Easy Discrete Low Drop Regulator

This circuit was designed to ensure that an amplifier circuit containing a TDA1516Q would not exceed its maximum supply voltage when the load is small. This amplifier is used in a PC to increase the audio power somewhat. The PC power supply, however, created so much interference that an additional power supply was required.

Discrete Low-Drop Regulator Circuit Diagram

The power supply has its own power trans-former with a secondary voltage of 12 V AC. After rectification and filtering this results in a DC voltage of about 16 V. The regulator consists of a P-channel MOSFET SJ117, the gate of which is driven via a voltage divider connected to T2. The base of T2 is held at a constant voltage by LED D2, so that the volt-age across emitter resistor R2 is also constant and therefore carries a constant cur-rent. 

When the output voltage is higher than about 13.5 V, zener diode D1 will start to con-duct and supply part of the current through R2 — as a result the MOSFET will be turned on a little less. In this way there is a balance point, where the output voltage will be a little over 13.5 V (1.5 V across R2 plus the 12 V zener voltage). The regulator is capable of deliver-ing up to about 2 A — in any case it is a good idea to fit the MOSFET with a heatsink.

It is possible to add an optional potentiometer in series with the 12-V zener diode, which will allow a small amount of adjustment of the output voltage.The relay at the AC powerline input ensures that the power supply is only turned on when the PC is turned on. This relay is driven from a 4-way power supply connector from the PC.

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SOFT START MECHANISM FOR L200 VOLTAGE REGULATOR ELECTRONIC DIAGRAM

SOFT START MECHANISM FOR L200 VOLTAGE REGULATOR ELECTRONIC DIAGRAM

Ic (constant current) is charge capacitor C, where Ic = Vsc/R.

The output reaches its nominal value after the time ton. Vo-Vsc=(Ic.ton)/C.

ton=C.[(Vo-0.45)/0.45].R = CVoR/0.45.

Vo follows the voltage in pin 2 at less than 0.45 volt. It is because voltage of more than 0.45 V can’t be produced between pin 2 and pin 5. Read More

2N3055 and 748 Regulator 15V 400mA circuit

Regulator 15V 400mA by 748 and 2N3055
Today try come to see linear regulator 15volt 400mA Circuit. It is use IC op-amp IC748 perform control Voltage Regulator 15V. by have ZD1 5.1V be the referable voltage. For Transistor 2N3055 , perform enlarge current tallly go up and Q3-2N3904 help protect something through the circuit. This circuit can give Current get about 400mA only. Be regarded as the circuit experiences that interesting help give understand the system Voltage Regulator well. The detail is other , a friend has seen in the circuit please sir. Read More

Increasing Regulator Current PSU Circuit

Description:
An outboard pass transistor used to increase the current output of a voltage regulator IC.

Notes
Although the 78xx series of voltage regulators are available with different current outputs, you can boost the available current output with this circuit. A power transistor is used to supply extra current to the load the regulator, maintaining a constant voltage. This transistor is known as an outboard bypass transistor.

Currents below 600mA will flow through the regulator. Above 600mA the input current flowing through the 1 ohm resistor develops a voltage. As this voltage increases above 0.6V (600mA through 1 ohm) then the TIP2955 power transistor starts to conduct, supplying the extra current to the load. The 10 ohm resistor limits excessive base current. The power transistor requires an adequate heat sink as it is likely to get very hot. Suppose you use a 12v regulator, 7812. The minimum input voltage should always be a few volts higher than the regulator output voltage to allow for voltage drops.

The 1 ohm resistor needs to be rated 3 Watts for load currents up to 3 amp and rated 7 Watts for load currents of 5 amps. As the HFE of a power transistor falls with increased collector current it is not recommended to draw more than 5 amps with this circuit. The 10 ohm base resistor drops less power and a 0.5 Watt resistor can be used at all output currents.

Power Dissipation in Bypass Transistor
Assume a supply of 20 volts and that the load will draw 5amps. The power dissipation in the transistor will be Vce * Ic.
Vce = Vcc - Vreg
so
Pdiss = (20-12) * 5 = 40 Watt.

It may keep you warm in the Winter, but you will need a large heatsink with good thermal dissipation. If however the input voltage was 15V then the dissipation would be reduced to just 15 Watts. If you want to increase the output current with a negative regulator, such as the 79xx series, then the circuit is similar, but an NPN type power transistor is used instead.

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CAR POWER FILTER REGULATOR USING LM1084

 Sometimes may built-in babble botheration has from electricity auto system. I thinks Power Clarify Regulated for car by LM1084-12 may advice break a botheration this get. Because of application way LC clarify and IC LM1084-12 (5A Low Dropout Positive Regulators) as a aftereffect can advice adapt voltage well. If there is beat babble 12V added although a little aloof will change this ambit has a little. And this ambit still can accord the trend alpine arrives at 5A can administer to the accessories awning very.

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Negative Output Switching Regulator

There are only a limited number of switching regulators designed to generate negative output voltages. In many cases, it’s thus necessary to use a switching regulator that was actually designed for a positive voltage in a modified circuit configuration that makes it suitable for generating a negative output voltage. The circuit shown in Figure 1 uses the familiar LM2575 step-down regulator from National Semiconductor (www.national.com). This circuit converts a positive-voltage step-down regulator into a negative-voltage step-up regulator. It converts an input voltage between –5 V and –12 V into a regulated –12-V output voltage.

Note that the output capacitor must be larger than in the standard circuit for a positive output voltage. The switched current through the storage choke is also somewhat higher. Some examples of suitable storage chokes for this circuit are the PE-53113 from Pulse (www.pulseeng.com) and the DO3308P-153 from Coilcraft (www.coilcraft.com). The LM2575-xx is available in versions for output voltages of 3.3V, 5 V, 12 V and 15 V, so various negative output voltages are also possible. However, you must pay attention to the input voltage of the regulator circuit. If the input voltage is more negative than –12 V (i.e., Vin <–12 v), the output voltage will not be regulated and will be lower than the desired –12 v.


The LM2575 IC will not be damaged by such operating conditions as long as its maximum rated input voltage of 40 V is not exceeded. High voltage (HV) types that can withstand up to 60 V are also available. Although the standard LM2575 application circuit includes circuit limiting, in this circuit the output current flows via the diode and choke if the output is shorted, so the circuit is not short-circuit proof. This can be remedied by using a Multifuse (PTC) or a normal fuse. There is also an adjustable version of the regulator with the type designation LM2575-ADJ (Figure 2). This version lacks the internal voltage divider of the fixed-voltage versions, so an external voltage divider must be connected to the feedback (FB) pin. The voltage divider must be dimensioned to produce a voltage of 1.23 V at the FB pin with the desired output voltage. The formula for calculating the output voltage is:

Vout = 1.23 V × (1 + [R1 ÷ R2])

The electrolytic capacitors at the input and output must be rated for the voltages present at these locations.
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PHILCO PHILIPS PH32S86DG – LED LCD TV POWER SUPPLY REGULATOR and AUDIO OUTPUT SCHEMATIC

Power Supply Regulator Circuit & Audio Output schema_ PHILCO [PHILIPS] PH32S86DG – LED LCD TV 

ICs used [TPA3020 (Audio Output) – D7537R (Power Control)

SMPS SCHEMATIC

AUDIO OUTPUT SCHEMATIC

CLICK ON THE SCHEMATICS TO MAGNIFY

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LM1458 and 2N3055 DC Variable Regulator Power Supply

LM1458 and 2N3055 DC Variable Regulator Power Supply

Power ascendancy is adjustable 3-25 volts and is accepted bound to 2 amps as shown,but may be up to 3 amps in a baby accepted faculty resistor by options (0.3 ohm). 2N3055 transistors 2N3053 and should be in the sinks. actual hot appropriate now and resistor should be rated at 3 watts or more. voltage that is controlled by 1 / 2 of the op amp LM1458 or 1458-AMP. It may be commissioned in the ambit below, but sources advance pressure. dispensing pin 8 is bound to 30 VDC, which can access by 6.2 volt zener or 5.1 resistor K alternation is 8 pin. best voltage DC accumulation for 1458 and 1558 are 36 and 44, respectively. ability agent should be. As can be accepted in the accepted voltage. Enter at atomic 4 volts college than the adapted achievement voltage but not beat the best bulk of op-AMP beneath low amount conditions. Agent is apparent as a centermost broke 25.2 volt AC / AMP 2 units to advice ascendancy the 24 volts at 0.7 amps, 15 volts at 2 amps or 6 volts at 3 amps. Achievement AMP 3 is the centermost of the water. agent that changes the 18 volt position. All apparatus charge accept a Radio berth barring of LM1458 op-AMP.

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Battery Switch With Low Dropout Regulator Wiring diagram Schematic

This is a simple Battery Switch With Low-Dropout Regulator Circuit Diagram. In the form of the LT1579 Linear Technology (www.linear-tech.com) has produced a practical battery switch with an integrated low-dropout regulator. In contrast to previous devices no diodes are required. The schema is available in a 3.3 V version (LT1579CS8-3.3) and in a 5 V version (LT1579CS8-5), both in SO8 SMD packages. There is also an adjustable version and versions in an SO16 package which offer a greater range of control and drive signals. The main battery, whose terminal voltage must be at least 0.4 V higher than the desired output voltage, is connected to pin IN1. The backup battery is connected to pin IN2. The regulated output OUT can deliver a current of up to 300 mA. The LDO regulator part of the IC includes a pass transistor for the main input voltage IN1 and another for the backup battery on IN2.

The IC will switch over to the backup battery when it detects that the pass transistor for the main voltage input is in danger of no longer being able to maintain the required output voltage. The device then smoothly switches over to the backup battery. The open-drain status output BACKUP goes low to indicate when this has occurred. When neither battery is able to maintain the output voltage at the desired level the open-drain output DROPOUT goes low. The LT1579 can operate with input voltages of up to +20 V from the batteries. The regulator output OUT is short-schema proof. The shutdown input switches off the output; if this feature is not required, the input can simply be left open.

Streampowers

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12 to 28V Boost Regulator LM2585

This boost regulator is for those times when you have a 28v relay, but want to use it with a 12v source. The schema is built around the National Semiconductor LM2585, and uses the energy stored in an inductor to boost the 12 to 28v. Output voltage can be varied by adjusting the ratio of resistor values on the feedback pin.

The voltage regulator schema does it’s switching around 100 Khz, but generates no noise if SMT components are used. Output is good for about half an amp continuous, enough to power two or three large microwave relays. The board measures 1.5″x2″.

It is important to note at least these three cautions before powering up the board:

• A short-schema on the output will kill U1 and D1. Always use a 1 ohm 5w resistor, or a 2.5A fast fuse on the 12v input lead.
• Do not omit the LED (D2); It provides a visual indicator of a properly operating boost condition, but more importantly, it also provides a minimum load for the output, preventing an output “spike” which will otherwise appear when the load is disconnected abruptly.
• Keep the ratio of r2 and r3 to 22 or less to keep the output voltage within the ratings of C4 (C4 on my board is rated at 35wvdc). This ratio plus 1, multiplied times 1.25v, determines the output voltage.

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