Self switching Power Supply Circuit

Self switching Power Supply Circuit

One of the capital appearance of the adapted ability accumulation ambit actuality presented is that admitting fixed-voltage regulator LM7805 is acclimated in the circuit, its achievement voltage is variable. This is accomplished by abutting a potentiometer amid accepted terminal of regulator IC and ground. For every 100-ohm accession in the in-circuit amount of the attrition of potentiometer VR1, the achievement voltage increases by 1 volt. Thus, the achievement varies from 3.7V to 8.7V (taking into annual 1.3-volt bead above diodes D1 and D2).

Another important affection of the accumulation is that it switches itself off back no amount is affiliated above its achievement terminals. This is accomplished with the advice of transistors T1 and T2, diodes D1 and D2, and capacitor C2. Back a amount is affiliated at the output, abeyant bead above diodes D1 and D2 (approximately 1.3V) is acceptable for transistors T2 and T1 to conduct. As a result, the broadcast gets energised and charcoal in that accompaniment as continued as the amount charcoal connected. At the aforementioned time, capacitor C2 gets answerable to about 7-8 volt abeyant through transistor T2. But back the amount is disconnected, transistor T2 is cut off. However, capacitor C2 is still answerable and it starts absolution through abject of transistor T1. After some time (which is basically bent by amount of C2), broadcast RL1 is de-energised, which switches off the mains ascribe to primary of agent X1. To resume the ability again, about-face S1 should be apprenticed momentarily. Higher the amount of capacitor C2, added will be the adjournment in switching off the ability accumulation on break of the load, and carnality versa.

Though in the ancestor a agent with a accessory voltage of 12V-0V, 250mA was used, it can about be afflicted as per user’s claim (up to 30V maximum. and 1-ampere accepted rating). For cartoon added than 300mA current, the regulator IC charge be adapted with a baby calefaction bore over a mica insulator. Back the transformer’s accessory voltage increases above 12 volts (RMS), potentiometer VR1 charge be redimensioned. Also, the broadcast voltage appraisement should be redetermined.

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Basic Power Supply Circuit for 300W Subwoofer Amplifier

Basic Power Supply Circuit for 300W Subwoofer Amplifier Circuit

The basal ability accumulation is apparent in account above. It is absolutely accepted in all respects. Use a 40-0-40 V transformer, rated at 300VA for accustomed use. For best connected power, a 50-0-50V (500VA or more) agent will be needed. This will accord a connected ability of about 450W, and aiguille ability of over 500W is accessible with a acceptable transformer. Remember my warnings about application the amp in this way, and the charge for the added achievement transistors, big heatsink and fan.

For 115V countries, the agglutinate should be 6A, and in all cases a apathetic draft agglutinate is appropriate because of the arrival accepted of the transformer. For annihilation aloft 300VA, a soft-start ambit is awful recommended (see Project 39).

The accumulation voltage can be accepted to be college than that quoted at no load, and beneath at abounding load. This is absolutely normal, and is due to the adjustment of the transformer. In some cases, it will not be accessible to access the rated ability if the agent is not abundantly rated.

Bridge rectifiers should be 35A types, and clarify capacitors charge be rated at a minimum of 63V (or 75V if you use 70V supplies). Wiring needs to be abundant gauge, and the DC charge be taken from the capacitors - not from the arch rectifier.

Although apparent with 4,700uF clarify capacitors, above ones may be used. Annihilation above 10,000uF is too expensive, and will not advance achievement to any advantageous degree. Probably the best is to use two 4,700uF caps per ancillary (four in all). This will absolutely assignment bigger than a distinct 10,000uF device, and will be cheaper as well.

NOTE: It is capital that fuses are acclimated for the ability supply. While they will not stop the amp from declining (no agglutinate anytime does), they will anticipate adverse accident that would aftereffect from not attention the ambit from over-current conditions. Fuses can be army in fuseholders or can be inline types. The closing are preferred, as the accumulation leads can be kept as abbreviate as possible. Access from alfresco the anatomy is not bare - if the fuses blow, the amplifier is about absolutely damaged.
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Car Adapter Circuit with ECG184

for audio ,playstation,DVD,tv etc., is that we have designed for 12DC to 9DC converters that we bring to our design circuit . They are all effective in Switch Mode Power Supplies regulated output. We have developed a series of DC-DC power supply models ranging from 1 watt to 500 watts, which we incorporated into the new controller of DC converters. We are also developing new areas whenever necessary to meet customer requirements. We can provide some custom products that changes on the following products and fully custom DC-DC, new products, such as DC Battery Backup Power Supplies.

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12 Volt |30 Amp POWER SUPPLY

12 Volt |30 Amp POWER SUPPLY

A single 7812 IC voltage regulator and multiple outboard pass transistors, this power supply can deliver output load currents of up to 30 amps. The input transformer is likely to be the most expensive part of the entire project. As an alternative, a couple of 12 Volt car batteries could be used. The input voltage to the regulator must be at least several volts higher than the output voltage (12V) so that the regulator can maintain its output. If a transformer is used, then the rectifier diodes must be capable of passing a very high peak forward current, typically 100amps or more. The 7812 IC will only pass 1 amp or less of the output current, the remainder being supplied by the outboard pass transistors. As the circuit is designed to handle loads of up to 30 amps, then six TIP2955 are wired in parallel to meet this demand. The dissipation in each power transistor is one sixth of the total load, but adequate heat sinking is still required. Maximum load current will generate maximum dissipation, so a very large heat sink is required. In considering a heat sink, it may be a good idea to look for either a fan or water cooled heat sink. In the event that the power transistors should fail, then the regulator would have to supply full load current and would fail with catastrophic results. A 1 amp fuse in the regulators output prevents a safeguard.

This circuit is a fine example of Kirchoff’s current and voltage laws. To summarise, the sum of the currents entering a junction, must equal the current leaving the junction, and the voltages around a loop must equal zero. For example, in the diagram above, the input voltage is 24 volts. 4 volts is dropped across R7 and 20 volts across the regulator input, 24 -4 -20 =0. At the output :- the total load current is 30 amps, the regulator supplies 0.866 A and the 6 transistors 4.855 Amp each , 30 = 6 * 4.855 + 0.866. Each power transistor contributes around 4.86 A to the load. The base current is about 138 mA per transistor. A DC current gain of 35 at a collector current of 6 amp is required. This is well within the limits of the TIP2955. Resistors R1 to R6 are included for stability and prevent current swamping as the manufacturing tolerances of dc current gain will be different for each transistor. Resistor R7 is 100 ohms and develops 4 Volts with maximun load. Power dissipation is hence (4^2)/200 or about 160 mW. I recommend using a 0.5 Watt resistor for R7. The input current to the regulator is fed via the emitter resistor and base emitter junctions of the power transistors. Once again using Kirchoff’s current laws, the 871 mA regulator input current is derived from the base chain and the 40.3 mA flowing through the 100 Ohm resistor. 871.18 = 40.3 + 830. 88. The current from the regulator itself cannot be greater than the input current. As can be seen the regulator only draws about 5 mA and should run cold.

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10 Amp 13.8 Volt Power Supply Circuits

10 Amp 13.8 Volt Power Supply Circuits

This circuit uses the LM723 IC which gives us excellent voltage regulation. The circuit uses 3 pass transistors which must be heat sinked. Resistor R9 allows the fine tuning of the voltage to exactly 13.8 volts and the resistor network formed by resistors R4 through R7 controls the current limiting. The LM723 limits the current when the voltage drop across R5 approaches .7 volts. To reduce costs, most commercial units rely on the HFE of the pass transistors to determine the current limiting.

The circuit in Figure 2 senses when the voltage exceeds 15 volts and causes the zener diode to conduct. When the zener diode conducts, the gate of the SCR is turned on and causes the SCR to short which blows the 15 amp fuse and shuts off the output voltage. A 2N6399 was used for the SCR in the prototype but any suitable SCR can be used. While over voltage protection is a good idea, it should not be considered a substitute for large heat sinks. I personally feel the best protection from over voltage is the use of large heat sinks and a reliable current limiting circuit. Be sure to use large heat sinks along with heat sink grease for the 2N3055 transistors.

Component/Parts List
R1 : 1.5K ¼ Watt Resistor (optional, tie pins 6 & 5 of IC1 together if not used.)
R2,R3 : 0.1 Ohm 10 Watt Resistor (Tech America 900-1002)
R4 : 270 Ohm ¼ Watt Resistor
R5 : 680 Ohm ¼ Watt Resistor
R6,R7 : 0.15 Ohm 10 Watt Resistor (Tech America 900-1006)
R8 : 2.7K ¼ Watt Resistor
R9 : 1K Trimmer Potentiometer (RS271-280)
R10 : 3.3K ¼ Watt Resistor
C1,C2,C3,C4 : 4700 Microfarad Electrolytic Capacitor 35 Volt (observe polarity)
C5 : 100 Picofarad Ceramic Disk Capacitor
C6 : 1000 Microfarad Electrolytic Capacitor 25 Volt (observe polarity)
IC1 : LM723 (RS276-1740) Voltage Regulator IC. Socket is recommended.
Q1 : TIP3055T (RS276-2020) NPN Transistor (TO-220 Heat Sink Required)
Q2,Q3 : 2N3055 (RS276-2041) NPN Transistor (Large TO-3 Heat Sink Required)
S1 : Any SPST Toggle Switch
F1 : 3 Amp Fast Blow Fuse
D1-D4 : Full Wave Bridge Rectifier (RS276-1185)
T1 : 18 Volt, 10 Amp Transformer Hammond #165S18 (Digi-Key HM538-ND)

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LM338 Power Supply Regulator 13.8V 5A

LM338 Power Supply Regulator 13.8V 5A Scheme

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. The circuit it uses known completed that is capable gives in the his exit, current in continuous operation 5A and 12A peak current. It does not only need few external component. Exist a point which it will be supposed you are careful in the drawing and in board. Board has been drawn so as to exist the possibility of using also two case types completing. 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.

A other point is the refrigeration of rectifier B1. If it?s placed above in pcb, then it will be supposed clinch on his piece aluminium in form U, in opposite case, if the rectifier B1 is placed except pcb should clinch in a point in his chassis and terminal are connected with suitable cross-section cables in the corresponding points above in pcb. The regulation of voltage in + 13.8V become with the trimmer TR1, (multiturn). The IC1 should in every case be placed on one suitable heatsink, which good is supportable by one fan. All the connections by the circuit become with big cross-section cables , beacause the current that passes from in them is enough high. If they are not used the connectors that appear in pcb, then you can place pins or solderer the cables at straight line above in pcb

LM338 Power Supply Regulator 13.8V 5A Layout

LM338 Power Supply Regulator 13.8V 5A Component List:
R1=270R 1/4W 2% C4-5=10uF 25V T1=220Vac/15VAC - 8A Mains Transformer
TR1=4k7 (Multiturn) D1-2=1N4002 (1A/100V) S1=2 Pole Single Throw Mains Switch
C1=10000uF 40V B1=25A Bridge Rectifier F1=250mA Fuse
C2-3=100 nF 100V Polyester IC1=LM338

Source :: http://users.otenet.gr/~ahisrod/power_supply_13_8V_5A_with_LM338.htm

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Rangkaian Power Supply Sederhana

Basic Power Supply Circuit

The basic power supply is shown in Figure 2. It is completely conventional in all respects. Use a 40-0-40 V transformer, rated at 300VA for normal use. For maximum continuous power, a 50-0-50V (500VA or more) transformer will be needed. This will give a continuous power of about 450W, and peak power of over 500W is possible with a good transformer. Remember my warnings about using the amp in this way, and the need for the additional output transistors, big heatsink and fan.


For 115V countries, the fuse should be 6A, and in all cases a slow blow fuse is required because of the inrush current of the transformer. For anything above 300VA, a soft-start circuit is highly recommended (see Project 39).

The supply voltage can be expected to be higher than that quoted at no load, and less at full load. This is entirely normal, and is due to the regulation of the transformer. In some cases, it will not be possible to obtain the rated power if the transformer is not adequately rated.

Bridge rectifiers should be 35A types, and filter capacitors must be rated at a minimum of 63V (or 75V if you use 70V supplies). Wiring needs to be heavy gauge, and the DC must be taken from the capacitors - not from the bridge rectifier.

Although shown with 4,700uF filter capacitors, larger ones may be used. Anything beyond 10,000uF is too expensive, and will not improve performance to any worthwhile degree. Probably the best is to use two 4,700uF caps per side (four in all). This will actually work better than a single 10,000uF device, and will be cheaper as well.

NOTE: It is essential that fuses are used for the power supply. While they will not stop the amp from failing (no fuse ever does), they will prevent catastrophic damage that would result from not protecting the circuit from over-current conditions. Fuses can be mounted in fuseholders or can be inline types. The latter are preferred, as the supply leads can be kept as short as possible. Access from outside the chassis is not needed - if the fuses blow, the amplifier is almost certainly damaged.

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