JNTUK 4 2 Results - JNTU Kakinada Results 2011 - www.jntuk.edu.in

JNTUK 4 2 Results - JNTU Kakinada Results 2011 - www.jntuk.edu.in : The Jawaharlal Nehru Technological University (JNTU) Kakinada formerly known as JNTUK has announced the Results of B.Tech 4 2 (4th Year 2nd Semester) (R07, R05, RR) Regular / Supplementary examinations April / May 2011. JNTUK 4 2 Results will declared soon online at the main official website (www.jntuk.edu.in) of the University. After the examination, all the students (who had appeared the JNTUK B.Tech 4 2 examination 2011) were waiting the results. As per announcement, JNTUK 4 2 Results will be published soon online at the main official website (www.jntuk.edu.in) of the JNTUK. Candidates, who had appeared the JNTU Kakinada (JNTUK) B.Tech 4 2 (R07, R05, RR) Regular / Supplementary examination April / May 2011 will get the results easily by visit link given as follow.

The Jawaharlal Nehru Technological University (JNTU) Kakinada or JNTUK has regularly updates its website (www.jntuk.edu.in) to declare the result for the exams held regularly. JNTUK has made the script especially for the candidates which can produce the result only enter by roll number. So candidates need only the roll number to know the Result. We made this page especially for the JNTUK 4 2 Results.

Remember it, if you are unable to get your result please visit on link given below regularly. Because, when JNTUK will be uploaded B.Tech 4 2 results or any other result in 2011. We will update the result immediately. Candidates can get the JNTUK 4 2 Results directly in your inbox by subscribe your e-mail id in a form given below. You can visit also (www.jntuk.edu.in) to get all the updates of the new and old exam results.

Important link : JNTUK 4 2 Results April / May 2011

Simple Power Battery Tester Circuit

This is a simple design circuit for battery tester circuit. In this circuit, operating will controlled by transistor 2N3904. This is the figure of the circuit;

In the circuit, LED will turn on if the voltages is over 42V. Threshold will increase about 1 V per 1 kilo ohm increase in R2. The current drain is about 7 mA with button pressed.

[Circuit schematic source: Hobby Projects Application Notes]

Simple pH-Electrode Circuit

A pH electrode measures hydrogen ion (H+) activity and produces an electrical potential or voltage. The operation of the pH electrode is based on the principle that an electric potential develops when two liquids of different pH come into contact at opposite sides of a thin glass membrane. This is a design circuit for the measurement. This is the figure of the circuit.

Amplifier U1 off sets the pH electrode by 512 mV. This is achieved by using National's LM4140A-1.0 precision micro power low-dropout voltage reference that produces an accurate 1.024V. That voltage is divided in half to equal 512 mV by the 10 kΩ resistor divider. The output of amplifier U1, which is set up in a unity-gain configuration, biases the reference electrode of the pH electrode with the same voltage, 512 mV, at low impedance. The pH-measuring electrode will produce a voltage which rides on top of this 512 mV bias voltage. In effect, the circuit shifts the bipolar pH-electrode signal to a uni-polar signal for use in a single-supply system. The second amplifier U2 is set up in a unity-gain configuration and buffers the output of the pH electrode. Again, a high-input impedance buffer between the pH electrode and the measurement instrument allows the circuit to interface with a greater variety of measurement instruments including those with lower input impedance. In most applications, the output voltage of the pH electrode is high enough to use without additional amplification. If amplification is required, this circuit can easily be modified by adding gain resistors to U2.

Simple Emitter Follower Driver with Speed-Up Capacitor

This is a design circuit for follower driver circuit. This circuit is give illustrated an alternate method to reverse bias the MOSFET during turn-off by inserting a capacitor in series with the pulse transformer. The capacitor also ensures that the pulse transformer will not saturate due to DC bias. This is the figure of the circuit;

This is s simplest form design circuit. The Opto-isolators may also be used to drive power MOSFETs but their long switching times make them suitable only for low frequency applications. [Circuit source: National Semiconductor Notes].

Simple Programmable Current Source/Regulator Circuit

This is a simple circuit of programmable current source/regulator. This circuit is used to generate current. This is the figure of the circuit;

This circuit uses L 200 as main component. The error amplifier of this circuit is disabled by shorting pin 4 to ground. The value R is used to fix the output Io :

Io=(V5-2)/R
The output voltage can reach a maximum value Vi
– Vdrop=Vi 2 V (Vdrop depends on Io ).

Simple Stable Low Frequency Crystal Oscillator Circuit

This is the design circuit for a Colpitts-crystal oscillator circuit. It is suitable for low frequency crystal oscillator circuits. Using the 2N3823 JFET, this circuit has excellent stability because the temperature will not vary the 2N3823 JFET circuit loading. This is the figure of the circuit.

This is a simple form circuit for the oscillator. [Circuit Schematic Source: National Semiconductor Application Note]

Simple Current Monitor Circuit

This is a simple design circuit for monitoring and detecting the current flow. This circuit is based on LM301A and FET. This is the figure of the circuit;

On the circuit diagram, R1 is used to senses current flow of a power supply. We could use JFET as a buffer because Id=Is, therefore the power supply current flow is accurately reflected by the output monitor.

Simple 4 Channel Commutator Circuit

This is design circuit for commutator circuit. This circuit is simplest form. The circuit is built by four FET that can be use for 4 channels. This is the figure of the circuit;

To reach low channel ON resistance (<30 Ohm) and low OFF current leakage, 4-channel commutator uses the 2N4091. The DM7800 voltage translator is a monolithic device. This devices give us +10V to -20V gate drive to the JFETs while at the same time giving DTL-TTL logic compatibility.

Simple Step-up PWM DC-DC Converter Integrated with 4 Buffers

This is a circuit for converter that is a simple form for DC to DC Converter circuit. This circuit is based on LM2711 from National Semiconductor. This is the figure of the circuit;

The LM2711 has a current mode PWM step-up DC/DC converter with a 1.4A, 0.17 internal switch. Capable of generating 8V at 300mA from a Lithium Ion battery, the LM2711 is ideal for generating bias voltages for large screen LCD panels. The LM2711 can be operated at switching frequencies of 600 KHz or 1.25MHz, allowing for easy filtering and low noise. An external compensation pin gives the user flexibility in setting frequency compensation, which makes possible the use of small, low ESR ceramic capacitors at the output. The LM2711 uses a patented internal circuitry to limit startup inrush current of the boost switching regulator without the use of an external soft start capacitor. An external soft start pin enables the user to tailor the soft start to a specific application. The LM2711 contains 4 Gamma buffers capable of supplying 50mA source and sink. The TSSOP-20 package ensures a low profile overall solution. [Schematic circuit source: National Semiconductor Notes]

Simple Precision Power Regulator Circuit

Making a precision voltage source is easy, but not so easy if the voltage should be consistent over wide range of ambient temperature. Such requirement might be needed in high precision measurement system, for providing reference voltage in analog to digital conversion for example. This is a design circuit for precision power regulator. This is the figure of the circuit;

This circuit is based on LM 336. LM336 voltage references are easier to use than zener diodes. Their low impedance and wide current range facilitate biasing in any circuits. Besides, the breakdown voltage or the temperature coefficient can be adjusted so as to optimize the performance of the circuit. [Circuit diagram source: STMicroelectronics Application Note]

Simple Analog Multiplier Circuit

This is a circuit for a simple embodiment of the analog multiplier. This circuit provides three quadrant analog multiplication which is relatively temperature insensitive and which is not subject to the bias current errors which is plague most multipliers and circumvents many of the problems associated with the log-antilog circuit. This is the figure of the circuit;

By considering A2 as a controlled gain amplifier, amplifying V2, whose gain is dependent on the ratio of the resistance of PC2 to R5 and by considering A1 as a control amplifier which establishes the resistance of PC2 as function of V1, circuit operation may be used. It is seen that Vout is a function of both V1 and V2 in that way. Drive for the lamp L1 is provided by the control amplifier(A1). L1 is driven by A1 until the current to the summing junction from the negative supply through PC1 is equal to the current to the summing junction from V1 through R1 when an input voltage (V1) is present. This forces the resistance of PC1 to a value proportional to R1 and the ratio of V1 to V- since the negative supply voltage is fixed. L1 also illuminates PC2 and causes PC2 to have a resistance equal to PC1 if the photoconductors are matched. The controlled amplifier (A2) behaves as an inverting amplifier whose gain is equal to the ratio of the resistance of PC2 to R5. Vout becomes simply the product of V1 and V2 if R5 is chosen equal to the product of R1 and V-. To provide any required output scale factor, R5 may be scaled in powers of ten.

Since the T.C. of resistance is related to resistance match for cells of the same geometry, PC1 and PC2 should be matched for best tracking over temperature. Varying the value of R5 as a scale factor adjustment is used to compensate small mismatches. The photoconductive cells should receive equal illumination from L1, a convenient method is to mount the lamp midway between them. Controlled spacing and a thermal bridge between the two cells to reduce differences in cell temperature is provided by this mounting method. To the use of FET’s or other devices to meet special resistance or environment requirements, we can extend this technique.

An inverting output whose magnitude is equal to one-tenth the product of the two analog inputs is given on this circuit. Positive value is restricted for input V1 but V2 may assume both positive and negative value. By the lamp time constant, his circuit is restricted to low frequency operation. To minimize errors due to input offset current as outlined in the section describing the photocell amplifier, R2 and R4 are chosen. To reduce in-rush current when firdt turning on the lamp (L1), R3 is included.

[Circuit source: National Semiconductor Notes]

Simple Microphone Amplifier Circuit

This is a circuit diagram of a device which can hear faint sounds and those sounds which any normal microphone can not hear. This is a very useful circuit and one can use this circuit for many tasks this circuit can be used as a hearing aid. Use direct coupling and do not use bulky coupling or bypass capacitors. The circuit using only a few components the size of the circuit is very small so one can easily fit it in a small box. This is the figure of the circuit;

Capacitor 1 bypasses ac negative feedback due to which the gain is not affected. Q1, Q2 and Q3 are bc 337. Resistor 1 is used for volume control. Transistor 1, transistor 2 and transistor 3 all are direct coupled amps. Their operation is stabilized by direct current (DC) negative feed back through resistor 4.

Simple Loud Hailer Circuit

This is a simple and useful circuit project of loud hailer the circuit uses only one transistor connected with transformer which puts out a loud sound. The circuit can be easily fixed in a metal package with the speaker mounted on the top. Heat sink is essential for the transistor or it will burn out, fix the circuit in metal package and also use this metal package as heat sink of transistor. This is the figure of the circuit;

Use carbon mic or telephone mic/telephone transmitter element. The circuit can be build inside of a speaker trumpet like the loudhailers available in market. Make sure that the mic is isolated from the speaker to prevent feedback. Use the transformer which will able to provide 5 watt output power.

Simple Lie Detector Circuit

If you want to know someone is lying or not we can use lie detector. This is a simple lie detector that can be made in minutes. It works to detect someone who telling lie but it is not as sophisticated as the ones the professionals use. This is the figure of the circuit;

The skin resistance will go down when someone telling lie and this circuit works by measuring it. We can use electrode pads, alligator clips, or just wires and tape as the electrodes. We have to adjust R2 to position the meter at the center at the beginning of the interrogation (relax condition), then we can know someone is lying when the meter changes in response to a question.

[Schematic circuit source: aaroncake.net]

Simple DC Motor PWM Speed Control Circuit

This is a circuit for DC motor circuit. This circuit is used PWM speed control using 555 timer IC. This is the figure of the circuit;

The 555 Ic is wired as an astable and the frequency is constant and independent of the duty cycle, as the total resistance (R charge + R discharge, notice the diode) is constant and equal to 22Kohm (givin a frequency of about 1Khz, notice the hum). When the potentiometer is all up, the Rcharge resistance is 1,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 21 Kohm, giving a 5% on duty cycle and a 1Khz frequency.

When the potentiomenter is all down, the Rcharge resistance is 21,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 1 Kohm, giving a 95% on duty cycle and a 1Khz frequency. When the potentiometer is at 50% , the Rcharge resistance is 11,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 11 Kohm, giving a 50% on duty cycle and a 1Khz frequency. The 555 provide good current capability to drive the mosfet fast and to drive a bipolar transistor.

Simple DC Motor PWM Speed Control Circuit

This is a circuit for DC motor circuit. This circuit is used PWM speed control using 555 timer IC. This is the figure of the circuit;

The 555 Ic is wired as an astable and the frequency is constant and independent of the duty cycle, as the total resistance (R charge + R discharge, notice the diode) is constant and equal to 22Kohm (givin a frequency of about 1Khz, notice the hum).

When the potentiometer is all up, the Rcharge resistance is 1,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 21 Kohm, giving a 5% on duty cycle and a 1Khz frequency.

When the potentiomenter is all down, the Rcharge resistance is 21,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 1 Kohm, giving a 95% on duty cycle and a 1Khz frequency. When the potentiometer is at 50% , the Rcharge resistance is 11,0 Kohm (the diode prevents the capacitor to charge through the second potentiometer section and the other 1,0 Kohm resistor) , and Rdischarge is 11 Kohm, giving a 50% on duty cycle and a 1Khz frequency. The 555 provide good current capability to drive the mosfet fast and to drive a bipolar transistor.

Simple Shunt Voltage Stabilizer Circuits

This is a circuit for a simple voltage stabilizer circuit that employs a zener diode and a single resistor. In this circuit, the zener diode, which is the stabilizing component, is in parallel (or in shunt) with the load, which is why it is also called a shunt stabilizing circuit. This is the figure of the circuit;

The value of R must be chosen so that a 'holding current' of 2 mA will flow into the zener diode even at the lowest input voltage and maximum load current. The zener diode maintains the output voltage level by 'conducting' the excess current to ground whenever the voltage across it becomes excessive.

Simple Series Voltage Stabilizer Circuits

This is a circuit for simple voltage stabilizer circuit that employs a resistor, a zener diode, and an NPN transistor. In this circuit, the zener diode is used to stabilize the base voltage of the NPN transistor, which carries the load current. This is the figure of the circuit;

The load transistor is in series with the load, which is why this circuit is also known as a series stabilizer. Unlike the amplified zener shunt stabilizer, the dissipation of the transistor increases only when the actual load current increases, making its operation more efficient.

Simple OP90 Single Op Amp Full-Wave Rectifier

This is a design circuit for a full-wave rectifier circuit that provides the absolute value of input signals up to ±2.5 V even though operated from a single 5 V supply. This is the figure of the circuit;

The amplifier acts as a unity-gain inverter for negative inputs. The op amp output is forced by positive signal to ground. The 1N914 diode becomes reversed-biased and the signal passes through R1 and R2 to the output. Load impedance cause an asymmetric output since output impedance is dependent on input polarity. This can be corrected by reducing R2 for constant load impedance. A second OP90 can buffer varying or heavy loads. The output of the full-wave rectifier with a 4 Vp-p, 10 Hz input signal also shown in figure below. [Circuit's schematic diagram source: analog.com]

Simple Negative Feedback Series Voltage Stabilizer Circuit

| author: Free schematics and tools

This is a design circuit for more complex series voltage stabilizer circuit, utilizing an operational amplifier (IC1) to 'slow down' or turn off the load transistor Q1 when the output voltage is excessive. This is the figure of the circuit;

The zener diode ZD1 in this circuit is just used as a reference voltage for defining the threshold at which the op amp will turn Q2 and Q1 on or off. Because of this negative feedback mechanism, power is consumed more efficiently, since the load is only supplied with current when it needs it.

Simple Light Activated Buzzer Circuit

This is a circuit for a simple buzzer circuit that is activated by light, i.e., the buzzer is on when there's ample light and off when it is dark. A general-purpose operational amplifier, the 741, is used as a comparator that determines whether there's enough light to turn on a self-oscillating piezoelectric buzzer. Its non-inverting input is connected to a photo resistor, a component whose resistance decreases as more light shines on it. Its inverting input, on the other hand, is connected to an almost fixed voltage, i.e., a proportion of the supply voltage as set by trimmer resistor R2. This is the figure of the circuit;

If there isn't enough light shining on the photo resistor, the buzzer is quiet. As more light shines on the photo resistor, its resistance decreases and causes the voltage across R1 to increase. At a certain level of lighting, the voltage across R1, which is also the voltage at the non-inverting input of the 741, becomes larger than the voltage at the inverting input. At this point, the 741 is triggered to output a 'high' level, turning on Q1. Q1 then activates the self-oscillating piezoelectric buzzer.

Simple DC Voltage Ripple Remover Circuit

This is a circuit for a simple circuit for removing an AC ripple from a DC voltage. The main component of the circuit is an operational amplifier configured as a simple amplifier in common-mode operation. This means that both the inverting and non-inverting inputs of the op-amp get the same input voltage, i.e., a DC voltage Vin with an AC ripple Vripple. The only difference is that the inverting input has an input capacitor that blocks the DC voltage. This is the figure of the circuit;

Since the op-amp amplifies just the difference between the voltages at its two inputs, it cancels out the AC ripple (which appears at both inputs). On the other hand, the op-amp amplifies the DC voltage Vin since this is only present at the non-inverting input. However, the op-amp is configured to have a DC voltage gain equal to 1, so the output of this circuit is just equal to Vin. Since the AC ripple can only be cancelled cleanly if both op-amp inputs have equal gains, the 10K potentiometer is used to compensate for any inherent differences between the inputs' gains.

Simple 3A Switching Regulator Circuit

This is a design circuit for a simple and low cost switching regulator using the IC LM317 that can deliver up to 3A of current. The input voltage range of this circuit is between 8 to 35V DC and the output voltage can be adjusted between 1.8 to 32V DC. The output voltage can be adjusted by using the POT R4. This is the figure of the circuit;

When compared to linear voltage regulators the switching voltage regulators are much power efficient. In the case of linear voltage regulators the difference between the input and output voltage is just wasted and for switching regulators there is almost no such wastage and that’s why the switching regulators have great power efficiency ranging up to 85% . In simple words, the switching regulator operates by taking small bits of energy from the input voltage source and then transferring it to the output with the help of a solid state switch and a control circuitry. Since the switching element is either fully open or closed at any moment, no energy is wasted across it. The control circuit controls the duty cycle of the solid state switch which in turn determines rate at which energy is transferred to the output.

Simple 3 Band Tone Control Circuit

This is a design circuit for the simple design of a 3 Band Tone Control Circuit Diagram. This is the figure of the circuit;

R1 is left up to the user depending on gain needs. This circuit design was originally intended for home audio use, but should be able to hacked into an effect circuit with very minor modification.

Simple Basic Symmetric Power Supply Circuit

This is a design circuit for the basic for standard symmetrical power supply. If your circuit need high current then this circuit is suitable. This is the figure of the circuit;

You need a center-tapped transformer to build this symmetric power supply. This power supply circuit is widely used in op-amp application, as well as in high-rated power amplifier.

Wireless Telephone Line Spy Circuit

Here’s a design of a phone bug circuit. This wireless telephone line spy circuit can be used to transmit the phone conversation to a nearby FM radio. This circuit must connected to a normal phone line. This is the figure of the circuit;

The first transistor is turned off, if the voltage drops to less than 15v (if the telephone line is in use). It will enable the second transistor to oscillate at approx 100MHz. Then transmit the phone conversation to a nearby FM radio.

Phone Incoming Call Flasher Circuit

Here’s a design circuit of phone message flasher, an alternative way to get alarmed when there is an incoming call. This is the figure of the circuit;

When the phone rings, high line voltage will be detected by A differential amplifier with hysteresis (Q2, Q3, and Q1). This action will turn on multi vibrator Q5/Q6, Q4. The LED will flashed via Q7. When the phone line voltage drops to less then 9V, the Q2 and Q1 will be turned off, which indicates an off hook condition.

Low Cost Precision Light Control / Dimmer Circuit

Using a the controlled-half-plus-fixed-half-wave phase control method, this circuit can regulate an 860 a watt lamp load from half to full power. This circuit control the light output of the lamp from 30% to 100% because Half power applied to an incandescent lamp gives 30% of full light output. This is the figure of the circuit;

Simple Positive (+) to Negative (-) Voltage Inverter Circuit

This is a simple circuit that can be used to convert the positive input voltage become negative voltage. Here’s the figure of the circuit;

Component list:

Part Total Qty. Description
R1 1 24K 1/4 Watt Resistor
R2 1 56K 1/4 Watt Resistor
C1 1 3300pF 25V Ceramic Capacitor
C2 1 47uF 25V Electrolytic Capacitor
C3 1 10uF 25V Electrolytic Capacitor
D1, D2 2 1N4148 Silicon Diode
U1 1 555 Timer
MISC 1 Wire, Board

In this circuit, V+ can be anywhere from 4 to 16V. -V is one volt less than V+. So, for -12V output, use +13V input. The maximum current output of the circuit is about 280mA, more than enough for a few op amps. For better regulation, a 79LOxx series regulator can be used. A zener diode may also be used to regulate the output voltage.

Simple Galvanometer Circuit

This circuit is design for galvanometer circuit. According to Wikipedia.org, a galvanometer is an analog electromechanical transducer to be used for detecting and measuring electric current (ammeter). In this circuit design, the voltage across Rm and Rv is the same because they are in parallel. The resistor Rv is a variable resistor. Here’s the figure of the circuit;

Simple of XTal Tester Circuit

This is a design circuit for a simple XTal tester circuit. T1 and XTal have formed an oscillator. Here’s the figure of the circuit;

In this circuit, C1 and C2 are voltage divider for oscillator. If the XTal is safe, the oscillator will work well and its output voltage will be rectified by C3, C4, D1 and D2, then T2 will run and LED will light. The circuit is suitable to test 100KHz - 30MHz Xtal.

Simple Positive (+) to Negative (-) Voltage Inverter Circuit

This is a simple circuit that can be used to convert the positive input voltage become negative voltage. Here’s the figure of the circuit;

Component list:

Part Total Qty. Description
R1 1 24K 1/4 Watt Resistor
R2 1 56K 1/4 Watt Resistor
C1 1 3300pF 25V Ceramic Capacitor
C2 1 47uF 25V Electrolytic Capacitor
C3 1 10uF 25V Electrolytic Capacitor
D1, D2 2 1N4148 Silicon Diode
U1 1 555 Timer
MISC 1 Wire, Board

In this circuit, V+ can be anywhere from 4 to 16V. -V is one volt less than V+. So, for -12V output, use +13V input. The maximum current output of the circuit is about 280mA, more than enough for a few op amps. For better regulation, a 79LOxx series regulator can be used. A zener diode may also be used to regulate the output voltage.

Simple Galvanometer Circuit

This circuit is design for galvanometer circuit. According to Wikipedia.org, a galvanometer is an analog electromechanical transducer to be used for detecting and measuring electric current (ammeter). In this circuit design, the voltage across Rm and Rv is the same because they are in parallel. The resistor Rv is a variable resistor. Here’s the figure of the circuit;

Simple of XTal Tester Circuit

This is a design circuit for a simple XTal tester circuit. T1 and XTal have formed an oscillator. Here’s the figure of the circuit;

In this circuit, C1 and C2 are voltage divider for oscillator. If the XTal is safe, the oscillator will work well and its output voltage will be rectified by C3, C4, D1 and D2, then T2 will run and LED will light. The circuit is suitable to test 100KHz - 30MHz Xtal.

Simple Voltage Doubler Circuit

This is a design circuit that is output a voltage Vout that is approximately twice the level of the Vcc voltage. The circuit uses a 555 timer IC configured as an astable multi vibrator, i.e., it generates a continuous square wave signal of a set frequency as long as its reset pin (pin 4) is held high. This means that the 555 output toggles between '1' and '0' continuously at the set frequency. This is the figure of the circuit;

When the circuit is powered up and the 555 output (pin 3) goes to logic '1' for the very first time, its near-Vcc voltage level causes C3 to charge up through D2 and also reach near-Vcc level. When the output goes to logic '0', C2 charges from Vcc through D1, also to a near-Vcc level. When the 555 output goes back to logic '1' again, C3 may still have some (if not most) of its charge left, and will allow to charge up to a higher level since it is now effectively in parallel with the series circuit of the 555 level '1' output and the charged C2.

After several cycles of C2 and C3 alternately charging, C3 will subsequently build up a voltage level equal to almost twice the Vcc level. This C3 voltage comes from the charge pumped in by the sum of the C2 voltage (near-Vcc) and the 555 output voltage when it is at logic '1' (also near-Vcc). At this point, the output Vout of the circuit will already be almost twice the Vcc level.

Simple Transistor Circuit Substitute for SCR

A silicon-controlled rectifier (SCR) is a solid-state device that doesn't allow current to flow until it is triggered to conduct. The SCR is a four-layer device, i.e., its structure consists of four layers of alternating semiconductor material type: p-n-p-n. Once triggered, it will conduct current in only one direction. SCR's are generally used for AC switching. This is the figure of the circuit;

This circuit is equivalent to a silicon-controlled rectifier (SCR). It employs a PNP and an NPN bipolar transistor to mimic the p-n-p-n structure of an SCR. In this circuit, once NPN transistor Q2 is triggered by a positive input to its base, it starts pulling down the voltage at the base of PNP transistor Q1. This would drive Q1 to conduct, which will then supply Q2's base with continuous current to keep it 'on'.

Under this state, both transistors will conduct indefinitely, as long as there is available current flowing between the anode (A) and the cathode (K). The circuit will only turn 'off' if the supply of current from A to K is interrupted.

Simple Integrator Circuit

This is a design circuit for simple integrator circuit. The potentiometer is connected to the "rails" of the power source through 100 kΩ resistors, one on each end. This is to limit the span of the potentiometer, so that full movement produces a fairly small range of input voltages for the op-amp to operate on. At one extreme of the potentiometer's motion, a voltage of about 0.5 volt (with respect the ground point in the middle of the series battery string) will be produced at the potentiometer wiper. This is the figure of the circuit;

At the other extreme of motion, a voltage of about -0.5 volt will be produced. When the potentiometer is positioned dead-center, the wiper voltage should measure zero volts. Connect a voltmeter between the op-amp's output terminal and the circuit ground point. Slowly move the potentiometer control while monitoring the output voltage. The output voltage should be changing at a rate established by the potentiometer's deviation from zero (center) position. To use calculus terms, we would say that the output voltage represents the integral (with respect to time) of the input voltage function. That is, the input voltage level establishes the output voltage rate of change over time. This is precisely the opposite of differentiation, where the derivative of a signal or function is its instantaneous rate of change.

If you have two voltmeters, you may readily see this relationship between input voltage and output voltage rate of change by measuring the wiper voltage (between the potentiometer wiper and ground) with one meter and the output voltage (between the op-amp output terminal and ground) with the other. Adjusting the potentiometer to give zero volts should result in the slowest output voltage rate-of-change. Conversely, the more voltage input to this circuit, the faster its output voltage will change, or "ramp."

Simple Proportional-Integral Motor Speed Control

This is a design of frequency-to-voltage converter application similar with RPM/Speed Indication is motor speed control. Here the converter is used to measure the actual speed which will be fed back to keep the actual speed stabilized according to a reference. This is the figure of the circuit;

If the speed is to high, the output of the F/V converter will reduce the drive power delivered to the motor, and vice versa. The resistor across the output and the inverting input determine the proportional gain, and the capacitor determine the integral gain. This negative feedback mechanism is the core of this proportional motor speed control system. [System's block diagram source: Microchip Application Note]

Simple Transistor Tester Circuit Using 555 IC

This is a circuit for testing whether a transistor is shorted or open usually done by ohm meter. You test if the base to emitter or collector permit a current flow in one direction. This is the figure of the circuit;

The 555 timer ( IC1 ) operate as a 12hz oscillator. The output of this oscillator (pin 3) drives the 4027 flip-flop (IC2). Clocked by the oscillator, this flip-flop give complementary voltage outputs on pin 15 and 14. The outputs drives LED1 and LED2 through the current limiting resistor R3. The LED’s are arranged so that if the polarity across the circuit is one way then only one LED will light and if the polarity reverses then the other LED will light, and when no transistor is connected to the tester then the LED’s will alternately flash. The IC2 outputs are also connected to resistors R4 and R5 with the junction of these two resistors connected to the base of the transistor being tested. If a good transistor connected to the tester, the transistor will turn on and produce a short across the LED pair. If a good NPN transistor is connected then only LED1 will flash. If a good PNP transistor is connected then only LED2 will flash. If the transistor is open both LED’s will flash and if the transistor is shorted then neither LED will flash. After receiving a feedback from our reader, I’ve checked the datasheet of 4027 JK flip-flop, and found that the pin 12 and 13 in the schematic diagram above should be interchanged.

Simple Remote Sensor System Pre-Amp

| author: Free schematics and tools

This is a design circuit for remote sensor might cause a trouble if it’s a passive type, has very low power output, and should be connected with relatively long cables. By supplying a current or voltage source through its connection wire, it’s possible to make long enough wiring without suffering much noise/interference. The following schematic diagram show a circuit consist of LM10 to make a remote vibration sensor connection works fine. We don’t need a separate wires for signal and power supply, we send them on the same cable pair. This is the figure of the circuit;

[Circuit diagram source: National Semiconductor Application Notes]

Simple Humidity Sensor Circuit

This is a humidity sensor to give an alert of boat leakage, or when your books start being flooded by heavy rain attack on your broken roof, or anything you can imagine. A simple humidity sensor (a humidity probe) can be constructed using two copper wires placed as close as possible to each other, but no touching. This simple circuit can be used to make your simple humidity detector. This is the figure of the circuit;

If the humidity increase, the probe resistance will drop and the Schmidt trigger formed by Q1 and Q2 will be triggered, and the Q2 collector become low, this condition will trigger the S-R (set-reset) flip-flop formed by U1A, U1B. After triggered, the relay will remain active until you reset the circuit by pressing the SW1 switch.

10th Result Gujarat Board 2011, Gujarat Secondary Education Board - www.gseb.org

10th Result Gujarat Board 2011, Gujarat Secondary Education Board - www.gseb.org : The Gujarat Secondary and Higher Secondary Education Board (GSEB) - Gujarat Board - Secondary School Certificate SSC (10th Class) Result 2011 has been announced at the main official website's (www.gseb.org) of the Gujarat Board. Gujarat Board 10th examination is conducted every year normally in March / April in 335 Centers for more than 7 Lakh Students. Gujarat Board 10th 2011 examination was held in March 2011. After the examination, all the students (who had appeared the Gujarat Board SSC, 10th examination 2011) were waiting the results. As per announcement, 10th Result Gujarat Board has been published online on 01.06.2011
at the main official website's (www.gseb.org) of the Gujarat Board. Candidates, who had appeared the Gujarat Board 10th 2011 examination can be download the results easily by visit link given as follow.