STABILIZED POWER SUPPLY 3 30 V 2 5 A

This is a versatile power supply that will solve most of the supply problems arising in the everyday work of any electronics workshop. It covers a wide range of voltages being continuously variable from 30 V down to 3 V. The output current is 2.5 A maximum, more than enough for most applications. The circuit is completely stabilised even at the extremes of its output range and is fully protected against short-circuits and overloading.

Circuit Diagram

Working

The power supply is using a well known and quite popular VOLTAGE STABILIZER IC the LM 723. The IC can be adjusted for output voltages that vary continuously between 2 and 37 VDC and has a current rating of 150 mA which is of course too low for any serious use. In order to increase the current handling capacity of the circuit the output of the IC is used to drive a darlington pair formed by two power transistors the BD 135 and the 2N 3055. The use of the transistors to increase the maximum current output limits the range of output voltages somewhat and this is why the circuit has been designed to operate from 3 to 30 VDC. The resistor R5 that you see connected in series with the output of the supply is used for the protection of the circuit from overloading. If an excessively large current flows through R5, the voltage across it increases and any voltage greater than 0.3 V across it has as a result to cut the supply off, thus effectively protecting it from overloads. This protection feature is built in the LM 723 and the voltage drop across R5 is sensed by the IC itself between pins 2 and 3. At the same time the IC is continuously comparing the output voltage to its internal reference and if the difference exceeds the designer’s standards it corrects it automatically. This ensures great stability under different loads. The potentiometer P1 is used to adjust the out put voltage at the desired level. If the full range from 3 to 30 V is desired then you should use a mains transformer with a secondary winding having a rating of at least 24 V/3 A. If the maxi mum voltage output is not desired you can of course use a transformer with a lower secondary voltage output. (However, once rectified the voltage across the capacitor C2 should exceed by 4-5 volts the maximum output expected from the circuit.

Parts List

Resistors

R1 = 560R 1/4W

R2 = 1,2 K 1/4W

R3 = 3,9 K 1/4W

R4 = 15K 1/4W

R5 = 0,15R 5W 

Capacitors

C1 = 100nF

C2 = 2200uF 35-40V

C3 = 100 pF

C4 = 100uF/ 35V

Miscellaneous

D = B40 C3300/2200, 3A Rectifier Bridge

P1 = 10K Potentiometer

TR1 = BD 135

TR2 = 2N3055

IC = LM723

BD 135

2N3055

LM723

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Transformerless 5 Volt DC Power Supply

An increasing number of appliances draw a very small current from the power supply. If you need to design a mains-powered device, you could generally choose between a linear and a switch-mode power supply. However, what if the appliance’s total power consumption is very small? Transformer-based power supplies are bulky, while the switchers are generally made to provide greater current output, with a significant increase in complexity, problems involving PCB layout and, inherently, reduced reliability.

Is it possible to create a simple, minimum part-count mains (230 VAC primary) power supply, without transformers or coils, capable of delivering about 100mA at, say, 5 V? A general approach could be to employ a highly inefficient stabilizer that would rectify AC and, utilizing a zener diode to provide a 5.1 V output, dissipate all the excess from 5.1 V to (230×√2) volts in a resistor. Even if the load would require only about 10mA, the loss would be approximately 3 watts, so a significant heat dissipation would occur even for such a small power consumption.

 At 100mA, the useless dissipation would go over 30 W, making this scheme completely unacceptable. Power conversion efficiency is not a major consideration here; instead, the basic problem is how to reduce heavy dissipation and protect the components from burning out. The circuit shown here is one of the simplest ways to achieve the above goals in practice. A JVR varistor is used for over-voltage/surge protection. Voltage divider R1-R2 follows the rectified 230 V and, when it is high enough, T1 turns on and T3 cannot conduct.

When the rectified voltage drops, T1 turns off and T3 starts to conduct current into the reservoir capacitor C1. The interception point (the moment when T1 turns off) is set by P1 (usually set to about 3k3), which controls the total output current capacity of the power supply: reducing P1 makes T1 react later, stopping T3 later, so more current is supplied, but with increased heat dissipation. Components T2, R3 and C2 form a typical ‘soft start’ circuit to reduce current spikes — this is necessary in order to limit C1’s charging current when the power supply is initially turned on. At a given setting of P1, the output current through R5 is constant.

Thus, load R4 takes as much current as it requires, while the rest goes through a zener diode, D5. Knowing the maximum current drawn by the load allows adjusting P1 to such a value as to provide a total current through R5 just 5 to 6mA over the maximum required by the load. In this way, unnecessary dissipation is much reduced, with zener stabilization function preserved. Zener diode D5 also protects C1 from over voltages, thus enabling te use of low-cost 16 V electrolytics. The current flow through R5 and D5, even when the load is disconnected, prevents T3’s gate-source voltage from rising too much and causing damage to device. In addition, T1 need not be a high-voltage transistor, but its current gain should exceed 120 (e.g. BC546B, or even BC547C can be used).

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5 1 Classic Home Theater System Energy

Low Distortion and Resonance - spokesman method is distortion- otherwise resonance-without charge, but Energy has achieved a significantly decrease distortion level, a plainly audible perfection.

The Take Classic 5.1 home theater system also offers terrific performance and great features:

• Our patented Convergent Source Module (CSM) 3-edge your way poly-titanium woofer and .75-inch hyperbolic aluminum-field tweeter -the kindness of Energy speakers
• Patented corrugated Elliptical Surround woofers create from top to toe efficiency, low distortion
• An aluminum auditorium tweeter on behalf of sonic accuracy
• Front and rear venting for additional powerful low response

Take Classic raises the piece for 5.1 narrator classification performance. It includes a powerful 200-watt subwoofer with a front-firing seaport, 8-shuffle driver and wavy Elliptical Surround™ in support of deep with the intention of you feel when much as hear. The Convergent Source Module (CSM), with its 3-shuffle poly-titanium woofer and .75-inch hyperbolic aluminum-pitch tweeter, focuses sound for clearer dialogue and stirring melody. The CSM gives soundtracks a dynamic frequency range and a colossal soundstage, used for smooth, realistic sound from every one satellite lecturer and the base channel. song and motion picture lovers rejoice. Take Classic puts the passion back into your favorite films.

Exclusive Energy® Brand Technologies

Convergent Source Module

The Convergent Source Module, before CSM, provides broad dispersion, low distortion and amazing midrange performance. The lecturers midrange and tweeter are positioned inside close proximity to individual an alternative and accomplish seeing that a single source, by this means increasing overall dispersion and falling some lobing effect. The chambering of the middle and tweeter lowers the drivers resonance, plummeting distortion.

wavy Elliptical Surround knowledge

Energys patented ridged Elliptical Surround technology (U.S. patent #6,725,967, Canadian patent #2,407,123) increases excursion, eliminates distortion and raises efficiency on woofers and subwoofers. The Elliptical Surround encompasses the conduit, allowing it to move identically concerning both instructions, follow-on in come up to nil distortion. And while standard designs are often plagued with surround dimpling, which causes them to give off in and off of segment and distort on all listening levels, Energys designs arent influenced by dimpling on all, as a substitute proprietary grooved Elliptical Surround expertise allows representing a better conduit come up, resultant trendy greater efficiency. This design as well lets the conduit do greater crest to peak movement, in this way allowing it to travel added than bend in half the distance of the competition. These attributes enable Energy woofers and subwoofers to move incredible amounts of air, ultimately allowing them to joke about drop frequencies with greater low lean-to and fidelity.

come again?s voguish the Box

A 6-example, soaring spin black place of Energy Take Classic 5.1 speakers: 4-Take satellite speakers, 1-faultlessly matched Take interior channel spokeswoman, 1-perfectly matched Take powered subwoofer; 1-owners guide.

Technical Specifications

• Frequency Response - Sat: 115Hz-20KHz; Center: 110Hz-20KHz; Subwoofer: 33Hz-150Hz +/- 3dB
• Crossover purpose - 2.9 kHz
• Sensitivity - 89dB
• Power use - Sat & core: 100 Watts; Subwoofer: 200 Watts
• Recommended Amplifier Power - 20 - 100 Watts RMS (permanent)
• Impedance - 8-ohm compatible
• Subwoofer adaptable Low Pass Filter - 40Hz-150Hz @ 18dB/octave
• Tweeter - ¾-shuffle (19 mm) Hyperbolic™ aluminum-ground
• Woofer - Sat & crux: 3-edge your way poly-titanium; junior: 8" IM cone-shaped tool with Patented grooved Elliptical Surround
• Dimensions (inches) - Sat: 6 7/8 x 4 1/8 x 4 1/8; Center: 4 1/8 x 10 1/4 x 4 1/8; Subwoofer: 12 5/8 x 12 5/8 x 12 5/8 (add 2 1/6" pro feet)
• power - Sat: 2.9 lbs; foundation: 3.2 lbs; Subwoofer: 19.7 lbs

Performance Tips: 

The center channel spokeswoman needs to be alive centrally located so so as to the dialogue appears to be approach from the center of the screen. It needs to be more than or else underneath the overseer, while faithfully to it as feasible. If youon the subject of using a rear projection television, the nearly all likely option is to place it over the screen. If you say a front projection method, you have choices-rack mounting, otherwise placement on furniture, in support of illustration. It is principal, though, to place the orator so to facilitate its front frame is even with the edge of the shelf or else stand underneath it. unsolicited diffraction occurs whilst the foundation channel is too far back into a cabinet or else other exterior with edges with the aim of possibly will impede sound dispersion.

In support of not here or else utterly front channels, the distance concerning the speakers be supposed to live 6-8 feet on smallest amount for the greatest stereo imaging. The optimum extent identity is rectangular, with the speakers along solitary of the shorter walls, facing the opposite margin. If probable, figure out not place speakers hostile to a fence or else by rear of a bookshelf; corner placement is generally the most evil option. Try to keep the speakers-especially rear vented models-next to smallest amount two feet from the plane behind it, save you manipulation a vent plug. pro superlative results mounting on a rear cage up, pose the speakers so they flank the major listening area and item with regard to the front of the opportunity. They be supposed to be situated raised to a height of approximately six feet and ought to ideally give a window of six feet involving them.

The three a good number normal subwoofer locations include corners (which can upshot taking part in boomy otherwise exaggerated low frequency response), placement along a mountain, away from the corner (producing moderate low performance with increased fidelity terminated corner placement), otherwise beside a front spokeswoman (creating a better blend with the front speaker, but sacrificing overall volume). Experimentation with subwoofer placement is highly encouraged; slight adjustments can create giant differences clothed in sound reproduction. To test subwoofer placement, install it in the short term in your chief listening attitude and march around the listening space while on stage a familiar bit of melody until you catch the most excellent sounding position.

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5 Zone Alarm System

This is a complete alarm system with 5 independent zones suitable for a small office or home environment. It uses just 3 CMOS ICs and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators for each zone a "system armed" indicator. The schematic is as follows:

Circuit Notes

Each zone uses a normally closed contact. These can be micro switches or standard alarm contacts (usually reed switches). Suitable switches can be bought from alarm shops and concealed in door frames, or window ledges.

Zone 1 is a timed zone which must be used as the entry and exit point of the building. Zones 2 - 5 are immediate zones, which will trigger the alarm with no delay. Some RF immunity is provided for long wiring runs by the input capacitors, C1-C5. C7 and R14 also form a transient suppressor. The key switch acts as the Set/Unset and Reset switch. For good security this should be the metal type with a key.

Operation
At switch on, C6 will charge via R11, this acts as the exit delay and is set to around 30 seconds. This can be altered by varying either C6 or R11. Once the timing period has elapsed, LED6 will light, meaning the system is armed. LED6 may be mounted externally (at the bell box for example) and provides visual indication that the system has set. Once set any contact that opens will trigger the alarm, including Zone 1. To prevent triggering the alarm on entry to the building, the concealed re-entry switch must be operated. This will discharge C6 and start the entry timer. The re-entry switch could be a concealed reed switch, located anywhere in a door frame, but invisible to the eye. The panic switch, when pressed, will trigger the alarm when set. Relay contacts RLA1 provide the latch, RLA2 operate the siren or buzzer.

Author : Andy Collinson

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