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Showing posts from 2012

Simple Split Power Supply 9V

This is a simple circuit design of 9V split power supply. This power supply circuit delivers plus and minus 9V to substitute the two 9V batteries. The rectifier circuit is certainly two separate full-wave rectifiers fed from the secondary of the transformer. One full-wave rectifier consists of diodes Dl and D2, which produce +9 V, and then the other consists of D3 and 4, which produce -9 V.

+15V / 1A Regulated Power Supply using uA723

This is the design diagram of +15V / 1A regulated power supply using uA723.
Circuit operation: The supply receives +20VDC from the rectifier / filter section (diode bridge). This is applied to pins 11 and 12 of the IC uA723, as well as to the collector of the 2N3055 series-pass transistor. The output voltage is simpled through R1 and R1, providing about 7V with respect to ground at pin 4. The reference terminal at pin 6 is tied directly to pin 5, the noninverting input of the error amplifier. For fine tuning output voltage, a potensiometer can be installed between R1 and R2. A 100 pF capacitor to pin 4 furnishes gain compesation for the amplifier.

-15V / 1A Regulated DC Power Supply

This is the scheme design of -15V / 1A Regulated DC Power Supply. It used uA723 precision voltage regulator and TIP105 PNP Epitaxial Silicon Darlington transistor. The supply receives -20V from the rectifier/filted which is fed to the collector of the Darlington PNP pass transistor, a TIP105. The base drive to the TIP105 is supplied through resistor R5. The base of the TIP105 is driven from Vz terminal at pin 9, which is the anode of a 6.2V zener diode that connects to the emitter of the uA723 output control transistor.

LM317T Voltage Regulator Circuit with Pass Transistor

This is the schematic diagram of voltage regulator circuit with pass transostor. The regulator is based regulator IC of LM317T. The LM317T output current can be raised by utilizing an additional power transistor (on circuit, it is 2N2955) to share a portion of the total current. The amount of current sharing is established with a resistor placed in series with the LM317 input and a resistor placed in series with the emitter of the pass transistor.


In the above scheme design, the pass transistor will start conducting when the LM317 current reaches about 1 ampere, due to the voltage drop across the 0.7 ohm resistor. Current limiting happens at about 2 amperes for the LM317 which will drop about 1.4 volts across the 0.7 ohm resistor and make a 700 millivolt drop across the 0.3 ohm emitter resistor. Thus the total current is limited to about 2+ (.7/.3) = 4.3 amperes.

High Current 5V DC Power Supply

This is the high current dc power supply circuit with 5V output. The high current regulator utilizes an extra winding or a separate transformer to deliver power for the LM317 regulator so that the pass transistors can run closer to saturation and increase performance. For excellent performance the voltage at the collectors of the two parallel 2N3055 pass transistors ought to be near to the output voltage. The LM317 needs a couple extra volts on the input side, plus the emitter/base drop of the 3055s, plus whatever is lost across the (0.1 ohm) equalizing resistors (1volt at 10A), so a separate transformer and rectifier/filter circuit is utilized which is several volts higher than the output voltage.

9V Dual Polarity Power Supply from 9V Battery

Here the schematic design of 9V dual polarity power supply from 9V battery. Dual-voltage power supply is necessary particularly for running the op-amps and some of the instrumentation amplifiers. Some low-power audio pre-amplifiers also use dual-voltage power source.

This circuit delivers both +9V as well as -9V DC output from a single 9V battery. It contains timer IC NE555 (IC1), negative-voltage regulator IC 7909 (IC2) along with several discrete parts.

Unregulated Split Power Supply for Audio Amplifier

This is the unregulated Split power supply circuit, intended to supply the hi-fi audio amplifier. This power supply circuit is very simple, and no great skill is needed to assemble this circuit.

Simple Variable Power Supply 0-15VDC / 1A

This is the very simple general purpose variable power supply capable of delivering 0-15V DC output with about 1A electric current. The power supply circuit has regulated output and can be used for most small electronic circuit application.

12V Transformerless Power Supply

Here the low power 12V transformerless power supply circuit with full-wave rectification. A lot of circuits could be powered straightaway in the electric mains using the support of a series capacitor (C1). The problem with this method is the fact that typically only one half cycle of the mains wave-form can be used to deliver a DC voltage. An obvious option is to work with a bridge rectifier to accomplish full-wave rectification, which improves the amount of current that can be delivered and makes it possible for the filter capacitor to become smaller sized. The associated circuit in fact does this, but in a clever manner that makes use of fewer parts. Right here we take benefit of the reality that a Zener diode can also be a standard diode that conducts electric current in the forward direction. During one half wave, the current flows via D1 through the load and back via D4, whilst during the other half wave it flows via D3 and D2. Keep in mind that with this circuit (and with the b…

Lithium-ion (Li-ion) Battery Charger with MAX1879

Above diagram is the circuit of Lithium-ion (Li-ion) battery charger which built based single chip MAX1879. This is the simple and low cost battery charger for single-cell Li+ battery that does not dissipate power (no heat.

The MAX1879, in conjunction with the AC linear transformer adapter and a PMOS FET, allows safe and fast charging of a single Li+ cell. The MAX1879 is not only an inductorless required solution, but also the lowest power dissipated solution among single-cell Li+ battery chargers.

Solid State Tesla Coil with 555 Timer

Here the circuit diagram of solid state tesla coil with 555 timer.

Single transistor flyback driver induced a lot of complications on account of it really is operating principle. I received e-mails from those who had been unable to obtain it functional even after they are positive that their flyback and transistor is Okay. Moreover, because it is resonance frequency is determined by each individual a part of the method, any time you seek to draw an arc in the transformer, it alterations substantially in a lot of the circumstances. Simply because the operating frequency is vital for your security criteria, (each for mine and electrical power transistor's), I determined to generate it run on a continuous frequency and developed up yet another easy circuit, attempting to keep within the specified limits in the 555 timer.

Simple Power Supply Circuit for Laser

This is a very simple high voltage power supply circuit for laser device. It is low cost circuit and very easy to built. This power supply can be built with common parts, most of which you probably already have in your junk box. The secret of this circuit is the transformer used. It is a common 9V 1A transformer unit, connected backwards for step up. Please note that some people may have trouble with this supply. This is due to the slight difference in transformers. 

Regulated Current Booster for Power Supply

This is the regulated current booster designed to increase the DC current of a power supply.

Even though the 78xx series of voltage regulators are readily available with diverse current outputs, you could increase the obtainable current output with this circuit. A power transistor is utilized to provide additional current for the load the regulator, preserving a continuous voltage. Currents as much as 650mA will flow by way of the regulator, above this value along with the power transistor will start out to conduct, supplying the additional existing for the load. This needs to be on an sufficient heat sink as it is actually most likely to obtain rather hot. Suppose you use a 12V regulator, LM7812. The input voltage must be a number of volts greater to permit for voltage drops. Assume 20 Volts. Lets also assume that the load will draw 5 amps. The power dissipation within the transistor will likely be Vce * Ic or (20-12)*8 = 40 Watt. It may possibly preserve you warm within the Winter,…