A Doorbell for the Deaf

This circuit provides a delayed visual indication when a door bell switch is pressed. In addition, a DPDT switch can be moved from within the house which will light a lamp in the door bell switch. The lamp can illuminate the words "Please Wait" for anyone with walking difficulties.
A Doorbell for the Deaf Circuit Diagram :


Notes :
The circuit uses standard 2 wire doorbell cable or loudspeaker wire. In parallel with the doorbell switch, S1, is a 1N4001 diode and a 12 volt 60mA bulb. The bulb is optional, it may be useful for anyone who is slow to answer the door, all you need to do is flick a switch inside the house, and the bulb will illuminate a label saying Please Wait inside the doorbell switch or close to it. The double pole double throw switch sends the doorbell supply to the lamp, the 22 ohm resistor is there to reduce current flow, should the doorbell switch, S1 be pressed while the lamp is on. The resistor needs to be rated 10 watts, the 0.5 Amp fuse protects against short circuits.

When S2 is in the up position (shown as brown contacts), this will illuminate the remote doorbell lamp. When down, (blue contacts) this is the normal position and will illuminate the lamp inside the house. Switch S1 will then charge the 47u capacitor and operate the transistor which lights the lamp. As a door bell switch is only pressed momentarily, then the charge on the capacitor decays slowly, resulting in the lamp being left on for several seconds. If a longer period is needed then the capacitor may be increased in value.

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Simple Telephone Record Control

This circuit will allow you to connect any tape recorder that has a mic and remote input to a phone line and automatically record both sides of a conversation when ever the phone is in use. You will need to take a couple of voltage readings before connecting the circuit. First determine the polarity of your phone line and connect it to the circuit as shown and then determine the polarity of the remote input and connect it to the circuit. Circuit operation is as follows. When the phone is on hook the voltage across the phone line is about 48volts dc. When the phone is off hook the voltage will drop to below 10volts dc. When the line voltage is at 48volts the FET is off which causes Q2 and Q3 to be off. When the phone is picked up the FET turns on along with Q2 and Q3 which turns your recorder on. The tape recorder must be in the record mode at all times. As you can see the power source for the circuit is the phone line.

Circuit Diagram

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Surf Sound Synthesizer

Many people who live close to the ocean have the benefit of being lulled to sleep by the sound of the surf. This circuit may provide a similar benefit to all those poor unfortunates who don’t live near the seaside but who do have the small consolation that they don’t have to worry about rust and corrosion in a salty atmosphere. The circuit consists of four unsynchronised oscillators which are mixed together to modulate a white noise source to simulate the more or less random nature of surf sounds. You won’t hear the waves crashing but the ebb and flow of the white noise will help mask other noises which would otherwise disturb your sleep.


The four oscillators are based on four op amps in a TL074 or TL084 quad op amp package (IC1). IC1a, IC1b, IC1c & IC1d are configured as Schmitt trigger oscillators with their operating frequencies defined by the resistor connected between their outputs (pins 1, 7, 8 & 14) and the respective inverting inputs (pins 2, 6, 9 & 13), as well as the electrolytic capacitors connected between these latter pins and 0V. The result is a triangle waveform at each of the respective inverting inputs and square waves at the same frequencies at the op amp outputs. We don’t use the square outputs but instead feed the four triangle waveforms to op amp IC2a which is connected as a mixer. Its output is used to drive and modulate a noise source based on NPN transistor Q1. This is operated with reverse bias across its base-emitter junction and the controlled reverse current is very noisy.

By varying the amount of reverse bias, we vary the amount of white noise produced. Since the amount of noise produced by the transistor varies markedly between types, the gain of IC2a can be varied over a wide range to produce the optimum output voltage to drive Q1. From there, the noise signal from the emitter of Q1 is fed via a 47nF capacitor to op amp IC2b which can also have its gain varied over a wide range to drive IC3, an LM386 power amplifier which drives the loudspeaker. In use, first adjust trimpot VR2 to set the volume level from the loudspeaker, then adjust trimpot VR1 to get the best range of white noise which simulates the surf sounds. Sleep well.

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Board Circuit diagram



In the final few yrs, the to be had vary of operating systems for PCs has increased dramatically. Various free (!) operating methods were added to the record, the kind ofs BeOS, OpenBSD and Linux. These programs are additionally available in numerous colors and flavours (versions and distributions). Windows can be no lengthyer merely Windows, as a outcome of there are actually a few different versions (Windows ninety five, ninety eight, ME, NT, XP, Vista and 7). Computer users subsequently have a large variety of choices in regards to the working machine to be used. One drawback is that now not all hardware works equally smartly underneath the quite loads of operating techniques, and with reference to software, compatibility is a meanss from being universal. In other words, it’s difficult to make a just right selection.


Switching from one working system to every different - that’s a unsafe industry, isn’t it? Although this may just be somewhat of an exaggeration, the protectedst method continues to be to put in two different operating methods on the identical PC, so that you can always easily use the ‘old’ operating machine if the model new one fails to fulfill your desires (or fit your taste). A software solution is continuously used for the sort of ‘dual device’. A program known as a ‘boot supervisor’ can be utilized to permit the user to choose, during the start-up course of, which exhausting disk will be used for starting up the pc. Unfortunately, this doesn't at all times work flawlessly, and in most instances this boot manager is changed by way of the usual boot loader of the working system when a new working system is put in.

In many cases, the only remedy is to reinstall the software program. The resolution presented right here does not endure from this problem. It is a exhaustingware resolution that causes the main and secondary hard disk drives to ‘swap places’ when the computer is began up, if so desired. From the point of view of the computer (and the software operating on the computer), it appears as though these two arduous disks have actually changed locations. This trick is made possible through a feature of the IDE specification called ‘CableSelect’. Every IDE arduous disk can also be configured to make use of either Master/Slave or CableSelect. In the latter case, a signal on the IDE cable informs the exhausting disk whether it's to act as the master or slave device. For this motive, in every IDE cable one lead is interrupted between the connectors for the 2 disk drives, or the relevant pin is disregarded from the connector.


This lead tos a low degree to be current on the CS pin of one of the pressures and a excessive stage to be present on the CS pin of the different one (at the a lengthy way end of the cable). The circuit proven here is linked to the IDE bus of the motherboard via connector K1. Most of the signals are fed right away from K1 to the opposite connectors (K2 and K3). An IDE hard disk is related to K2, and a second one is connected to K3. When the computer is swaped on or reset, a pulse will seem on the RESET line of the IDE interface. This pulse clocks flip-flop IC1a, and relying on the state of change S1, the Q output will go both excessive or low. The state on the Q output is of course all the time the alternative of that on the Q output. If we expect that the change is closed all the manner in which via start-up, a low stage will most doubtless be current on D enter of IC1a, so the Q output will probably be low following the reset pulse.


This low degree on the Q output will cause transistor T1 to conduct. The present flowing through T1 will cause LED D1 to light up and transistor T2 to habits. The onerous disk attached to attachor K2 will to that end see a low level on its CS pin, with a function to cause it to behave as the grasp force and for this reason appear to the pc as the C: force. A high level will appear on the Q output following the reset pulse. This will stop T3 and T4 from habitsing, with the consequence that LED D2 will most certainly be extinguished and the laborious disk attached to attachor K3 will see a high level on its CS pin. For this disk, this means that it is to behave as a slave pressure (D: force).


If S1 is open when the reset pulse occurs, the above scenario is after all reversed, and the exhausting disk hooked up to connector K2 will act because the D: drive, whereas the laborious disk hooked up to attachor K3 will act because the C: pressure. Flip-flop IC1a is included right here to forestall the onerous disks from swapping roles right via use. This may have disastrous outcomes for the information on the exhausting disks, and it will most seemingly result in the pc to crash. This implies that you shouldn't have to fret about affecting the operation of the pc for these who alternate the swap atmosphere while the computer is running. The state of the flip-flop, and to that end the configuration of the laborious disks, can simplest be modified during a reset.

The circuit is powered from an influence connector for a three.5-inch drive. This good thing about the use of this connector is that it simply fits onto a normal 4-way header. However, it's essential to have a look at the correct polarity when attaching the connector. The purple lead should be related to pin 1. Constructing the exhausting disk selector is simple if the illustrated printed circuit board is used. You will need three IDE cables to attach the circuit. The best concept is to make use of brief cables with only two connectors, with all pins related 1:1 (no interruption within the CS line). The IDE connector on the motherboard is hooked up to K1 using one cable. A cable then runs from K2 to first exhausting disk, and any other cable runs from K3 to the 2nd laborious disk. This means that it is not possible to connect more than two laborious disks to this circuit. You must additionally be certain that the jumpers of each disk drives are configured for CableSelect. To learn how to do this, check with the person manual(s) for the pressures.

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Programming The Propeller IC

Parallax, well-known for its successful Basic Stamp IC, has not too lengthy ago offered the Propeller: a brand new microcontroller with a certain distinction. It packs a minimal of eight three2-bit processors (referred to as COGs in Propeller jargon) right into a single package deal with only 40 pins. That design takes real simultaneous multiprocessing possible, and the subtle inside construction of the instrument makes it somewhat simple to put in force video and signal-processing utilitys.

The Propeller will also be programmed in meeting language or the high-level Spin language. The processor and the programming instruments were developed completely in-house with the help of Parallax, with the hardware being designed from scratch beginning on the transistor stage. Circuit diagram: Programming The Propeller IC Circuit Diagram The basic concept in the back of that was to keep away from turning into interested in all sorts of patent disputes with other manufacturers. The result is amazing, and for software program developers it indubitably requires a transformation in psychological toolss. As is widespread with brand new microprocessors, the Propeller has a easy serial programming interface.

The developer’s softwarekit from Parallax has a brand new USB port for that function, however a fairly simple alternative (illustrated here) is also that which you may imagine for any person preferrings to work with the familiar RS232 port. Don’t disregard that the Propeller works with a three.3-V supply voltage.

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Digital Fan Regulator

The circuit introduced right here can be utilized to control the velocity of  fanatics using induction motor. The speed keep watch over is nonlinear, i.e. in steps. The present step quantity is displayed on a 7-segment display. Speed may also be different over a huge range since the circuit can alter the voltage utilized to the fan motor from 130V to 230V RMS in a most of seven steps.  The triac used within the remaining stage is fired at totally different attitudes to get different voltage outputs by applying short-dura-tion current pulses at its gate. For this pur-pose a UJT relax-ation oscillator is used that outputs sawtooth waveform. This waveform is coupled to the gate of the triac thru an optocoupler (MOC3011) that has a triac driver output stage. 

Pedestal voltage keep an eye fixed on is used for varying the firing angle of the triac. The power provide for the comfort oscillator is derived from the rectified mains by the use of 10-kilo-ohm, 10W series dropping/limit-ing resistor R2.  The pedestal voltage is derived from the non-filtered DC thru optocoupler 4N33. The behaviorivity of the Darlington pair transistors inside this optocoupler is different for getting the pedestal voltage. For this, the sure sup-ply to the LED inside the optocoupler is attached via completely different values of resistors the use of a multiplexer (CD4051). 

Circuitdiagram:

Digital Fan Regulator Circuit Diagram

The value of resistance selected through the multiplexer is determined via the keep watch over in-put from BCD up-/down-counter CD4510 (IC5), which, in flip, keep an eye ons ahead bi-asing of the transistor inside optocoupler 4N33. The comparable BCD outputs from IC5 are also linked to the BCD-to-7-seg-ment decoder to display the step quantity on a 7-segment display.  NAND gates N3 and N4 are config-ured as an astable multivibrator to supply rectangular clock pulses for IC5, while NAND gates N1 and N2 generate the active-low rely let (CE) enter using either of push-to-on switches S1 or S2 for rely up or count down operation, respectively, of the BCD counter. 

Optocoupler 4N33 electrically isolates the high-voltage section and the digital section and as a consequence prevents the user from shock hazard when the usage of switches S1 and S2. BCD-to-7-segment decoder CD4543 is used for riding each common-cathode and common-anode 7-segment shows. If phase enter pin 6 is ‘high’ the decoder works as a common-anode decoder, and if phase input pin 6 is ‘low’ it acts as a common-cathode decoder.  Optocoupler 4N33 should habits reasonably even when the show is zero, i.e. pin 13 (X0, at ground level) is switched  output pin three. To keep away from this problem, regulate preset VR1 as required the use of a plastic-handled screwdriver to get no output at zero studying in the display.

http://www.ecircuitslab.com/2011/10/digital-fan-regulator.html

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Simple metal detector circuit diagram using CS209A

This simple metal detector circuit diagram is used to sense the presence of metal. A 100uH is used as a sensor. IC C209A has a build in oscillator circuit and the coil L1 form a part of its external LC circuit which determines the frequencies oscillation. When there is a presence of metals, the inductance of the coil is change and the resultant change in oscillation is demodulated to create an alarm. The LED also gives as a visual indicator. This circuit can sense metals up to a distance of few inches. Adjust the value of R1 POT to adjust the sensitivity.

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Telephone Ring Repeater

Even though cordless phones have invaded our homes and offices, you don’t always have them at hand, and as their ringtones are usually very much quieter than the old rotary-dial- type analogue phones, it can happen that you miss a call you’ve been waiting for while you’ve been going about your daily business.

Until quite recently, you could still find remote ringers that could be plugged into any standard phone socket in order to have an additional ringer, but it seems as if these accessories are currently being phased out as everyone is ‘going cordless’. So we decided to suggest something better, with this phone ring repeater that makes it possible to control any device connected to the AC power outlet using the ringtone available on any subscriber line, and naturally, with all the guarantees of safety and isolation that are of course rightly expected. So it’s capable of driving a ringer, or indeed even a high-powered sounder to alert you when you are in the  garden, for example; but it is equally able to light a lamp for a ‘silent ring’ so as to avoid waking a sleeping baby or elderly person.

 Telephone Ring Repeater Circuit Diagram

This circuit has been designed to be compatible with all phone systems the author is  aware of and also to be totally stand-alone. What’s more, the circuit can be connected to the phone system without any danger though in some countries, it is forbidden to connect non-approved devices to the public  switched telephone network (PSTN). Check local regulations in this respect.

In order to understand the principle of it, we just need to remember that the ringtone present on a phone installation is an alternating voltage, whose amplitude and frequency vary somewhat between countries, but always with comparable orders of magnitude except in the case of exchange systems  used in large companies. However, when the  line is quiescent or a call is in progress, it carries only a direct voltage. Capacitor C1 makes  it possible to pick off just the AC ringing volt-age, which is then rectified by D2 and amplitude-limited by D1. The resulting DC voltage charges capacitor C2, which makes it possible to light LED D3 as well as the LED in the  optocoupler IC1. This is no ordinary optocoupler, but is in fact an AC power zero-crossing  detecting optotriac, which allows us to con-trol the chosen load while generating no, or  less, interference, which would not be the  case using a standard optotriac.

The output triac it contains is not powerful  enough to drive a load directly connected  to the mains, so it is used to drive the trigger of triac TRI1, which is a totally standard  400 V device, rated at x amps, where x is chosen to suit the maximum power of the load  you want to control using this circuit. Resistors and capacitors R5 and C3 on the one  hand, and R6 and C4 on the other help, serve  to suppress the switching transients, which  are already inherently low because of the AC  zero-crossing switching provided by IC1.

Construction is not at all difficult, but does  require a few precautions in choosing some of the components. First of all, capacitor C1  must be an MKT type, mylar or equivalent,  with a 250 V operating voltage because of  the relatively high amplitude of the ringing  voltage. For safety reasons, it is essential that  capacitors C3 and C4 are self-healing types  intended for AC power use at 250 VAC. These  capacitors are generally known as Class X or  X2 capacitors.

As for the triac, it should have a 400 V operating voltage (but see below for users on 120  VAC power) and maximum current slightly  greater than the maximum current drawn by the load being driven. As this will usually be a sounder or a common lamp, a 2 A type will  usually be more than adequate in most situations. As the circuit can be expected to operate for short periods only, there is no need to  mount the triac on a heatsink. One final important point: as the right hand  part of the circuit is connected directly to AC  power, it is vital to fit this inside a fully-insulated housing, for obvious safety reasons.  Make sure you cannot touch any part when  the circuit is in use.

The circuit should work at once and without  any problems, but if you notice that D3 doesn’t  light up fully, and hence incorrect or erratic  triggering of the triac, because of too low a  ringing voltage, all you need to put things to rights is reduce the value of resistor R1.  The circuit as shown was dimensioned for  operation from 230 VAC power. Readers on  120 VAC power should modify the following  component values: R4 = 180 Ω; R5 = 220 Ω;  TRI = 200 V model; IC1 = MOC3031. Option-ally, C3 and C4 may be rated at 120 VAC.

Source:  http://www.ecircuitslab.com/2012/05/telephone-ring-repeater.html

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Water Level Controller Detector

In most houses, water is first stored in an underground tank (UGT) and from there it is pumped up to the overhead tank (OHT) located on the roof. People generally switch on the pump when their taps go dry and switch off the pump when the overhead tank starts overflowing. This results in the unnecessary wastage and sometimes non-availability of water in the case of emergency.  The simple circuit presented here makes this system automatic, i.e. it switches on the pump when the water level in the overhead tank goes low and switches it off as soon as the water level reaches a pre-determined level. It also prevents ‘dry run’ of the pump in case the level in the underground tank goes below the suction level. 

 

In the figure, the common probes connecting the underground tank and the overhead tank to +9V supply are marked ‘C’. The other probe in underground tank, which is slightly above the ‘dry run’ level, is marked ‘S’. The low-level and high-level probes in the overhead tank are marked ‘L’ and ‘H’, respectively.  When there is enough water in the underground tank, probes C and S are connected through water.As a result,transistor T1 gets forward biased and starts conducting. This, in turn, switches transistor T2 on. 

Initially, when the overhead tank is empty, transistors T3 and T5 are in cut-off state and hence pnp transistors T4 and T6 get forward biased via resistors R5 and R6, respectively.  As all series-connected transistors T2, T4, and T6 are forward biased, they conduct to energise relay RL1 (which is also connected in series with transistors T2, T4, and T6). Thus the supply to the pump motor gets completed via the lower set of relay contacts (assuming that switch S2 is on) and the pump starts filling the overhead tank. 

Once the relay has energised, transistor T6 is bypassed via the upper set of contacts of the relay. As soon as the water level touches probe L in the overhead tank, transistor T5 gets forward biased and starts conducting. This, in turn, reverse biases transistor T6, which then cuts off. But since transistor T6 is bypassed through the relay contacts, the pump continues to run. The level of water continues to rise.  When the water level touches probe H, transistor T3 gets forward biased and starts conducting. This causes reverse biasing of transistor T4 and it gets cut off. As a result, the relay de-energises and the pump stops. Transistors T4 and T6 will be turned on again only when the water level drops below the position of L probe. 

Presets VR1, VR2, and VR3 are to be adjusted in such a way that transistors T1, T3, and T5 are turned on when the water level touches probe pairs C-S, C-H, and C-L, respectively. Resistor R4 ensures that transistor T2 is ‘off’ in the absence of any base voltage. Similarly, resistors R5 and R6 ensure that transistors T4 and T6 are ‘on’ in the absence of any base voltage. Switches S1 and S2 can be used to switch on and switch off, respectively, the pump manually.  You can make and install probes on your own as per the requirement and facilities available. However, we are describing here how the probes were made for this prototype. 

The author used a piece of non-metallic conduit pipe (generally used for domestic wiring) slightly longer than the depth of the overhead tank. The common wire C goes up to the end of the pipe through the conduit. The wire for probes L and H goes along with the conduit from the outside and enters the conduit through two small holes bored into it as shown in Fig. 2. Care has to be taken to ensure that probes H and L do not touch wire C directly. Insulation of wires is to be removed from the points shown. The same arrangement can be followed for the underground tank also. To avoid any false triggering due to interference, a shielded wire may be used.

http://www.ecircuitslab.com/2011/09/water-level-controller.html

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Updatemassive Animal Airlift Brings Dogs Washington Kill

Joseph L Bianchi Lockhaven Com News Sports Jobs Community.



Aircraft Ownership.



Update Massive Animal Airlift Brings 60 Dogs To Washington From Kill.

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Software V0 2 1 4 Software Exe Dali Commissioning Software.



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Diagramstudio Electrical Wiring Diagram Software.



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Aircraft Wallpapers 4 U Predator Aircraft Wallpapers.



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Unmanned Drone The Mq 9 Predator B Unmanned Drone Photo Reuters.

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18W Car Stereo Amplifier Rise

This automobile stereo amplifier project is a class AB audio energy amplifier utilizing the Hitachi HA13118 module. It no longer handiest can be used in car utility but additionally in any transportable or residence amplifier process. It is inconspicuous to construct & has a most of outdoor phases. The module has a high power output from a low voltage supply utilizing the bridge tied load system, & a excessive achieve of 55dB.

This project will probably be useful in softwares where the input sign is a low stage, with out requiring using a separate pre-amplifier. This IC module has a inbuilt surge safety circuit, thermal shutdown circuit, ground fault protection circuit & power provide fault protection circuit making it reliable.

The Specifications of this undertaking 
D.C. Input : eight – 18V at 1-2 A

Power output : 18W maximum, 4 ohm load, 18V DC supply

S/N ratio : > 70 dB

THD : < 0.2% @ 1W

Freq. Response : ~ 30 Hz to 30 okHz, –3 dB

Input stage : < 25 mV, for full output (G > 50dB)

Input Impedance : ~ 30 ok ohm

The provide voltage vital for this challenge is eight -18V DC, as a minimum one to two Amps. Maximum output power will handiest be bought with a power supply of 18V at larger than two A, using a 4 ohm speaker. The power supply needs to be neatly filtered to scale back mains hum, a regulated provide will scale back noise even additional. Additional filtering is now not sensible if working from a battery supply.

Circuit Diagram Description

Most of the circuitry is contained inside the amplifier module. C10 is the enter coupling capacitor and blocks DC from the input. C11 bypasses any RF which could additionally be current at the input. C1 & C2 provide an AC floor for the inverting inputs of the IC. R1/C7 and R2/C8 provide a excessive frequency load for stability with difficult speakers. C five & C six present bootstrap feedback for the IC. C9 & C12 present power provide filtering.

An externally mounted logarithmic potentiometer of between 10k ohm and 50k ohm, is used relying on the specified input impedance. The impedance should be keep as excessive as feasible for a guitar amp, except utilizing a separate pre-amp. Make sure-that the heat sink is hooked up to the module.

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1967 69 Chevrolet Camaro Wirng Diagram

1967-69 Chevrolet Camaro Wirng Diagram

The Part of 1967-69 Chevrolet Camaro Wirng Diagram: battery, generator, clutch switch, ignition
switch, voltage regulator, starter relay, neutral safety sitch, black wire, blower motor, widhshield wiper motor, heater ctrl light, radio illumination light, dome light, headlight switch

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2003 Chevrolet Impala Wiring Diagram

2003 Chevrolet Impala Wiring Diagram

The Part of 2003 Chevrolet Impala Wiring Diagram: message center, instrument panel, coolant temp,
schematics, cooling fan, relay ctrl, serial data, high speed ctrl, black wire, blue wire, junction block, logic

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Numeric Water Level Indicator

Most water-level indicators for water tanks are based upon the number of LEDs that glow to indicate the corresponding level of water in the container. Here we present a digital version of the water-level indicator. It uses a 7-segment display to show the water level in numeric form from0 to 9. The circuit works off 5V regulated power supply. It is built around priority encoder IC 74HC147 (IC1), BCD-to-7-segment decoder IC CD4511 (IC2), 7-segment display LTS543 (DIS1) and a few discrete components. Due to high input impedance, IC1 senses water in the container from its nine input terminals. The inputs are connected to +5V via 560-kilo-ohm resistors.

The ground terminal of the sensor must be kept at the bottom of the container (tank). IC 74HC147 has nine active-low inputs and converts the active input into active-low BCD output. The input L-9 has the highest priority. The outputs of IC1 (A, B, C and D) are fed to IC2 via transistors T1 through T4. This logic inverter is used to convert the active-low output of IC1 into active-high for IC2. The BCD code received by IC2 is shown on 7-segment display LTS543. Resistors R18 through R24 limit the current through the display.


When the tank is empty, all the inputs of IC1 remain high. As a result, its output also remains high, making all the inputs of IC2 low. Display LTS543 at this stage shows 0, which means the tank is empty. Similarly, when the water level reaches L-1 position, the display shows 1, and when the water level reaches L-8 position, the display shows 8. Finally, when the tank is full, all the inputs of IC1 become low and its output goes low to make all the inputs of IC2 high. Display LTS543 now shows 9, which means the tank is full. Assemble the circuit on a general-purpose PCB and enclose in a box. Mount 7-segment LTS543 on the front panel of the box. For sensors L-1 though L-9 and ground, use corrosion-free conductive-metal (stainless-steel) strips.

 

 

 

 

Source by : Streampowers

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Learn all you need from home theater reviews

If you are contemplating on acquiring a home theater system because you want to enjoy watching movies but hate tiding traffic jams to go to a movie theater, you may find it useful to read home theater reviews. Home theater reviews will help you understand the benefit of owning a home theater. It will help you acquire the most suited home theater setup that will give you the best experience you long for. Being able to watch movies after movies with no limit may be an enjoyment you want after a long day of work. Thus, owning a home theater is best for your, find the benefits that people who own home theater systems enjoy in a home theater review.

Home theater reviews provide deeper understanding of home theater equipment and furniture. These reviews will help you avoid buying inferior products, because it will be able to provide the most useful information that you need. Additionally, these reviews will help you avoid buying extremely superior products that will overload your home theater setup. Reading home theater review is thus important to be able to get the best out of your home theater system.

In a home theater review, you may find the best location you may place your home theater and the best set up that will suit you best. The recommendations of home theater furniture by home theater experts may also be beneficial to complete the home theater package. Learning how big the room may be, and the component to complete the sight and surround sound requirement for your home theater is a good knowledge you may acquire form home theater reviews. Additionally, reviews will provide you with in-depth knowledge of the home theater equipments, the intrinsic benefits and the possible defects of certain home theater equipment may also be a learning you will get from home theater reviews. Reading these reviews will prove to be beneficial for people who want to own a home theater system. Even for those who already own a home theater system, these reviews may be able to provide additional information on how to enhance their home theater system.

The in-depth review of home theater furniture and the best place where you will find superior products will help you avoid buying inferior products that will annoy you in the end. Home theater reviews will also give you various options for the best arrangement of your home theater. The best place to find reasonably priced high-end products may also be a benefit home theater reviews may be able to provide.

Finally, these home theater reviews are reviews done by industry experts, thus you will be able to get the best tips and recommendations that will help you decide if home theater system is going to be beneficial for you and if it will answer your need to be entertained. It may also help you decide on the brand and quality of your home theater equipments and furniture. Even the recommendation of a well-experienced home theater designer is available from the lines of a home theater review.

When you finally decide to acquire home theater system, this will benefit you and your family. You will then be able to watch movies and other entertaining functions of your very own home theater, and the best part is, you enjoy all these with your family beside you.

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Test Beeper For Your Stereo

The test beeper generates a sinusoidal signal with a frequency of 1,000 Hz, a common test  frequency for audio amplifiers.  It consists of a classical Wien- Bridge oscillator (also known as  a Wien-Robinson oscillator). The network that determines the  frequency consists here of a series connection of a resistor and  capacitor (R1/C1) and a parallel connection (R2/C2), where  the values of the resistors and  capacitors  are  equal  to  each  other. This network behaves, at  the oscillator frequency (1 kHz  in this case), as two pure resistors. The opamp (IC1) ensures  that the attenuation of the net- work  (3  times)  is  compensated  for.  In  principle  a  gain  of  3 times should have been sufficient to sustain the oscillation,  but  that  is  in  theory.  Because  of tolerances in the values, the  amplification needs to be (automatically) adjusted.

Circuit diagram:

Test Beeper For Your Stereo circuit Diagram

Instead of an intelligent amplitude  controller  we  chose  for  a  somewhat simpler solution. With  P1, R3 and R4 you can adjust  the gain to the point that oscillation takes place. The range of P1 (±10%) is large enough the cover the tolerance range. To sustain  the oscillation, a gain of slightly  more than 3 times is required,  which  would,  however,  cause  the amplifier to clip (the ‘round-trip’ signal becomes increasingly  larger, after all). To prevent this  from happening, a resistor in se-ries with two anti-parallel diodes  (D1 and D2) are connected in  parallel  with  the  feedback  (P1  and R3). If the voltage increases to the point that the threshold  voltage of the diodes is exceed-ed, then these will slowly start to  conduct.

The consequence of this  is that the total resistance of the  feedback  is  reduced  and  with  that  also  the  amplitude  of  the  signal. So D1 and D2 provide a  stabilising function. The distortion of this simple oscillator, after adjustment of P1 and  an output voltage of 100 mV (P2  to  maximum)  is  around  0,1%.  You can adjust the amplitude of  the output signal with P2 as required for the application. The  circuit is powered from a 9-V battery. Because of the low current  consumption  of  only  2 mA  the  circuit will provide many hours  of service.

 

 

http://streampowers.blogspot.com/2012/05/test-beeper-for-your-stereo.html 

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Blinking LED circuits

This led series will Blinking alternately, The way it works is determined by IC NE555 and transistors are used as reinforcement for each section (20 upper, 20 lower) work optimally. 555 circuit below is a flashing bicycle light powered with four C, D or AA cells (6 volts). 

Two sets of 20 LEDs will flash alternately at about 4.7 cycles per second using RC values ​​shown (4.7K for R1, 150K for R2 and 1uF capacitor). Time intervals for two lights about 107 milliseconds (T1, LED on) and 104 milliseconds (T2 lower LEDs). 

Two transistors are used to provide additional time beyond the current limit of 200mA from the NE555 timer. A single LED is placed in series with the PNP transistor base so that the 20 LED 555 is turned off when the output is high during a time interval T1. High-level output timer 555 is 1.7 volts less than the supply voltage. Adding the LED forward voltage increase is required for the PNP transistor to about 2.7 volts, so the 1.7 volt difference from the supply to the output is not sufficient to activate the transistor.

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4 x 25 W CAR AMPLIFIER TDA7381 SCHEMATIC DIAGRAM

4 x 25 W CAR AMPLIFIER TDA7381 SCHEMATIC DIAGRAM



The TDA7381 is a class AB audio power amplifier in Flexiwatt25 package designed for car radio applications. You you can also use this circuit for other purposes. Thanks to the fully complementary PNP/NPN output configuration the TDA7381 allows a rail to rail output voltage swing with no need of bootstrap capacitors.



The extremely reduced components count allows very compact sets. The on-board clipping detector simplifies gain compression operations. The fault diagnostics makes it possible to detect mistakes during Car- Radio assembly and wiring in the car.



Absolute maximum ratings of IC TDA7295 IC

• Operating supply voltage = 18 V
• DC supply voltage = 28 V
• Peak supply voltage (t = 50 ms) = 50 V
• Output peak current Repetitive (duty cycle 10 % at f = 10 Hz) = 3 A
• Output peak current Non repetitive (t = 100 µs) = 4A
• Power dissipation, (Tcase = 70 °C) = 80 W
• Junction temperature = 150 °C
• Storage temperature = -40 to 150 °C

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1 W Home Stereo Amplifier Rise

This is a one watt home stereo amplifier module project using the KA2209 IC from Samsung, which is equivalent to the TDA2822. It operates from 3-12V DC & will work from a battery since the dormant current drain is low. It requires no heat sink for normal use. The input & output are both ground referenced. Maximum output will be obtained with a 12V power supply & 8 ohm speaker, however it is suitable for driving headphones from a supply as low as 3V.

The Specifications of the home stereo amplifier :

D.C. input : 3 – 12 V at 200 – 500 mA max
Idle current : approx. 10 mA
Power output : > 1 Watt max. 4-8 ohms, 12V DC
Freq. Resp. : approx. 40 Hz to 200 kHz, 8 ohm, G=10
THD : < 1 % @ 750 mW, 4-8 ohm, 12V
Gain : approx. x10 (20 dB) OR x100 (40dB)
S/N ratio : > 80 dB, G = 20 dB
Sensitivity : < 300 mV, G = 20 dB
Input Impedance : approx. 10 k ohm

Description 

The gain is adjustable from ten to 100, i.e. twenty to 40 dB. Start with feedback resistors R1 and R3 of 1k ohm, this will give a gain of ten which ought to be adequate for most applications. In case you need more gain, you can remove resistors R1 and R3.This will give a gain of about 100, or 40 dB.The input attenuation can be adjusted by the potentiometer which can be used as a volume control. The IC gain ought to be kept as low as necessary to accomplish full output, with the in put potentiometer and your signal source at maximum.

Voltage Gain = 1+ R1/R2 = 1+R3/R4, however the maximum gain with no outside feedback is about 100, or 40dB. (GdB = 20log Gv)

This will keep the signal to noise ratio as high as feasible. Additional gain provided by the amplifier will reduce the S/N ratio by a similar amount, since the input noise figure is constant. Other values for R1 and R3 of between 1k and 10k ohm can be used if an intermediate gain level is necessary.

If driving a pair of headphones, you may also need a 100 ohm resistor in series with each output to reduce the output level, depending on headphone impedance & sensitivity. Make positive you start with the volume right down to check. Numerous headphones may be driven from the amplifier in the event you wish, since most headphones have at least 16 ohm impedance, or more often 32 ohm.

There are only a few outside parts, the IC contains most of the necessary circuitry. R1,R2 and R3,R4 are the feedback resistors. C1 provides power supply decoupling. C2 and C3 are the input coupling capacitors, which block any DC that might-be present on the inputs. C4,C5 block DC in the feed back circuit from the inverting inputs, and C6,C7 are the output coupling capacitors. C8, R5 and C9,R6 act as Nobel networks providing a high frequency load to maintain stability at frequencies where loud speaker inductive reactant may become excessive. The pot provides adjustable input level attenuation.

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Telephone line Based Audio Muting and Light On

Very often when enjoying music or watching TV at high audio level, we may not be able to hear a telephone ring and thus miss an important incoming phone call. To overcome this situation, the circuit presented here can be used. The circuit would automatically light a bulb on arrival of a telephone ring and simultaneously mute the music system/TV audio for the duration the telephone handset is off-hook. Lighting of the bulb would not only indicate an incoming call but also help in locating the telephone during darkness.

Telephone line Based Audio Muting and Light-On Circuit Diagram

On arrival of a ring, or when the handset is off-hook, the inbuilt transistor of IC1 (opto-coupler) conducts and capacitor C1 gets charged and, in turn, transistor T1 gets forward biased. As a result, transistor T1 conducts, causing energisation of relays RL1, RL2, and RL3. Diode D1 connected in antiparallel to inbuilt diode of IC1, in shunt with resistor R1, provides an easy path for AC current and helps in limiting the voltage across inbuilt diode to a safe value during the ringing. (The RMS value of ring voltage lies between 70 and 90 volts RMS.) Capacitor C1 maintains necessary voltage for continuously forward biasing  transistor T1 so that the relays are not energised during the negative half cycles and off-period of ring signal. Once the handset is picked up, the relays will still remain energised because of low impedance DC path available (via cradle switch and handset) for the in-built diode of IC1.

After completion of call when handset is placed back on its cradle, the low-impedance path through handset is no more available and thus relays RL1 through RL3 are deactivated. As shown in the figure, the energised relay RL1 switches on the light, while energisation of relay RL2 causes the path of TV speaker lead to be opened. (For dual-speaker TV, replace relay RL2 with a DPDT relay of 6V, 200 ohm.) Similarly, energisation of DPDT relay RL3 opens the leads going to the speakers and thus mutes both audio speakers. Use ‘NC’ contacts of relay RL3 in series with speakers of music system and ‘NC’ contacts of RL2 in series with TV speaker. Use  ‘NO’ con-tact of relay RL1 in series with a bulb to get the visual indication.

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Step Up Converter For 20 LEDs

The circuit described here is a step-up converter to drive 20 LEDs, designed to be used as a home-made ceiling night light for a child’s bedroom. This kind of night light generally consists of a chain of Christmas tree lights with 20 bulbs each consuming 1 W, for a total power of 20 W. Here, in the interests of saving power and extending operating life, we update the idea with this simple circuit using LEDs. 

Power can be obtained from an unregulated 12 V mains adaptor, as long as it can deliver at least about 330 mA.  The circuit uses a low-cost current-mode controller type UCC3800N, reconfigured into voltage mode to create a step-up converter with simple compensation. By changing the external components the circuit can easily be modified for other applications. To use a current-mode controller as a voltage-mode controller it is necessary to couple a sawtooth ramp (rising from 0 V to 0.9 V) to the CS (current sense) pin, since this pin is also an input to the internal PWM comparator.

Circuit diagram :

Step-up Converter For 20 LEDs Circuit Diagram

The required ramp is present on the RC pin of the IC and is reduced to the correct voltage range by the voltage divider formed by R3 and R2. The RC network formed by R4 and C6 is dimensioned to set the switching frequency at approximately 525 kHz. The comparator compares the ramp with the divided-down version of the output voltage produced by the potential divider formed by R6 and R7. Trimmer P1 allows the output voltage to be adjusted. This enables the current through the LEDs to be set to a suitable value for the devices used. The UCC3800N starts up with an input voltage of 7.2 V and switches off again if the input voltage falls below 6.9 V. The circuit is designed so that output voltages of between 20 V and 60 V can be set using P1.

This should be adequate for most cases, since the minimum and maximum specified forward voltages for white LEDs are generally between 3 V and 4.5 V. For the two parallel chains of ten LEDs in series shown here a voltage of between 30 V and 45 V will be required. The power components D1, T1 and L1 are considerably over specified here, since the circuit was originally designed for a different application that required higher power. To adjust the circuit, the potentiometer should first be set to maximum resistance and a multimeter set to a 200 mA DC current range should be inserted in series with the output to the LEDs. Power can now be applied and P1 gradually turned until a constant current of 40mA flows. The step-up converter is now adjusted correctly and ready for use.

www.ecircuitslab.com

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50 W Power Amplifier Circuit using STK084

This is the circuit diagram of 50W power amplifier circuit which built based on single power amplifier chip of STK084. Its an well-known old IC for audio frequency (AF) amplifier.

This circuit requires dual polarity / split power supply with maximum supply of ± 50. The recommended supply is ± 35 / 2-3A DC current. You may use this split power supply circuit for the amplifier. Use 28V center tap transformer to get about ± 36V output.

Technical Details:

Power output: 50W
RL : 8 Ohm
TDH : 0.2 %
Rin : 52K
Gain : 26.4 dB
Noise : 0.3 mV

Take a note that heatsink is required to be mounted on the power IC since it will going to hot when operated and deliver high power output (high audio volume level). Link

50W Power Amplifier Circuit using STK084,

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