Power Supply Circuits

Linear power supplies work by getting the 127 V or 220 V from the power grid and lowering it to a lower value (e.g. 12 V) using a transformer. This lower voltage is still AC. Then rectification is done by a set of diodes, transforming this AC voltage into pulsating voltage. The next step is filtering, which is done by an electrolytic capacitor, transforming this pulsating voltage into almost DC.On high-frequency switching power supplies, the input voltage has its frequency increased before going into the transformer (10-20 KHz are typical values). A power supply of good quality and with enough capacity can increase the durability of your equipment. Just to have an idea, a high-quality power supply will cost less than 5% of the PC total amount. On the other hand, a low-quality power supply can cause several intermittent problems, which are mostly difficult to be solved.Although linear power supplies work very well for several low-power applications – cordless phones and video games consoles are two applications that come in mind –, when high power is needed, linear power supplies can be literally very big for the task.

Tesla Circuits	AC to DC & DC to DC	High Voltage
Inverter Circuits	Solar Cell Circuits	Switching Power Supplies
Free Energy Circuits	Current Limiting
Chargers	Mirco Power Circuits

Bipolar power supply for battery instruments

To generate regulated Â± 5-V supplies from a pair of dry batteries, the circuit of Fig. 1 is commonly used. In order to give protection from inadvertent reverse connection of a battery, a diode in series with each battery would produce an unacceptable voltage drop. The more effective approach is to fit diodes Dl and D2 as shown in Fig. 2, in parallel with each battery. When the supply is switched off, there is the risk of a reverse bias being applied across the.....

Diode Cmos Stabilizer

The simple diode network can stabilize the voltage supplied to CMOS circuitry from a battery. D1 and D2 must have a c..

Charger Extends Lead-Acid Battery Life

The circuit furnishes an initial charging voltage of 2.5 V per cell at 25Â°C to rapidly charge a batt..

Battery charger with LM317

An LM317 voltage regulator is configured as a constant-current source. It is used to supply the 50 mA charging current to S01-S06, an array of AA-cell battery holders. Each of the battery holders is wired in series with an LED and its associated shunt resistor. When the battery holder contains a battery, the LED glows during charging. Each battery holder/LED combination is paralleled by a 5.1-volt Zener diode. If the battery holder is empty, the Zener conducts the current.....

High voltage supply

A 6 V battery can provide 100-150 Vdc center-tapped at a high internal impedance (not dangerous though it can inflict an unpleasant jolt). A 6.3 V transformer is connected ' 'in reverse'' with a transistor used in a Hartley oscillator configuration. The frequency of operation may be controlled by varying the value of the 10 ohm resistor. ..

Room Ioniser circuit

This is a voltage multiplier circuit acting as an Ioniser. Its calculated to feed 220V from mains and the output is about 6KV. Caution should take with the circuit as can be dangerous due to mains. You can place a needle at the output 3cm long. ..

Battery-Temperature Sensing Nicad Charger

Two simple circuits permit Nicad charging of a battery based on temperature differences between t..

Regulator Loss Cutter Circuit

Large input-to-output voltage differentials, caused by wide input voltage variations, reduce a linear regulator`s efficiency and increase its power dissipation. A switching preregulator can reduce this power dissipation by minimizing the voltage drop across an adjustable linear regulator to a constant 1.5-V value. The circuit operates the LT1084 at slightly above its dropout voltage. To minimize power dissipation, a low-dropout linear regulator was chosen. The LT1084.....

Synchronous Stepdown Switching Regulator Circuit

A shows a typical LTC 1148 surface-mount, application providing 5 V at 2 A from an input voltage of 5.5 V to 13.5 V. The operating efficiency, shown in B, peaks at 97% and exceeds 90% from 10 mA to 2 A with a 10-V input. Ql and Q2 comprise the main switch and synchronous switch, respectively, and inductor current is measured via the voltage drop across the current shunt. /vgENSE is the key component used to set the output, current capability according to the formula/QUT.....

Cold-Cathode Fluorescent-Lamp Supply

For back-lit LCD displays, this supply will drive a lamp. LT1072 drives Ql and Q2, and a sine wave app..

Ni-cad charger

This circuit uses constant current LEDs to adjust charging current. It makes use of LEDs that pass a constant current of about 15 mA for an applied voltage range of 2-18 V. They can be paralleled to give any multiple of 15 mA and they light up when current is flowing..

Power pack for battery-powered devices

This circuit gives a regulated output of between 5 V and 15 Vdc, adjusted and set by a preset resistor. Current output up to about 350 mA..

Low voltage regulators

These short-circuit protected regulators give 6, 7, and 9 V from an automobile battery supply of 13 V nominal; however, they will function just as well if connected to a smoothed dc output from a transformer/rectifier circuit. Two types are shown for both positive and negative ground systems. The power transistors can be mounted on the heatsink without a mica insulating spacer thus allowing for greater cooling efficiency. Both circuits are protected against overload or.....

General-purpose-power-supply

The supply 6-66 can be used for supply output voltages from 1 to 35 V. The line transformer should be selected to give about1.4 times the desired output voltage from the positive side of filter capacitor C1 to ground. Potentiometer R2 sets the output voltage to the desired value by adjusting the reference input. Rsc is the current limit set resistor. ..

Three-rail-power-supply

This circuit generates three supply voltages using a minimum of components. Diodes D2 and D3 perform full-wave rectification, alternately charging capacitor C2 on both halves of the ac cycle. On the other hand, diode D1 with capacitor C1, and diode D4 with capacitor C3 each perform half-wave rectification. The full-and half-wave rectification arrangement is satisfactory for modest supply currents drawn from -5 and +12-V regulators IC3 and IC2. ..

Intelligent Battery-Charging Circuit Circuit

Intended for a Nicad application this charging circuit can be used with a wide range of batteries. A low-battery detector is intended. The trip voltage is set via the 500-kQ pot...

Battery-powered-high-voltage-generator

Output voltage great enough to jump a l-inch gap can be obtained from a 12-V power source. A 555 timer IC is connected as an astable multivibrator that produces a narrow negative pulse at pin 3. The pulse turns Ql on for the duration of the time period. The collector of Ql is direct-coupled to tbe base of tbe power transistor Q2, turning it on during the same time period. ..

Diodeless Rectifier Circuit

It`s common knowledge that when working with single-supply op amps, implementing simple functions in a bipolar signal environment can be difficult. Sometimes additional op amps and other electronic components are required. Taking that into consideration, can any advantage be attained from this mode The answer lies in this simple circuit (A). Requiring no diodes, the circuit is a high-precision full-wave rectifier with a liigli-frequency limitation equalling that of the op.....

Power-mosfet-inverter

This inverter can deliver .high-voltage ac or de, with a rectifier and filter, up to several hundred volts. The secondary and primary of T1-a 12.6 to 440 V power transformer, respectively-are reversed; e.g., the primary becomes the secondary and the secondary becomes the primary. Transistors Q1 and Q2 can be any power FET. ..