Variable dc to dc converter circuit,free globe internet on phone,telephone directory thames nz - Videos Download

27.11.2015
Random electronic project: Nicd Nimh Battery Charging Circuit PIC16F876 Delta-Peak suggest reading the article.
Ni-cd, Ni-mh battery charger as a power supply used in digital circuit PIC16F877 microcontroller source software used and the file’s schema. A textbook TL494 circuit, this produces regulated 24V from a 12V input (automotive, perhaps).
This circuit was designed to use a quad of droolingly high current darlingtons I obtained from an old school reel-to-reel data tape drive. Bipolar transistors, particularly those with symmetrical junctions, also make excellent analog switches. While entertaining myself brainstorming LED lighting driver circuits, I created this circuit, which drives a series of LEDs from a higher voltage source using a buck switching regulator. A representative schematic for a current-mode induction heater, inspired by the textbook CFL circuit. A simple differential amplifier circuit, which can be used directly as a simple discrete operational amplifier. Logic level input, speaker driver circuit, for audio demonstration of the pseudorandom generator above. A typical RTL (Resistor-Transistor Logic) flip-flop, with edge triggered input A and level triggered input B. A high current regulated electrolysis power supply, with high efficiency, high power factor and digital control. Inspired by CC_Buck.png above, this circuit drives a series chain of LEDs from a high voltage supply, wasting no power on a series dropping resistor. Representative diagram of an LLC output network, typical of quasi-resonant switching supplies and early induction heater designs. A latch suitable for overload protection, this circuit block comes from my newer induction heater circuit.
The complete circuit, showing two power mirrors (as above), the mirrors to drive them, and the bootstrap supplies as required. This circuit was built to observe photoflash response; the compensation was developed based on the square wave response to a superbright red LED (which, amazingly, was just barely visible to the black-cased photodiode).
This simple circuit contains a hysteresis oscillator and pulse width modulation comparator. A single transistor self-excited blocking oscillator, this flyback supply is capable of a reasonable 30W output in a surprisingly small size, at a maximum frequency of 200kHz.
A possible (partial) formulation for the solution to the "resistance of two points in an infinite grid of resistors" nerdsniping problem.
A high bandwidth, high impedance, temperature compensated buffer stage suitable for an oscilloscope.
A remarkably simple "discrete" 12V regulator; functionally similar to a 7812, though the dropout voltage will be lower at low current. This preamplifier is intended for high bandwidth and could be used as a gain-of-10 block in an oscilloscope.
Then open up the case of the desktop computer and hook up the input line of is circuit to a free available (hanging) four-pin drive power connector of the SMPS properly. The addition of variable frequency drives will provide the pump station with efficient operation, which will lead to energy savings for the customer.
Consider the application of a drive to a cane milling unit where the speed is to be variable from full to half rated speed. This state of affairs would, in all probability, be unacceptable and can only overcome by installing an over-size turbine. The turbine is basically a constant speed device and if it is called upon to operate at a speed other than that for which it is designed, its efficiency drops and it becomes an uneconomical prime mover. A variable-frequency drive (VFD), also termed adjustable-frequency drive, variable speed drive, AC drive, micro drive or inverter drive is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage.
Instead of placing line reactors in series with the VFD, a DC choke can be added to the drive’s DC bus reducing approximately the same amount of harmonics as the AC reactor. Passive filters consist of static components like inductors, capacitors, and resistors arranged in predetermined fashion to either attenuate the flow of harmonic currents through them or to shunt the harmonic component into them. There are several types of passive filters but the most effective is the low pass broadband filter, which offers great performance and versatility with low risk of resonance with the line.
Apart from the active front ends, there also exist active shunt filters that introduce a current waveform into the distribution network that when combined with the harmonic current cancels the later and results in an almost perfect sinusoidal waveform. The advantages of HT VFDs over LT VFDs are quite appealing……but how can HT VFD be an alternative if the driven motors installed are of such capacity for which HT voltage levels are impractical??
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This is a high quality bench power supply with adjustable output voltage from 0 to 30V and adjustable output current from few miliamperes to 4 amperes. If you are starting to learn electronics variable bench power supply is the first thing you should build to power your projects.
I normally use a USB port as power supply for my projects but some ICs need 3.3V instead of 5V. A few useful application circuits using IC LM317, collected from National Semiconductor's PDF datasheet are meticulously explained in this section with the help of the relevant circuit diagrams.
An 50v bench power supply can be made using electronic diagram below which is designed using LM10 op amp and 2n3055 transistors. This is a basic universal variable Power Supply voltage regulator circuit using an LM317, 3-terminal regulator in a TO-220package.
Such a relay would be quite difficult to find, so I designed this, it is a simple two transistor circuit which will switch off the output should the voltage raise above 6.2v this can be changed by selecting a different value of zener diode. Presented here is a circuit for 30V 10A variable bench power supply that offers variable voltage and current adjustment. This isn’t strictly astro stuff but the main reason I built it is to experiment with TFT backlight panels that I use for my lightboxes. Here's variable power supply voltage regulator circuit based around LM317 that provides fully regulated output voltage between 1.25 and 37v with current up to 1A.
100Ω resistors are used for stability and prevent current swamping as the tolerances of dc current gain will be different for each transistor. The linear laboratory power supply, shown in the schematic, provides 0-30 volts, at 1 amp current, using a discrete transistor regulator with op-amp feedback to control the output voltage. Remote sensing means there are two additional wires which sense the delivered voltage at the load and compensate for any voltage drop along the cables which carry the delivered current. I like to have a switch which lets me choose between limiting the output current continuously (useful for charging batteries), or shutting down the output if the current limit is reached (useful for protecting equipment being repaired). Another thing I like to have in the power supplies I build is a push button switch which multiplies the current scale by a factor of 10. This is a DC power supply circuit using the LM317T voltage regulator IC, which is the IC of this type is very popular among electronics hobby. LM317 output voltage of this circuit is 6V DC, source from the stress out of the 12V CT AC transformer, and then converted to DC half-wave voltage by diodes D1-D2, and filtered by C1 capacitor.
I'm replacing my old power-hog home server with a new one based on the Intel D945GSEJT mainboard. With a maximum capacity of 20 volts and 1 amp, it will supply most of your projects, it's greatest quality is the protection all your projects, it is capable of limiting the maximum current to as low as 1mA, saving your ICs and transistors in case of an accidental short circuit during the experimenting period of your projects.
As you might expect, I have several power supplies that have more than enough capacity to power my new KN-Q7 transceiver.


The high current regulator below uses an additional winding or a separate transformer to supply power for the LM317 regulator so that the pass transistors can operate closer to saturation and improve efficiency.
Amateur radio has been somewhat slow to accept switching power supplies for powering communication equipment. Some early switchers produced an objectionable amount of RF noise, bringing the whole switching technology into bad reputation. For circuits using TTL ICs the supply voltage is a great concern and a slight increase in supply from the rated 5V may damage the IC. The selected switching topology is called a "push-pull" converter, because the transformer has a double primary (or a "center-tapped" one, if your prefer). A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist's workbench. The main balanced power supply is constructed with the usual suspects, 7815 (pos 15 volt regulator) and 7915 (neg 15 volt regulator). I frequently have a need for a variable supply when testing homebrew circuits, and the triple power supply is just what I need on the bench. Many times we needed one relatively powerful supply in order to we supply various appliances with + 13.8V, as transceivers CB, charge lead-acid batteries, etc. By applying the input voltage from 3v to 15v outlet will receive a fixed value that you set. One output is shown; more LM393 or 339 sections can be added to expand the number of outputs.
It is possible to also work with your digital multimeter in case the digital voltmeter isn’t around.
Refer refer to the following picture for the pin configuration of LM317, just before soldering it on the PCB. When this occur while the turbine is running at rated speed and under full throttle, it will be incapable of supplying the extra torque unless it slows down. It is interesting to note that the installed turbine horsepower of most installations is twice that which is required to mill the rated quantity of fiber. Some types of single-phase motors can be used, but three-phase motors are usually preferred.
Elevated voltage stresses imposed on induction motors that are supplied by VFDs require that such motors be designed for definite-purpose inverter-fed duty in accordance to such requirements as Part 31 of NEMA Standard MG-1. This is a relatively inexpensive solution and can lower harmonics by 50% depending on the amount of impedance added to the line.
The advantage of DC chokes is they are smaller in size and are often mounted inside the VFD.
Active filters, or active front ends, use dynamic switches like IGBTs and other power components to stop harmonics from occurring in the first place. As such the Co-Gen sugar plant generating 11KV system voltage, the 11KV VFD drives can be used in the place LT – VFD Drives. An attempt can be made in Co-gen sugar plants using 11KV VFD drives system in the milling plant and avoid step down Transformers. Every day, the generation and usage of energy produces more pollution than any other single industry. Built-in electronic output current limiter that effectively controls the output current makes this power supply indispensable in the experimenters laboratory as it is possible to limit the current to the typical maximum that a circuit under test may require, and power it up then, without any fear that it may be damaged if something goes wrong. The IC LM317 is so versatile that an almost unlimited number of different, small, high grade power supply circuits can be built using it.
Max input voltage is 37V and output is adjustable via potentiometer between 1.2 up to 36 volts. It has been built to power three OPA627 opamps of Audio DAC I am building with PCM1792 & PCM1794 chips.
This LM10 2n3055 50v bench power supply allows an output voltage regulation in a range between 0 and 50 volts and the output current can be limited to a maximum of 2A.
The Universal Power Supply output voltage can be set to anywhere in the range 1.5V to 30V by selecting two resistances. It is a voltage regulator that allows a 6V portable supply to be derived from the 12V car battery.
Most are designed to convert high voltage AC mains electricity to a suitable low voltage supply for electronics circuits and other devices. In many cases we can manage with a suitable fixed voltage regulator such as 5v or 12v, but occasionally we need a non-standard voltage.
Power supply uses LM7812 IC and can deliver up to 30A to the load by the help of the TIP2955 pass transistors. A 1 amp fuse is connected after the LM7812 to protect the IC against high current transients. When the load current is high, the power dissipation of each transistor also increases so excess heat may cause the transistors to fail. The supply was constructed in 1975 and has a constant current mode that can be used to recharge batteries. This improves voltage regulation at the load considerably but requires two additional wires for the sensing. That way one can momentarily press the button and get a much more precise reading of current.
Parameter to regulate the output DC voltage carried by the LM317 circuit with a maximum current of 1A.
Diodes D3-D4 on the LM317 voltage current circuit to protect poor return for LM317 circuit IC. However, my largest power supply is normally connected to my main 100W PEP SSB transceiver. For good efficiency the voltage at the collectors of the two parallel 2N3055 pass transistors should be close to the output voltage. This is a pity, because "switchers", as they are often called, offer very attractive features, like small size, low weight, high efficiency, and low heating. But by proper design techniques and careful EMI filtering it is possible to build very quiet switchers. Using fuses alone does not solve the problem because a fuse may take several milliseconds to blow off and that’s enough time for the IC to get damaged. The center tap is permanently connected to the car battery (via an LC filter to avoid creating peaks in the battery lines, which could affect other electronic equipment in the car).
In the previous article I talked about the first approach the LM317 constant current source which didn’t worked out that well but could of been improved as suggested by some of my readers in the comments.
This circuit is not an absolute novelty, but it is simple, reliable, "rugged" and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A.
There is absolutely nothing special about the circuit, except that as shown, it is quite capable of up to 20 Amps intermittently or 10A continuous.
The circuit it uses known completed that is capable gives in the his exit, current in continuous operation 5A and 12A peak current. An adjustable three-pin voltage regulator chip LM317T (IC1) is applied right here to deliver the desired voltages. Switch on S1 and set the needed voltage through potensiometer VR1 and start reading it on the digital voltmeter.
Cane mills are invariably run at speeds other than their rated full speed and it is under these conditions that the turbine suffers its greatest drawback. Various types of synchronous motors offer advantages in some situations, but three phase induction motors are suitable for more purposes and are generally the most economical choice. Current flow through a switch is manipulated to recreate a waveform that linearly follows the applied voltage waveform.


There is also a visual indication that the current limiter is in operation so that you can see at a glance that your circuit is exceeding or not its preset limits. The LM317 is one of the most popular voltage regulators on the market, and for good reason. Power supply uses two low dropout voltage regulators that provide up to 800mA of output current and come in TO-220 package.
The configurations can be introduced for different applications for upgrading an existing unit with features that would virtually make it indestructible.
Output voltage increases linearly with the amount of resistance potentiometer P1, while the current can be adjusted linear using potentiometer P3. By using a potentiometer, R2, as one of the resistors you can dial up the output voltage wanted. Most parts are easily accessible, including a 6"x3"x2" project box, 12V 1.2A center tap transformer, pots, knobs, etc. A power supply can by broken down into a series of blocks, each of which performs a particular function. A switch allows internal sensing at the output terminals for simpler operation when remote sensing is not required. By making the switch a push button one cannot forget to turn the function off and risk the instrument being damaged when a large current is put through it.
This is a very interesting circuit if you have a large toroid with big electrolytic caps connected to the power supply, since these will act like short circuits for a small amount of time if they start charging. As for the other capacitors C3-C4 is used to refine the output voltage, and complete power supply circuits.
True, they are generally more complicated than linear power supplies, but this is easily compensated by the fact that they can be built for a lower cost. The two ends of the primary are connected to a pair of paralleled MOSFETs each that tie them to ground in each conduction cycle (Vgs of the corresponding MOSFET high). I have use four diodes in a bridge rectifier configuration rather than a dedicated bridge rectifier as people have had trouble finding P04 and W04 rectifiers and it allows you to get esoteric with low noise switching diodes. I did add a few things, but it's essentially the same and I am not writing here to claim any shred of originality. Only current adjust is missing but I overcome this situation by using an LCD panel ampermeter. The LM317T regulator, in TO-220 pack, could deal with current of approximately 1 ampere in reality. Reference to the steam consumption at constant torque and variable speed, the horsepower at constant torque is proportional to speed. To achieve the multiple pulse effect, additional converter bridges and phase shifting transformers are used making the solution expensive and increasing panel size. LM317 is the most useful and inexpensive adjustable regulator and for this circuit you can also use LM317L that can give 100mA, that's enough for transistor bias.
If you could find a relay that would operate from 6.2V right up to 12v that you could connect in such a way that if over voltage occurred, then the relay would automatically switch off the output preventing damage to any connected equipment. I have had this circuit in use now for over 20 years and has never let me down and is one of the most handiest gadgets i have built.
This is a cool way of making an old wall-wart (plug in power supply) into a useful USB power supply and requires very few extra components.
In this case and for now I am not installing this function because I am using the instrument's shunt resistor to sense the current for the electronic control system and I would have to change several things.
The disadvantage of this circuit is the danger of an electrical shock, so it cannot be used if the circuit is in contact with the user. The reason I chose this board is that it consumes 13W in idle and 18W under full CPU and GPU load which is pretty much the lowest power consumption one can get with an Atom system (excluding some server-specific boards that were beyond my budget).
The main supply must be connected to a rectified source (transformer + 20-30A bridge rectifier).
I also have a smaller 8A power supply, but I use this to power some other VHF and UHF transceivers. Another advantage of this circuit, when the drawn current exceeds 1A (practically 0.85A), the current protector in LM317 intervens and LED indicator warns you about the very low output voltage. I used the simple and easy to get IN4004 but some at Tech Talk have suggested more exotic devices. I spent somewhere around 80$ US on the project (including the GIANT transformer), which isn't bad compared with commercial supplies boasting similar features.
If you choose one Ampere 1 wherein the charge in the battery if you connect five pieces in series you connect the battery.
Diode D2 keeps the output voltage from increasing above the input voltage when a capacitive or inductive load is hooked up at the output. D1 and D2 are protection diodes because when you turn the circuit off the output capacitors are discharging and can damage the transistor or regulator.
To be safe for continuous operation the maximun input DC voltage to the regulator should not be over 33V. With a stronger external power supply the total output current can be higher, up to 1.5A per output.
It?s not obligatory to use one but it is a good idea, specially if you have a big toroidal transformer larger than 300 VA. Not wanting to use an ATX PSU I've decided to build a completely new power supply for the board. This technique can also be applied to other dc-dc converters with a bit of reading on the subject. Board has been drawn so as to exist the possibility of using also two case types completing. Please note that I DID find a few minor errors in Kilpatrick's schematic, which have been fixed here. 100nf capacitors are in parallel with electrolytic capacitors to remove high frequency noise because large value electrolytic have large ESR and ESL and can't remove high frequency noise. On the secondary side of transformer are connected two fuses 100mA and after them is bridge rectifier.
This unit has a delay circuit and for the delayed time the mains power is supplied through power resistors minimizing in this way the big inrush current due to big capacitors and big toroidal transformers in the power supply. In the first case the IC1 in case TO-220 is placed above in pcb, in second with case TO-3, it can it�s placed above in heatsink and terminal his they are connected in the connector G3, in this case, certain we leave empty the place of IC1 above in pcb. The input DC voltage to the regulator must be at least 2.5V above the required output voltage. D5, C4, C5, R15, and R16 provide a small amount of negative supply for the op-amps so that the op-amps can operate down to zero volts at the output pins (pins 6). When everything is stable it shorts the power resistors and supplies the mains power directly. Next are positive and negative voltage regulators 78L12 and 79L12 with decoupling capacitors C3 to C6 close to regulators. A more modern design might eliminate these 4 components and use a CMOS rail-to-rail op-amp.
Current limit is set by R3, D1, R4, R6, Q12, R10, and R13 providing a bias to U2 that partially turns off transistors Q9 and Q11 when the current limit is reached.
R4 is a front panel potentiometer that sets the current limit, R22 is a front panel potentiometer that sets the output voltage (0-30 volts), and R11 is an internal trim-pot for calibration.



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