energy is converted into electrical energy in a
a) Microphone b) earphone c) sonometer d) loudspeaker
18. The unit of magnetic dipole moment is
a) Weber meter2 b) ampere meter c) Weber meter d) none
19. Which is used to make the core of transformer & generator?
a) Cobalt steel b) soft iron c) tungsten steel d) alnico
20. Imaginary lines having constant value of dip angle are:
a) Isobaric b) isogonics c) isodecline d) isodynamic
21. Two parallel conductors carrying current in opposite directions
a) Attract each other b) repel each other c) won’t experiences d) cancel each other field
22. An AC circuit contains capacitor and resistance. In the circuit
a) Current leads the voltage b) repel each other
c) Current lags behind the voltage d) voltage lags behind the current
23. One Fermi is equal to
a) 10-9 m b) 10-12 m c) 10-15 m d) 1015m
24. The rate of decay of atom in a radioactive sample is proportional to
a) The half period b) the number of undecayed atom
c) The number of the decayed atom d) the mass number of atom
25. In a semi conductor, the value band and the conduction band are
a) Very close b) Wide apart c) Overlapping d) Continuous
Tick ( ) on the correct answer.
26. A canal lock gate is 20 m wide and 10m deep. The thrust acting on it when water in the canal is in the level In the gate is:
a)5*103N b)10*103 c)2*103 d)9.8*106
27. An electron accelerated through a P.D. of 100 Volts acquires energy equals to:
a) 100 b) 160 c) 1.610-19 d) 1.6*10-17
28. At what temperature will the velocity of sound in air be double its velocity at 0°C?
a) 130° b) 222° c) 630° d) 819°
29. A body starts from rest and falls freely under the action of gravity. The distance covered by it the first two seconds is
a)4.9m b)9.8m c)19.6m d)39.2m

30. Two capacitor of 4 and 8 in series is equivalent to a single capacitor of
a)12μF b)4μF c )2.67μF d)0.5μF
31. The half-life of radium is16010 years. The fraction of a sample of radium would remain after 6400 years is:
a) ¼ b)1/8 c)1/16 d)1/32
32. The resistance of the filament of a bulb market 100W/220V is:
a) 100Ω b)220Ω c)484Ω d)22000Ω
33. An elongation of 0.1%in a wire of cross-section area 10-6m2 causes tension of 100N. The Young’s Modulus for the material of the material of the wire is :
a) 102N/m2 b) 1010N/m2 c) 101N/m2 d) 1012N/m2
34. Two then convex lenses of focal length 10cm and 20cm are placed coaxially in contact with each other. The length of the equivalent lens is
a)6.67cm b)10cm c)30cm d)200cm
35. A constant torque of 5 N-m turns a wheel of moment of inertia 10kgm2. The angular acceleration of the wheel is:
a)0.5rads-2 b)1.0rads-2 c)1.5rads-2 d)2.0rads-2
36. A block weighing 20 N rests on a horizontal surface. The coefficient ot static friction between the block and the surface is 0.40 and the coefficient of sliding friction is 0.20. the minimum force that will keep the block in motion once it has been started is
a)4N b)8N c)50N d)100N

37.Mercury has specific gravity 13.6. it density is:
a) 1360kg/m2 b) 1360kg/m2 c) 136kg/m2 d) 13.6kg/m2
38. The density of oxygen id 16 times that of hydrogen. If the speed of sound in oxygen is 320m/s at 100°C. The speed of sound in hydrogen at the same temperature is:
a) 5120m/s b) 1280m/s c) 80m/s d) 20m/s
39. The time period of simple pendulum depends upon
a) mass b) length c) total energy d)speed
40. The half- life of radioactive substance is 693 years. Its disintegration constant is :
a)1386 years b)1000 years c)0.001 years d)1/693 years
GROUP C
Tick ( ) on the correct answer.
41. The half- life of radon is 3.5 days. How long will it take for 40% of a same remain undecayed
a)3.8 days b)4 days c)5 days d)6 days
42. One gram of water at 100°C is converted into steam at the same temperature. If the volume of steam is1671 cc. , find the change in internal energy of the system( latent heat of steam 2256 J/g and the density of water is1000 kg/m3)
a)1585J b)2256j c)2096j d)2590j
43. Two identical sonometer wires have the fundamental frequency of500 Hz, when kept under same tension. What % increase in tension a one wire would cause an occurrence of 5 beats/sec when both wires vibrate together?
a )1.1% b) 2.2% c) 1.01% d) 2.01%
4. A n electron projected with velocity of 107 m/s in a uniform magnetic field and the initial path of the electron being 25. Find the pitch of the electron path (s/m=1.8*1011 kg):
a)3.2*10-3m b)6.4*103m c)4.8*103m d)1.6*103m
45. The noise in a street is 70db. What is the intensity of their intensities?
a)10:1 b)100:1 c)1000:1 d)100000:1

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Way to happiness

Happiness is not far away of you understand life and embrace it. To live life to the fullest and make it more positive you just have to follow simple rules. Here are some simple rules of life that will help you to better you and better tomorrow.
1. LEARN TO LISTEN
Only the mind that listens can understand anything. Listen is not passive as most of us think. It means to let a message sink in, without being judgmental. Don’t comment. Let not your conditioning interfere with understand in what you are hearing. Put off your filters. Let your intelligence take break. Don’t validate us anything. Listen with a still, calm mind and you’ll hear the deeper meanings. You’ll understand the truth.
2. UNDERSTAND YOURSELF
Go inward. Look inside you. Just relax and let your thoughts come out. Don’t try to comment, criticize or judge them. Your anger, greed, jealous and envy must be understood by you. Only when you know the filth land mistakes inside can you are bad or deny it, then you can never be happy.
3. BE IN SYNC WITH NATURE
You must understand the larger perspective of life. We are designed to live with nature, we depend on it for air, water, food et cetera. We can’t go against it. Love the flowers, plant and trees. Do what you can to protect and nature it. Live in harmony with it. Remember, as a child, you were thrilled by the first sprout of the seed you sowed in the garden.
4. LOVE UNCONDITIONALLY
The whole world seems to be doing this wrong. As children grow up, we ask them to do certain things. If they do, we shower love on them. If they don’t we scold them. We deny them our love.
The teacher does it. The boss is no different. And the partner is the same too. Rejection, scorn, cold shoulders, that’s what people get when they don’t flow the carrot and stick policy.
Do what I say, do what I like, only you’ll be my best friend, you’ll get my love. But, conditional love works in the short term. Unconditional love to children, friends, partners and parents, that’s the winning strategy. Try and you won’t regret.


5. SPEAK THE TRUTH
Truth is the foundation on which true love is built. Lies and falseness can crush a romantic relationship. Sooner or later, the person is going to find out the truth and then the love bonds are gone_ disappearing into the thin air. When you’re wrong or make a mistake, accept it. And the person will forgive you, not just that the bonds of love grow stronger after that.

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