Tuesday, April 30, 2013

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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Saturday, April 13, 2013

100W Guitar Power Amplifier Rise

The power amp board has remained unchanged since it used to be first published in 2002. It indubitably shouldn't be damaged, so there is not any purpose to fix it. The image under presentations a completely assembled board (obtainable as proven as M27). Using TIP35/36C transistors, the output stage is deliberately large overkill. This be sure thats reliability beneath the most arduous stage conditions. No amplifier can additionally be made immune from the complete lot, but this does come shut.

Guitar Power Amplifier Board

The power amp (like the earlier model) is loosely based on the 60 Watt amp traditionally in the past published (Project 03), however its increased acquire to check the preamp. Other changes include the short circuit safety - the tiny groups of sections subsequent to the bias diodes (D2 and D3). This new version is not hugely totally different from the unique, but has adjustable bias, and is designed to provide a \"constant present\" (i.e. excessive impedance) output to the audio system - that is executed using R23 and R26. Note that with this arrangement, the gain will trade depending on the burden impedance, with lower impedance giving lower energy amp gain. This isn't an argument, so may protectedly be disregarded.

Ought to the output be quicked, the regular current output attribute will provide an preliminary level of safety, but is no lengthyer foolproof. The brief circuit protection will restrict the output current to a relatively protected degree, however a sustained short will cause the output transistors to fail if the amp is driven hard. The safety is designed to now not function below customary prerequisites, however will restrict the peak output current to about 8.5 Amps. Under these conditions, the internal fuses (or the output transistors) will most likely blow if the short just isn't detected in time.

Figure 2 - Power Amplifier

Figure two shows the facility amp PCB phases - excluding for R26 which doesnt mount on the board. See Figure 1B to bathroom toiletk where this ought to be bodily set up. The bias present is adjustable, & ought to be set for about 25mA dormant present (more on this later). The counselation for energy transistors has been changed to better power devices. This will give more advantageous reliability underneath sustained heavy usage.

As proven, the energy transistors will have an simple time using any load right down to 4 ohms. In case you dont use the PCB (or are chuffed to mount power transistors off the board), you will have to use TO3 transistors for the output stage. MJ15003/4 transistors are high power, & will run cooler as a consequence of the TO-3 casing (lower thermal resistance). Watch out for counterfeits though! Theres a entire lot of different excessive energy transistors that can be used, & the amp is tolerant of replaces (as lengthy as their scores are at the least equal to the tools proven). The PCB can accommodate Toshiba or Motorola 150W flat-pack power transistors with relative ease - when you preferred to go that manner. TIP3055/2966 or MJE3055/2955 may additionally be used for light or ordinary accountability.

At the enter end (as proven in Figure 1B), there is provision for an auxiliary output, & an enter. The latter is switched via the jack, so you want to use the \"Out\" & \"In\" connections for an out of doors impacts unit. Alternatively, the input jack can be utilized to connect an outside preamp to the ability amp, disconnecting the preamp.

The speaker connections allow as much as eight Ohm speaker cabinets (giving 4 Ohms). Do not use not as a lot as 4 ohm heaps on this amplifier - it's no lengthyer designed for it, & wont give dependable service!

All the low value (i.e. zero.1 & 0.22 ohm) resistors must be rated at 5W. The zero.22 ohm resistors will get heat, so mount them faraway from different parts. Needless to assert, I recommend using the PCB, as this has been designed for superior performance, and the amp gives an awesome account of itself. So good in reality, that it's going to even be used as a hi-fi amp, and it sounds very good. In case you have been to make use of the amp for hi-fi, the bias present should be elevated to 50mA. Ideally, you could probably use higher (faster / more linear) output transistors as well, however even with these distinctive the amp performs well certainly. This is essentially because they are run at comparatively low energy, and the extreme non-linearity impacts would predict with best transistors don't occur as a end result of the parallel output stage.

Make positive that the bias transistor is hooked up to of the motive forces (the PCB is laid out to make this easy to do). A some quantity of warmth sink compound in addition to a cable tie will do the job smartly. The diodes are there to offer safety to the amp from catastrophic failure must the bias servo be incorrectly wired (or set for maximum present). All diodes needs to be 1N4001 (or 1N400? - anything within the 1N400x vary is fine). A heat sink will not be wanted for any of the driver transistors.

The life of a guitar amp is a difficult, and I counsel that you simply use the largest warmth sink you can afford, on the grounds that it is common to have increased temperatures on stage (chiefly because of all the gentleing), and this scale backs the securety margin that typically applies for domestic gear. The warmth sink must be rated at zero.5° C/Watt to allow for worst case long term operation at as so much as 40°C (this is now not unusual on stage).

Make positive that the speaker connectors are remoted from the chassis, to keep the integrity of the earth isolation sections in the power supply, & to ensure that the excessive impedance output is maintained.
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Lighting Up Model Aircraft

This circuit presents plane modellers with extremely life like beacon and marker milds at minimum  outlay. The project ’s Strobe out-put (A) presents four temporary pulses repeated periodically for the wing  (white strobe) gentles. In addition the Beacon output (B) offers a double pulse to drive a red LED for indicating the aircraft’s active operational standing. On the proto-type this is regularly a red rotating  beacon often called an Anti-Collision Light (ACL). The circuit is equally helpful for street automobile modellers, who can use it to flash headlights and blue emergency milds. 

Circuit diagram :

Lighting Up Model Aircraft Circuit Diagram

All signals are generated with the help of a 4060 14-stage binary counter and a few minimal output selection common sense. Cycle time is determined by means of the best possible way the internal oscillator is con-figured (resistor and capacitor on pins 9/10) and can also be diversified within quite broad limits. High-efficiency LEDs are your first possibility for the indications linked to the Bea-con and Strobe outputs (remember to fit collection resistors acceptable to the operating voltage Ub and the present designated for the LED used). 

The sample circuit is for operating voltages between 5 and 12 V. Cur- hire waft through the two BS170 FET devices must now not exceed 500 mA.

Author : Werner Ludwig
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Temperature warning indicator circuit

The circuit is a low temperature regulator, supervisor, warns us about international warming. Temperature control is completed by the thermistor TH1, which is a negative issue. The resistance varies between 10KO at 25 ° C and about 1KO at ninety four ° C. The trimmer TR1 keep watch over the precise temperature at which the Q1-2, related as a Darlington, lead me, making the relay K1 to close and IZ, sound. 

The alarm is activated when the temperature is better than the default. The thermistor must be positioned far from the remainder of the circuit, in order not to possibility from the warmth. The power circuit is battery 9V, but whether it is established in a exhausting and fast position, then we can provide with a relentless voltage power supply. The relay contacts might be linked load which we, as a bulb, another circuit, and many others. It may also add an LED, if we're to sign and visual stimulation. 

The adjustment is done by using immersing the thermistor TH1, within the water which we all know the temperature (contacts should be neatly insulated so we don't have brief circuit) and adjusting the trimmer except the circuit is happy. The cable connecting the circuit with the TH1 have to be shielded.


Part List
R1= 820 ohm
R2-3= 1Kohm
C1= 220uF 16V
TR1= 2.2Kohm Trimmer D1= 5.6V 0.5W Zener
D2-3= 1N4148
Q1-2= BC550C
TH1= Thermistor 10Kohm at 25° C
 K1= 6V 200 ohm Relay
BZ1= Buzzer
S1= 1×2 Switch
BATT= Battery 9V or exterior supply

Application
This circuit is designed not only putting a become aware ofion of high temperatures, however can also be modified to be set on the detection of low temperatures in some houses. It can be utilized for refrigeration, walk-in fridge or freezer and other environments which can be sensitive to temperature. Some built-in circuits excessive-temperature alarm modules might be used in motor autos to the occupation through which the temperature component experiences a temperature very dangerous in the inside of a motor automobile, and motivates the employment sensor realizes the presence or resolve the absence of an occupant. In the absence of the inhabitants, the sensor is that after a length during which an audible alarm is activated to offer the attention to the motor car within the presence of an occupant. This kind of alarm will be reset with a key.

Take a temperature alarm could be advantages this form ofs give safety toion of valuable equipment by way of high temperature, low temperature, high humidity or every so often equipped. Other packages of excessive temperature can be utilized to offer protection to against loss of or against the air conditioning machine for heating off. Instead, this machine for low-temperature failure of the heating machine be used to forestall frozen pipes. The alarm may additionally scale back downtime, get a telephone call and the now notification of a conceivable power failure or failure before damage occurs in one unit

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Friday, April 12, 2013

Flugzeugepiper Cockpit

Piper Aircraft on Flugzeuge De   Piper P28 T Cockpit Map
Flugzeuge De Piper P28 T Cockpit Map.


Piper Aircraft on Flugzeuge De   Piper Saratoga Tc Ln Aaf
Flugzeuge De Piper Saratoga Tc Ln Aaf.


Piper Aircraft on Flugzeuge De   Piper Pa28 Im Airshampoo Aerodrome
Flugzeuge De Piper Pa28 Im Airshampoo Aerodrome.


Piper Aircraft on Flugzeuge De   Piper Saratoga Tc Ln Aaf
Flugzeuge De Piper Saratoga Tc Ln Aaf.


Piper Aircraft on Flugzeuge De   Piper Saratoga Tc Ln Aaf
Flugzeuge De Piper Saratoga Tc Ln Aaf.


Piper Aircraft on Aerostar Aircraft History Performance And Specifications
Aerostar Aircraft History Performance And Specifications.


Piper Aircraft on This Aircraft Will Not Be Finished In The Traditional Cub Yellow But
This Aircraft Will Not Be Finished In The Traditional Cub Yellow But.


Piper Aircraft on Flugzeuge De   Piper Saratoga Tc Ln Aaf Cockpit
Flugzeuge De Piper Saratoga Tc Ln Aaf Cockpit.


Piper Aircraft on Flugzeuge De   Piper Pa 32rt 300 Lance Ii
Flugzeuge De Piper Pa 32rt 300 Lance Ii.


Piper Aircraft on Flugzeuge De   Pa 28 181 Archer Ii
Flugzeuge De Pa 28 181 Archer Ii.


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Simple Electronic Quiz Switch

One of the common  rounds in the  quizzes is the buzzer round. We are describing here a simple electronic circuit that can be used in any test or quiz competition. In this circuit, only four persons can participate,  and  every  participant is assigned a certain number. Whenever a switch is pressed, the circuit locks the remaining three entries. At the same time, an alarm sounds and the designated switch number is displayed on the seven segment LED display.When a player presses his switch, the corresponding output of IC1 goes high. Let us suppose, when switch S1 is pressed, D1 input of IC1 goes low and its corresponding output Q1 goes high. As a result, current passes through D5 to piezo buzzer PZ1, which creates a beep. At the same time, current also passes through diodes D6-D7 to show the number on the LED display.
Circuit diagram:
Simple Electronic Quiz Switch Circuit Diagram
Simple Electronic Quiz Switch Circuit Diagram

Similarly, when any other switch (S2-S4) is pressed, the corresponding  number  gets  displayed  on  seven segment displaying DIS1 and buzzer sounds. Switch S5 is used to reset the display exclusively. Switch S5 is a push to on switch. The circuit is powered by 9V battery. Assemble the circuit on a general purpose PCB and enclose it in a suitable  case along with seven segment display and piezo buzzer. The assembled circuit can be kept near the host and the switches connected through the external can be assigned to the players.



http://streampowers.blogspot.com/2012/06/simple-electronic-quiz-switch.html
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Battery Switch With Low Dropout Regulator

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 circuit 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.

Battery_Switch_With_LDO_Regulator_Circuit_Diagramw

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-circuit 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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Infra Red IR LED Flood Light Circuit Diagram


Infra Red (IR) LED Flood Light Circuit Diagram


The adjoining design shows a simple IR flood light circuit diagram for IR illumination applications.



The 4049 section is the basic voltage doubler circuit which effectively boosts the 9 V supply to a level of around 15 V which further becomes the suypply voltage for the next 555 pulse modulator section.

 The voltage is suitably pulsed as per the settings of P1 and P2 for driving the associated IR LEDs.

The main feature of this circuit is that it utilizes just a single PP3 9 volt battery and yet is able to provide lights (IR) at dazzling levels.



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1W BTL Audio Amplifier Circuit Diagram

The TDA8581(T) from Philips Semiconductors is a 1-watt Bridge Tied Load (BTL) audio power amplifier capable of delivering 1 watt output power into an 8-Wload at THD (total harmonic distortion) of 10% and using a 5V power supply.
The schematic shown here combines the functional diagram of the TDA8551 with its typical application circuit. The gain of the amplifier can be set by the digital volume control input. At the highest volume setting, the gain is 20 dB. Using the MODE pin the device can be switched to one of three modes: standby (MODE level between Vp and Vp–0.5 V), muted (MODE level between 1 V and Vp–1.4 V) or normal (MODE level less than 0.5 V). The TDA8551 is protected by an internal thermal shutdown protection mechanism. The total voltage loss for both MOS transistors in the complementary output stage is less than 1 V.
Circuit diagram:
1 Watt BTL Audio Amplifier Circuit Diagram
1 Watt BTL Audio Amplifier Circuit Diagram
Using a 5-V supply and an 8-W loudspeaker, an output power of 1 watt can be delivered. The volume control has an attenuation range of between 0 dB and 80 dB in 64 steps set by the 3-state level at the UP/DOWN pin: floating: volume remains unchanged; negative pulses: decrease volume; positive pulses: increase volume Each pulse at he Up/DOWN pin causes a change in gain of 80/64 = 1.25 dB (typical value).
When the supply voltage is first connected, the attenuator is set to 40 dB (low volume), so the gain of the total amplifier is then –20 dB. Some positive pulses have to be applied to the UP/DOWN pin to achieve listening volume. The graph shows the THD as a function of output power. The maximum quiescent current consumption of the amplifier is specified at 10 mA, to which should be added the current resulting from the output offset voltage divided by the load impedance.
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Thursday, April 11, 2013

Simple Analogue Electronic Key

This circuit uses two comparator that are combined in what is called a window comparator, i.e. resistors R2, R5, and R10 determine a voltage window within which the voltage applied to the junction of D2 and D6 must lie in order for the outputs of IC2.A and IC2.B to both be high at the same time. Given the value used for these resistors, this window is from 10/21 to 11/21 of the comparator supply rail (5 V). If IC2.A and IC2.B outputs are both high at the same time, transistor T1 is saturated via the AND gate formed by D3 and D4, and relay RE1 is energized to operate the electric latch or any other locking device.

Analogue Electronic Key Circuit Diagram


The key is defined by the generation of the specif ic voltage at the junction of D2 and D6, formed, for example, by a simple stereo jack containing the two resistors R4 and R8. Together with R1 and R9, they form a potential divider that needs to be suitably calculated in conjunction with the values of R2, R5, and R10 so that the key can open the lock. Clearly, all this will only work correctly is the supply voltage to these two dividers is stable, which is ensured by IC1, regulating it to 5 V.If we had set the values for R1 and R9, all the readers of this edition of Elektor would have had the same key, which is clearly not a good idea! So you need to decide for yourself not only R4 and R8, which form the key, but also R1 and R9 which let you customize the ‘lock’.1 Here are the relationships between the values of resistors R1, R4, R8, and R9 for the key to be able to open the lock:

10 · R8 · R9 < 11 · (R1 + R4) · (R8 + R9) 10 · (R1 + R4) · (R8 + R9) < 11 · R8 · R9

 Given the size of the window for me d by R2, R5, and R10, 5 % tolerance resistors are adequate.

Note too that, as the relationships consist of inequalities, and that there are only two (un)equations for four unknowns, this leaves quite a wide choice for the resistor values. We advise you to set at least two of them to preferred values, which will then let you work out the others. If, as is more than likely, this does not result in other preferred values, you’ll then need to use series/parallel combinations to obtain the calculated values or else choose different starting values in order to arrive at a better compromise.
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Motorbike Alarm

This simple to build alarm can be fitted in bikes to protect them from being stolen. The tiny circuit can be hidden anywhere, without any complicated wiring. Virtually, it suits all bikes as long as they have a battery. It doesnt drain out the battery though as the standby current is zero. The hidden switch S1 can be a small push-to-on switch, or a reed switch with magnet, or any other similar simple arrangement. The circuit is designed around a couple of low-voltage MOSFETs configured as monostable timers. Motorbike key S2 is an ignition switch, while switch S3 is a tilt switch. Motorbike key S2 provides power supply to the gate of MOSFET T2, when turned on. 
 
When you turn ignition off using key S2, you have approximately 15 seconds to get off the bike; this function is performed by resistor R6 to discharge capacitor C3. Thereafter, if anyone attempts to get on the bike or move it, the alarm sounds for approximately15 seconds and also disconnects the ignition circuit. During parking, hidden switch S1 is normally open and does not allow triggering of mosfet T1. But when someone starts the motorbike through ignition switch S2, MOSFET T2 triggers through diode D1 and resistor R5. Relay RL1 (12V, 2C/O) energises to activate the alarm (built around IC1) as well as to disconnect the ignition coil from the circuit. Disconnection of the ignition coil prevents generation of spark from the spark plug. Usually, there is a wire running from the alternator to the ignition coil, which has to be routed through one of the N/C1 contacts of relay RL1 as shown in Fig.1 Fig.2 shows the pin configurations of SCR BT169, MOSFET BS170 and transistor BC548.
Circuit diagram :

Motorbike Alarm-Circuit-Diagram
 Motorbike Alarm Circuit Diagram
Motorbike Alarm-Pin Configurations :

Motorbike Alarm-Pin configurations
Pin configurations of BT169, BS170 and BC548
Also, on disconnection of the coil, sound generator IC UM3561 (IC1) gets power supply through N/O2 contact of relay RL1. This drives the darlington pair built around T3 and T4 to produce the siren sound through loudspeaker LS1.  To start the vehicle, both hidden switch S1 and ignition key S2 should be switched on. Otherwise, the alarm will start sounding. Switching on S1 triggers SCR1, which, in turn, triggers MOSFET T1. MOSFET T1 is configured to disable MOSFET T2 from functioning. As a result, MOSFET T2 does not trigger and relay RL1 remains de-energised, alarm deactivated and ignition coil connected to the circuit.  Connection to the ignition coil helps in generation of spark from the spark plug. Keeping hidden switch S1 accessible only to the owner prevents the bike from pillaging. Tilt switch S3 prevents attempt to move the vehicle without starting it. Glass-and metal-bodied versions of the switch offer bounce-free switching and quick break action even when tilted slowly. 
 
Unless otherwise stated, the angle by which the switch must be tilted to ensure the contact operation (operating angle), must be approximately 1.5 to 2 times the stated differential angle. The differential angle is the measure of the just closed position to the just open position. The tilt switch has characteristics like contacts make and break with vibration, return to the open state at rest, non-position sensitivity, inert gas and hermetic sealing for protection of contacts and tin-plated steel housing. If you find difficulty in getting the tilt switch, you may replace it with a reed switch (N/O) and a piece of magnet. The magnet and the reed switch should be mounted such that the contacts of the switch close when the bike stand is lifted up from rest.
 
 
 
http://streampowers.blogspot.com/2012/05/motorbike-alarm.html 
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Mains Frequency Monitor

Here is a simple frequency counter designed to monitor the 240VAC mains supply. It as a frequency range of 0-999Hz, so it could also be used with 400Hz equipment. Standard TTL/CMOS logic is employed for the counters and display drivers, while an ELM446 (IC1) generates accurate 1Hz pulses for gating. This device utilizes a 3.579545MHz crystal for its timebase, as commonly found in TV and video circuits and even on old PC motherboards.

Circuit diagram:
mains-frequency-monitor-circuit diagram
Mains Frequency Monitor Circuit Diagram


Source by : Streampowers
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Circuit Guards Amplifier Outputs Against Overvoltage

A universal requirement for automotive electronics is that any device with direct connections to the wiring harness must be able to withstand shorts to the battery voltage. Though brutal, this requirement is necessary for reliability and for safety. One example of the need for this protection is an audio amplifier that produces indicator noises in the automotive interior. Though operating from a voltage of 3.3 or 5V, which is lower than the battery voltage, the amplifier must be able to stand off the full battery voltage.
Circuit diagram :
amplifier outputs against overvoltage
Figure 1 : This output circuit provides continuose protection against overvoltge faults
You can also use a protection network appropriate for these amplifiers for other automotive circuits (Figure 1). A dual N-channel MOSFET disconnects the amplifier’s outputs from the wiring harness in response to a high-voltage condition on either output. The MOSFETs, Q1A and Q1B, are normally on; zener diode D4 and its bias components drive the MOSFETs’ gates to approximately 11V. Dual diode D3 provides a diode-OR connection to the dc voltage on each output, thereby producing a voltage that controls the output of shunt regulator IC2. The circuitry protects IC1, a 1.4W Class AB amplifier suitable for audible warnings and indications for the automotive electronics.
During normal operation, the amplifier outputs’ dc components are at one-half of the VCC supply—2.5V in this case, for which VCC is 5V. The 11V gate drive fully enhances the MOSFETs, and the shunt-regulator output is off because its feedback input, Pin 5, is below its internal 0.6V threshold. If either output exceeds 5V, current flows through D3 into the R5/R6 divider, pulling the feedback terminal above its threshold. The shunt-regulator output then pulls the MOSFET-gate voltage from 11V almost to ground, which blocks high voltage from the amplifier by turning off the MOSFETs. The MOSFETs easily withstand the continuous output voltage, and the circuit returns to normal operation when you remove the short. Because the circuit does not respond instantaneously, zener diodes D1 and D2 provide protection at the beginning of a fault condition.
Figure 2. Figure 2. In Figure 1, one of U1s two audio outputs (top trace) is protected when its external terminal accidentally contacts an 18V supply voltage (2nd trace).

The waveforms of Figure 2 represent an operating circuit. One of the amplifier’s outputs (Trace 1) is a 1-kHz sine wave biased at a dc voltage of 2.5V. Trace 2 is the signal on the wire harness. It also starts as a 1-kHz sine wave biased at a 2.5V-dc voltage, but, at 200 µsec, it shorts to an 18V supply. Trace 3 is the shunt regulator’s output, initially biased at 11V but pulled to ground in response to the overvoltage condition. Trace 4 is current in the wire harness. Initially a sine wave, this current drops to zero in response to the overvoltage condition.
The components in Figure 1 optimize this circuit for 5V operation. For other voltages, you can adjust the R5/R6 resistor values. The shunt regulator must be able to function in saturation and, therefore, requires a separate supply pin in addition to the shunt output pin. The circuit repeatedly withstands 28V shorts without damage.

Source :   http://www.ecircuitslab.com/2012/06/circuit-guards-amplifier-outputs.html
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Simple Audio Power Meter Circuit


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Wednesday, April 10, 2013

300W POWER AMPLIFIER FOR SUBWOOFER CIRCUIT DIAGRAM

300W POWER AMPLIFIER FOR SUBWOOFER CIRCUIT DIAGRAM

Continuous power into 8 ohms is typically over 150W (250W for ±70V supplies), and it can be used without additional transistors at full power into an 8 ohm load all day, every day. The additional transistors are only needed if you want to do the same thing into 4 ohms at maximum supply voltage

Although I have shown MJL4281A and MJL4302A output transistors, because they are new most constructors will find that these are not as easy to get as they should be. The alternatives are MJL3281/ MJL1302 or MJL21193/ MJL21194.

Because this amplifier circuit operates in "pure" Class-B (something of a contradiction of terms, I think), the high frequency distortion will be relatively high, and is probably unsuited to high power hi-fi. At the low frequency end of the spectrum, there is lots of negative feedback, and distortion is actually rather good, at about 0.04% up to 1kHz. My initial tests and reports from others indicate that there are no audible artefacts at high frequencies, but the recommendation remains.
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Pulse Generator And Signal Tracer

Dual-purpose test-instrument, Very simple circuitry, 1.5V Battery-operated
This simple circuit generates narrow pulses at about 700-800Hz frequency. The pulses, containing harmonics up to the MHz region, can be injected into audio or radio-frequency stages of amplifiers, receivers and the like for testing purposes. A high-pitched tone can be heard from the speaker of the device under test when all is working properly. The clip must be connected to the ground of the device under test, touching with the probe the different stages of the circuit, starting from the last stage and going up towards the first. When the tone is no longer heard, the defective stage has been found.

Connecting an earclip or headphone to J1, the circuit will automatically change into a two-stage amplifier and any audio signal coming from the device under test and picked-up by the probe will be heard through the headphones. The testing of a circuit should be made in the reverse manner, i.e. starting from the first stage and going down until the last stage. When nothing is heard, the defective stage has been found.

Circuit diagram:
Pulse Generator And Signal Tracer Circuit Diagram
Pulse Generator And Signal Tracer Circuit Diagram

Parts:
R1________________1M 1/4W Resistor
R2,R4_____________2K7 1/4W Resistors
R3________________150K 1/4W Resistor
C1________________2n2 630V Ceramic or Polyester Capacitor (See Notes)
C2,C3_____________4n7 63V Ceramic or Polyester Capacitors
D1_______________1N4148 75V 150mA Diode
Q1_______________BC547 45V 100mA NPN Transistor
Q2_______________BC557 45V 100mA PNP Transistor
SW1______________SPST miniature Slider Switch (See Notes)
J1_______________Stereo switched 3mm. Jack socket (See Notes)
Probe____________Metal Probe 3 to 5 cm. long
Clip______________Miniature Crocodile Clip
B1_______________1.5V Battery (AA or AAA cell etc.)

Circuit operation:

Q1 & Q2 form a complementary astable multivibrator, whose operating frequency is set mainly by R3, C2 & C3 values. Output pulses are taken at Q2 Collector and applied to the probe by means of decoupling capacitor C1. D1 provides a symmetrical shape for the output waveform. If an earclip or headphone jack is plugged into J1, the connection from Q2 Collector and C1 - C2 is broken by the switch incorporated into J1: in this case the circuit becomes a two-stage amplifier.

Notes:
  • If you intend to use the circuit to test valve operated devices C1 must be a 630V type. Working with low voltage supply transistor devices the voltage of C1 can be lowered to 63 or 100V.
  • If instead of a short probe, you intend to connect the circuit to the device under test by means of a piece of wire longer than a few centimeters, a small ceramic capacitor (470 to 1000pF) should be added in parallel to D1 to prevent unwanted RF oscillation.
  • Current drawing when in Pulse-Generator mode is about 60µA and 1.2mA when in Signal-Tracer mode operation. Therefore SW1 can be omitted, provided that the earclip or headphones are unplugged when the circuit is unused.
  • J1 is a stereo switched jack socket wired to obtain a series connection of the two earpieces forming a stereo headphone. In this manner the circuit is loaded with a higher impedance and sensitivity will be improved.
  • Therefore, the higher the load impedance the more sensitive the Signal-Tracer. In any case, common 32 Ohm impedance mini-headphones suitable for walkman sets will work fine.
  • A crystal (high impedance) earpiece is a good solution, provided you substitute J1 with a mono switched jack socket.
  • The entire circuit can be easily fitted into a pen-like enclosure, with the probe protruding like a nib.

Streampowers
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Simple Daul Regulator Handles Two Input Voltages

The circuit in Fig 1 supplies both 3.3 and 5V to transitional circuits that employ both the new 3.3V and older 5V devices. Additionally, because the regulator accepts either 3.3 or 5V inputs, you could plug it into either a new 3.3V system or an old 5V system.The circuit consists of two sections: a dc/dc converter and a double-pole, double-throw (dpdt) switch. The dpdt switch comprises a pair of dual n-channel MOSFETs (Q2 and Q3) and their associated high-side drivers.

Upon power-up, the comparator in IC2 determines the state of the circuit. The comparator’s output, IC2 pin 6, goes to the input of the MOSFET driver, IC1. The driver internally generates a gatedrive voltage 8.8V above the device’s supply voltage. This high voltage drives the appropriate MOSFETs in Q2 and Q3.

IC2 is also the heart of a flying-capacitor, buck/boost dc/dc converter. Unlike other switching-regulator schemes, this topology needs no transformers. Transistor Q1 controls this section’s output voltage, VS. When VIN is at 5V, Q1 is off, forcing the section to operate as a step-down converter. In this mode, the section produces 3.3V, which goes to the output through Q3B. Also in this mode, 5V power goes directly through Q2A, and Q2B and Q3A are both off.
 
 
When VIN is 3.3V, IC1 turns on Q1, shorting out the 140-kΩ resistor and forcing the dc/dc-converter section into step-up mode. In this mode the converter section generates 5V at VS, powering the 5V output via Q2B. Also in this mode, 3.3V goes directly from the circuit’s input to the output via Q3A. Q2A and Q3B are both off.No-load quiescent current consumption is approximately 500 μA.

Lower-frequency converters would reduce power consumption at the expense of a larger inductor. The efficiency of the dc/dc-converter section is 73% in either mode. But because this power accounts for only half of the circuit’s output power, the circuit’s overall efficiency is approximately 80% with VIN=3.3V and 86% with VIN=5V. 
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Digital Fan Regulator

The circuit presented here can be used to control the speed of  fans using induction motor. The speed control is nonlinear, i.e. in steps. The current step number is displayed on a 7-segment display. Speed can be varied over a wide range because the circuit can alter the voltage applied to the fan motor from 130V to 230V RMS in a maximum of seven steps.  The triac used in the final stage is fired at different angles 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 through an optocoupler (MOC3011) that has a triac driver output stage.

Pedestal voltage control is used for varying the firing angle of the triac. The power supply for the relaxation oscillator is derived from the rectified mains via 10-kilo-ohm, 10W series dropping/limit-ing resistor R2.  The pedestal voltage is derived from the non-filtered DC through optocoupler 4N33. The conductivity of the Darlington pair transistors inside this optocoupler is varied for getting the pedestal voltage. For this, the positive sup-ply to the LED inside the optocoupler is connected via different values of resistors using a multiplexer (CD4051).

Digital Fan Regulator Circuit diagram:
Digital Fan Regulator Circuit Diagram

The value of resistance selected by the multiplexer depends upon the control in-put from BCD up-/down-counter CD4510 (IC5), which, in turn, controls forward bi-asing of the transistor inside optocoupler 4N33. The same BCD outputs from IC5 are also connected to the BCD-to-7-seg-ment decoder to display the step number on a 7-segment display.  NAND gates N3 and N4 are config-ured as an astable multivibrator to produce rectangular clock pulses for IC5, while NAND gates N1 and N2 generate the active-low count enable (CE) input using either of push-to-on switches S1 or S2 for count up or count down operation, respectively, of the BCD counter.

Optocoupler 4N33 electrically isolates the high-voltage section and the digital section and thus prevents the user from shock hazard when using switches S1 and S2. BCD-to-7-segment decoder CD4543 is used for driving both common-cathode and common-anode 7-segment displays. If phase input 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 may still conduct slightly even when the display is zero, i.e. pin 13 (X0, at ground level) is switched  output pin 3. To avoid this problem, adjust preset VR1 as required using a plastic-handled screwdriver to get no output at zero reading in the display.

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






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Tuesday, April 9, 2013

Separate Wiring Carry Energy Loads House

House Wiring Diagram on House Wiring Diagram
House Wiring Diagram.


House Wiring Diagram on Whole House Wiring Basics Part 4     Reviews And News From
Whole House Wiring Basics Part 4 Reviews And News From.


House Wiring Diagram on The Floor Plan At Right Is Only Part Of An On Going Electrical
The Floor Plan At Right Is Only Part Of An On Going Electrical.


House Wiring Diagram on Have Separate Wiring To Carry Energy Loads To And From The House
Have Separate Wiring To Carry Energy Loads To And From The House.


House Wiring Diagram on House Plan   Wikipedia  The Free Encyclopedia
House Plan Wikipedia The Free Encyclopedia.


House Wiring Diagram on Home House Wiring Installation
Home House Wiring Installation.


House Wiring Diagram on Home Theater Wiring Diagram   Best Plasma Display Deals And Reviews
Home Theater Wiring Diagram Best Plasma Display Deals And Reviews.


House Wiring Diagram on Solar Power Diagram House
Solar Power Diagram House.


House Wiring Diagram on Draw Your Own House Design Plans For An Affordable Home That Looks
Draw Your Own House Design Plans For An Affordable Home That Looks.


House Wiring Diagram on Intrasonic I1000m Intercom Home Distributed Audio   Bec Audio
Intrasonic I1000m Intercom Home Distributed Audio Bec Audio.


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Wide Voltage Range 1 8 Watt Audio Power Amplifier with Short Circuit Protection


This is a design circuit for audio power amplifier using protection circuit. This circuit is based on LM4951A.  This is the figure of the circuit;


The LM4951A is an audio power amplifier designed for applications with supply voltages ranging from 2.7V up to 9V. The LM4951A is capable of delivering 1.8W continuous average power with less than 1% THD+N into a bridge connected 8Ω load when operating from a 7.5VDC power supply. Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The LM4951A does not require bootstrap capacitors, or snubber circuits. 

The LM4951A features a low-power consumption active-low shutdown mode. Additionally, the LM4951A features an internal thermal shutdown protection mechanism and short circuit protection. The LM4951A contains advanced pop & click circuitry that eliminates noises which would otherwise occur during turn-on and turn-off transitions. The LM4951A is unity-gain stable and can be configured by external gain-setting resistors.

[Circuit schematic source: National Semiconductor Notes] 

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Installing Home Electrical Wiring Breakers Fuses

House Wiring on Solar Powered House Wiring
Solar Powered House Wiring.


House Wiring on Home Electrical Wiring   New Home  Remodels  Additions   As You Wish
Home Electrical Wiring New Home Remodels Additions As You Wish.


House Wiring on Twelve Common Wiring Problems By Rex Cauldwell
Twelve Common Wiring Problems By Rex Cauldwell.


House Wiring on Keywords House Wiring Diagram Electrical Schematic Wiring A House
Keywords House Wiring Diagram Electrical Schematic Wiring A House.


House Wiring on Telecom Tips   Wiring Your Home For Voip Service   O Reilly Emerging
Telecom Tips Wiring Your Home For Voip Service O Reilly Emerging.


House Wiring on Installing Home Electrical Wiring For Breakers And Fuses Inside A
Installing Home Electrical Wiring For Breakers And Fuses Inside A.


House Wiring on Kitchen Blueprint And Wiring Design Layout
Kitchen Blueprint And Wiring Design Layout.


House Wiring on House Wiring
House Wiring.


House Wiring on Floorplans With Power  Low Voltage And Structured Wiring Symbols
Floorplans With Power Low Voltage And Structured Wiring Symbols.


House Wiring on House And Home Wiring Diagram And Electrical System
House And Home Wiring Diagram And Electrical System.


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