GATE 2014 Notification

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GATE 2014 Notification poster has been released by IIT Kharagpur, the organizing institute for this year. The tentative examination schedule is also released. The exam will be conducted On Saturdays and Sundays between 1st February 2014 and 2nd March 2014. The exact schedule will be given on the GATE 2014 website.

GATE exam is a way to join in Post Graduate courses in Engineering like M.E, M.Tech or PhD in National level institute which is very crucial for engineering graduates. GATE 2014 will be organized by IIT Kharagpur.

What is New in GATE 2014 -

Gate 2014 will be conducted Online (Computer Based Test) all streams - AE, AG, AR, BT, CE, CH, CY, GG, MA, MN, MT, PH, TF, XE and XL, CS, EC, EE, IN , ME and PI .

GATE 2014 Eligibility :

The following categories of candidates are eligible to appear in GATE :

    Bachelor's degree holders in Engineering / Technology / Architecture / Pharmacy (Post - Diploma / Post-B.Sc / 4 years after 10+2) and those who are in the final year of such programs.

    Candidates in the final year of the Four-year Bachelor's degree program in science (B.S.) (Post-Diploma/4 years after 10+2)

    Master's degree holders in any branch of Science / Mathematics / Statistics / Computer Applications or equivalent and those who are in the final year of such programs.

    Candidates in the second or higher year of the Four year Integrated Master's degree program or (Post-B.Sc.) in Engineering / Technology.

    Candidates in the fourth or higher year of Five year Integrated Mater's degree program or Dual Degree program in Engineering / Technology

    Candidates in the final year of Five-year integrated M.Sc. or Five year integrated B.S. - M.S. program

    Candidates with qualification obtained through examination conducted by professional AMIE by IE (I), AMICE (I) by ICE (I) as equivalent to B.E/B.Tech. Those who have completed section A or equivalent of such professional courses are also eligible.


GATE 2014 Application Fee :

Category have to apply only Online - General/OBC (Male Candidates) 1500/-

750 for Women candidates

1500 for General / OBC other candidates

750 for the SC/ST/PD category candidates.

The application fee can be paid either online or through a bank challan via SBI or Syndicate bank.

GATE 2014 dates of Examination -

Admission to Postgraduate course (Master's and Doctoral) with MHRD and other Government Scholarships / Assistantships in Engineering / Technology / Architecture / Science open to those who qualify in GATE. GATE 2014 score will be valid for a period of TWO YEARS ONLY from the date of announcement of results.

Important Dates (tentative)

COMMENCEMENT OF ONLINE APPLICATION 2nd September 2013 (Monday)

Last date for submission of Application (Website closure) : 3rd October 2013 (Thursday)

Last date for receipt of hard copy of application with supporting document at respective GATE Offices: 10th October 2013 (Thursday)

Last date for on Saturdays and Sundays between 1st February 2014 and 2nd March 2014. The exact schedule will be given on the GATE 2014 website.

How to Apply :

Application must be done ONLINE. Further details and ONLINE Application form can be obtained by accessing any of the websites given below (or by scanning the image below using a QR reader facility that is available on most of the Mobile phones).


GATE 2014 Notification Poster - http://gate.iitkgp.ac.in/gate2014/poster2014.pdf

For more information GATE 2014 visit the given link - http://gate.iitkgp.ac.in/gate2014/
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Build a Bootstrapped Amp Current Source Circuit Diagram

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Build a Bootstrapped Amp Current Source Circuit Diagram. This circuit responds to the difference between Vj and V2. Rq on sets gain. Resistors XR2 and (1 -X) R2 produce the bootstrap effect. These two resistors convert the circuit`s output voltage to a current. IC1 and IC2 are Burr-Brown OPA2107 or equal.


Bootstrapped Amp Current Source Circuit Diagram


Build a Bootstrapped Amp Current Source Circuit Diagram
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Simple Battery charger Circuit Diagram

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This is a simple Battery charger circuit diagram. A diac is used in the gate circuit to provide work for the signal being applied to the gate. R1 a threshold level for firing the triac. C3 and R4 is selected to limit the maximum charging cur-provide a transient suppression network Rl, rent at full Totation of R2. R2, R3, Cl, and C2 provide a phase-shift net.


Simple Battery charger Circuit Diagram




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Build a Remotely Adjustable Solid State High-voltage Supply Circuit Diagram

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How to build a remotely adjustable solid state high-voltage supply Circuit Diagram. The output voltage changes approximately linearly up to 20 KV as the input voltage is varied from 0 to 5 V. The oscillator is tuned by a 5-0 potentiometer to peak the output voltage at the frequency of maximum transformer response between 45 and 55 kHz. 

The feedback voltage is applied through a 100-KO resistor, an op amp, and a comparator to a high-voltage amplifier. A diode and varistors on the primary side of the transformer protect the output transistor. The transformer is a flyback-type used in color-television sets. A feedback loop balances between the high-voltage output and the low-voltage input.


Remotely Adjustable Solid State High-voltage Supply Circuit Diagram





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Build a 12v to 5v DC high efficiency SMPS buck converter using 34063 IC

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This project converts 12v DC to a regulated 5v DC at up to 1.8 amps, suitable for driving a tablet computer from a 12v car battery in a power blackout etc.

The circuit for this buck converter is nothing original, basically it is the circuit from the 34063 IC datasheet, and all I did was to use an external PFET instead of the external PNP transistor shown in the datasheet. The external PFET allows currents up to a few amps at good efficiency, however I have used hard current limiting at 1.8A for safety and good performance in this prototype.

Energy conversion efficiency is very high due mainly to the choice of external components used with the cheap 34063 SMPS IC.

Build a 12v to 5v DC high efficiency SMPS buck converter using 34063 IC


 PCB layout.
The prototype was tested in hardware, please excuse the messiness. The layout is far from ideal, I did it this way to allow easy swapping of parts and just to be lazy, to save the effort of making a PCB. However it still works pretty good, and a proper PCB would improve performance a little bit.

PFET choice.
I did not have a lot of PFETs in my parts box so I used a 100v 8A rated part. This was an SMD PFET so I just tacked it on the bottom of the PCB. It is efficient enough to not need a heatsink even at 5v 1.5A continuous output. The PFET I used was not ideal, it's "Rds on" value is about 0.3v at 1.5A (0.2 ohms) which is too high and costs efficiency. Going to a 50v >20A PFET with an RDS <0.1 ohms or <0.05 ohms would give a noticable increase in efficiency.

Schottky diode choice.
I used a TO-220 60v dual 10A schottky diode pack (total 20A). This is a no-brainer, although this is overkill these diodes are only $1-$2 and can also be pulled for free from any old PC PSU and most commercial SMPS supplies. Besides the safety of being very large and over-rated, the main benefit is these diodes have a very low forward voltage drop of <0.3v at 1.5A or 2A and this equates to reduced losses (more efficiency).

Inductor choice.
This is just a commercial "3 amp" 24mm total diameter inductor/choke available from hobby suppliers like Altronics Australia. I think it is a 220uH or 330uH value, but sorry I lost the paperwork.  A few other powdered-iron toroid inductors were tried and it is not that critical. It has 51 turns of 1.0mm diameter wire if that helps. The inductor measured 0.32mV at exactly 1A DC, so DC resitance was measured at 32 milliohms.

Build a 12v to 5v DC high efficiency SMPS buck converter using 34063 IC


Schematic and operation.
Sorry for the hand-drawn schematic! As you can see the circuit is minimum parts. It uses just two resitors to drive the PFET from the IC (same as the datasheet), this is not ideal but was done to test the concept and see if a PFET can be driven as easily as the PNP transistor normally is. PFET turnon is good at 0.07uS, but turnoff is not great taking 0.8uS. This costs about 1-2% efficiency. The 560 ohm resistor could be reduced to speed up the turnoff, but this would increase losses in that resistor so it is a tradeoff.

34063 SMPS IC.
The 34063 IC does all the clever stuff, mainly it regulates voltage at 1.25v on VFB pin5. Because of the 6k8:2k2 voltage divider on the output, this gives very close to 5v, I actually saw about 5.01v-4.99v Vout in testing, very nice.

Max current limit resistor.
The resistor between Vin and pin7 sets the max inductor current limiting, this was set by me to roughly 0.18 ohms to give 1.8A current limiting. (Imax = 0.32v / R = 0.32v/0.18 = 1.78A). The current limit is best at slightly above the max required current. This gives better safety and also helps stabilise oscillation.

Caps etc.
CT used the datasheet value of 1nF. That gave oscillator value of 26.2kHz measured on pin3 (with no load), however the whole circuit usually operated at 29-33kHz because of the way the regulation works in the IC. The filter caps; 680uF on the input and 1000uF on the output were chosen to be "good enough". Output ripple was approx 25-30mV which is fine.

Measured efficiency!

Vin    Iin   Pin        Vout  Iout   Pout      Eff %    
12.5v 670mA 8.375W 4.99 1.53A 7.63W 91.1%
12.5v 430mA 5.375W 5.00 1.00A 5.00W 93.0%
12.5v 210mA 2.625W 5.00 0.50A 2.50W 95.2%

Note! Readings were taken from meters with only 2 decimal point resolution and were not lab grade accuracy, so there may be a couple of percent error in readings.

Calculating efficiency (at 1.5A output).
The static power losses were seen on the 'scope and can be calculated;

PFET Rds on period loss = 0.3v / 12.5v = 2.4% loss

DIODE Vf off period loss = 0.28v * 1.53A * 0.56 offduty = 240mW = 2.8% loss

Inductor resistance loss = 1.53A squared * 0.032 ohms = 75mW = 0.9% loss

560 ohm resistor loss = 10.5v squared / 560 * 44% onduty = 87mW = 1.0% loss

Total static losses at 1.53A output = 7.1%
Calculated other (switching) losses = 100% - 91.1% - 7.1% = 1.8%



Scope current L1 inductor (on period) at 5v 1.5 amps.
Above is the on period current through the PFET and L1 inductor. As it is a PFET this is inverted so the pointy bit at the bottom is the max current, the top is zero current. At 1.5A and 32kHz the SMPS is very stable, as switching period is reduced becuase the peaks just hit the 0.32v max current limit set by my choice of 0.18 ohm resistor. (However voltage regulation is still the main regulation).

Duty cycle is about 44%, and current ripple in the inductor is nice and low with inductor current averaging 1.5A (ripple of 0.56A, between 1.22A and 1.78A). The noise spikes I suspect are from from my messy PCB with power and load wires everywhere and 'scope leads laying around next to the PCB and wiring.




Scope current L1 inductor at 5v 1.0 amps.
Same thing but at 1A. Frequency dropped a bit, closer to the 34063 oscillator freq of 26.2kHz, but still (just) triggering on the max current peaks. Current ripple now larger from approx 0.5A to 1.6A (average output 1A). Timing is still 20uS/hdiv but says 40uS on the screen as I had zoomed my h-axis (sorry).



Scope current L1 inductor at 5v 0.5 amps.
Here the L1 current has gone "discontinuous" meaning the L1 current is reduced to zero during the end of the off period, and has to start from 0 amps again during every on period. Typical of the regulation system used in a 34063 IC, the timing will "stutter" as needed to maintain Vout regulation at a steady 5.0v. This does not matter and the 34063 can be quite energy efficiency when "stuttering" in discontinuous mode like this. At less than 0.5 amps the stuttering can become very erratic looking, but this is all normal.



PFET drain/source voltage (main switching waveform).
(The PFET on period is the top of the waveform). Above you can see the PFET turnon (through a 10 ohm resistor) is nice and fast, It was about 0.07uS turnon time. However the turnoff is poor, because the turnoff is from a 560 ohm resistor and is slow at 0.8uS. This costs significant efficiency.

Using an external digital driver (like a 12v CMOS digital buffer/inverter chip?) to drive the PFET would improve turnoff time a lot and increase efficiency, but this was a test of using the simple datasheet example circuit with an external PFET (instead of the suggested external PNP) and as proof of concept it still works well enough.



5v DC output showing voltage ripple.
Because it is a switching regulator there will always be some ripple on the DC output voltage. This is shown when running at 5v 1.5A and the ripple is typical and acceptable enough at 30-35mV.

Improving efficiency.
This circuit was thrown together very quickly to show how to use a cheap common 34063 IC to get a high efficiency supply from 12v->5v DC at 0-1.5A or so. If you want to invest some effort it can be improved further;

1. My PFET is not a good choice, using a better PFET will give an easy 1% more efficiency, and would be the first choice.

2. The inductor is just an ordinary "off the shelf" type. A properly selected inductor or a good core hand wound for best performance could allow lower operating frequency and less current ripple, and maybe less DC ohms, and maybe pick up another 0.5% efficiency or so. (For lower operating freq CT should also be increased to 1.2nF or 1.5nF etc).

3. The PFET turnoff is too slow. Adding a cheap digital buffer IC could pick up 0.8-1.2% efficiency there from reduced switching losses and reduced loss from the 560 ohm resistor.

4. My PCB has very thin long tracks. Using a well designed PCB with thick short tracks for the main current paths might save 30 milliohms and give maybe 0.5% or more efficiency.

Bill of materials.
* 34063 SMPS 8pin IC (Fairchild/ON Semi/AIS etc, ie MC34063A or NCV34063A).
* 8pin IC socket (optional).
* PFET, rated more than double the input voltage and a few times the desired output current, preferably well under 0.1 ohm Rds on.
* Inductor L1 is a powdered iron toroid of 20-30 mm diameter, with thick wire >1.0mm preferred, 3A rated for a 1.5A capable supply. Value in the 150-470uH range, you may need to try a couple of different types. Ideally current ripple will be <50% at full output current.
* Schottky TO-220 dual 10A or dual 16A diode pack. Choose for low forward voltage, most brands are very good, parts can be found in any old PC PSU.
* 470-1000uF 35v electro cap.
* 1000uF 16-25v electro cap (25v will be larger and generally have a longer life).
* CT 1nF 25-50v ceramic or greencap.
* some 1/4W resistors; 560 ohm, 10 ohm, 6k8, 2k2.
* If you need a test load then a large 10W 4.7 ohm resistor will do.

Modifying the circuit for 12v car operation.
This circuit was designed for a car battery, generally 13.8v to 12.0v when running. If used in a car the circuit needs more protection as the Vin might be >15v at times. I would use a 100 ohm resistor instead of the 10 ohm resistor. Also a 13v zener diode across the 560 ohm resistor will add safety for the PFET. A 12v line filter might also be advised, they can be bought from auto stores.

Modifying the circuit for 24v operation.
Use 560 ohms instead of 10 ohms, so it now has two 560 ohm resistors. And again a 13v zener from PFET gate to source pin. With a 24v Vin you should use a higher inductor value and larger inductor core, 470uH and up are recommended.

[b]Modifying the circuit for high output currents.[b]
The circuit is meant for 5v out, 0-1.8A. It will do ok up to 2.5A just by changing the current limit resistor (at 2.5A the resitor should be 0.12 ohms or so).

Currents up to 5 amps or more should be ok, but use a larger inductor core size rated for more than the max amps you need, and again a larger inductor value helps >470uH is good. The diode pack will be fine, but the PFET should be rated for a few times more current than your max current. If needing 5A output I would use a 40-50v 60A TO-220 PFET which are a common size.

Changing output voltage.
Just change the 6k8 resistor, to change the output voltage to something other than 5.0v. Like most SMPS circuits it works best with roughly 2:1 Vin:Vout ratio, if using different ratios then again increasing the inductor value >470uH will help.


Source: http://forum.allaboutcircuits.com/showthread.php?t=7885 
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Precision full wave Rectifier Circuit Diagram

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The circuit provides accurate full wave rectification. The output impedance is low for both input polarities, and the errors are small at all signal levels. Note that the output will not sink heavy current, except a small amount through the 10K resistors. Therefore, the load applied should be referenced to ground or a negative voltage. Reversal of all diode polarities will reverse the polarity of the output

Since the outputs of the amplifiers must slew through two diode drops when the input polarity changes, 741 type devices give 5% distortion at about 300 Hz.


Precision full wave Rectifier Circuit Diagram

Precision full wave Rectifier Circuit Diagram

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400V-60W Push-Pull DC-DC Converter Circuit Diagram

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The TL494 switching regulator governs the operating frequency and regulates output voltage. Switching frequency approximately 100 kHz for the values shown. Output regulation is typically 15% from no-load to full 60 W.


400V-60W Push-Pull DC-DC Converter Circuit Diagram

400V-60W Push-Pull DC-DC Converter Circuit Diagram

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Simple Switching Regulator Circuit Diagram

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This is the simple switching regulator circuit diagram. The LTC10432 switched-capacitor building block provides nonoverlapping complementary drive to the Ql to Q4 power MOSFETs. The MOSFETs are arranged so that Cl and C2 are alternately placed in series and then parallel. During the series phase, the + 12 V battery`s current flows through both capacitors, charging them, and furnishing load current. 

During the parallel phase, both capacitors deliver current to the load. Ql and Q2 receive similar drive from pins 3 and 11. The diode-resistor networks provide additional nonoverlapping drive characteristics, preventing simultaneous drive to the series-parallel phase switches. Normally, the output would be one-half of the supply voltage, but C1 and its associated components close a feedback loop, forcing the output to 5 V. With the circuit in the series phase, the output heads rapidly positive. 

When the output exceeds 5 V, Cl trips, forcing the LTC1043 oscillator pin, trace D, high; this truncates the LTC1043`s triangular-wave oscillator cycle. The circuit is forced into the parallel phase and the output coasts down slowly, until the next LTC1043 clock cycle begins. Cl`s output diode prevents the triangle down-slope from being affected and the 100-pF capacitor provides sharp transitions. The loop regulates the output to 5 V by feedback controlling the turn-off point of the series phase.

Simple Switching Regulator Circuit Diagram


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Simple Hot-Lead Regulator Circuit Diagram

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This Simple Hot-Lead Regulator Circuit Diagram derives 5 Vdc from 2-AA cells—even at their end-life voltages of 1.05 V, and is approximately 80% efficient, providing 5 V at 4 mA from 2.1 V at 11 mA. IC1 is manufactured by Maxim Integrated Products, Inc.


Hot-Lead Regulator Circuit Diagram

Simple Hot-Lead Regulator Circuit Diagram

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Flyback Converter Circuit Diagram

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A low-current fly-back converter is used here to generate ±15 volts at 20 mA from a +5 volt regulated line. The reference generator in the SG1524 is unused with the input voltage providing the reference. Current limiting in a fly-back converter is difficult and is accomplished here by sensing current in the primary line and resetting a soft-start circuit.

Flyback Converter Circuit Diagram

Flyback Converter Circuit Diagram

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Build a Full Wave Rectifier Circuit Diagram

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This is the simple full wave rectifier circuit diagram.When equality of two equations shown in satisfied, full-wave output of circuit is symmetrical. The circuit uses a CA3140 BiMOS op amp in an inverting gain configuration.

Full Wave Rectifier Circuit Diagram

Full Wave Rectifier Circuit Diagram

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Simple Rapid Battery Charger Circuit Diagram

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This is the simple rapid battery charger circuit Diagram. Rectified and filtered voltage from the 24 Vac transformer is applied to the LM723 voltage regulator and the npn pass transistor set up for constant current supply. 

The 470 ohm resistor limits trickle current until the momentary pushbutton (S2) is depressed, the SCR turns on and current flows through the previously determined resistor network limiting the charging current. The SCR will turn off when the thermal cutout circuit inside the battery pack opens up. 



Simple Rapid Battery Charger Circuit Diagram


Simple Rapid Battery Charger Circuit Diagram


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Simple Dc/Ac Inverter Circuit Diagram

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This dc-to-ac inverter is based on the popular 555. A 555 oscillator circuit drives a buffer amplifier consisting of Ql, Q2, and Q3. 

The circuit operates at 150 to 160 Hz. Tl can be a 6.3-V or 12.6-V filament transformer as applicable.The frequency can be changed by changing the values of Rl and/or Cl.


Simple Dc/Ac Inverter Circuit Diagram

Simple Dc/Ac Inverter Circuit Diagram

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Inverter as High Voltage low Current Source Circuit Diagram

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The Inverter as High Voltage low Current Source Circuit Diagram is capable of providing power for portable Geiger counters, dosimeter chargers, high resistance meters, etc. The 555 timer IC is used in its multivibrator mode, the frequency adjusted to optimize the transformer characteristics. 

When the output of the IC is high, current flows through the limiting resistor, the primary coil to charge C3. When the output is low, the current is reversed. With a suitable choice of frequency and C3, a good symmetric output is sustained.


 Inverter as High Voltage low Current Source Circuit Diagram


Inverter as High Voltage low Current Source Circuit Diagram
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Simple Crowbar Circuit Diagram

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These circuits provide overvoltage protection in case of voltage regulator failure or application of an external voltage. Intended to be used with a supply offering some form of short circuit protection, either foldback, current limiting, or a simple fuse. The most likely application is a 5 V logic supply, since TTL is easily damaged by excess voltage. 

The values chosen in A are for a 5 V supply, although any supply up to about 25 V can be protected by simply choosing the appropriate zener diode. When the supply voltage exceeds the zener voltage +0 V, the transistor turns on and fires the thyristor. This shorts out the supply, and prevents the voltage rising any further. In the case of a supply with only fuse protection, it is better to connect the thyristor the regulator circuit when the crowbar operates. 

The thyristor should have a current rating about twice the expected short circuit current and a maximum voltage greater than the supply voltage. The circuit can be reset by either switching off the supply, or by breaking the thyristor circuit with a switch.


 Simple Crowbar Circuit Diagram

 Simple Crowbar Circuit Diagram

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Switch Selected Fixed Voltage Power Supply Circuit Diagram

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This Switch Selected Fixed Voltage Power Supply Circuit Diagram can serve as a battery eliminator for various devices (such as tape recorders, small radios, clocks, etc.). Si selects a resistance that is predetermined to provide a preselected output voltage. In this circuit, various commonly used supply voltages produced by batteries were chosen, but any voltages up to the rating of Tl (approximately) can be produced by choosing an appropriate resistor. Remember to provide adequate heatsinking for Ul.


Switch Selected Fixed Voltage Power Supply Circuit Diagram


Switch Selected Fixed Voltage Power Supply Circuit Diagram

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Switching Improves Regulator Efficiency Circuit Diagram

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In this circuit, a full-wave bridge is switched to a full-wave center tap to reduce regulator dissipation. SCR D6 switches between configurations. When D6 is off, the circuit is an FWCT rectifier using Dl, D2, and D5. It applies 17 V plus ripple to the regulator input. 

The drop across the regulator supplies base drive to Q2. If Q2 is on, Ql is off, and D6 is off. If the regulator voltage drops below about 3 V, Q2 turns off, and turns Ql on, which turns on D6. This changes the circuit to an FW bridge using Dl through D4.

Switching Improves Regulator Efficiency Circuit Diagram

Switching Improves Regulator Efficiency Circuit Diagram


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Charge Pool Power supply Circuit Diagram

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It is usually desirable to have the remote transmitter of a 4 to 20 mA current loop system powered directly from the transmission line. In some cases, this is not possible because of the high-power requirements set by the remote sensor/transmitter system. In these cases, an alternative to the separate power supply is still possible. 

If the remote transmitter can be operated in a pulsed mode where it is active only long enough to perform its function, then a charge pool power supply can still allow the transmitter to be powered directly by the current loop. In this circuit, constant current II is supplied to the charge pool capacitor, CP, ~! the HA-5141 (where II ~ 3 mA). 

The voltage VI continues to rise until the output of the HA-5141 approaches + V, or the optional voltage limiting provided by Z2. The LM2931 voltage regulator supplies the transmitter with a stable + 5 V supply from the charge collected by CP. Available power supply current is determined by the duration, allowable voltage droop on CP, and required repetition rate.

Charge Pool Power supply Circuit Diagram



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Rosalind Franklin birthday

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Rosalind Franklin,.
Molecular Biologist:

Rosalind Franklin (July 25, 1920 – April 16, 1958)

Rosalind Franklin, one the world’s most celebrated scientists, is also one of its most controversial. So controversial, in fact, that her work is the subject of a film, Race for the Double Helix, and two books, The Double Helix and Rosalind Franklin and DNA.

British molecular biologist Franklin was critical in discovering the structure of DNA. Her work has helped scientists understand how our genetic material is stored and copied. Yet when it was time to hand out Nobel prizes in 1962, they went to three male researchers, James Watson, Francis Crick and Maurice Wilkins. Franklin was shut out.

Rosalind Franklin,.    
Molecular Biologist: 

Rosalind Franklin (July 25, 1920 – April 16, 1958)

Rosalind Franklin, one the world’s most celebrated scientists, is also one of its most controversial. So controversial, in fact, that her work is the subject of a film, Race for the Double Helix, and two books, The Double Helix and Rosalind Franklin and DNA.

British molecular biologist Franklin was critical in discovering the structure of DNA. Her work has helped scientists understand how our genetic material is stored and copied. Yet when it was time to hand out Nobel prizes in 1962, they went to three male researchers, James Watson, Francis Crick and Maurice Wilkins. Franklin was shut out.

Franklin had been fighting for gender fairness since childhood. Her father pressured her to become a social worker because that was a traditional career for women. Eventually he relented and allowed her to attend Newnham College in Cambridge, where she obtained a degree in natural sciences in 1941. Next, she went to Cambridge University to get a doctorate in physical chemistry.

In 1951, after graduation, Franklin began work as a research associate at King’s College in London. The talented researcher was placed in charge of a DNA project. Unfortunately, women weren’t allowed in the university’s dining rooms or the pubs where her male colleagues would go to discuss their work. Franklin faced a major slight when Maurice Wilkins—a peer working on another DNA project—assumed she was an assistant because of her gender.

Two years later, Wilkins showed Franklin’s images of DNA to Watson without her permission. After viewing her work, Watson solved the mystery of DNA’s structure. Franklin was close to finding the answer, but Watson beat her to it, publishing a paper without fully crediting her.

In 1956, while studying the polio virus, Rosalind Franklin was diagnosed with ovarian cancer. She died less than two years later, at age 37. While Watson and his research partner, Francis Crick, eventually acknowledged the critical role of Franklin’s data, debate continues.
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2.5A-1.25 To 25V Regulated Power Supply Circuit Diagram

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This power supply uses an LM317J adjustable regulator and an MJ2955 pass transistor. Ql and U2 as well as Ul should be heats inked. A suitable heat-sink would typically be 4` 4` 1` fins, extruded type, because up to 65 W dissipation can occur. R8 and R9 should be 1% types or selected from 5% film types with an accurate ohmmeter. Capacitors are disc ceramic except for those with polarity marked, which are electrolytic. D1, D2—1-A, 100-PIV rectifier diode. DS1—Red LED. F1 —1,5-A, 3AG fuse in chassis-mount holder. J1, J2—Standard five-way binding post, one red, one black. M1—Milli-ammeter, 0-1 mA dc. Q1—NPN power transistor MJ2955 (Radio Shack) or equiv device with a + 70-V, 10-A, 150-W rating in a -204 case. R1, R2, R7—5-W wire-wound resistor. See Notes 3 and 4 for source, or, use 17 inches of no. 28 enam wire, single-layer wound, on a 10-KOhmhm, 1-W carbon-composition resistor for R1 and R7. For R2, use 36 inches of no. 30 enam wire on a 10-KOhmhm, 1-W carbon composition resistor (scramble wound). R-4—Panel-mount, 5-kfi, 2-W or 5-W potentiometer, carbon or wire wound (See Note 8). R8, R9—See text. 51—SPST toggle switch. 52—DPDT toggle or rotary wafer switch. T1—25.2-V, 2.75-A power transformer (see text). U1—6-A, 200 PIV bridge rectifier with heat sink. See text. U2—LM317T +1.25- to 30-V, 1.5-A 7-220 regulator. Use an LM317HVK (T0-204 case) for dc output voltage greater than 40. See text.

2.5A-1.25 To 25V Regulated Power Supply Circuit Diagram

2.5A-1.25 To 25V Regulated Power Supply Circuit Diagram

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12V Latch Circuit Diagram

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This circuit controls a solenoid by the operation of a single push-button switch. The circuit will supply loads of over 1 A and can be operated up to a maximum speed of once every 0.6 second. When power is first applied to the circuit, the solenoid will always start in its off position. Other features of the circuit are its automatic turn-off, if the load is shorted, and its virtually zero-power consumption when off.

12V Latch Circuit Diagram

12V Latch Circuit Diagram

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50W Offline Switching Power supply Circuit Diagram

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The schematic shows a 50W power supply with a 5-V 10-A output. It is a fly back converter operating in the continuous mode. The circuit features a primary side and secondary side controller will full-protection from fault conditions such as over current. After the fault condition has been removed, the power supply will enter the soft-start cycle before recommencing normal operation.

50W Offline Switching Power supply Circuit Diagram

50W Offline Switching Power supply Circuit Diagram

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High Voltage DC Generator Circuit Diagram

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This circuit is fed from a 12-V de power supply. The input to the circuit is then amplified to provide a 10,000-Vdc output. The output of the up-converter is then fed into a 10 stage, high-voltage multiplier to produce an output of 10,000 Vdc.


High Voltage DC Generator Circuit Diagram

High Voltage DC Generator Circuit Diagram

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Super Universal Battery Charger Circuit Diagram

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The Super Universal Battery Charger Circuit Diagram output voltage is adjustable and regulated, and has an adjustable constant-current charging circuit that makes it easy to use with most NiCad batteries. The charger can charge a single cell or a number of series-conoected cells up to a maximum of 18 V. 

Power transistors Ql and Q2 are conoected as series regulators to control the battery charger`s output voltage and charge-current rate. An LM317 adjustable voltage regulator supplies the drive signal to the bases of power transistors Ql and Q2. Potentiometer R9 sets the output-voltage level. A current-sampling resistor, R8 (a 0.1-!J, 5-W unit), is conoected between the negative output lead and circuit ground. For each amp of charging that flows through R8, a 100 mV output is developed across it. 

The voltage developed across RS is fed to one input of comparator U3. The other input of the comparator is connected to variable resistor RIO. As the charging voltage across the battery begins to drop, the current through RS decreases. Then the voltage feeding pin 5 of U3 decreases, and the comparator output follows, turning Q3 back off, which completes the signal`s circular path to regulate the battery`s charging current. The charging current can be set by adjusting RlO for the desired current. The circuit`s output voltage is set by R9. 

Super Universal Battery Charger Circuit Diagram

Super Universal Battery Charger Circuit Diagram
 


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Simple split power supply circuit Diagram

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This circuit utilizes the quasi-complementary output stage of the popular LM380 audio power IC. The device is internally biased so that with no input the output is held midway between the supply rails Rl, which should be initially set to mid-travel, is used to nullify any inbalance in the output. 

Regulation of Vout depends upon the circuit feeding the LM380, but positive and negative outputs will track accurately irrespective of input regulation and unbalanced loads. 

The free-air dissipation is a little over 1 watt, and so extra cooling: may be required. The device is fully protected and will go into thermal shutdown if its rated dissipation is exceeded. Current limiting occurs if the output current exceeds 1 A. The input voltage should not exceed 20 V.

Simple split power supply circuit Diagram

Simple split power supply circuit Diagram

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Simple Squib Firing Circuit Diagram

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This is a Simple Squib Firing Circuit Diagram . Capacitor Cl is charged to +28 V through Rl and stores energy for firing the squib. A positive pulse of 1 mA applied to the gate of SCR1 will cause it to conduct, discharging Cl into the squib load XI. 

With the load in the cathode circuit, the cathode rises immediately to + 28 V as soon as the SCR is triggered on. DiodeD1 decouples the gate from the gate trigger source, allowing the gate to rise in potential along with the cathode so that the negative gate-to-cathode voltage rating is not exceeded. 

This circuit will reset itself after test firing, since the available current through Rl is less than the holding current of the SCR. After Cl has been discharged, the SCR automatically turns off—allowing Cl to recharge.

Squib Firing Circuit Diagram


Squib Firing Circuit Diagram

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Variable Zener Diode Circuit Diagram

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The circuit behaves like a zener diode over a large range of voltages. The current passing through the voltage divider R1-R2 is substantially larger than the transistor base current and is in the region of 8 mA. The stabilizing voltage is adjustable over the range 5-45 V by changing the value of R2. The total current drawn by the circuit is variable over the range 15 mA to 50 mA.This value is determined by the maximum dissipation of the zener diode. In the case of a 250 mW device, this is of the order of 50 mA.

Variable Zener Diode Circuit Diagram

Variable Zener Diode Circuit Diagram

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Ni-cad Charger Circuit Diagram

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Ni-cad charger with current and voltage limiting. Lamp LI will glow brightly and the LED will be out when the battery is low and being charged, but the LED will be bright and the light bulb dim when the battery is almost ready. Ll should be a light bulb rated for the current you want (usually the battery capacity divided by 10). Diode D1 should be at least 1 A, and Z1 is a 1W zener diode with a voltage determined by the full-charge battery voltage minus 1 V. After the battery is fully charged, the circuit will float it at about battery capacity divided by 100 mA.

Ni-cad Charger Circuit Diagram


Ni-cad Charger Circuit Diagram

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Power Supply Balance Indicator Circuit Diagram

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This circuit uses two comparator pairs from an LM339N quad comparator; one pair drives the yellow positive (+)and negative (-)indicators, the other jointly drives the red warn LED3. The circuit draws its power from the unregulated portion of the power supply. The four comparators get their switching inputs from two parallel resistor-divider strings. Both~strings have their ends tied between the power supply`s positive and negative output terminals. 

The first string, consisting of R4, R5, and R6, divides the input voltage in half, with output taps at 0.5%. The other string, made up of R7, R8, and R9, also divides the input voltage in half, with taps at + lO%. The 0.5% R4/R5/R6 string drives the two comparators controlling the positive and negative indicators (LEDl and LED2). Their inputs are crossed so that LED2 does not fire until the positive supply is at least 0.5% higher than the negative; the positive indicator does not go off until the negative supply is at least 0.5% higher than the positive-in relative levels. 

That overlap permits both LEDs to be on when the two supplies are in 1 % or better balance. The +lOT R7/R8/R9 string drives the other two comparators, which control the warn indicator. If either side of the supply is lO% or more higher than the other, one of the two comparators will switch its output low and light the redLED3the LM339N has opened-collector outputs, allowing such wired OR connections. The inputs are not crossed, as with the other comparator pair, so there is a band in the middle where neither comparators output is low and the LED remains off.

Power Supply Balance Indicator Circuit Diagram

Power Supply Balance Indicator Circuit Diagram

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Offline Converter Circuit Diagram

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This nonisolated, unregulated, minimum component converter fills the void between low-power zener regulation and the higher power use of a 60-Hz input transformer. It is intended for use where)`er a nonisolated supply can be used safely. 

The circuit operates~by conducting only during the low-voltage portion of the rectified sine wave. Rl and D2 charge Cl to approximately 20 V, which is maintained by Ql. This voltage is applied to the gate of Q2, turning it on. When the rectified output voltage exceeds the zener voltage ofD4, Ql turns on, shunting the gate of Q2 to ground, turning it off.

Offline Converter Circuit Diagram


Offline Converter Circuit Diagram

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Super High Power Portable TV and FM Jammer Circuit Diagram

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This is the Super High Power Portable TV and FM Jammer Circuit Diagram. There are still neighbors that keep annoying you by having loud the TV or the radio? Well I have you the solution. In fact all neighborhood will face your jamming waves at their TVs and radios, so be careful. 

This Jammer is the improved version of the old `TV and FM jammer schematic` with the difference of much higher power. Many of you where asking for a stronger and wider effect but to be as portable as can be. Looking at the schematic you can see that, only the parts are changing keeping the basic circuit intact. Have in mind that this version needs heat sink and antenna to keep the transistor alive.

Super High Power Portable TV and FM Jammer Circuit Diagram

Super High Power Portable TV and FM Jammer Circuit Diagram



The power source comes from three 9 volt batteries in series, so we use 27 volts at input, and we get a power full 2,5 Watts at output.  
 
You are going to need 70cm to 2 meter simple wire antenna.  
 
As for the transistor Q its the 2N3553. Its a RF Power Silicon NPN Transistor in a TO39 type  package designed to be used in amplifiers and oscillator applications in military and industrial equipment.
  
Usually found as an output driver, or in predriver  stages in VHF equipment, but because here we don't care about the modulation of the signal but just the power, that's why we use it as a first and final output driver. 
The transistor is specified at 175MHz and 28V to give: Output Power: 2.5W, Minimum Gain: 10dB and Efficiency: 50%. 
 
The parts are: R1=10k, R2=2,2K, R3=100 C1=47uF/50V, C2=2.2nF, C3=10pF, SW=switch, B=Battery 9V. 
 
The coil L should be closely wound 5 turns (start tunning with the closely wound distance of turns and then play with it and the C4 capacitor, to find the desired frequency )of enameled copper wire 1.5mm and internal coil diameter of 1cm (leads 2x20mm). 
 
The variable capacitor C4 should be air trimmer capacitor rating 4 to 30 pf or the closest to this value. 
 
Connect the batteries in series place the best heat sink for TO39 case you can get and pack it all in a small plastic box. Enjoy ;)



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Power Supply Monitor-Memory Protector Circuit Diagram

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This Power Supply Monitor-Memory Protector Circuit Diagram detects low-voltage supply conditions, down to 0.6 V. Dl sets the trip point of the circuit. The circuit is useful to protect memory circuits from accidental writes in the event of power-supply low-voltage conditions, which cause other circuits to turn off, etc. Response time is about 700 ns. R6 provides some hysteresis to ensure clean transitions.

Power Supply Monitor-Memory Protector Circuit Diagram

Power Supply Monitor-Memory Protector Circuit Diagram

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13.8Vdc 2A Regulated Power Supply Circuit Diagram

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This 13.8Vdc 2A Regulated Power Supply Circuit Diagram consists of step-down transformer Tl, a full-wave rectifier bridge (D1 through D4), and a filtering regulator circuit made up of Cl, C2, Rl, R2, R8, D5, and Ql, When 120 Vac is provided, the neon-lamp assembly LI lights up, and transformer Tl changes 120 Vac to about 28 Vac. 

The rectifier bridge, )1 through D4, rectifies the ac into pulsating dc, which is then filtered by Cl. Capacitor Cl acts as a storage capacitor. Zener diode 1)5 keeps the voltage constant across the base of Darlington regulator Ql, causing constant voltage across resistor R3 and the (+) and (-) output terminals, where the load is connected. Fuse F2 is used to open (blow), if the current through the output terminals is too high. Make sure to take proper precautions when using projects powered by 120 Vac.

 13.8Vdc 2A Regulated Power Supply Circuit Diagram


13.8Vdc 2A Regulated Power Supply Circuit Diagram

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Battery Charge-Discharge Indicator Circuit Diagram

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This Battery Charge-Discharge Indicator Circuit Diagram monitors car battery voltage. It provides an indication of nominal supply voltage as well as low or high voltage. RV1 and RV2 adjust the point at which the red/yellow and yellow/green LEDs are on or off. For example the red LED comes on at 11V, and the green LED at 12V. The yellow LED is on between these values.


Battery Charge-Discharge Indicator Circuit Diagram

Battery Charge-Discharge Indicator Circuit Diagram

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100Khz Multiple Output Switching Power Supply Circuit Diagram

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The 100Khz Multiple Output Switching Power Supply Circuit Diagram uses two VN4000A 400-V MOSPOWER FETs in a half-bridge power switch configuration. Outputs available are + 5 Vat 20 A and ±15 V (or ±12 V) at 1 A. Since linear three-terminal regulators are used for the low-current outputs, either ±12 V or ±15 V can be made available with a simple change in the transformer secondary windings. 

A TU94 switching regulator IC proVides pulse-width modulation control and drive signals for the power supply. The upper MOSPOWER FET, Q7. in the power switch stage is driven by a simple transformer drive circuit. The lower MOS. Q6, since it is ground referenced. is directly driven from the control !C.

 100Khz Multiple Output Switching Power Supply Circuit Diagram

100Khz Multiple Output Switching Power Supply Circuit Diagram

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High Voltage Regulator Circuit Diagram

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The High Voltage Regulator Circuit Diagram delivers 100-V at 100 mA and withstands shorts to ground. Even at 100 V output, the LT317A functions in the normal mode, maintaining 1.2 V between its output and adjustment pin. Under these conditions, the 30-V zener is off and Ql conducts. When an output short occurs, the zener conducts, forcing Q1`s base to 30 V. 

This causes Q1`s emitter to clamp 2 VnEs below Vz. well within the V.w VouT rating of the regulator. Under these conditions, Q1, a high-voltage device, sustains 90 V-VcE at whatever current the transformer specified saturates at 130 mA, while Q1 safely dissipates 12 W. If Q1 and the LT317 A are thermally coupled, the regulator will soon go into thermal shutdown and oscillation will commence. 

This action will continue, protecting the load and the regulator as long as the output remains shorted. The 500-pF capacitor and the 10 0/0.02 11F damper aid transient response and the diodes provide safe discharge paths for the capacitors. 

High Voltage Regulator Circuit Diagram

High Voltage Regulator Circuit Diagram
 


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Tracking Dual Output Bipolar Supply Circuit Diagram

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This Tracking Dual Output Bipolar Supply Circuit Diagram is useful for a bench supply in the lab. Separate or tracking operation is possible. The regulators should be properly heatsinked. Tl is a 24-Vac wall transformer of suitable current capacity. 

Tracking Dual Output Bipolar Supply Circuit Diagram 

Tracking Dual Output Bipolar Supply Circuit Diagram

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Current to Voltage Converter Circuit Diagram

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A filter removes the dc component of the rectified ac, which is then scaled to RMS. The output is linear from 40 Hz to 10 kHz or higher.

 Current to Voltage Converter Circuit Diagram

Current to Voltage Converter Circuit Diagram

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Hand Held Transceiver dc Adapter Circuit Diagram

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This Hand Held Transceiver dc Adapter Circuit Diagram provides a regulated 9-V source for operating a Kenwood TR-2500 hand-held transceiver in the car. The LM317T`s mounting tab is electrically connected to its output pin, so take this into account as you construct your version of the adapter. The LM317T regulator dissipates 2 or 3 W in this application, so mount it on a 1-x -2-inch piece of `is-inch-thick aluminum heatsink. 

 Hand Held Transceiver dc Adapter Circuit Diagram

Hand Held Transceiver dc Adapter Circuit Diagram

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Precision Voltage Inverter Circuit Diagram

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This Precision Voltage Inverter Circuit Diagram allows a reference to be inverted with 1 ppm accuracy, features high input impedance, and requires no trimming.

Precision Voltage Inverter Circuit Diagram 

Precision Voltage Inverter Circuit Diagram

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Super Ni-Cd Battery Charger 12-18V Circuit Diagram

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A clever charger circuit that safely can charge any Ni-Cd battery. Offers charge current sellection, polarization detection and protection and the ability to connect many batterys in siries. Ni-Cd bateries can be recharged more than 1000 times before become useless. the charging current shoud be the 1/10 of the (Ah) of the battery. The bateries need 14 hours to be fully charged.Swhitch S2 is the current selection as folows: 50mA, 200mA and 400mA. LED D10 is the indicator for proper batery connection and/or wrong polarity checking. LED D9 is the charging indicator. The transformer is a 220V/2x12V 0.5A. 

Super Ni-Cd Battery Charger 12-18V Circuit Diagram


Super Ni-Cd Battery Charger 12-18V Circuit Diagram





 PARTS LIST
R1,R4,R5=10K 
R2,R3=100K 
R6,R8,R10=1K 
R7=820 
R9=100 
R11=15 
R12=3,9 
R13=1,8 
C1=1000uF/40v 
C2=470pf 
D1-D4,D6=1n4001-7 D7,D8=1n4148 
D9,D10=LED IC=741 
TR1=BC548 
TR2=BD137 
TR3=2N3055

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Basic single-supply voltage regulator Circuit Diagram

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The circuit uses a CA3140 BiMOS op amp capable of supplying a regulated output that can be adjusted from essentially 0 to 24 volts. The circuit is fully regulated.

 Basic single-supply voltage regulator Circuit Diagram


Basic single-supply voltage regulator Circuit Diagram
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Simple 8V From 5V Regulator Circuit Diagram

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If you have trouble locating an 8-V regulator, although they are commonly available,a 5-V unit can replace it by connecting the regulator, as is shown here. 

 Simple 8V From 5V Regulator Circuit Diagram


Simple 8V From 5V Regulator Circuit Diagram
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Over voltage Protection for Logic Circuit Diagram

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Zener diode ZD1 senses the supply, and should the supply rise above 6 V, Ql will turn on. In turn, Q2 conducts clamping the rail. Subsequent events depend on the source supply. It will either shut down, go into current limit or blow its supply fuse. None of these will damage the TTL chips. The rating of Q2 depends on the source supply, and whether it will be required to operate continuously in the event of failure. Its current rating has to be in excess of the source supply. 


 Over voltage protection for logic Circuit Diagram


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Build a high-volt supply Circuit Diagram

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A light dimmer, a 1 µf capacitor and a 12 V car ignition coil form the simple line powered HV generator. The current in the dimmer is shown in Fig. B. At times tp t2, set by the dimmer switch, the inner triac of the dimmer switches on, and a very high and very fast current pulse charges the capacitor through the primary of the induction coil. 

Then at a rate of 120 times per second for a 60 Hz line, a very high voltage pulse appears at the secondary of the coil. To obtain an HV dc output, use a voltage doubler. Dl and D2 are selenium rectifiers (TV 18 Siemens or ITT) used for the supply of television sets. High value output shock protection resistors, R, are recommended when suitable. 

 Build a high-volt supply Circuit Diagram

Build a high-volt supply Circuit Diagram

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