crossfeed acoustic simulator for headphone amplifier

Figure shows the schematic of the modified crossfeed circuit. The "low impedance" version of this circuit described in the article by Chu Moy can be connected directly to the headphones, so that the headphone impedance interacts with the output impedance of the simulator. I optimized mine to go at the input of my headphone amplifier, a luxury I had because my headphone amp has such a high input impedance. This circuit presents an input impedance of about 150K ohms to the source driving it, which means it is well-matched to the output of any "line" source - like the output of a CD player or tape deck. The output impedance of this circuit is about 50K ohms, so if the input impedance of the headphone amp is lower than about 250K ohms, a buffer should be used to prevent loading (not a problem if you use my headphone amp).

This circuit has a very subtle effect on the perceived soundfield. It typically makes the sound appear to come from a point slightly ahead of your ears (as opposed to exactly in your ears) and improves the "spacious" of headphones and reduces listening fatigue. The component values are the result of a lot of tweaking so that the tonal quality would not affected as the pot is adjusted from min to max. The dual audio taper pot is sold at Radio Shack (RS 271-1732)

The changes in the soundfield are dependent on the type of music and (of course) frequency content. It has the greatest effect when a single source is placed in only one channel. With some music, switching in and out appears to have no effect. With other songs, it is very easy to tell the difference. A friend of mine did a "blind A-B" switch test while I listened to see if I could pick up the difference, and I missed more times than I hit. But then, I listen to rock music. Interestingly, there are some songs I found where the effect was very pronounced ("Starider" by Foreigner was one).

As you crank the pot for minimum resistance (full CW rotation), you get maximum crossfeed. It sounds as if the sound is moving from at your ears to a little in front of your ears. If a vocal was fully in the left ear, it would sound as if the person moved more toward center and more out front of you. The crossfeed makes it so there are no "isolated" sound sources sitting either directly to the left or right. Another way to look at it might be that you are stepping back a bit and making the sound sources be more in front of you.

Overall, I never switch to "BYPASS" or adjust the pot to any setting below full CW rotation (zero resistance). Therefore, I would say both the BYPASS switch and the POT are not really necessary and could be left out. But, the BYPASS switch is fun to play with to do A-B testing to see how much change you can pick up switching it in and out.

I can confirm that I get less listening fatigue using the circuit. I think I know the reason why, based on recent research done into the causes of tinnitus (a ringing sound usually heard in one ear more than the other). PET scans of the brain show that even when a sound is fed into only one ear, there is brain activity on both sides (i.e., in both "hearing" centers). It is becoming clear that the ears are "cross-wired" in a complex way that is not fully understood.

What is absolutely known is that the brain cannot tolerate assymetry: it cannot process two images when one is out of whack. Ears listening to loudspeakers always hear in both ears, even if a particular sound is 100% in one channel. The "off-side" ear hears the sound (mostly via reflection), so it is lower in volume and arrives a bit later. It is the differential volume and time phase shift that allows the brain to perceive the direction of the source of the sound.

Headphones violate the brain's normal processing method because some of the sounds originate in only one channel and the other ear does not pick up the reduced-volume/time-delayed signal that should accompany the source signal. Fortunately, most music is not channeled with such absolute separation, so the effect is not overwhelming, just annoying. Using crossfeed improves this, although I think that acoustic simulators with more accurate time-delay capability would probably be better (assuming they were done correctly).

555 Upgraded Two-fer – Baby swing and a Headphone tube amp

The first item is a circuit that automatically resets an infant swing. [Jay], who built both items, has an infant swing for his daughter that spins a mobile and plays music. It’s great but it only works for 7 minutes and 15 seconds before a button push is required to trigger it again. He found this limitation to be annoying, and as I have owned the same swing, I can echo his frustrations. He probed the swing and found that a 5v pulse was required to reactivate the mobile, but it had to be sent after it turned off to have any effect. He put together a simple circuit that would do the button pushing for him,

[Jay's] other entry is a headphone tube amp using a quartet of 6DJ8 vacuum tubes. The 555 timer in the amp is used to drive a FET and the hand-wound transformer he built for the amp.

S: www.electronicsinfoline.com

Selecting and Installing Digital tv antenna

Do you really need a “digital tv antenna”?
Digital TV Antenna is used to receive digital TV signals and is no different from a conventional off-air TV antenna. This is just an ordinary TV antenna that constitutes the front-end of digital TV transmisison system. TV antennas may seem like relics from the last century, but a growing number of viewers are finding them to be indispensable in getting the best picture from their HDTVs.

The switch to digital TV broadcasting has eliminated the most annoying picture distortions that made analog off-air reception so hit-or-miss. With digital TV signals, you’ll either see a crisp, ghost-free picture or no picture at all. At the present time, Cable TV is the primary source of television programming for the majority of U.S. TV viewers; additionally, multiple-millions of viewers are DBS TV subscribers.

Choosing a digital antenna

A TV Antenna that can receive traditional analog tv signals, is NOT different than an antenna that receives Digital-HDTV Signals. A TV-Antenna does not discriminate between Analog TV and Digital / HDTV Signals.

So, don’t be fooled by manufacturers and retailers which are taking advantage of the current, heightened consumer interest in all things related to Digital-HDTV. There is no thing such as digital HDTV antenna.
A digital tv antenna is the same as an analog antenna!

So choose any tv antenna you like! Like analog signals, digital TV signals can be broadcast over two different frequency ranges: VHF and UHF. The VHF channel range is 2-13 — low-band VHF is channels 2-6; high-band VHF is channels 7-13. The UHF channel range is 14-69.

Indoor vs. outdoor tv antennas
Indoor antennas are small, designed to be placed on or near your TV but are affected by the walls of a house and even by movement of people in the room, household interference include fluorescent lights, computers and cordless phones.

tv antenna" width="150" height="103">Outdoor antennas are larger and intended for roof. In general, the larger an antenna’s surface area is, the stronger the signal it will provide. Nearly all outdoor antennas perform better than even the best indoor antennas.

Installing a digital tv antenna

For digital antenna cabling always use 75-ohm coax cable. Coax cable is superior to twin-lead in every way and should be used if possible or for the best performance and reliability, use RG-6 cable.
Large outdoor antennas can be installed on a roof or a free-standing pole and for the best results, your antenna should have the clearest possible view of the transmitter tower.

• locate and avoid power lines and other wires in the work area
• do not climb onto a roof when there is no one else around
• if possible, avoid chimney-mounting an antenna as smoke and gases from the chimney can impair the antenna’s performance and shorten its life

When you’re aiming the antenna it’s best to have a helper who can check picture quality and relay the information to you. Most HDTVs and HDTV tuners include an onscreen signal strength meter but be sure to check the picture on all channels you want to receive before securing the antenna in place.

S: http://electroschematics.com

listen your heartbeat using Electronic Stethoscope

Electronic Stethoscope Circuit diagram

An electronic stethoscope is used to listen to your heartbeat and you would normally use a listening tube or stethoscope. This electronic stethoscope circuit uses a piezo sounder from a musical greetings card or melody generator, as a microphone. This transducer has an output signal in the order of 100 mV and its low frequency response is governed by the input impedance of the amplifier.

For this reason we have chosen to use an emitter follower transistor amplifier. This has a high input impedance and ensures that the transducer will have a very low frequency response. At the output you just need to connect a set of low impedance headphones to be able to listen to your heartbeat.

Replacing the emitter follower with a Darlington transistor configuration will further increase the input impedance of the amplifier.

S:electroschematics.com

A low-cost, tropicalized, and rugged sensor that is capable of testing the impurities in water.

The objective of the project is to create a low-cost, tropicalized, and rugged sensor that is capable of testing the impurities in water.

Explanation

The sensors developed are for ionic contaminants and for some physical parameters for quality testing of water. Some basic techniques are used during the testing such as potentiometry where the changes in the potential of the electrodes are detected by the potentiometric sensor. Another technique is conductometry where the changes in conductance between two electrodes are detected by the conductometric sensor.

This specific version contains microcontroller based conductometry system. It operates with low power with requiring only 6V batteries. It has real-time clock and 20x4 LCD display. The unit has the MSP430F449 microcontroller with 64KB flash memory as well as 8-channel 12-bit ADC for 8 different parameters. For pH and Analytes, there are 2 separate PI controllers and the direct readout of parameters values are provided with 1 decimal precision. The Enter and Abort keys are user friendly interface and uploading is made through Serial Data.

The current instrument can measure more parameters and more sensors were also developed. A pocket pen version prototype was also made.

S:www.circuit-projects.com

The X10 technology in order to control the different strand of Christmas lights

The project uses the X10 technology in order to control the different strand of Christmas lights.

Explanation

The use of X10 provides more simplicity for controlling the 3 strands of lights per color. Each strand has its own X10 lamp module which enables the lights to fade in and out instead of instantly turn ON or OFF. The lights are wired in series with one plugged into the end of the other and the head strand is plugged into each X10 module. Behind the tree is a power strip where all the X10 modules are plugged, which keeps them out of sight of visitors.

The X10 computer interface module (CM11A) is the main controlling feature of the entire system. A server running Ubuntu that is turned ON all the time is connected to the interface. As long the equipments are on the same power grid, they don’t have to run in the same place since X10 is a power-line radio protocol. The tree can be placed in a separate room while the computer is in another room. A simple serial string is sent by the computer to the CM11A module.

A simple state machine Synthesizer Device for Sine Waves

The project intends to record and playback notes as well as some pre-recorded tunes by creating a synthesizer.

Explanation

A simple state machine is used for sectioning the multiple options of the synthesizer. The generation of the sine wave output will be interrupt driven since the main program would be the state machine. Since the state machine for the main program does not have to worry creating tones, a lot of freedom is given to the main program functions.

To convert the 8-bit PCM data into an analog, sinusoidal signal, the DAC0808 is used in the design of sin wave generation. The full range of PCM data can be outputted by the microcontroller and only the first 15 notes can be played by the synthesizer with additional op-amp.

The program involves the use of a state machine since the design allows the user to choose from several different playback options. The change of one state to another is done through the buttons on the proto-board. In order to play the notes of a song, the buttons that the user should hit are represented by the characters being displayed on the LCD.

odd-looking apparatus is used to measure earth’s rotation

This somewhat odd-looking apparatus is being used to measure earth’s rotation. At the heart of the system is a PlayStation Move controller, used because of its dual-axis gyroscope which has the highest dynamic range compared to other available products like the Wii Motion Plus. It rests on a column perched atop a record player that was chosen because of its precision rotation rate. The two rings that flank the controller make up a Helmholtz coil which is used to cancel out the earth’s magnetic field which was found to be interfering with measurements taken by the Move controller. By recording data over time the experimenter can prove that the earth is indeed rotating, as well as ascertain longitude data and find true north. Check out the data-packed video after the break.

Simplest RF control from just about any device

[Miro] is working on a library that will allow you to add RF control to just about any device. The only requirement is that the device be capable of running a Linux kernel, and that it have a few GPIO pins available. One example is fairly straight forward, a Netgear router. Many, if not most routers run a Linux kernel natively and most have solder points on the board for unused IO pins so patching into the hardware is very straight forward. Less obvious and much more impressive is the hack seen in the image above. [Miro] built an SD card adapter cable and uses the contacts in the card reader to bit bang four-wire SPI to communicate with that RF module.

S:www.electronicsinfoline.com/New/Wireless_and_Networking/rf-control-from-just-about-any-device.html

Human Immunodeficiency Virus [HIV] 3-D Simulation model

3-D Simulation of an HIV Particle
When you look at the image below, you may think it is just a fuzzy ball of wool that is spun together. But, amazingly it is the best 3-D Simulation model of the Human Immunodeficiency Virus [HIV] which displays even the tiniest proteins from the HIV virus and the host it infects. This model has become the winner of the 2010 Science and Engineering Visualization Challenge, sponsored by Science and the National Science Foundation.

In the model you can see many colours like orange, and gray in many shapes and sizes.

Orange denotes the parts of the particle encoded by the virus genome. Gray denotes the parts captured from the host cells. The orange structure that is seen to push or jut outwards denotes surface glycoprotein trimers, which allow HIV to bind and fuse with the host cell. The viral plasma membrane is mostly chosen from the host cell as newly formed viruses bud from infected cells. The orange structure that is seen at the center of the model is the capsid, a cone-shaped pod that holds the viral RNA and enzymes.

It is amazing that such an accurate model can be created when we know that each HIV particle only has a diameter between 100 and 180 nanometers. Its genome consists of just nine genes encoding 15 different proteins.

Today, the total number of people supposed to be carrying this virus is almost 35 million people.

S:www.circuitstoday.com/category/tech-news

IC HT8950 versatile voice modulator circuit

Description.
This is a very versatile voice modulator circuit using IC HT8950A from Holtek Semiconductors. The IC is capable of creating 7 upward or downward steps on the frequency of the input voice at a rate of 8Hz. There is also two special variation effects namely Vibrato mode and Robot mode. This circuit finds a lot of application in systems like telephone, speech processors, toys, mixers etc. A microphone is used to pick up the input voice. Push button switches S2 and S3 can be used for the upward and downward frequency stepping .Push button switch S1 can be used to activate Vibrato mode and push button switch S4 can be used to activate the Robot mode. IC HT82V733 (also from Holtek) is used to amplify the output of the voice modulator.LED D1 indicates the voice level.
Important to know:

• The circuit can be assembled on a Vero board.
• Do not give more than 4.5v to the circuit.
• Switches S1 to S4 can be miniature push button switches.
• S5 can be a miniature ON/OFF switch.
• K1 can be an 8 ohm speaker.
• IC1 and IC2 must be mounted on holders.

Few transistors and NE555 For Automatic night light

Explanation:
A cheap and simple automatic night light using few transistors and NE555 timer is shown here. The circuit will automatically switch on the AC lamp when night falls and the lamp will be automatically switched off after a preset time.The working of this night light circuit very simple. An LDR is used as the sensor here. At day time the resistance of the LDR will be low and so do the voltage drop across it, the transistor Q1 will be in the conducting mode. When darkness falls the resistance of LDR increases and so do the voltage across it. This makes the transistor Q1 OFF. Base of Q2 is connected to the emitter of Q1 and so Q2 is biased on which in turn powers the IC1. NE555 is wired as monostable multivibrator that is automatically triggered at power ON. This automatic triggering is achieved with the help of capacitor C2. The output of IC1 remains high for a time determined by resistor R5 and capacitor C4. When output of IC1 goes high transistor Q3 is switched ON which triggers triac T1 and the lamp glows. A 9V battery is included in the circuit in order to power the timer circuit during power failures. Resistor R1, diode D1, capacitor C1 and Zener D3 forms the power supply section of the circuit. R7 and R8 are current limiting resistors.

Important to know:

• The circuit can be assembled on a vero board.
• Preset R2 can be used to adjust the sensitivity of the circuit.
• Preset R5 can be used to adjust the ON time of the lamp.
• With R5 @ 47M the ON time will be around three hours.
• The wattage of L1 must not exceed 200W.
• Heat sink is recommended for BT136.
• IC1 must be mounted on a holder.

FM1208 monolithic dual differential multiplexer for differential analog circuit switches

This circuit is a differential analog circuit switches. The FM1208 monolithic dual differential multiplexer used in applications where the RDS (ON) must be the same match. Since RDS (ON) for monolithic dual tracks at better than 1% of the broad temperature range (-25 to 125 C) is making an unusual choice, but ideal for a multiplexer accurate. This greatly reduces the close tracking errors due to common mode signals. OP-Amp used are LM107. Here is a schematic drawing:

Source : National semiconductor Application

Simplest Radio Transmitter

This is probably the simplest radio transmitter that you will find anywhere. It has a total of five parts and can be constructed into a very small space. It is great for science fair projects or other science related projects where short range transmission is useful.It runs on 1.5 to 3 Volts, with small hearing aid batteries or lithium “coin” cells being ideal. A thermistor or photoresistor can be inserted in series with R1 to have a varying output frequency dependent on the input.

The frequency can also be changed by changing the value of C1. A 2N2222 transistor is recommended, but you can try other types also. Performance tends to vary from type to type as well as from transistor to transistor. L1 is 20 to 30 turns of thin magnet wire (24 to 32 ga.) close wound around a 1/8 to 1/4″ diameter non-conductive form. The coil is tapped 1/3 of the way from one end and the tap connected to the emitter of Q1. Experiment with all of the values in this circuit. Nothing is critical, but performance can be varied considerabl

Timer Circuit used to switch OFF a particular device after around 35 minutes.

This timer circuit can be used to switch OFF a particular device after around 35 minutes. The circuit can be used to switch OFF devices like radio, TV, fan, pump etc after a preset time of 35 minutes. Such a circuit can surely save a lot of power.

The circuit is based on quad 2 input CMOS IC 4011 (U1).The resistor R1 and capacitor C1 produces the required long time delay. When pushbutton switch S2 is pressed, capacitor C1 discharges and input of the four NAND gates are pulled to zero. The four shorted outputs of U1 go high and activate the transistor Q1 to drive the relay. The appliance connected via the relay is switched ON. When S2 is released the C1 starts charging and when the voltage at its positive pin becomes equal to ½ the supply voltage the outputs of U1 becomes zero and the transistor is switched OFF. This makes the relay deactivated and the appliance connected via the relay is turned OFF. The timer can be made to stop when required by pressing switch S1.

Important to know:

• Assemble the circuit on a good quality PCB or common board.
  
• The circuit can be powered from a 9V PP3 battery or 12V DC power supply.
  
• The time delay can be varied by varying the values of C1&R1.
  
• The push button switch S2 is for starting the timer and S1 for stopping the time.
  
• The appliance can be connected via contacts N1 & N2 of the relay RL1.
• The IC U1 is 2 input quad NAND gate 4011.

7490(IC2) Based for 0 to 9 display

Circuit Diagram
Explanation:
The circuit shown here is of a simple 0 to 9 display that can be employed in a lot of applications. The circuit is based on asynchronous decade counter 7490(IC2), a 7 segment display (D1), and a seven segment decoder/driver IC 7446 (IC1).
The seven segment display consists of 7 LEDs labelled ‘a’ through ‘g’. By forward biasing different LEDs, we can display the digits 0 through 9. Seven segment displays are of two types, common cathode and common anode. In common anode type anodes of all the seven LEDs are tied together, while in common cathode type all cathodes are tied together. The seven segment display used here is a common anode type .Resistor R1 to R7 are current limiting resistors. IC 7446 is a decoder/driver IC used to drive the seven segment display.
Working of this circuit is very simple. For every clock pulse the BCD output of the IC2 (7490) will advance by one bit. The IC1 (7446) will decode this BCD output to corresponding the seven segment form and will drive the display to indicate the corresponding digit.

Notes.

• The circuit can be assembled on a perf board.
• Use 5V DC for powering the circuit.
• The clock can be given to the pin 14 of IC2.
• D1 must be a seven segment common anode display.
• All ICs must be mounted on holders.

LM2585 DC to DC converter (6V to 15V)

Voltage converter using LM2585
Description.
A very efficient 6V to 15V DC to DC converter using LM2585 is shown here. LM2585 is a monolithic integrated voltage converter IC that can be used in various applications like flyback converters, boost converters, forward converters, multiple output converters etc. The circuit requires minimum number of external components and the IC can source up to 3A output current.
Here the IC is wired as a boost converter where resistors R1 and R2 are used to set the output voltage .The junction of R1 and R2 is connected to the feedback pin of IC1. Capacitor C4 is the input filter while capacitor C1 the filter for output. Network comprising of resistor R1 and capacitor C2 is meant for frequency compensation. Inductor L1 stores the energy for acquiring boost conversion.

Notes.

• Assemble the circuit on a good quality PCB.
• LM2585 requires a heatsink.
• Output voltage is according to the equation Vout =( (R1/R2)+1) x 1.23.
• Capacitors other than C4 and C1 are ceramic capacitors.
• Maximum output current LM2585 can source is 3A.

S:www.circuitstoday.com

Transformer Based 110 to 220 Converter

Transformer 220v Converter Diagram
If you want to 220V AC voltage from 110V AC source, then a 220 converter that is known as the step-up voltage converter needs to be applied for this purpose. It is very easy to do, just by using a step-up transformer.

Measuring Power Transformer Rating

In order for your 220 converter is the right choice, you need to determine wattage requirements of electronic applications that will be used to it. If your device requires 220V 1100W to work properly it needs the current 5 amperes, then the minimum current required 10 amperes at 110V input voltage.

Because of the current in the transformer is influenced by the diameter of the wire coils used in secondary and primary winding transformer. The greater the wattage you need, the greater the form of the transformer stepped up / down.

Highly recommended for a higher wattage provided for 220 converter from the load device work with it. This value can be up to 50% larger for voltage converter transformers working properly.

Warning of floods by Water Leak Detector

Water Leak Detector

A water leak detector circuit is designed to give early warning of floods that can be sourced from the water heaters, washing machines, swimming pools, water tanks and so forth. Leakage, temperature changes, and / or water levels at some extreme conditions can be detected by a sensing system.

In this article will explain how to make a simple water leak detector utilizing a door bell transformer. A door bell transformer produces 6-20V AC, which can be converted into DC voltage to drive a buzzer or relay based sensing system.

On the water leak detection circuit consists of three parts, namely the DC power supply, relay or buzzer drive circuit, and sensor probe.

The voltage of the AC transformer converted into DC voltage by connecting the wires on the secondary side with a bridge rectifier and then into an electrolytic capacitor that functions as a filter from the output voltage of approximately 26V DC. Power supply ready for use to supply voltage to the buzzer driver circuit.

Buzzer driving circuit on the water leak detector is a switching circuit using a general purpose NPN and PNP transistors. Water probe made from copper wire 1 inch.

Sine Wave Inverter used as high end electronic equipment

The inverter is an electronic device to convert DC into AC electricity. Pure sine wave inverter used to operate the high-end electronic equipment such as medical equipment, digital music amplifiers, higher-end televisions, and a must for laser printers. There is the very low harmonic distortion in the output voltage waveform.
There are two types of inverter are True / Pure sine wave inverter and Modified sine wave inverter, both transformer based. The sine wave transformer based can operate medium to larger units. These types of inverters are required for net metered installations. This is also used in large RV’s and boats.

Generating pure sine wave is done through mathematical representation manipulation of the original sine wave by dividing the half-sine wave to a few number segmentation.

Pure sine wave inverter will convert the 12V from the battery into 110V AC, 50 Hz sine wave. Microcontroller IC used is the Atmel 89S2051. The 89S2051 produce pulse train alternately from port A and Port B for half the positive and negative half sine wave.

Pulse train is directed at the primary side of the transformer through the IRF44N MOSFET power switching circuit. The output voltage 110V AC will be available on the secondary side of the transforme and then filtered through a filter LPF and generate a sine wave.

KT3170 used for Telephone operated DTMF remote

The circuit given below is of a telephone operated DTMF remote. The circuit can be used to switch up to 9 devices using the keys 0 to 9 of the telephone. Digit 0 is used to switch the telephone system between remote switching mode and normal conversation mode. IC KT3170 (DTMF to BCD decoder) is used to decode the DTMF signals transmitted over the telephone line to corresponding BCD format. IC 74154 ( 4 to 16 demultiplexer) and IC CD4023 (dual D flip flop) is used to switch the device according to the receive DTMF signal.
The operation of the circuit is as follows. After hearing the ringtone from the phone at receiver end, press the 0 button of the remote phone. The IC1 will decode this as 1010.The pin 11 of IC2 will go low and after inversion by the NOT gate in IC3 it will be high. This will toggle the flip flop IC5a and the transistor Q1 will be switched on. This will make the relay K1 ON. The two contacts C1 and C2 of the relay K1 will be closed. C1 will form a 220 Ohm loop across the telephone line in order to disconnect the ringer from the telephone line (this condition is similar to taking the telephone receiver off hook).C2 will connect a 10KHz audio source to the telephone line in order to inform you that the system is now in the remote switch mode. Now if you press 1 on the transmitter phone, the IC1 will decode it as 0001 and the pin 2 of IC2 will go low. After inversion by the corresponding NOT gate inside IC3, it will be high. This will toggle flip flop IC5b and transistor Q2 will be switched ON. The relay will be energized and the device connected through its contacts gets switched. Pressing the 1 again will toggle the state of device. In the same ways Keys 2 to 9 on the transmitter phone can be used to toggle the state of the device connected to the channels O2 to O9. After switching is over, press the O key on the transmitter phone in order to toggle the flip flop IC5a to de-energize the relay K1.The 200 Ohm loop will be disconnected from the line, the 10 KHz audio source will be removed and the telephone receiver will be ready to receive new calls.
S:www.circuitstoday.com/telephone-operated-remote

BC147 Balance display circuit

This Balance display circuit,be the circuit shows the equilibrium in the sound in stereo system. By indicate that stereo system signal on the left and right have or not is a signal equal ? Which if signal both of channel left sound and right channel equilibrium or balance prevent. The LED bilateral switch off but conversely if 2 both of channel sounds are rough LED any one stick bright.
When one party power circuit. And input audio stereo signal into the input box if the left and right channel audio signal equal to the Q1 and Q3 the same stream. There was no difference in the LED voltage on both be ill. If the signal is not balanced. Hypothetical signaling through the right channel signal rather than left to the LED1 and LED2 light off signal indicating that the signal over the right-left channel.

NiCd cell for Battery-backup Converter

Notebook computers and other portable equipment often use a backup battery to retain memory contents during replacement of the main battery. Such "bridge batteries" usually consist of five or six series-connected NiCd coin cells. They're expected to keep the system alive for approximately 5 minutes—plenty of time to swap batteries. The circuit in Figure 1 reduces size, weight, and cost by using one NiCd cell instead of five or six. A Saft VB4E 40-mAhr NiCd coin cell has enough capacity to keep a typical notebook computer in suspend mode for approximately 10 minutes. All components (excluding the coin cell) consume less than 1/2 in.2 of pc-board area, and the cost savings from fewer cells help pay for the added circuitry.

When it's operational, the main battery provides power to the system's dc/dc converters. The LT1304 boost converter constantly monitors the dc/dc-converter input via the feedback divider comprising R₃ and R₄. Once the FB pin drops below 1.24V (corresponding to approximately 6V at the dc/dc-converter input), boost converter IC₁ begins switching. Current comes from B₁, through L₁, and into the SW pin on IC₁. When IC₁'s internal switch turns off, the SW pin goes high, delivering current through D₂ into the dc/dc converter's input capacitor, C₄. C₄ already exists for the dc/dc converter, so you need no additional output capacitor.

The LT1304 switches at approximately 200 kHz; thus, L₁ can be small. Switching occurs automatically as needed to hold the dc/dc converter's input at approximately 6V. Power for IC₁ is "bootstrapped" from the 5V dc/dc converter's output, so it never needs to operate directly from the 1.2V NiCd coin cell. Should the backup battery ever fully discharge, the 5V output drops below the LT1304's minimum operating voltage of 1.5V, and the entire system shuts down. At that point, the NiCd cell becomes unloaded, thereby preventing overdischarge damage. Backup operation is re-established only after the main power source (main battery or ac power) is restored to the system.

It is often necessary to generate a logic signal to indicate that the system is receiving its power from the backup battery. This signal can serve to shed load (the backup converter cannot support full system power) or to open a MOSFET switch that prevents current from flowing back into the main battery. When the LT1304 is operating, the flyback pulse present at the SW pin turns on Q₁, thereby peak-charging C₁ through D₁. Once the voltage on pin 1 exceeds 1.17V (the LBI comparator threshold), the LBO open-collector driver is released and pulled high by the resistors within Q₂.

You can connect the LBO signal to logic circuitry or to a microcontroller input. LBO also turns off Q₂ to disable charging during backup operation. During normal nonbackup operation, LBO is low, keeping Q₂ saturated. In this state, approximately 350 mA of charging current flows through R₅ into the battery. You can scale R₅ for different charge currents as appropriate. (DI#1985)

Biomedical Blood Analyzer

Common blood analyzers include features such as flat panel display, data logging and communication to host. The block diagram facilitates your selection among a wide selection of recommended applicable products.

Simple Circuit Uses to Detect Airflow

This simple circuit uses an incandescent lamp to detect airflow. With the filament exposed to air, a constant current source is used to slightly heat the filament. As it is heated, the resistance increases. As air flows over the filament it cools down, thus lowering it's resistance. A comparator is used to detect this difference and light an LED. With a few changes, the circuit can be connected to a meter or ADC to provide an estimation on the amount of air flow.

8085 / 8085A for Stack

Stack I/O, and Machine Control Instructions:

The following instructions affect the Stack and/or Stack Pointer:

PUSH Push Two bytes of Data onto the Stack

POP Pop Two Bytes of Data off the Stack

XTHL Exchange Top of Stack with H & L

SPHL Move content of H & L to Stack Pointer

The I/0 instructions are as follows:

IN Initiate Input Operation

OUT Initiate Output Operation

The Machine Control instructions are as follows:

EI Enable Interrupt System

DI Disable Interrupt System

HLT Halt

NOP No Operation

ASCII Table Gives Values Which Used in Different ElectronicEquations

S: http://www.hobbyprojects.com

Basic JK Master Flip-Flops with Features

The J-K flip-flop can be wired to behave as most other types of flip-flop.

If J is high and K is low, Q will go high on the negative going edge of the clock pulse.

If K is high and J is low, Q will go low on the negative going edge of the clock pulse.

If J and K are both low, Q will not change.

If J and K are both high, the output toggles on the negative going edge of the clock pulse.

Serious Problems in Relay Operated Circuits and Solutions

Relay Driver Circuit
One of the serious problems in relay operated circuits is the relay clicking or chattering during the on/off of the relay driver transistor. This problem is severe if the input circuit is a light / temperature sensor. During the transition of light / temperature levels, the relay clicks which may cause sparking of contacts. By using a simple tip, this problem can be avoided.

Below is the circuit of a Relay driver using the NPN transistor BC 548. The relay is connected between the positive rail and the collector of the transistor. When the input signal passes through the I K resistor to the base of the transistor, it conducts and pulls the relay. By adding a 470 uF electrolytic capacitor at the base of the relay driver transistor, a short lag can be induced so that the transistor switches on only if the input signal is persisting. Again,even if the input signal ceases, the transistor remains conducting till the capacitor discharges completely. This avoids relay clicking and the offers clean switching of the relay.

Another 470 uF capacitor is added parallel to the relay coil which maintains steady current through the relay coil so that relay clicking can be avoided if the power supply varies momentarily.

IN 4007 diode eliminates back e.m.f when the relay switches off and protects the transistor

LED indicates the on status of the relay.

6V Battery Operated Doorbell Light Circuit

Doorbell Light Circuit
This 6V battery operated doorbell light circuit can be connected in parallel with any existing AC230V doorbell. When anyone push the doorbell switch, the bell sounds as usual and ac mains supply available across the doorbell is routed to the input of this circuit through an opto-coupler(IC1).

Conduction of IC1 triggers a monostable, wired around the good old 555 timer (IC2). As a result the high-bright white LED (D2) at the output of IC2 is switched on for a short time. This circuit is highly useful at night/midnight as it gives sufficient indoor light to help you locate switches for room lamp/porch light, etc. On/Off duration of the LED light can be increased/decreased by increasing/decreasing the value of C2.

The electronic doorbell light circuit is fully safe because it is perfectly isolated from the fatal ac mains supply by IC1. However, keep to avoid accidental contacts with the front end of the circuit, which is directly connected to the ac supply. Use of a good and convenient ABS enclosure is recommended for this doorbell light unit.

S:www.electroschemetics.com

Simple Automatic Light Switch Circuit for Bedrooms

Automatic Light Switch Circuit Schematic

Here is an ultra simple automatic light switch circuit for bedrooms. After construction,connect the input terminals of this circuit in parallel to the internal buzzer terminals of a Quartz-Alarm Clock. When the clock alarm is activated at a time set by the user, electromagnetic relay in the circuit is energised for a short duration, controlled by the timer IC 555.
Contacts of the relay can be used to switch on a bedlamp, table lamp or similar electric light loads. The circuit works off unregulated 12V.U se any12VDC/500mA rated standard ac mains adaptor.



When the clock alarm rings, input pulses are fed to the trigger input point (T1+Pin2) of IC1, through an RC filter (C1,R1&C2). Here IC1 is wired as a monostable and dc voltage at its output (Pin 3) terminal goes high instantly after receiving a trigger,and remains in the condition for about10 seconds, as configured by the components values of R3 and C3.

Output from IC1 directly drives the low current relay RL1 through diode D1. Note that diode D2 is here used as a freewheeling diode to suppress the counter emf generated during relay switching.

Basic Quartz 1Hz Timebase Circuit

Quartz 1Hz Timebase Generator Circuit

Here is one basic circuit of a simple but accurate 1Hz timebase generator built around a standard Quartz clock circuit board. Just lift the clock PCB from any cheap quartz clock and carefully remove all extra components like the drive coil, buzzer, alarm switch and clock mechanism (quartz movement), etc.
Next wire the circuit as shown in the schematic diagram, observing correct connection points and polarities, and power it from a 5VDC supply. Precision 1Hz clock signal generator is now ready to serve you. With suitable modification(s) at the output you can use this circuit to drive blinkers, beepers and microcontroller based ciruits.

Notes:

• 1. Stable 1.5-1.6 VDC supply for the clock PCB is derived from the 5VDC input supply with the help of componets R1, D1 and C1. Only use a 10mm Red color (Vf=1.6V) LED for D3.
• 2. Drive coil outputs (L1&L2) of the clock PCB are joined together to get one second pulse output with the help of two schottky diodes (D1&D2). Such low-drop diodes are crucial for this circuit.
• 3. The circuit is inverting output type and hence, the output is normally at high level,and pulses low once a second.By adding a second (optional) transistor, this can be reversed, ie non inverting, so that the output is normally at low level, and pulses high once a second.

Only Few Minutes to Build Lie Detector

Here's a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by measuring skin resistance, which goes down when you lie.

Parts

Part Total Qty. Description Substitutions R1 1 33K 1/4W Resistor R2 1 5K Pot R3 1 1.5K 1/4W Resistor C1 1 1uF 16V Electrolytic Capacitor Q1 1 2N3565 NPN Transistor M1 1 0-1 mA Analog Meter MISC 1 Case, Wire, Electrodes (See Nots)	Total Qty.	Description	Substitutions
R1	1	33K 1/4W Resistor
R2	1	5K Pot
R3	1	1.5K 1/4W Resistor
C1	1

Notes

1. The electrodes can be alligator clips (although they can be painful), electrode pads (like the type they use in the hospital), or just wires and tape.

2. To use the circuit, attach the electrodes to the back of the subjects hand, about 1 inch apart. Then, adjust the meter for a reading of 0. Ask the questions. You know the subject is lying when the meter changes.

S:www.aaroncake.net

Too Simple Mini Emergency Light Circuit

Mini Emergency Light Circuit

This is an LDR based Emergency Lamp that turns on a High watt White LED when there is darkness in the room. It can be used as a simple emergency lamp in the child’s room to avoid the panic situation in the event a sudden power failure.It gives ample light in the room.

The circuit is too simple so that it can be enclosed in a small box. A 12 volt miniature battery is used to power the circuit. Two transistors T1 and T2 are used as electronic switches to turn on / off the white LED. When there is sufficient light in the room, LDR conducts so that the base of the PNP transistor T1becomes high and it remains off. T2 also remains off since its base is grounded. In this state, White LED remains off. When the light falling on the LDR decreases, it cease to conduct and T1 forward bias providing base current to T2. It then turns on and White LED switches on.
White LED used in the circuit is 1 watt High bright Luxeon LED . Since 1 watt White LED consumes around 300 milli ampere current, it is better to switch off the lamp after few minutes to conserve battery power.

3 volt Lithium Cell Operated LED Flasher as a Keyhole Finder

Keyhole Finder Circuit

This 3 volt Lithium cell operated LED flasher can be used as a key hole finder in darkness. A small lithium button cell can power the circuit more than 6 months continuously with day and night flashes. The circuit can also be used in key stand to search key in darkness.Use a high bright transparent 5 mm Yellow LED and fix the unit near the keyhole. The circuit is a simple oscillator comprising two complementary transistors BC 547 and BC557. These NPN and PNP transistors are wired as a simple oscillator with components C1 and R1 so that the LED flashes based on the charging and discharging of C1. Current consumption of LED is very low so that a normal 3 volt lithium battery can power the circuit for long time. A miniature 12 volt battery used in Car remote can power the circuit more than 2 years continuously.

Features of Radio Mobile

Radio Mobile-Main Windows

Radio Mobile is a free and powerful tool for plotting RF patterns and predicting the performance of radio systems. Using freely available terrain elevation data it can produce grey scale, x-ray and rainbow colored virtual maps. One can also produce 3-D and stereoscopic views as well as flyby animations. Background images can be merged with scanned maps, satellite photos and Mapquest maps to produce accurate prediction plots. You can obtain your copy of Radio Mobile from the official website.

Installing Radio Mobile
There are two ways to install Radio Mobile. You can either download the installer file available through this website or download the individual compressed files from the Radio Mobile website or the QSL.net mirror.

Obtaining Elevation Data
Before you can really do anything with Radio Mobile you need to obtain the proper elevation data for the area in which you are creating plots. Radio Mobile accepts elevations in a number of formats including SRTM, DTED and GTOPO30. Fortunately most of this data is available free of charge and with a little effort is easily installed.

Installing Elevation Data
You have downloaded some elevation data you first need to extract it and then configure Radio Mobile so that it can find it. If you downloaded GTOPO30 or DTED data from the sites mentioned previously you may notice the files have the extension tar.gz. In the UNIX world this is known as a “tarball” and this short 7-Zip Tutorial will show you how to extract the data contained within the tarball you downloaded.

Creating A Map
You have Radio Mobile configured to use your elevation data you can begin creating maps. Click on File | Map Properties and you will again be presented with the Map Properties window. This time make sure you uncheck “ignore missing files” and have SRTM set as one of your data sources. The reason for doing this is to get Radio Mobile to tell you which SRTM data files are missing so you download the missing pieces. There are some holes in the SRTM coverage so there is a chance you will not be able to download the missing files. If this is the case check “ignore missing files” after you have filled in as many missing pieces as possible.

Inexpensive Way to Build Your Own Jamming Gripper

Here’s an inexpensive way to build your own jamming gripper. [Steve Norris] combined a robot arm with a few inexpensive items to achieve similar results as the original. Much like the last DIY version he started with a balloon and some coffee grounds, but instead of using his own body as a vacuum pump he sourced a Reynolds Handi-Vac, an inexpensive food vacuum sealer. It connects to the balloon using some plastic tubing, and sucks all of the air out, locking the coffee grounds around an object for a firm grip. The video after the break even shows the gripper picking up two aspirin. At first we thought a servo motor was being used to seal off the tube once the air had been pumped out. Instead, it is covering a hole in the tubing, which breaks the vacuum when it’s time to let go of an object.

Secret Box Project Atmega88 Microcontroller Based

Deddie Lab has two interesting Secret Dice projects, this one is the original but there is also a metal one that Deddie has since made. The object is to get inside the box, no smashing the box on the ground doesn’t count. The boxes have a secret

code stored in them, to enter the secret code you must tilt the box in the correct ways to enter the code. When the correct code has been entered a servo will unlock the box so you can get your reward. This project was based on this secret box project. The code and schematics are provided if you are thinking of making your own.

Playing Guitar Hero and Build Banjo Hero

[Johnny Chung Lee] put together a system that is perfect at playing Guitar Hero. He’s using the PlayStation 2 version and, as you can see above he’s combined a controller connector and a Teensy microcontroller board to communicate with the console using its native SPI protocol. This custom guitar controller receives its signals via USB from a computer that is monitoring the video from the console and calculating the controller signals necessary for perfect gameplay. [Johnny] wrote an OpenCV program that monitors the video, removes the perspective from the virtual fretboard, and analyzes color and speed of the notes coming down the screen.

As you can see after the break it works like a charm. It’s fun from a programming standpoint, but if you want a hack you can actually play maybe you should build your own Banjo Hero.

Simplest 555 Bistable Multivibrator Circuit

555 Bistable Multivibrator circuit acts as a basic flip-flop. The Output will stable in two states: output high and output low. The switching of the output waveform is achieved by controlling the Trigger and Reset inputs which are held "HIGH" by the two pull-up resistors, R1 and R2. By taking the Trigger input (pin 2) "LOW", switch in Set position, changes the output state into the "HIGH" state and by taking the Reset input (pin 4) "LOW", switch in Reset position, changes the output into the "LOW" state. This 555 timer circuit will remain in either state indefinitely and is therefore bistable. Then the Bistable 555 timer is stable in both states, "HIGH" and "LOW".

Skema Rangkaian 555 Bistable Multivibrator

Note:

• Trigger (555 pin 2) makes the output high, Trigger is 'active low', it functions when <>
• Reset (555 pin 4) makes the output low. Reset is 'active low', it resets when <>
• The power-on reset, power-on trigger and edge-triggering circuits can all be used as described above for the

Desired Output Waveform Frequency | Signal Generator

Frequency | Signal Generator circuit is a circuit that produces a variety of different waveforms at a desired frequency. It can generate Sine waves, Square waves, Triangular and Sawtooth waveforms as well as other types of output waveforms. There are many "off-the-shelf" waveform generator IC's available and all can be incorporated into a circuit to produce the different periodic waveforms.

Skema Rangkaian 8038 frequency | Signal Generator

IC 8038 Pinout

One such device is the 8038 a precision waveform generator IC capable of producing sine, square and triangular output waveforms, with a minimum number of external components or adjustments. Its operating frequency range can be selected over eight decades of frequency, from 0.001Hz to 300kHz, by the correct choice of the external R-C components.

The frequency of oscillation is highly stable over a wide range of temperature and supply voltage changes and frequencies as high as 1MHz is possible. Each of the three basic waveform outputs, sine, triangle and square are simultaneously available from independent output terminals. The frequency range of the 8038 is voltage controllable but not a linear function. The triangle symmetry and hence the sine wave distortion are adjustable.

A Normal Variable Resistor VS Darlington Pair of Transistors

A normal variable resistor cannot directly control the speed of a motor since motors draw large amounts of current which would burn out the potentiometer. Instead, the small amount of current that the potentiometer can pass can be amplified into order to run the motor. This amplification can be achieved using Darlington Pair of transistors.

Darlington Pair to Drive DC motor Circuit

Pin-out BFY61 & TIP31C Transistor

The circuit above shows a linear potentiometer connected Between Vs and 0V Such That the voltage at its wiper terminal will of always be somewhere at or Between these two voltages. The small amount of current flowing out of the potentiometer's wiper is amplified by two transistors, connected together in a configuration known as a 'Darlington pair'. The current from the potentiometer is amplified by the first transistor, and then again by the second transistor, greatly Increasing the amount of current That cans be controlled by the potentiometer.

There are, however, a couple of disadvantages of this simple circuit. Firstly, about 0.7V is lost in EACH of the transistor, so the maximum voltage cans That ever be applied to the motor is Vs - 1.4V. Secondly, the transistors are not absolutely linear so the change in motor speed for a given rotation of the potentiometer will from some more subtle in the middle of its range. Because a motor is an inductive load, it will from Produce a 'back-emf' Could the which damage to the second transistor. The 1N4148 signal diode prevents this damage by shorting out the back-emf.

The power supply for this circuit should preferably be un-smoothed (i.e. directly from the power supply rectifier). This helps prevent the motor 'sticking' at low speeds. With the TIP31C transistor given, the maximum power supply voltage may be 60V and the maximum motor current consumption may be 3A.

Source: www.eleinmec.com

IC NE5534/2 Headphone Amplifier

Here I present a very simple and powerful headphone amplifier Circuit using NE5534/2 . In addition to the IC NE5534/2, the circuit uses only few passive components and can easily generate a lot of sound from even the most inefficient headphones and there will be no compromise for the quality.

Circuit of 9 Volt Portable Headphone Amplifier

The 5534/2 is a low-distortion, low-noise device, having also the ability to drive low-impedance loads to a full voltage swing while maintaining low distortion. Furthermore, it is fully output short-circuit proof. Therefore, this circuit was implemented with a single 5532 chip forming a pair of stereo, inverting amplifiers, having an ac gain of about 3.5 and capable of delivering up to 3.6V peak-to-peak into a 32 Ohm load (corresponding to 50mW RMS) at less than 0.025% total harmonic distortion (1kHz & 10kHz).

List Component of Portable Headphone Amplifier

P1 = 22K
R1 = 18K
R2 = 68K
R3 = 68K
R4 = 68K
R5 = 18K
R6 = 68K
C1 = 4.7uF/25v
C2 = 4.7uF/25v
C3 = 22pF
C4 = 220uF/25v
C5 = 220uF/25v
C6 = 4.7uF/25v
C7 = 22pF
C8 = 220uF/25v
J1 = 3.5mm Stereo Jack
B1 = 9V Alkaline Battery
IC1 = NE5532 or NE5534
SW1 = SPST Toggle Switch

S: www.redcircuits.com