Tuesday, July 31, 2012

12V Battery Checker Circuit

This is a 12V battery checker circuit that uses 3 LEDs that light up at their respective voltages. The red LED lights up when the battery voltage is between 8 to 10V, the orange one at voltages between 10.5V to 12V and the green one when the battery voltage is above 12.5V.

This is a tried and tested battery checker circuit using one NPN and one PNP transistor. A PCB is given along with the schematic.


Automatic light activated switch circuit

The circuit can be used for switching OFF a particular lamp or group of lamps in response to the varying ambient light levels. The unit once built can be used for switching OFF a lamp when dawn breaks and switching it ON when dusk sets in. The power supply is a standard transformer, bridge, capacitor network, which supplies a clean DC to the circuit for executing the proposed actions.

Automatic light activated switch circuit
Automatic light activated switch circuit schematic

The LDR must be placed outside the box, meaning its sensing surface should be exposed toward the ambient area from where the light level is required to be sensed. The circuit can be used as an automatic street light controller system or a simple light activated switch.

Sunday, July 29, 2012

Eight Band Sub-Woofer Graphic Equaliser

Your sub is installed and set up as best you can, but you can't quite get it to sound right. Some frequencies are too prominent, while others seem subdued. If this sounds familiar, then this equaliser is what you need to fix it. It is not a panacea, and will not cure an impossible room, but the majority of lumps and bumps in the subwoofer response will respond very well to an equaliser as described here.

The unit is an 8 band variation on the expandable equaliser described in the Project Pages, and is dedicated to its task. Boards can be stacked to get more bands if desired, but the arrangement shown will be quite sufficient for most installations.

Eight Band Sub-Woofer Graphic Equaliser

Photo of Completed P84 Board

The equaliser is a constant Q design, so unlike most "ordinary" equalisers, it does not have a very low Q at low settings of boost and cut. This is a major problem with the standard (graphic) equaliser circuit, and is completely avoided by the constant Q version. Using the Multiple Feedback Bandpass design, these filters can be designed for any (reasonable) frequency and Q desired. As a 1/3 Octave equaliser, the filter Q should be 4.3, but I have deliberately lowered this to 4 for this design to allow a little overlap.

While there will always be "that" room which defies all attempts to make anything sound halfway decent, this EQ will dispose of the majority of problems likely to be encountered.

Fluorescent Tube Basics

While they have been with us for many years, fluorescent lamps remain somewhat mysterious to most people. This isn't really surprising, since their operation isn't simple. The tube itself contains a mixture of gases, but the active ingredient is mercury. When operated as an arc, mercury vapour emits a vast amount of short-wave ultraviolet light. This is invisible, but phosphors on the inside of the tube itself fluoresce when struck by UV, and are designed to emit visible light. Most of the remaining UV light is absorbed by the glass, which is opaque to ultraviolet (this is why you can't get a suntan from behind a glass window). Refer to Figure 1 to follow the explanation. This also shows a representation of the fitting that was used for the illumination tests. For all tests, only the centre tube was installed, with the others removed to ensure that each lamp was operating under near identical conditions.

Fluorescent Tube Basics
Figure 1 - Wiring Diagram For a Conventional "Troffer" (Fluorescent Light Fitting)

In order to start the arc inside the tube, a starter is used. This is a small neon lamp, with a bimetallic strip contact mechanism built in. When power is first applied, the neon conducts a small current - enough to heat the bimetallic strip, and this causes the switch to close. Once closed, current flows through the filaments at each end of the tube via the ballast, bringing them to working temperature. The ballast limits the current to a safe value. The filaments themselves are fairly rugged, and are typically around 2 Ohms resistance each.

While the switch in the starter is closed, there is no current flow through the neon gas in the starter. The bimetal strip cools and the contacts open. When current drawn through an inductor is suddenly interrupted, a high voltage is generated as the magnetic field collapses. This high voltage will (hopefully) strike the arc in the tube. As most people will have noticed, fluoros usually flicker a few times when turned on. This is usually because the initial strike is insufficient to maintain the arc because the gas temperature is too low. After a few strikes, the temperature is high enough that the arc maintains itself. Maximum light output is usually not achieved for around 5 minutes, but the difference is not very noticeable with tubes in reasonably good condition.

Once the arc is struck (and maintained), the ballast has a new task. An arc has negative resistance, so as the voltage across the tube falls, the current increases. The ballast limits the current to a safe value, as determined by the tube's ratings. With a continuous arc, the voltage across the tube is too low to allow the neon gas in the starter to conduct, so the starter is effectively bypassed. Old tubes will often be unable to maintain an arc, and this is why they flash and flicker, with the starter constantly opening and closing because the arc is not self-sustaining. Since AC is applied to the tube, the arc actually stops and re-strikes on each half cycle, causing the light to flicker at 100 (or 120) Hz. This is normally not visible, but a tube at the end of its life may only conduct fully in one direction. This causes a 50/60Hz flicker that is often visible and annoying to some people.

Because the ballast is an inductor, it should dissipate no power, but this can never be the case in reality. Inductors are wound with copper wire, which has resistance. If nice thick wire were used, this resistance could be minimised, but to do so is very expensive. A compromise is reached where ballast losses are deemed "reasonable", and cause the temperature rise due to power loss to remain within allowable limits. New regulations will soon specify the maximum allowable power loss in ballasts, which will see a return to larger (and more expensive) types than we commonly see today.

Finally, a capacitor is (or should be) installed in parallel with the incoming mains. This is sized to suit the ballast inductance and supply frequency. The capacitive reactance of the PFC (Power Factor Correction) cap should exactly balance out the inductive reactance of the ballast. If this is done properly, the power factor will be 1 - a perfect result. This cannot happen with a fluorescent lamp though, because the current drawn is not linear. The voltage across the tube is a reasonable approximation to a squarewave because of the arc characteristics, and the maximum achievable power factor is normally around 0.9 (90%). Typical fittings manage 0.85 or so (some are better than others).

This means that the current drawn from the mains will be 10% higher than necessary to produce the lamp's rated power. This means that for a 36W fluorescent lamp, the minimum attainable current will be around 190mA at 230V because of ballast losses. The ideal current (if power factor correction were perfect) would be 174mA, allowing for a total typical load of 40W.

Fluorescent Tube Basics
Figure 1A - Wiring Diagram For a "Lead-Lag" Fluorescent Fitting

For many commercial and industrial installations, the 'lead-lag' circuit shown above is common. By including the power factor correction cap in series with one of the ballasts, the power factor is brought to around 0.85 as with the approach shown above, but the capacitor is smaller and thus cheaper than would be the case if the ballasts were in parallel.

Note that where 120V (60Hz) mains voltages are used, you may find that ballast is actually an auto-transformer. This is used because the voltage is not quite high enough to ensure reliable operation, and the auto-transformer configuration boosts the voltage. Figures 1 and 1A are for fittings operating from 220-230V, which need no voltage boost for normal operation. Predictably, the circuits for auto-transformer ballasts are different from those shown here, but similar techniques are used.

Saturday, July 28, 2012

Ballast and Starter Fluorescent Lamp

Installation of fluorescent lamp circuits, we can see that most of the foot fluorescent lamp mounted in series with the ballast and partly installed pareral the starter.

Ballast resistor is basically a coil (choke coil) is an iron core. Fluorescent lamp ballasts in the works:
  •     Provide the initial installation of the electrodes in order to provide free electrons in large numbers
  •     Provide a potential wave big enough to hold a spark between two electrodes
  •     Preventing the occurrence of an increased flow of sparks that exceeds a certain limit for each lamp size.
Besides ballast serves to reduce the influence of the changes that interfere with the movement of light (stroboscopic) and reduce the loss side (auxiliary losses). Therefore, each fluorescent lamp ballast has always had a planned to power, voltage, and frequency are adjusted to the light TLnya respectively.

Starter on a fluorescent lamp consists of a small glass balloon filled with noble gases. Inside the bubble there are two metal electrodes as dual filament. The distance between the two electrodes are arranged with a certain distance so that the starter will turn on voltage of 100-200 V. Starter switch serves as the delay time (time delay switch) are connected in parallel with two-foot fluorescent lamp.

When the fluorescent lamp is connected to the voltage of tissues, then in a short time starter filament is connected (on) and then decide again if the lamp has been lit with a stable NE. At the time of the filament is connected, a large current will flow through the ballast from the power grid, then to the lamp electrodes, wire electrodes and the other starter, for subsequent return to the network. The existence of these currents will make the incandescent lamp electrodes and removing electrons.

Meanwhile, the voltage at the starter has been lost, so that the starter went out and become cool. Both dual metal electrodes in the starter going straight back and decided that the current is flowing. Because of the sudden termination of this, the ballast will be raised an electromotive force is quite high. Shock voltage is in series with line voltage. When raised at the right time, the voltage at the two filament lamps TL will be high enough to ignite the filament-provided tube filaments are hot enough.

In the first cycle of the tube is not already on the events as described above will be repeated, until the tube lights up. After the fluorescent lamp is lit, the starter will be parallel with the lamp. Therefore, the voltage on the lamp voltage is lower than the starter, the starter will remain extinguished.

To reduce the spark at the spark electrode bi-metal can be mounted a small capacitor in parallel with the starter. Installation of condenser is also able to improve the termination of the current in the starter and reduce radio interference.

LNB Cable Data Transceiver Circuit

This circuit was designed and used to transmit commands over LNB coaxial cable. An LNB (or LNC) is a low-noise block downconverter typically used for satellite TV reception. It’s fitted in the focal point of a satellite dish. [LNB Cable Data Transceiver Circuit] The circuit is based on generating a modulated signal on the bus which can be decoded by a tone decoder IC like the familiar LM567 from National Semiconductor.Data and carrier signals are ORed using D1 and D2. T1 acts as a current source whose current depends mainly on the value of R3. L1 and C5 form a (damped) resonance circuit for the centre frequency of the carrier. C6 acts as a very low impedance bypass, so the impedance seen by T1 at the carrier frequency equals roughly R4. 


As the current passes through R4, the voltage generated across it can be detected by IC1 which has its input coupled to the bus via C4. The low DC resistance of inductor L1 allows current to flow to the circuitry connected to the bus. Components R1 and C1 control the centre frequency of the decoder, and C2 the bandwidth.

Relevant formulas may be found in the LM567 datasheets. C3 is output filter and its value depends on the ‘data’ frequency. In accordance to what’s found in the LM567 datasheet, the carrier frequency must be at least 20 times higher than the frequency of the ‘data’ signal. The maximum detectable carrier frequency is about 500 kHz. R5 is just a load for IC1, whose output is signal in phase with ‘data’. The Carrier frequency can be generated using any simple square wave generator. In the author’s application, the carrier frequency was 100 kHz with 1200 bps data, both generated by a microcontroller. The transmitter and receiver were installed at each side of the LNB cable to create a half-duplex transceiver. Author: Sajjad Moosavi. 

500Watt Power Amplifier Circuit

In this post I will publish the circuit schematic diagram of Power Amplifier with 500watt output mono, yesterday happened to date July 18, 2012 order I able to make Power Sound System 1000 watts stereo output, which is used Sanken Transistor Final original eight seeds, serial 2SC2922 and 2SA1216, while the circuit schematic that I made here just next to it / mono with 4 Sanken transistors, let's see diagram skematic 500Watt Power Amplifier Circuit :
500Watt Power Amplifier Circuit

Power circuit requires consumption voltage polarity is 3 - 42Vol; + 42 Vol; CT 0 V and there is a safety fuse / voltage connecting Fuse Fuse is the only positive and negative voltage is connected, the source voltage / transformer CT minimum of 10A, AC Vol 220, 50 Hz. you can make 1000W output on stereo power amplifier

Friday, July 27, 2012

Car Wiper Control Using 555

Car Wiper Control Using 555 Circuit In rainy seasons, it is very annoying that wiper of your car wiping instantly all the time. Have you ever think of speed control of the wiper?.There are wiper control modules available on the market but most of them are costly. So here is an automatic wiper control circuit which enables you to control your wiper sweep rates from 1 second to 10 second. 

Car Wiper Control Using 555 PCB

The heart of this circuit is an astable multivibrator using 555 Ic. We actually change the duty cycle of the square wave to obtain different sweep rates to control the wiper. The output pin 3 of the IC remains high for a time period set by R2. During this time the wiper motor will sweep at rates. The power supply to this wiper control circuit should be 12V. fit the potentiometer R2 anywhere on the dashboard of your vehicle and control the sweep rates according to the intensity of the rain.

Circuit Diagram of Remote Control Tester

Here is an infrared remote control tester circuit that can be made without spenting much money.This IR tester build around an infrared reciever module TSOP1738. We can observe the remote control state by listening to the buzzer sound. The circuit is very sensitive and it support a range of about 5 meters.

The infrared receiver module normally remains high and the piezo buzzer is in silent mode. When the IR module receives a signal from the remote control,Its output goes low and the piezo buzzer sounds.

Circuit Diagram of Remote Control Tester

  • Assemble the circuit on a Common PCB and enclose in a small box.
  • Make sure the IR receiver made visible outside.
  • You can directly plug the circuit into mains

Thursday, July 26, 2012

230V Flasher Circuit

This circuit operates with 230v.you can use this circuit to decorate your parties.I think this will be a wonderful circuit to you all. Here DIAC ER 900 and Triac BTW 11-400.

230V Flasher Circuit diagram

230V Flasher Circuit diagram

# Be careful when you deal with 230V
# Build this circuit on a PCB
# Use only mentioned values.

20 Watt Class A Power Amplifier Circuit

A single-ended Class-A amplifier is essentially one where there is only one active driven output device. The passive "load" may be a resistor, an inductor (or transformer) or - as in this amplifier - a current sink. Of the three basic options, the current sink offers the highest linearity for the lowest cost, so is the ideal choice.

20W class A power amplifier circuit

Some esoteric (some might say idiosyncratic) designs use inductors or 1:1 transformers, but these are bulky and very expensive. Unless made to the utmost standards of construction, they will invariably have a negative effect on the sound quality, since the losses are frequency dependent and non-linear.

This amp uses the basic circuitry of the 60W power amp (see Index), but modified for true Class-A operation - it should be pretty nice! This amp has been built by several readers, and the reports I have received have been very positive.

With simulations, everything appears to be as expected, but although I have yet to actually build it and test it out thoroughly, no-one has had any problems so far. Using +/-20 Volt supplies - either conventional, regulated or using a capacitance multiplier, it should actually be capable of about 22 W before clipping, but expect to use a big heatsink - this amp will run hot.

Saturday, July 21, 2012

Simple condenser microphone circuit

This is a very use full and simple circuit diagram for amplifying weak signal from a capacitive condenser microphone. You can use this circuit for sound sensing applications and some automatic robotic sensors. We have already posted an Efficient audio amplifier circuit using 1895 IC; it is somewhat complicated and suitable for very sensitive applications. But this condenser microphone DIY audio sound amplifier is very small and simple to implement because it uses only two BC547 transistors and some discrete components. You can construct this circuit with minimum of $2 price. This circuit apt for cheap amplification purposes in electronics such as pre amplifier for FM Transmitter.
Circuit diagram

Components required
    Resistors (2.2kΩ; 3.3kΩ; 470kΩ; 220kΩ; 1.2kΩ)
    Capacitors (0.1µF x 2; 10µF,16V)
    Transistors (BC547 x 2)
    Condenser mic
    Speaker (8Ω, ½ Watt)

Working mini audio amplifier 
The circuit is alienated into three divisions: Condenser mic, Audio amplifier and loudspeaker.
    Condenser mic is a type of capacitive audio sensor (audio transducer) that converts the sound (audio) signal into electrical signals.
    These electrical signals are too weak so it is amplified by the amplifier unit. The amplified output is obtained across the speaker.
    The output of condenser mic is coupled via a coupling capacitor of 0.1µF, the purpose of this capacitor is to remove DC contents in the audio signal.
    A 2.2kΩ resistor is used to give the required biasing to the condenser microphone.
    Transistor Q1 is configured as collector to base biasing mode. This is accomplished via 470kΩ resistance. This resistor provides negative feedback to the transistor Q1.
    The output of Q1 becomes available at the collector (across 3.3kΩ resistor), which is the input to the transistor Q2 via a 0.1µF capacitor. The capacitor removes DC voltages due to the biasing of Q1.
    Transistor Q2 is configured as fixed bias using 220kΩ resistor. It also provides further amplification.
    The amplified output from Q2 is available across the 1.2kΩ resistor.
    The 10µF electrolytic capacitor also used to block the DC voltages associated with the biasing of transistor Q2.
    Use 8Ω, ½ watt speaker to hear the amplified signal.


Sunday, July 15, 2012

Car Backup Alarm Circuit

The brake lights of the automobile trigger this circuit on and off. This save the annoyance of the alarm when it is not needed. This is an older circuit which was published in Popular Electronics Magazine, but still a good circuit today.
Car backup alarm circuit
Car backup alarm circuit diagram

Circuit 3 LED battery monitor

This is the circuit diagram of a 3 LED bar graph type battery monitor circuit that is ideal for monitoring the voltage level of an automobile battery.When battery voltage is 11.5V or less transistor Q1 will be On and the LED D1 will be glowing.When battery voltage is between 11.5 and 13.5V, the transistor Q2 will be On and the LED D2 will be glowing.When battery voltage is above 13.5V the transistor Q3 will be On and the LED D7 will be glowing.

Circuit diagram with Parts list.

Circuit 3 LED battery monitor
Assemble the circuit on a general purpose PCB.The battery to be monitored can be connected between the terminals namely A and B.It is always better to use LEDs of different colour.

Saturday, July 14, 2012

Two Colour LED Light Bar Circuit

This circuit is a circuit run on alternating two insignia.It uses the 2-color LED with a built-participating in 3-pin single.This preference look for away the glow of every LED until the base.It turns alternating to one more color.In in the least way to the moon on the moon essential end, afterward the LED end of the first LED.Circuit consists of, nand gate ic.Two 10 Counter circuits IC, and IC JK flip washout.

Two Colour LED Light Bar Circuit Diagram

company of the circuit is not speaking into 3 sets.It is a solid of gesture generators, a set of parade and control.Set the signal generator is IC1a,and IC1b quantity 4011 is a signal generator.The R2, R3, C2 determine the frequency generated.The hint is fed to a set of impressions is the figure 4011 IC2 and IC3.The 10 counter circuits to output to the LED, and Is the same, but the effort should ensue performed individual by the side of region. Therefore, the show from pin 11 of IC 2 and tested pro D2 and D3,To pin 3 of IC4.The integrated circuit IC 4 is a JK flip slump is connected to a T flip flop.The signal input pin 3 and pin 1 is the output hint at.Which sends a signal to the Reset IC either obstruct working.IC4 on the anniversary, it want output the originally moment in time, happening contrast to pin1.IC3 progress to handiwork, IC2 stopped.
IC2 is controlled by signals from pin 1 of IC4, to IC1c.earlier to control IC2.The IC3 is connected to pins 1 through D1 to the control again.

LM12 - High Power Amplifier circuit

LM12 - High Power Amplifier circuitThis is an amplifier circuit using ic LM12 as the main amplifier. This amplifier has a 150Watt power output and has a 4 ohm impedance. These amplifiers have a classified high output power. The frequency response of 10Hz to 30KHz. Supply Voltage at least 9 Volt and 50 Volt CT.

See schematic Below :

schematic LM12 high power amplifier
Schematic High Power amplifier with LM12

Class B power amplifier circuit

Class B power amplifier
Excessive heat to be problematic in the amplifier Class A. Then be made to class B amplifier with a point Q is shifted to point B. Point B is a point on the line load ,where this point intersects the line current Ib = 0. Because of the location of point Such, then the transistor works only active in one part wave phase only.

Therefore class B amplifier is always made with 2 of the transistor Q1 (NPN) and Q2 (PNP).
Point Q amplifier A, AB and B
Point Q amplifier A, AB and B

Since both these transistors work alternately, then the amplifier class B is often named as Push-Pull amplifier. If the signal a sine wave, then transistor Q1 is active in 50% of cycles The first (positive phase 0o-180o) and The next turn on transistor Q2 50% in the next cycle (phase negative 180o - 360o). Class B amplifier more efficient than the class A, because if there is no input signal (vin = 0 volts) then the bias current also Ib = 0 and practically made ​​a second trasistor is turned OFF.

 Series Class B Power Amplifier
Series Class B Power Amplifier
Class B amplifier efficiency approximately by 75%. But that does not mean the problem is over, because the transistor have to-not-an ideal. In in fact there kirakira VBE voltage clamp of 0.7 volts which causes transistor is in OFF state although the flow has a larger Ib some mA from 0. This is what led to the emergence of crossover problems active transition at the time of the transistor Q1 to the transistor Q2 turns become active.

Filter-PreAmp Subwoofer Circuit

Filter | PreAmp Subwoofer
Acoustic spectrum is extended by the 20Hz frequency is very low and reaches as high frequency 20000Hz. In the low frequency is lowered sense of direction. This reasoning leads us to attribute to the speaker's use of very low frequency. Making it to you we propose to distinguish these frequencies, in order for him to lead us on a suitable amplifier.

Acoustic filter are met at different points in the sound system. Applications knownest they are filter baxandal to organize low-and high-frequency tones and crossover filter where the acoustics are separated in the subareas, for it leads to the appropriate speakers. Applications that you can we propose is a simple filter that limits the acoustic region (20-20000Hz) in 20-100Hz region.

With manufacturing, we propose that you can you can make an active filter for you lead a very low frequency loudspeaker. With this you will put a big one between speaker HIFI speakers from you. In order for you to have a complete picture of sound you will need also an appropriate amplifier. In the entry of circuit you will connect the two roads out of the preamplifier or the exit of the preamplifier few. The series production in order to allocate out of the facility led a series of subwoofer power. If for some reason you do not have space for you to put the third speaker in the courtroom, then you can choose a smaller speaker. This output will depend on the type of music that you hear. If in deed you have the space, then after you create a filter and still say thank you, you can he recommend your friends or still makes each other to your friends.

Circuit diagram
Filter | PreAmp Subwoofer
Filter | PreAmp Subwoofer circuit diagram

R1 = 39 Kohm
R2 = 39 Kohm
R3 = 47 Kohm
R4 = 10 Ohm
R5 = 22 Kohm
R6 = 4.7 Kohm
R7 = 22 Kohm
R8 = 4.7 Kohm
R9 = 10 Ohm
R10 = 220 Ohm
C1 = 39 pF
C2 = 0.1 UF
C3 = 0.1 UF
C4 = 0.2 UF
C5 = 0.4 UF
C6 = 0.1 UF
C7 = 0.1 UF
IC1 = TL064

In the form that appears theoretical filter circuit. At first glance we see three different circuits which are mainly produced by two rounds of operational amplifiers. This circuit is a mixture, with the assistance variable amplifier and variable filters. Late-making requires a series of operations catering catering with the same trend with  ± 12. operational amplifier which is the active element for this circuit is the type of dual operation as a TL082 and NE5532. The operational amplifier is included in a family is equipped with field-effect transistor IFET in their entries. Each member is allocated a family in bipolar transistor circuits and field effect. This circuit can function in a high inclination, because of their high propensity to use transistors. Also they have the high honor rhythm elevation (slew rate), low polarization at this time for entry and little influenced by temperature. The operational amplifier has an area of ​​3MHz unity gain bandwidth. Another important element for them is a great choice reject noise, there are currently in the line of catering.
Price refused to greater than 80dB, their consumption is small, from 11 to 3 mA. They briefly sold internally with eight pins and allocate two operational amplifiers, In the same row 14 pin in short they combine four operations, the trade them for sale with code TL074, TL084 and TL064, a nutshell with eight pins they sold the operational amplifier TL071 TL061 kajTL081 . In manufacturing we use the TL082 that has two operational. First operation of TL082 he worked as an amplifier and mixed with two channels, the entry is negative, it is a little mixed with the two resistances. A potentiometer on the steps of determining the aid circuit. At this point the left wing and right-channel preamplifier they added means of two resistances. En operational continuity with the help strengthen the signal is made depending on the price that has been potentiometer.

Filter | PreAmp Subwoofer
PCB layout

Place runner comparable with the assistance of the circuit. The second operational amplifier is a filter manufacturing. Filters from the acoustic frequency from second grade and he made a round of operational amplifiers. This filter section with variable frequency low-cut. This frequency can be changed and took the price of very low frequency of 30Hz or still exceeds 150Hz. The frequency of the filter depends on the price cuts that have circuit elements. Change the value of the elements that we can have a frequency cut 150Iz, 130Hz, 100Hz, 7A? Z, 6A? Z even 3A? Z, is the price that they can be achieved by simple rotation of the double potentiometer. Filter circuit has been made about an operation 'that has completed a TL082 dual operational amplifier. In the filter out we will connect the plug load which is connected amplifier. In a series of exit are presented, which are limited as to the extent of frequency, the signal applied in the entry of the circuit.

Non-Switching Current-Drive Amplifiers

Non-Switching Amplifiers
Most of the distortion in Class-B is crossover distortion, and results from gain changes in the output stage as the power devices turn on and off. Several researchers have attempted to avoid this by ensuring that each device is clamped to pass a certain minimum current at all times. This approach has certainly been exploited commercially, but few technical details have been published. It is not intuitively obvious (to me, anyway) that stopping the diminishing device current in its tracks will give less crossover distortion .

Current-Drive Amplifiers
Almost all power amplifiers aspire to be voltage sources of zero output impedance. This minimizes frequency-response variations caused by the peaks and dips of the impedance curve, and gives a universal amplifier that can drive any loudspeaker directly.

The opposite approach is an amplifier with a suffi ciently high output impedance to act as a constant-current source. This eliminates some problems – such as rising voice-coil resistance with heat dissipation – but introduces others such as control of the cone resonance. Current amplifiers therefore appear to be only of use with active crossovers and velocity feedback from the cone . It is relatively simple to design an amplifier with any desired output impedance (even a negative one), and so any compromise between voltage and current drive is attainable. The snag is that loudspeakers are universally designed to be driven by voltage sources, and higher amplifier impedances demand tailoring to specifi c speaker types

3-Way Crossover Speaker Circuit

Design simply what best fit the drivers' capabilities while focusing on keeping the woofer in doing its job handling the bass, the mids handling the full midrange and so on. 500Hz and 4000Hz were chosen as the crossover frequencies. An L-pad circuit I felt was essential in keeping the response of the speaker perfect as possible. I didn't want anything to stick out. A schematic of the Hi-Vi 3 way crossover design is shown below.

3 Way Crossover Circuit Diagram
3 Way Crossover Speaker Circuit Diagram

10 W Audio Amplifier Circuit

This circuit is a general-purpose 10-W audio amplifier for moderate-power PA or modulator use in an AM transmitter. With higher voltages and a change in bias resistors, up to 30 W can be obtained. The Output Stage Amplifier using transistor 2N3055 and MJE2055.

10 W Audio Amplifier Circuit Diagram
10 W Audio Amplifier Circuit Diagram

Friday, July 13, 2012

TDA7294 150 W Power Amplifier

This is power amplifier based on IC TDA7294 with output power 150W with 8 ohm impedance, source voltage + - 25V. for circuit see image below.
TDA7294 150 W Power Amplifier
TDA7294 Power Amplifier
For PCB Layout design visit here : TDA7294 Power amplifier PCB Layout Design

Thursday, July 12, 2012

2 Way - Speaker Crossover circuit

crossover circuit
The series of crossover is an electronic circuit in which the point to separate the audio sound frequency. objective that only sound with a frequency range that can be accepted speakers are forwarded. less is more like a filter function, so the speakers work optimally.

2 way or 3 way or else, that determines how many channels would be separated voice. Each channel is handled by a single class of speakers. Eg 3 way, the frequency of sound produced by the head unit, separated by crossover as a low freq (big size distinguished speaker better known as the subwoofer), medium freq (medium speakers), usually in the middle) and hi freq (small speakers I would call a tweeter) Let me better sound and reduce noise.

Schematic 2 Way Crossover
Schematic 2 Way Speaker Crossover

Wednesday, July 11, 2012

Simple Power Amplifier Circuit [2N3055]

Simple Power Amplifier Circuit Diagram
Simple Power Amplifier Circuit Diagram

Tr1 BCY70 (or BC 182L or BC212L or BC214L)
Tr2/3/4 BFY50/51
Tr5 BFX88
Tr6/7 2N3055

Risk of instability if no input connected. When testing, connect R (about 3k3). The Simple Power Amplifier Circuit needs well smoothed power supply of about 20 to 30 volts. Peak power is well over 10 Watts.

Mono to Stereo Audio Signal Circuit Converter

This circuit is used to convert a mono audio signal into a stereo signal that can be panned between the left and right channel by a 0-10V control signal, it is intended for analog synthesizer systems.

Circuit Convert Mono to Stereo Audio Signal
Circuit Convert Mono to Stereo Audio Signal Schematic

LED Audio Level Meter Circuit

This circuit uses two quad op-amps to form an eight LED audio level meter. The op-amp used in this particular circuit is the LM324. It is a popular IC and should be available from many parts stores.

LED audio level meter
LED audio level meter schematic
The 1K resistors in the circuit are essential so that the LED's turn on at different audio levels. There is no reason why you can't change these resistors, although anything above 5K may cause some of the LED's to never switch on. This circuit is easily expandable with more op-amps, and is not limited to use with the LM324. Pretty much any op-amp will work as long as you look up the pinouts and make sure everything is properly connected.

The 33K resistor on the schematic is to keep the signal input to the circuit at a low level. It is unlikely you will find a 33K resistor, so the closest you can get should do. The value of this resistor may need to be changed, so it is best you breadboard this circuit before actually constructing it on PCB. The circuit in it's current form will accept line level inputs from sources such as the aux out on a Hi-Fi, all though could be easily modified to accept speaker inputs.

The audio + is connected to the main positive rail, while the audio - is used for signal input. The 50k pot can be used to vary the sensitivity of the circuit.

OCL Power Amplifier Circuit MJ15003,MJ15004

This Power Amp OCL 100 watt circuit by transistors.They has been an old circuits, but very well amplifier schematic.
We use only all transistor MJ15003 and MJ15004 is the main in circuits, and the power supply +38V 0 -38V 3A. follow stye of OCL amp and They has Specification are
power output : 105watt at 4 ohm load, 88watt at 8 ohms load
input sensitivity : 0.5V
Frequency response : 10-10kHZ +/- 1dB
THD: 0.07% at 50 watt , 0.1% at 100 watt.

This power amp OCL 100w is a very excellent sound quality. Since we provide the circuit in look All direct coupling form is connection join together direct all, to cut-off frequency low-loss problems, the super bass really do not tell who.
The signal Input of the tone controls enter via C1 to the base pin of transistor Q1, which together with the Q2 is differential amplifier, the signal from the collection pin of Q1 supplied to the bas pin of the Q5, which it acts as the pre-driver circuit.
- The transistor Q4 is setting level bias or act as to control Idle current in this circuit. Which we can adjust level idle current by By adjusting the VR1.
- The transistor Q3 acts as a boost trapping.
- The output signal from the Q5 will enter to base pin of Q8,Q9.which acts as the driver circuit. For the signal output to drive the output transistors Q10, Q11.
- Both output transistors Q10, Q11, we used the number on the circuit are MJ15003, MJ15004. This couple can use up to 200W, so not problem in durability.
If you want to save. May be represented by a pair of output are 2N3055, MJ2955 each of the two parallel each other instead.

OCL Power Amplifier Circuit MJ15003,MJ15004
100W OCL Power Amplifier Circuit MJ15003,MJ15004

-Check the assembly of all equipment to correct the circuit, without the output transistors, Using a voltmeter measure the voltage at the speaker. By also does not have a speaker. At the end of this process was completed and ready to operate immediately.
-Put the power supply to the circuit, then to measure the voltage is 0V or not higher than 0.25V, if not in this means that the circuit failure, need to check first.
-The later, on output transistors, and then use an ammeter to measure the current is supplied with short input circuit. Measuring that positive or negative wire. Then, adjust VR1 until reading about the current 20-40 mA.
- For transistor Q4, when the device successfully. Should be installed on the cooling pad. Which installation of the output transistor. To help control the the bias current output relative to the temperature change of the output transistor.
- The power supply circuit is got by power of transformer T1, which provides voltage to the coil in the secondary coil is 27-0-27 volt, 5 amp.
- The Diodes Bridge rectifier should be not lower than 5 Amp 100V, The filter capacitor C7, C8 we used a 1,000uF 50V, the voltage at the capacitor afer through the filter will can about 38V.

Inverter circuit 12V to 220V 100W

This circuit power Inverter 100W, it easy and good ideas. When use the electric appliances that want 220V AC 50HZ, which have small-sized about 100Watt not exceed. By when you apply outside home, as a result have to have Mini power inverter about 100Watt, perform modify from work electricity forces of battery 12V give tall fair the work. 

Inverter circuit 12V to 220V 100W

If you are New user electronics or want to economize or want to build electronics project use by oneself. I begs for to advise this circuit , because it uses , transistor number BC557 or the number replaces, perform oscillator generator. Then have power transistor 2N3055 numbers perform to drive coil transformer for converter voltage give tall go up 220V AC 50HZ at the electric power about 100 watt not exceed. When apply to transformer about 2A-3A.

0-300V Variable High Voltage Power Supply

Here is the variable high voltage dc power supply circuit, which we can customize the output voltage from 0 to 311Vdc, and it is protected the current over limit that we define at about 100 mA.

0-300V Variable High Voltage Power Supply

In the circuit you can see the T1 is a mains transformer with a ratio of 1:1, for security reasons , and reduces noise signal as well. Then the mains voltage from the T1 is rectified to DCvolt with bridge diode D1-D4, We use a No. 1N4007 that withstand voltage as 1,000V at the current 1A and and this DCV is filtered through the capacitor C1 – 220uF 400V be the big size electrolytic types, by the voltage drop across C1 is about 311VDC.

The power MOSFET Q1 is controlled the current output, with using the resistor R3 – 500K adjust the voltage gate pin of Q1. The ZENER diode ZD1-12V is available prevent over voltage at gate pin of the Q2 if we not has it when high volt the Q2 may be damaged.

The transistor Q2-BC337 and the shunt resistor R2 – 3.3ohm are added for as a current limiter. When the current output is too increased, the Q2 will stop the gate pin of the Q1 immediately, which will be guard the higher current output. The degree of R3 gets from testing in this circuit, which depending on the gain of the transistor or the hFE value, so you may need to tune the value of R2

Adjustable Power Supply 1.2 – 30V 5A using LM338

If you want to a variable dc voltage power supply circuit during 1.2V to 30Vdc and can provide a current maximum to 5A.

We may be have the many ways such as: to be modified the LM317 Variable Regulator 0-30V 1A by add the power transistor MJ2955 in circuit following Power supply regulator 1.2V-20V and 3V-6V-9V-12V 3Amp or will build the Variable dc regulator 0-30V 5A circuit to be well as well, But these methods. Rather cumbersome and wasting too money.

Adjustable Power Supply 1.2 – 30V 5A using LM338

However we can build this circuit easily and cheap, By using the packages IC No. LM338 only one, Similar to the LM317 IC number, but it can supply up to 5A, as the circuit shown in Fig.

How this circuit works
-The transformer T1 converts the AC 220V to 24 Vac, so be rectified the current by the bridge diode rectifier BD1 – 10A 400V. Until DCV has come out that the filter capacitor C1 is equal to 35 volt.
-The IC1 is the heart of the operation of this circuit. By the voltage output value obtained from the IC depends on the voltage value at the Adj pin of IC1, or can be varied by adjusting the VR1.
-However output voltage will be approximately equal to 1.25+1.25VR1/R1
The output voltage at the output pin of the IC1 is a more powerful filter with the capacitor C3.

Circuit High-Voltage Generator with HEX FET

The schematic diagram below show a circuit of high voltage generator. This circuit uses a 4049 hex inverter as an oscillator, and you can use ignition transformer from automotive engine. A fly-back transformer is possibly usable too. The 4049 will drive the IRF731 HEX FET. The Q1 must be heatsinked. Here is the schematic diagram of the circuit:

High-Voltage Generator with HEX FET

Subwoofer Speaker box design

The order of 4 or sealed rear chamber bandpass system is essentially a system of watertight enclosures with the addition of an acoustic filter for the driver. The resulting system usually provides a lower cut-off frequency, the compromise that a larger case. The space can be reduced by two drivers in isobaric configuration.

4th-order bandpass systems generally show better able to handle the functions that the other major systems are considered. The transient response and is second only to the sealed enclosure systems, making it a good choice for subwoofer applications.

Subwoofer Speaker box design
Subwoofer Speaker box design

Since all output 4th order bandpass system is via the port, the largest diameter possible for the port area should be used to minimize noise from the port. The ports must be incinerated where possible, for the same reasons.

The 4th order bandpass system rarely allows a perfect bandpass response - there is usually an out-of-band noise present in the production. A notch filter can be used simply to reduce the noise as audible. Otherwise, a lowpass filter used in series with the driver, but the in-band response system may be affected if this approach is taken.

As the speaker sound 4th order band pass issued by the openings or ports on the port side of the box, the port noise inevitable.

This unwanted noise can be minimized by a notch filter and the largest diameter possible for the port of the area should definitely be used. Another option is to burn the ports of the 4th order bandpass room as this will certainly help to reduce unwanted extra from the subwoofer.

Tuesday, July 10, 2012

Automatic detectors water tank pump circuit

This is a circuit detectors on the water pump. This circuit works automatically when the water is discharged to storage tanks or redundant. If the storage tank water runs out then the circuit will work running the pump, and an excess of water this circuit will automatically stop the pump working. Below the detection circuit:

Automatic detectors water tank pump
Automatic detectors water tank pump schematic diagram

R1                   10K ohms resistor
R2                   10K ohms resistor
R3                   10K ohms resistor
R4                   1K ohms resistor
R5                   10K ohms resistor
R6                   1K ohms resistor
C1                   100nF cap
Led1                5mm green led
Led2                5mm red led
D1                   4V7 zener diode
Piezo               Piezo HPE-120
VR1                78L05 regulator
IC1                  12F683 SOIC microcontroller from Microchip
S1                    Push button
9V battery
Metal strips
Hex program for the microcontroller

Doorphone Intercom Circuit

For the first time, this circuit is the design of the Canadian / English language and was designed by Mr Laurier Gendron of Burnaby in British Columbia, Canada, and myself. Make sure you visit this web site Laurier, Dandy Little Circuits Useful. This page is also available in French by clicking on the flag.

Doorphone Intercom Circuit schematic

In this doorphone circuit, 8 ohm speaker is used both as a microphone and also an output device. BC109C stage amplifies in common base mode, giving a low input impedance to match the speaker and the voltage gain is good.

The 270k resistor provides a simple DC bias and load resistor is 27k. The speaker produces weak DC output varies when used as a microphone is usually 100uV few. This DC signal is varied to be separated from the DC bias voltage is fixed and this is done with a 100u capacitor and 0.47u.

An LM386 is used in a non-inverting mode as a power amplifier to increase the voltage gain and drive 8 ohm speakers. 10k potentiometer acts as a volume control, and overall profitability can be adjusted using the 5k preset. The advantage of the LM386 can be as high as 200, is necessary because a small audio signal from the speaker. Double pole double throw switch, reverses the loudspeaker positions, so that one used to talk and others listen. Manual operation of the switch (from the house) allows two-way communication.

Monday, July 09, 2012

Emergency Light, & Flashlight

3 in 1 - LED Night Light, LED Emergency Light and LED Flashlight; Length: 4.0". The Night Light has an Automatic Sensor which allows On at Dusk and Off at Dawn. The Emergency Light features an 8 Hour Battery Back Up. Convenient White Light Flashlight.

The light is not terribly sharp-witted but it's first-class sufficient to facilitate you won't be real bumping into furniture all through a power outage. The light is by the side of its brightest at what time the power is rotten.
When its used having the status of a nightlight it is a not much dimmer but still upbeat adequate to perceive your way around.

Emergency Light, & Flashlight
The intensity of the light motivation vary depending on how dark the opportunity is. during the belatedly afternoon while the sun is still outside it will live very dim but will perk up up being the extent becomes darker. Although here is a photo sensor on the light a loss of power preference aim the light on in spite of of how dark before light the area is.

The light stays on a bunch longer than the circular emergency plug concerning illumination with the aim of I've used in the older and it looks a lot better than them. I carry out think it would look even better devoid of the flashlight part of the light and I would have a preference to grasp a version like with the aim of if they'd offer it.

Once plugging into a lookalike outlet it still leaves area intended for a lesser plug to progress into the outlet then to it.

Tuesday, July 03, 2012

Temperature Candle Using LED

LED based projects require a lot of skill and hence only experienced circuit designers try out these circuits. But there are also a few circuits in this genre that can be done by amateur electronic hobbyists. The temperature candle is one such circuit. Read on to know more about this.

Temperature Candle Using LED

The hardware components that are required to build this circuit are listed below:
- Microcontroller
- Temperature Sensor

The circuit design is pretty simple. The LED is made to flicker by the microcontroller and the color is based on the ambient temperature at that point. The temperature of the room can be known by observing the color of the LED.

The temperature value is obtained in degree Celsius. This value is received as a result of pressing the reset button on the PCB. This value can also be obtained by providing power to the device. Once the device is powered up, the change in temperature is indicated. The blue LED is triggered for a temperature increase of 10 degrees. The red LED is triggered for a temperature increase of a single degree.

Suppose, the ambient temperature is 23 degrees celsius, The circuit works in such a way that the blue LED is made to blink twice and the red LED is made to blink 3 times. Soon after this, an orange colored flicker is observed as the LED goes into canfle mode.

Since through hole components are used in this circuit, it is very cheap to construct and the components can be easily soldered. The circuit also contains a jack for connecting to a Microchip Pickit 3 programmer / debugger. This reduces the complexity involved in code modification and download.

Sunday, July 01, 2012

120 Volt 4 LED Light Circuit

This circuit uses can exist used in the same way as a night light. It uses a 120 V Mains to power the circuit. plant like a charm!

120 Volt 4 LED Light Circuit

120 Volt 4 LED Light Circuit
Circuit Schematic
4x - White LEDs
1x - 9.1K 5watt Resistor
1x - 1N4007
1x - 180or220uF 25v cap
1x - 1Meg 1/2watt Resistor
1x - 100mA fuse
1x - Enclosure

If the ac supply is 220 volts,then which resistir should  replace and by which one, 220v is twice of 110v so doubles the value due to the voltage work, try to replace 9k1 with 22k-100k and capasitor voltage 160v.