Top Circuits Page 193
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Including Preamp, Tone Controls, Reg dc Power Supply, 18 Watt into 8 Ohm 30W into 4 Ohm loads This project was a sort of challenge: designing an audio a....
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This FM transmitter circuit is very simple and it has a acceptable transmission . The signal transited from this FM transmitter circuit can be received at....
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If you`ve ever tried dimming a LED with a simple potentiometer, you know that the approach does not work very well. Just as with ordinary diodes, the voltage-current characteristic of LEDs is far from linear. The result depending on the potentiometer setting....
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This circuit uses a switched capacitor filter IC from National Semiconductor to filter signals with frequencies higher than the 3KHz needed for voice audi....
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This design will interest technicians who work on pneumatically operated valves and other 4-20mA current loop controlled devices. Although 4-20mA signal i....
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The operation of the converter is based on the weighted adding and transferring of the analogue input levels and the digital output levels. It consists of....
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High-quality modular design, 9V Battery powered Very low current drawing The target of this project was the design of a small portable mixer supplied by....
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These goals were achieved by using a discrete-components op-amp driving a BJT complementary common-emitter output stage into Class B operation. In this way, for small output currents, the output transistors are turned off, and the op-amp provides all of the....
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48 V ‘phantom powering has become the standard for professional condenser microphones. The supply (or rather bias) voltage is applied over both wires of....
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The circuit presented here may provide a solution in a number of cases, since it can be used to convert a single-ended supply voltage into a balanced set of supply voltages. That`s not so remarkable by itself, but the special feature of this circuit is that....
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This circuit enables the on/off times of a 555 timer to be independently varied over a wide range. This is not possible with a conventional 555 circuit wi....
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This 555 timer clap switch circuit electronic project is designed using some common electronic parts. This 555 timer clap switch circuit electronic projec....
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A radio camera on a model railway should transmit constantly while the train is moving and continue transmitting for a few minutes after the train stops ..
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The circuit of the running light comprises two integrated circuits (ICs), a resistor, a capacitor and seven light-emitting diodes (LEDs), Decade scaler IC....
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A 6 watt audio amplifier circuit using TDA2613 is shown here. TDA2613 is an integrated Hi-Fi audio amplifier IC from Philips Semiconductors. The IC is swi....
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Low-cut and Bass controls, Output power: 40W into 8 Ohm and 60W into 4 Ohm loads This design adopts a well established circuit topology for the power ampl....
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This design adopts a well established circuit topology for the power amplifier, using a single-rail supply of about 60V and capacitor-coupling for the speaker(s). The advantages for a guitar amplifier are the very simple circuitry, even for comparatively....
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This circuit lets an external 12V SLA battery power a camcorder which normally has an inbuilt 7. 2V battery. Such batteries can now be very difficult or expensive to obtain for earlier model camcorders. In essence, the circuit is a standard LM317 adjustable....
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This is a guest post by Olger Groen . If you would like to write for ExtremeCircuits, then drop us an email via contact form or simply comment. A long tim....
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*Useful circuit for self-powered speakers, Radios, TV, can be used as car power *amplifier Here is the schematic for an 8 watt audio power amplifier. This....
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A simple 9 Volt 2 amp supply using a single IC regulator. There is little to be said about this circuit. All the work is done by the regulator. The 7809 c....
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The ASUS Eee is a fantastic ultra-portable notebook with almost everything required for geeks (and nothing that isn t). Plus it features fantastic build q....
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The purpose of this circuit is to power a lamp or other appliance for a given time (30 minutes in this case), and then to turn it off. It is useful when reading at bed by night, turning off the bedside lamp automatically in case the reader falls asleep After....
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Charges and protects your mobile phone from voltage spikes and short-circuit Most mobile chargers do not have current/voltage regulation or short-circuit....
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Battery-Powered portable unit, Suitable for all type Televisions Using this low-cost project one can reproduce audio from TV without disturbing others. It....
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Six timing positions suited to different skin types, Timing affected by sunlight intensity This timer was designed for people wanting to get tanned but at....
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This simple LED tester consists of a current source with a potentiometer that can be used to adjust the current. The current source is implemented using a type TL081 opamp. The output current of the opamp flows through the diode and R2. The voltage drop....
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This circuit is intended for alerting purposes after a certain time is elapsed. It is suitable for table games requiring a fixed time to answer a question, or to move a piece etc. In this view it is a modern substitute for the old sandglass. Useful also for....
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This circuit breaks an input voltage signal down into its components: (1) the absolute value and (2) the polarity or ‘sign (+ or ). It will handle direc....
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Want a regulated voltage that can be adjusted to suit your application? This Adjustable Power Supply is small, easy to build and can be adapted to produce....
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The circuit was designed to provide an adjustment with a power supply that is symmetrically designed while providing a voltage range of 1.25V to 30V at 1A....
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The circuit was designed to produce a circuit that will alarm a sleeping person to prevent snoring by using a vibrator instead of an audio alert so as not....
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Readers who do not care to modify the power supply of an old PC into a suitable halogen power source (see our April 2006 issue), may find the present desi....
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The circuit presented here makes amplitude modulation possible, and it also has the significant advantage that it replaces the somewhat exotic and quite e....
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Small and very useful circuit, Can be built on a veroboard Volt regulators such as the LM708, and LM317 series (and others) sometimes need to provide a li....
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Turns-off your amplifier when idle for 15 minutes, Fed by amplifier tape-output This circuit turns-off an amplifier or any other device when a low level a....
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Built around an LM380, this amplifier includes tone controls and electronic “soft switchingâ€. The soft switching circuitry ensures power is b....
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The short circuit proof outputs of amplifiers and speakers, throw some interesting elements, such as the isolation of the speakers from the exit of the am....
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If you re a biker or scooter rider you ll know how easy it is to forget to cancel your flashing indicators after turning without an audible reminder. Cons....
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Small and portable unit, Can be built on a veroboard The amplifier s gain is nominally 20 dB. Its frequency response is determined primarily by the value....
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Detects clipping in preamp stages, mixers, amplifiers etc., Single LED display 9V Battery supply unit This circuit was intended to be used as a separate....
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This simple circuit indicates the amount of power that goes to a loudspeaker. The dual-color LED shows green at an applied power level of about 1 watt. At 1. 5 watts it glows orange and above 3 watts it is bright red. The circuit is connected in parallel....
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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. The 1K resistors in the circuit are essential so that the....
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This circuit uses a complementary pair comprising npn metallic transistor T1 (BC109) and pnp germanium transistor T2 (AC188) to detect heat (due to outbre....
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Voltage regulator ICs (78xx series) provide a steady output voltage, as against a widely fluctuating input supply, when the common terminal is grounded. A....
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Simple add-on module, Switchable “Control-flat†option In order to obtain a good audio reproduction at different listening levels, a different tone-contro....
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Most, if not all, recent cars have an impressive amount of electronics, whether it be ABS brake systems, engine control with injection calculators, airbag....
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Without any dedicated buck converter/white LED driver IC, you can safely drive many standard Hi-efficient white LED modules using the battery power available in automobiles. Here is a safe and simple white LED driver designed for 12V automobiles. In the....
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A useful timing strobe can be constructed using high-brightness LEDs and a few common components. Ignition pulses from the number 1 cylinder high-tension lead are used to trigger the circuit via a home-made inductive pickup. Transistors Q1 & Q2 buffer and....
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Before its move offshore, I was lucky enough to be involved in developing the avionics system for the Flightship Ground Effect FS8 craft....
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This circuit is intended to program AVR controllers such as the AT90S1200 via the parallel port. The circuit is extremely simple. IC1 provides buffering f....
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We published a design for a stereo microphone preamplifier with balanced inputs and a phantom power supply. The heart of this circuit was a special Analog....
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The preamplifier is intended for use with dynamic (moving coilMC) microphones with an impedance up to 200 ? and balanced terminals. It is a fairly simple....
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The Over-the-Top type of operational amplifier is ideal for use as a current sense for battery charger applications. The design described here can be used....
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Most off-the-shelf car battery chargers cannot not be left connected to the battery for long periods of time as over-charging and consequent battery damag....
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Almost all 24V power systems in trucks, 4WDs, RVs, boats, etc, employ two series-connected 12V lead-acid batteries. The charging system can only maintain the sum of the individual battery voltages. If one battery is failing, this circuit will light a LED.....
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A small electronic switch that connects a battery to the equipment for a certain amount of time when a push-button is momentarily pressed. And we have also taken the ambient light level into account; when it is dark you won`t be able to read the display so....
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Is the battery empty, or is there something wrong with the device? That s always a difficult question when your walkman or some other battery-powered devi....
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Monitors battery voltage, Three-LED Display Connecting this circuit to the battery of your vehicle, you will always know at a glance the approximate volta....
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This circuit is presented as an alternative to the IR beam break detector featured in the June 2009 issue (Silicon Chip). In order to make it relatively i....
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If you use a lamp with a motion sensor for outdoor lighting, the original electrical switch is actually no longer necessary. If you replace the switch with the circuit described here, an acoustical signal will be generated each time the outdoor lamp is....
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This circuit has been designed to provide a clearly visible light, formed by 13 high efficiency flashing LEDs arranged in a pseudo-rotating order. Due to low voltage, low drain battery operation and small size, the device is suitable for mounting on bicycles....
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This simple circuit allows a 12V battery pack to be charged via a bike generator. The generator is rated at 3W and with this voltage multiplier circuit pr....
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Firstly, it demonstrates how the combination of a blue and a white LED can be used to give a realistic imitation of a camera flashlight. Secondly, the goo....
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The well-known LM386 is an excellent choice for many designs requiring a small audio power amplifier (1-watt) in a single chip. However, the LM386 require....
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Sometimes it is desired to power a circuit from a battery where the required supply voltage lies within the discharge curve of the battery. If the battery....
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The quartz clocks which have dominated time-keeping for the past 20 years or so have one problem: their errors, although slight, are cumulative. After run....
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This circuit can be used for multiple cameras with one monitor. The circuit can be operated manually or automatically. When operated automatically the swi....
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The purpose of this circuit is to animate shop-windows by means of a capacitive sensor placed behind a post-card-like banner. The card is placed against the glass inside the shop-window, and the visitor can activate the relay placing his hand on the card,....
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Going camping nowadays involves taking lots of electronic equipment whether for day to day running or for fun and entertainment. Most of the time a charge....
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A car battery deteriorates in use and its life seldom exceeds four years. When new, its voltage may drop to only 2V while cranking the engine. As the batt....
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Most cars do not have delayed interior lights. The circuit presented can put this right. It switches the interior lights of a car on and off gradually. Th....
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Here is a simple circuit that starts playing the car horn whenever your car is in reverse gear. The circuit (1) employs dual timer NE556 to generate the s....
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The electronic dog repellent circuit diagram below is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller, w....
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Nowadays, just about every house has an outside lamp with a motion sensor. Such a device eliminates the need to feel your way to the front door, and it ap....
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Flashes a LED when detecting an incoming call, Powered by one 1.5V cell This circuit was designed to detect when a call is incoming in a cellular phone (e....
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The circuit of the Celsius thermometer in the diagram is based on the well-known Type LM334 from National Semiconductor. This IC is a sensor that provides....
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Some cheap car alarms do not have a connection for the central locking system. However, in most it should be possible to find a point in the alarm circuit....
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This circuit is based on mobile phone chargers. These chargers are based on the Motorola MC34063 switchmode IC. By changing the values of the feedback resistors (R1 & R2), the output voltage can be varied over a wide range. Just modify R1 and R2 according to....
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Here s a cheaper and easier method of making a telephone headset adapter. All that s required is a cheap headset ($5 at Harvey Norman), a DPDT switch and....
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The hobby circuit below uses an unusual method to generate about 12, 000 volts with about 5uA of current. Two SCRs form two pulse generator circuits. The two SCRs discharge a 0. 047uF a 400v capacitor through a xenon lamp trigger coil at 120 times a second.....
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Many battery powered devices use two AA alkaline cells. Often you will not know when it is time to replace the batteries until the device powered by them....
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This easy to construct “Handy pen torch†electronic circuit and low component count, uses two power white LEDs for lighting. Low volt (4.8V dc) supply ava....
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About one Watt RMS seems to be a convenient size, and this is also about the highest power that a simple amplifier fed from 12V can put into an 8 Ohm speaker. A very low saturation amplifier may go as high up as 2 Watt, but any higher power requires the use....
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With this sound activated switch, control by sound may be very useful, not just on a robot but also for a bit of home automation, for example a sound-acti....
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It is a wireless doorbell with a cost of about $10. 00. So, we have to change our attitude to building projects and use items such as this to learn how things work and modify them to suit our own requirements. This doorbell uses quality components. It`s not....
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This circuit can switch two or more devices on and off in response to a series of rapid handclaps. The claps are picked up by an electret microphone and a....
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3V Battery operated, Small portable unit This circuit was intended to activate a relay by means of a hand clap. Further claps will turn-off the relay. An....
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Crystals usually operate at fundamental frequencies up to about 15 MHz. Whenever higher frequencies are required a frequency multiplier is placed after th....
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Amplifiers which run from 12V DC generally don t put out much power and they are usually not hifi as well. But this little stereo amplifier ticks the powe....
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This simple circuit tests speakers, microphones, transformers and voltage. It`s basically a very low frequency oscillator that produces extremely short fruity` pulses. The type of sound produced is very easy to hear and to determine the precise direction it....
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You don t need access to fancy test gear to check and fault-find computer data cables. Instead, this simple device will give a quick indication of the sta....
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How often does it happen that you close down Windows and then forget to turn off the computer? This circuit does that automatically. After Windows is shut....
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The compact, low-cost condenser mic audio amplifier described here provides good-quality audio of 0.5 watts at 4.5 volts. It can be used as part of interc....
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Having good contacts is important not only in your daily life, but also in electronics. In contrast to social contacts, the reliability of electrical co....
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The adjustment control for the contrast of an LC-Display is typically a 10-k potentiometer. This works fine, provided that the power supply voltage is constant. If this is not the case (for example, with a battery power supply) then the potentiometer has to....
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This circuit allows you to turn on your holiday bulbs with a wave of the magic wand. The strings flash in sequence. At the heart of the idea is the magnet....
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In essence, this circuit is a 15 to 20-second courtesy light extender for cars. It is activated in the usual way by opening a door but it also samples the....
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Current generated flows through clips placed on the earlobes Output current adjustable from 80 to 600 microAmperes Owing to the recent launching in Europe....