New Circuits Page 222
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The circuit is actually a half-wave rectifier. It only charges the battery on every half cycle. The plug pack doesn't like this as it leaves residual flux in the core of the transformer and causes it to overheat. But that's the only drawback with the....
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This self-starting fixed frequency oscillator circuit gives excellent frequency stability. Rl and Cl comprise the frequency determining network while R2 provides the regenerative feedback. Diode Dl enhances the stability by compensating for the difference....
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S2 is used to initiate timing. A light-to-dark or dark-to-light transition stops this timer, depending on the setting of ..
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This circuit can cause a cassette recorder to automatically tum on and record when a sound or noise is present. Another use, is when the sound-activated switch is used to tum on a cassette player so that it operates as a burglar-alarm detector and sounder.....
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Al's positive input is biased by the thermocouple. Al's output drives a crude V — F converter, comprised of the 74C04 inverters and associated components. Each V — F output pulse causes a fixed quantity of charge to be dispensed into the 1 µ¥ capacitor....
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This circuit relies on extremely high input impedance for effective operation. The HA-5180 with its JFET input stage, performs well as a preamplifier. The standard three amplifier configuration is used with very close matching of the resistor ratios....
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The voltage to be measured is digitized in an analog-to-digital (A/D) converter and then displayed in three decimal d..
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The CMOS comparator in the successive-approximation system determines each bit by examining tbe charge on a series of binary-weighted capacitors. In tbe first phase of tbe conversion process, the analog input is sampled by closing switch SC and all ST....
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This circuit is one section of an octave equalizer used in audio systems. The table shows the values of CI and C2 that are needed to achieve the given center frequencies. This circuit is capable of 12 dB boost or cut, as determined by the position of R2.....
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The LM1036 is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected. Four control inputs provide control of....
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Building a foxhole radio is rewarding and the basic setup is very simple. It is, however, difficult to adjust, and it may take several attempts to find a proper razor blade for the detector. This is a project that requires patience and much trial and error,....
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Common designs for touch switches detect a decrease in resistance when a user`s fingertip either connects a contact to the circuit`s common ground or supplies an injection of 60-Hz ac voltage, resulting from immersion in the electrostatic field that nearby....
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Using a single 7812 IC voltage regulator and multiple outboard pass transistors, this power supply can deliver output load currents of up to 30 amps. The input transformer is likely to be the most expensive part of the entire project. As an alternative, a....
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Its a digial clock which make use of AT89C4051 to work as a Real time clock. Port 1 of the controller (AT89C4051) is used as the data lines for the LCD (starting from pin 7- pin14 of LCD). As you can see there is not much change in the hardware except the....
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Indicator lamp brightness varies in step with modulated RF signal. Adjust R2 with transmitter on (modulated) until the lamp flashes in step with modulation..
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Both oscillators are built using MPF102 or J310 FETs. The Mixer is BF998 dual gate MOSFET. Audio IC amplifier is LM386 which drives a speaker. I have used a stabilized supply for two oscillators and mixer. U1, a 78L05 is doing this job nicely. ..
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This circuit is on oscillator with LI being a 4" diameter coil of 35 turns of #26 magnet wire. Metal in proximity to LI will cause the oscillator to shift frequency. An AM transistor radio is used to detect the frequency shift...
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Getting microprocessor designs to work is notoriously difficult when both the software and hardware are new. The ..
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The simple modulator stage will accommodate most common LEDs. By adjusting the potentiometer, the bias of the transistor is varied until the LED is at its half output point. Then, audio will cause it to vary above and below this point..
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This compact LC oscillator offers a frequency range of about 1 kHz to almost 9 MHz and a low-distortion sine-wave ou..
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Using a Signetics NE602 in a varactor-tuned front end, the circuit of a shortwave receiver can be very simple and yet g..
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Three-terminal regulator device (LM78LXX) has Vout = Vm until the input rises 1.5 to 2 V above the output when the ..
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Power this project from sunlight with a CirKits solar power circuit board kit.
Other LED lamp circuits can be seen at FC`s Solar Circuits, another interesting LED project is my 13 Color LED Rainbow. This circuit makes a nice lamp that consumes little power,....
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The circuit converts a de voltage (V +) to a high-amplitude square wave in the audio-frequency range. The dual timer, IC2, provides an inexpensive alternative to the traditional transformer for providing complementary base drive to the power transistors,....
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Using the simple circuit in Figure 1, you can control the light intensity in your room or work area from your PC. The heart of the circuit is a low-power D/A converter that converts digital words from a computer's parallel port to analog-voltage signals. To....
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This system performs a complete conversion of 12 bits in 10 p unipolar or bipolar. This converter is accurate to ± 12-bit LSB Y2 and a typical gain TC of 10 ppm / ° C. In unipolar mode, the system range is 0 V to 9.9976 V, with each bit having a value of....
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This circuit mixer has an internal amplification with 2N3563 transistor. The two input signals can be independently controlled by VRI and VR2. The VR3 balance control is used to remove a signal while the other melted. ..
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If you`re the sort who`d like to have an HF receiver in every room, but can`t afford it, this idea is for you. It will also appeal to the beginner wishing to build the simplest possible direct conversion receiver. Using a readily-available FM wireless....
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Li-Ion batteries are normally charged with a current
limited constant voltage for a fixed length of time. At the
end of this time period, the voltage must be removed to
prevent internal chemistry changes in the battery. At a
minimum, a timer is needed to....
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This circuit consists of an astable multivibrator driving a push-pull pair of transistors into the transformer primary. The multivibrator frequency should~equal around 1 or 2kHz. ..
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This programmer was designed in view of to be flexible, economical and easy to built, the programmer hardware utilizes the standard TTL series parts and no special components are used. The programmer is interfaced with the PC parallel port and there is no....
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OSU8 began as a student project in 1994 to create a simple but functional 8-bit microprocessor, starting with a definition of the architecture to implementation in a Xilinx FPGA chip, and full-custom CMOS implementation. Over a period of about six months,....
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The compact circuit (Figure 1) overcomes these problems. The regulated buck/boost charge pump in a small µMAX package (U1) has a 100mA output-current capability. Configured as shown, the circuit directly regulates bias current flowing through the white LED.....
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The ·circuit includes a peak detector that irrunediately drives the readout to any new higher signal level and slowly lowers it after the signal drops to zero. The readout is a moving dot or expanding bar display. The circuit can be expanded for a longer....
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Gates Gl and G2 together with resistors Rl and R2 form a simple voltage monitor that has a trip point of 1 volts. Gate G3 is simply an inverter. The display section of the tester consists of a common anode alphanumeric LED and current-limiting resistors..
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The circuit in Figure 1 saves I/O pins. It uses an 8051 µC, and only four I/O pins (P1.0 to P1.3) drive the LCD, instead of the 11 pins other displays require. Data transfers in a serial mode through the P1.0 port of the µC. The µC interfaces to Pin 2 of....
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The Button Code is a system that allows a single button to act as a keypad. The user enters a 4 digit code into the system using button taps. The button can be placed where the public can access it since like a keypad there are many combinations to keep....
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Audio levels can be monitored using a small panel meter with this circuit built from discrete components. The circuit has a flat frequency response from about 20Hz to well over 50Khz. Input sensitivity is 100mV for a full scale deflection on a 100uA meter.....
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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. The circuit is mainly here for historical reasons, a....
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This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can....
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A ideal solution for the make a good, low cost power amplifier. Its a ideal solution for the creation a system of home cinema. The preamplifier and the driver support in a operational amplifier [IC1]. The voltage fall in resistors R5 and TR2/R6, drive the....
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Simple and low cost. The optimal supply voltage is around 50V, but this amp work from 30 to 60V. The maximal input voltage is around 0.8 - 1V. As you can see, in this design the components have a big tolerance, so you can build it almost of the components,....
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I built this headphone amplifier for dynamic headphones based on my rules of proper audio design. People who know my designs will realize that this amplifer is much more than just a headphone amp. It is a pure class A design containing a new....
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For most applications, the available power from op amps is sufficient. There are times when more power handling capability is necessary. A simple power booster capable of driving moderate loads uses an NE5535 device. Other amplifiers may be substituted only....
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The oscillator, Q1, is a standard overtone circuit. A fifth-overtone crystal, 80.545 MHz, is operated on the seventh overtone, 112.763 MHz. C6 couples the output of the oscillator to Q2, which operates as a doubler to 225.5 MHz. A double-tuned circuit....
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In the presence of smoke or gas, the ac output voltage increases and becomes rectified, filtered and zener-diode coupled (D2 for thresholding) to sensitivity control R3. Under no gas condition, the output equals approximately 0 V (high). When gas is....
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This circuit provides a precision voltage source that can be adjusted through zero to positive a..
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STS schematic. The Q2 gate voltage increases with the charge on C3. After 15 seconds of charging, the buzzer will warble. As the charging continues, the sound will grow louder.Circuit waveforms. Point A shows the signal from the flasher. The voltage at....
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Designing and testing embedded hardware can be frustrating if you have to rely on somebody else`s perhaps-unready firmware to test your hardware. Often, hardware is ready for testing before debugging and system firm-ware are available from software....
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This circuit is a church bell controller. Basic component is an ATmega32 microcontroller. At the circuit 1 24LC32 eeprom memories is being used. As control I created a menu who will be appeared on 4x20 LCD (Liquid Crystal Display). The menu browsing can be....
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The circuit for a powerful AM transmitter using ceramic resonator/filter of 3.587 MHz is presented here. Resonators/filters of other frequencies such as 5.5 MHz, 7 MHz and 10.7 MHz may also be used. Use of different frequency filters/resonators will involve....
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FM Wireless Mike can transmit voice signals to any FM Radio receiver 100 meters away. The circuit is basically a frequency modulated transmitter working at 100 MHz. The frequency of the transmitter can be varied slightly by changing the trimmer C5. You can....
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Three circuit options
Can be synchronized to Christmas tree flashing lights This circuit generates a dual-tone bells ringing similar to most door-bell units. It can be used in many applications other than door-bell. In the Notes below several options will....
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During summer nights, the temperature is initially quite high. As time passes, the temperature starts dropping. Also, after a person falls asleep, the metabolic rate of one's body decreases. Thus, initially the fan/cooler needs to be run at full speed. As....
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The Quad op amp MC4301 is used to configure a filter that will notch out a given frequency and produce that notched-out frequency at the BP terminal, useful in communications or measurement setups.
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This circuit uses the TDA2040V which is a monolithic power amplifier IC intended for use as a high quality, class AB audio power amplifier. Typically it provides 22W output power into 4ohm with 0.5% distortion, from 32V supply. The device is designed to....
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The AM signal is captured by the antenna , 10 mt long horizontal wire, WELL insulated from earth (I mean distant, to lower the stray capacitance coupling with ground which will adsorb some signal ). The Inductor and capacitor forms a resonator, that will....
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This amplifier utilizes a 2N6367 and a pair of 2N6368 transistors. The 2N6367 transistor is employed as a driver and is specified for up to 9 W (PEP) output. In the amplifier design the driver must supply on 5 W (PEP) at 30 MHz with a resulting !MD....
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This circuit features automatic Exit and Entry delays and a timed Bell Cut-off. It has provision for both normally-closed and normally-open contacts, and a 24-hour Personal Attack/Tamper zone. It is connected permanently to the 12-volt supply and its....
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Since my page was first posted, I have received a number of emails asking about a high current power supply. I looked around, but couldn`t find one that was suitable. So, I designed this. It is a linear supply, which might have a few of you rolling your....
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Battery-operated equipment can work on one set of batteries for a long time nowadays. However, if it is left on inadvertently,..
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Figure 1 shows a simple, cost-effective way of providing these bias voltages. A step-up regulator, IC1, forms the heart of the circuit. This regulator switches at a constant frequency of 1 MHz and a fixed duty cycle of 70%. IC1 steps up the input voltage to....
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I had designed up an oscillator with a Power Output circuit. Problem was when power was applied to the entire circuit, the output of the Oscillator gave a Momentary Spike into the output circuit. Thus Driving it full on for a split second. This Circuit....
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The filter produces three outputs: high-pass, bandpass, and low-pass. Frequency is linearly proportional to the gain of the two integrators. Two CA3080's, (IC2, 4) provide the variable gain, the resonant frequency being proportional to the current ^. Using....
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This cell phone jammer is not applicable for use in Europe, Middle East, nor Asia.
The GSM jammer circuit could block mobile phone signals which works on GSM1900 band, also called DCS. For more cell phone jammers check the related posts...
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Notch filters remove a single unwanted frequency from an input signal. They are also a vital component of pulse-shaping networks, such as time-averaging filters. You can tune a state-variable filter over a wide range by changing the time constants of its....
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Designed for self-powered 8, 4 & 2 Ohm loudspeakers. This amplifier was designed to be self-contained in a small loudspeaker box. It can be feed by Walkman, Mini-Disc, iPod and CD players, computers and similar devices fitted with line or headphone....
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A unique push-pull parallel circuit. It uses four MRF150 RF power FETs paralleled at relatively high power levels. Supply voltages of 40 to 50 Vdc can be used, depending on linearity requirements..
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This circuit utilising a 555 timer IC can be used as an alarm system to prevent the theft of your luggage, burglars breaking into your house etc. The alarms goes ON when a thin wire, usually as thin as a hair is broken.
The circuit is straightforward. It....
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The fixed voltage power supply is useful in applications where an adjustable output is not required. This supply is simple, but very flexable as the voltage it outputs is dependant only on the regulator and transformer you choose. The maximum output current....
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Normally the base of a cordless phone has an adaptor and the handset has Ni-Cd cells for its operation. The base unit becomes inoperative in case of power failure. In such conditions, it is better to provide a backup using Ni-Cd cells externally. Here is a....
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The need for a device that can detect and extinguish a fire on its own is long past due. Many house fires originate when someone is either sleeping or not home. With the invention of such a device, people and property can be saved at a much higher rate with....
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This is a simple circuit that does the day/night switchings you have in mind. POT1 is used to set the light level at which the circuit switches from enable to disable...
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This section describes an experimental low power, low bandwidth data signaling system that was initially made to operate at 55 MHz (television channel 2 in the U.S.). Before operating a radio transmitter, find out what kind of transmitter operation, if any,....
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The basic MK484 (Replacement for the ZN414) connected in its minimum configuration as a radio receiver for the A.M. Broadcast band and the upper half of the United States' FCC Part 15 Lowfer (1600-1750 meter) band. Its a circuit straight out of the....
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This RDF circuit consists of a square-wave oscillator (IC1), which switches two antennas alternately at an audio rat..
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In theory, synchronous clock multiplication is an easy task. A simple PLL with two digital dividersone inserted just after the VCO (voltage-controlled oscillator) and the second one placed directly at the input of the phase detectormay do the job. The....
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Transistors Ql, Q2, and Q3 monitor the two outputs of the stereo amplifier. If the offsets exceed 2 V, Q7 is turned off, which turns off Q8 and the normally on relay. Diodes D2 and D5, together with Q4, provide a mains voltage monitor. As soon as the ac....
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The output of a video amplifier is differentiated before being fed to a Schottky comparator. The propagation delay is reduced to typically 10ns. The output pulse width is set by the value of C, lOOpf giving a pulse of about 90ns duration.
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This DC Motor Controller circuit will control a 12V dc motor. The system will have three pushbuttons: a START button, a REVERSE button and a STOP button. Initially, the motor must not be running. When the START button is pressed, the motor will run in one....
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This circuit will allow you to control the speed of an AC motor, for example an electric drill. The way that this circuit works is as follows. The bridge rectifier produces dc voltage from the 120vac line. A portion on this current passes through the 10K ohm....
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This circuit outputs the maximum (or the minimum) of the four input voltages Vv V2, V3, and V4. Each of these input voltages is in the range 0 to 5 V. The output of the unit is the maximum of Vv V2, V3, and V4 if the control voltage input is 5 V (i.e.,....
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CodeLock AVR electronic combination lock is realised with Atmel AVR microcontroller AT90S2313 or ATtiny2313. Program in hex code is 2 kB long. User code is consisted of 1 to 4 digits. If you buy the chip than user code is consisted of 1 to 8 digits. If the....
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When button S12 (#) is pressed, a positive voltage fed through Rl appears at the base of transistor Ql, turning it on. When Ql is conducting, pin 1 of Ul is brought to ground 0ow) or the battery's negative terminal. With pin 1 low, two things occur: Pin 8 of....
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The circuit shown here with RC filter (Figure T). Micropoco capacitor has a temperature coefficient of 125 10"6 60.10" 6'C" V In simplified circuits a fixed resistor (e g. 620k) can be used for a guaranteed switching level of < l6mV.
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1. Full 5 watt output using a power MOSFET final that is resistant to high SWR and thermal runaway. This final is very efficient and runs much cooler than traditional bipolar designs.
2. Highly sensitive and selective superhetrodyne....
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Generating complementary clock signals in a Spice simulation is an easy task. However, this task gets much harder if you need to introduce some dead time into the signals. This difficulty is especially true when you`re dealing with a....
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Transistors Ql and Q2 are connected as a free running multivibrator. The output, at the emitter of Q2, drives the base of the common emitter amplifier Q3, which controls the lamp. This circuit configuration permits the flash duration, the interval between....
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The analog to digital converter (ADC) is a commonly required in most of the projects. Analog voltage measurement can be done using the ADC hardware built in together in a PIC. The picture below show a simple setup for measuring the voltage through the....
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These circuits are based on TEA2025 is a monolithic integrated audio amplifier in a 16-pin plastic dual in line package manufactured by UTC .Circuit has an Internal Thermal Protector. It is designed for portable cassette players and radios. You can also use....
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The SillOO series circuit input is connected to a capacitive field sensor-possibly a piece of doublesided circuit board. Any induced voltage change on the plate is fed to the input of the peak detector section of the op-amp circuit. The Schmitt trigger....
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Inverters U1a and U1b are connected in a simple RC oscillator circuit. The frequency is determined by the values of R1, C1 C2 and the internal characteristics of the integrated circuit. As long as the circuit is oscillating, a positive dc voltage is....
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Using the versatile L200 voltage regulator, this power supply has independent voltage and current limits. The mains transformer has a 12volt, 2 amp rated secondary, the primary winding should equal the electricity supply in your country, which is 240V here....
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As is commonly the case, this supply was born of necessity. There is absolutely nothing special about the circuit, except that as shown, it is quite capable of up to 20 Amps intermittently or 10A continuous. Simply use a bigger transformer, bridge rectifier....
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The dc-dc converter substitutes a voltage tripler in place of the external inductor and the diode that"s typically as..
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This bridge circuit is intended for those cases where two unequal supply voltages are required. The lower voltage is obtai..
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This is a simple, precise voltage-controlled current source. Bipolar supplies will permit bipolar output. Configurations featuring a grounded voltage- control source and a grounded load are usually more complex and depend upon several components for....
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Professional electronics designers often use peak-detector circuit sin such applications as amplitude measurement, automatic gain control, and data regeneration. You can build a simple and fast peak detector from a serial diode and a shunt capacitor, but it....
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Measures 10mV to 50Volt RMS in eight ranges.
Simply connect to your Avo-meter set to 50µA range. Connect J2 and J3 to an Avo-meter set to 50µA range. Switching SW2 the four input ranges will be multiplied by 5. Total fsd ranges are: 10mV, 50mV, 100mV,....
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The given circuit, when connected in parallel to a telephone, dis- plays the number dialled from the telephone set using the DTMF mode. This circuit can also show the number dialled from the phone of the called party. This is particularly helpful for....
The circuit is actually a half-wave rectifier. It only charges the battery on every half cycle. The plug pack doesn't like this as it leaves residual flux in the core of the transformer and causes it to overheat. But that's the only drawback with the....
This self-starting fixed frequency oscillator circuit gives excellent frequency stability. Rl and Cl comprise the frequency determining network while R2 provides the regenerative feedback. Diode Dl enhances the stability by compensating for the difference....
S2 is used to initiate timing. A light-to-dark or dark-to-light transition stops this timer, depending on the setting of ..
This circuit can cause a cassette recorder to automatically tum on and record when a sound or noise is present. Another use, is when the sound-activated switch is used to tum on a cassette player so that it operates as a burglar-alarm detector and sounder.....
Al's positive input is biased by the thermocouple. Al's output drives a crude V — F converter, comprised of the 74C04 inverters and associated components. Each V — F output pulse causes a fixed quantity of charge to be dispensed into the 1 µ¥ capacitor....
This circuit relies on extremely high input impedance for effective operation. The HA-5180 with its JFET input stage, performs well as a preamplifier. The standard three amplifier configuration is used with very close matching of the resistor ratios....
The voltage to be measured is digitized in an analog-to-digital (A/D) converter and then displayed in three decimal d..
The CMOS comparator in the successive-approximation system determines each bit by examining tbe charge on a series of binary-weighted capacitors. In tbe first phase of tbe conversion process, the analog input is sampled by closing switch SC and all ST....
This circuit is one section of an octave equalizer used in audio systems. The table shows the values of CI and C2 that are needed to achieve the given center frequencies. This circuit is capable of 12 dB boost or cut, as determined by the position of R2.....
The LM1036 is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected. Four control inputs provide control of....
Building a foxhole radio is rewarding and the basic setup is very simple. It is, however, difficult to adjust, and it may take several attempts to find a proper razor blade for the detector. This is a project that requires patience and much trial and error,....
Common designs for touch switches detect a decrease in resistance when a user`s fingertip either connects a contact to the circuit`s common ground or supplies an injection of 60-Hz ac voltage, resulting from immersion in the electrostatic field that nearby....
Using a single 7812 IC voltage regulator and multiple outboard pass transistors, this power supply can deliver output load currents of up to 30 amps. The input transformer is likely to be the most expensive part of the entire project. As an alternative, a....
Its a digial clock which make use of AT89C4051 to work as a Real time clock. Port 1 of the controller (AT89C4051) is used as the data lines for the LCD (starting from pin 7- pin14 of LCD). As you can see there is not much change in the hardware except the....
Indicator lamp brightness varies in step with modulated RF signal. Adjust R2 with transmitter on (modulated) until the lamp flashes in step with modulation..
Both oscillators are built using MPF102 or J310 FETs. The Mixer is BF998 dual gate MOSFET. Audio IC amplifier is LM386 which drives a speaker. I have used a stabilized supply for two oscillators and mixer. U1, a 78L05 is doing this job nicely. ..
This circuit is on oscillator with LI being a 4" diameter coil of 35 turns of #26 magnet wire. Metal in proximity to LI will cause the oscillator to shift frequency. An AM transistor radio is used to detect the frequency shift...
Getting microprocessor designs to work is notoriously difficult when both the software and hardware are new. The ..
The simple modulator stage will accommodate most common LEDs. By adjusting the potentiometer, the bias of the transistor is varied until the LED is at its half output point. Then, audio will cause it to vary above and below this point..
This compact LC oscillator offers a frequency range of about 1 kHz to almost 9 MHz and a low-distortion sine-wave ou..
Using a Signetics NE602 in a varactor-tuned front end, the circuit of a shortwave receiver can be very simple and yet g..
Three-terminal regulator device (LM78LXX) has Vout = Vm until the input rises 1.5 to 2 V above the output when the ..
Power this project from sunlight with a CirKits solar power circuit board kit. Other LED lamp circuits can be seen at FC`s Solar Circuits, another interesting LED project is my 13 Color LED Rainbow. This circuit makes a nice lamp that consumes little power,....
The circuit converts a de voltage (V +) to a high-amplitude square wave in the audio-frequency range. The dual timer, IC2, provides an inexpensive alternative to the traditional transformer for providing complementary base drive to the power transistors,....
Using the simple circuit in Figure 1, you can control the light intensity in your room or work area from your PC. The heart of the circuit is a low-power D/A converter that converts digital words from a computer's parallel port to analog-voltage signals. To....
This system performs a complete conversion of 12 bits in 10 p unipolar or bipolar. This converter is accurate to ± 12-bit LSB Y2 and a typical gain TC of 10 ppm / ° C. In unipolar mode, the system range is 0 V to 9.9976 V, with each bit having a value of....
This circuit mixer has an internal amplification with 2N3563 transistor. The two input signals can be independently controlled by VRI and VR2. The VR3 balance control is used to remove a signal while the other melted. ..
If you`re the sort who`d like to have an HF receiver in every room, but can`t afford it, this idea is for you. It will also appeal to the beginner wishing to build the simplest possible direct conversion receiver. Using a readily-available FM wireless....
This circuit consists of an astable multivibrator driving a push-pull pair of transistors into the transformer primary. The multivibrator frequency should~equal around 1 or 2kHz. ..
This programmer was designed in view of to be flexible, economical and easy to built, the programmer hardware utilizes the standard TTL series parts and no special components are used. The programmer is interfaced with the PC parallel port and there is no....
OSU8 began as a student project in 1994 to create a simple but functional 8-bit microprocessor, starting with a definition of the architecture to implementation in a Xilinx FPGA chip, and full-custom CMOS implementation. Over a period of about six months,....
The ·circuit includes a peak detector that irrunediately drives the readout to any new higher signal level and slowly lowers it after the signal drops to zero. The readout is a moving dot or expanding bar display. The circuit can be expanded for a longer....
Gates Gl and G2 together with resistors Rl and R2 form a simple voltage monitor that has a trip point of 1 volts. Gate G3 is simply an inverter. The display section of the tester consists of a common anode alphanumeric LED and current-limiting resistors..
Audio levels can be monitored using a small panel meter with this circuit built from discrete components. The circuit has a flat frequency response from about 20Hz to well over 50Khz. Input sensitivity is 100mV for a full scale deflection on a 100uA meter.....
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. The circuit is mainly here for historical reasons, a....
This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can....
A ideal solution for the make a good, low cost power amplifier. Its a ideal solution for the creation a system of home cinema. The preamplifier and the driver support in a operational amplifier [IC1]. The voltage fall in resistors R5 and TR2/R6, drive the....
Simple and low cost. The optimal supply voltage is around 50V, but this amp work from 30 to 60V. The maximal input voltage is around 0.8 - 1V. As you can see, in this design the components have a big tolerance, so you can build it almost of the components,....
I built this headphone amplifier for dynamic headphones based on my rules of proper audio design. People who know my designs will realize that this amplifer is much more than just a headphone amp. It is a pure class A design containing a new....
For most applications, the available power from op amps is sufficient. There are times when more power handling capability is necessary. A simple power booster capable of driving moderate loads uses an NE5535 device. Other amplifiers may be substituted only....
The oscillator, Q1, is a standard overtone circuit. A fifth-overtone crystal, 80.545 MHz, is operated on the seventh overtone, 112.763 MHz. C6 couples the output of the oscillator to Q2, which operates as a doubler to 225.5 MHz. A double-tuned circuit....
In the presence of smoke or gas, the ac output voltage increases and becomes rectified, filtered and zener-diode coupled (D2 for thresholding) to sensitivity control R3. Under no gas condition, the output equals approximately 0 V (high). When gas is....
This circuit provides a precision voltage source that can be adjusted through zero to positive a..
STS schematic. The Q2 gate voltage increases with the charge on C3. After 15 seconds of charging, the buzzer will warble. As the charging continues, the sound will grow louder.Circuit waveforms. Point A shows the signal from the flasher. The voltage at....
This circuit is a church bell controller. Basic component is an ATmega32 microcontroller. At the circuit 1 24LC32 eeprom memories is being used. As control I created a menu who will be appeared on 4x20 LCD (Liquid Crystal Display). The menu browsing can be....
The circuit for a powerful AM transmitter using ceramic resonator/filter of 3.587 MHz is presented here. Resonators/filters of other frequencies such as 5.5 MHz, 7 MHz and 10.7 MHz may also be used. Use of different frequency filters/resonators will involve....
FM Wireless Mike can transmit voice signals to any FM Radio receiver 100 meters away. The circuit is basically a frequency modulated transmitter working at 100 MHz. The frequency of the transmitter can be varied slightly by changing the trimmer C5. You can....
Three circuit options Can be synchronized to Christmas tree flashing lights This circuit generates a dual-tone bells ringing similar to most door-bell units. It can be used in many applications other than door-bell. In the Notes below several options will....
During summer nights, the temperature is initially quite high. As time passes, the temperature starts dropping. Also, after a person falls asleep, the metabolic rate of one's body decreases. Thus, initially the fan/cooler needs to be run at full speed. As....
The Quad op amp MC4301 is used to configure a filter that will notch out a given frequency and produce that notched-out frequency at the BP terminal, useful in communications or measurement setups. ..
This circuit uses the TDA2040V which is a monolithic power amplifier IC intended for use as a high quality, class AB audio power amplifier. Typically it provides 22W output power into 4ohm with 0.5% distortion, from 32V supply. The device is designed to....
The AM signal is captured by the antenna , 10 mt long horizontal wire, WELL insulated from earth (I mean distant, to lower the stray capacitance coupling with ground which will adsorb some signal ). The Inductor and capacitor forms a resonator, that will....
This amplifier utilizes a 2N6367 and a pair of 2N6368 transistors. The 2N6367 transistor is employed as a driver and is specified for up to 9 W (PEP) output. In the amplifier design the driver must supply on 5 W (PEP) at 30 MHz with a resulting !MD....
This circuit features automatic Exit and Entry delays and a timed Bell Cut-off. It has provision for both normally-closed and normally-open contacts, and a 24-hour Personal Attack/Tamper zone. It is connected permanently to the 12-volt supply and its....
Since my page was first posted, I have received a number of emails asking about a high current power supply. I looked around, but couldn`t find one that was suitable. So, I designed this. It is a linear supply, which might have a few of you rolling your....
Battery-operated equipment can work on one set of batteries for a long time nowadays. However, if it is left on inadvertently,..
I had designed up an oscillator with a Power Output circuit. Problem was when power was applied to the entire circuit, the output of the Oscillator gave a Momentary Spike into the output circuit. Thus Driving it full on for a split second. This Circuit....
The filter produces three outputs: high-pass, bandpass, and low-pass. Frequency is linearly proportional to the gain of the two integrators. Two CA3080's, (IC2, 4) provide the variable gain, the resonant frequency being proportional to the current ^. Using....
This cell phone jammer is not applicable for use in Europe, Middle East, nor Asia. The GSM jammer circuit could block mobile phone signals which works on GSM1900 band, also called DCS. For more cell phone jammers check the related posts...
Notch filters remove a single unwanted frequency from an input signal. They are also a vital component of pulse-shaping networks, such as time-averaging filters. You can tune a state-variable filter over a wide range by changing the time constants of its....
Designed for self-powered 8, 4 & 2 Ohm loudspeakers. This amplifier was designed to be self-contained in a small loudspeaker box. It can be feed by Walkman, Mini-Disc, iPod and CD players, computers and similar devices fitted with line or headphone....
A unique push-pull parallel circuit. It uses four MRF150 RF power FETs paralleled at relatively high power levels. Supply voltages of 40 to 50 Vdc can be used, depending on linearity requirements..
This circuit utilising a 555 timer IC can be used as an alarm system to prevent the theft of your luggage, burglars breaking into your house etc. The alarms goes ON when a thin wire, usually as thin as a hair is broken. The circuit is straightforward. It....
The fixed voltage power supply is useful in applications where an adjustable output is not required. This supply is simple, but very flexable as the voltage it outputs is dependant only on the regulator and transformer you choose. The maximum output current....
Normally the base of a cordless phone has an adaptor and the handset has Ni-Cd cells for its operation. The base unit becomes inoperative in case of power failure. In such conditions, it is better to provide a backup using Ni-Cd cells externally. Here is a....
The need for a device that can detect and extinguish a fire on its own is long past due. Many house fires originate when someone is either sleeping or not home. With the invention of such a device, people and property can be saved at a much higher rate with....
This is a simple circuit that does the day/night switchings you have in mind. POT1 is used to set the light level at which the circuit switches from enable to disable...
This section describes an experimental low power, low bandwidth data signaling system that was initially made to operate at 55 MHz (television channel 2 in the U.S.). Before operating a radio transmitter, find out what kind of transmitter operation, if any,....
The basic MK484 (Replacement for the ZN414) connected in its minimum configuration as a radio receiver for the A.M. Broadcast band and the upper half of the United States' FCC Part 15 Lowfer (1600-1750 meter) band. Its a circuit straight out of the....
This RDF circuit consists of a square-wave oscillator (IC1), which switches two antennas alternately at an audio rat..
Transistors Ql, Q2, and Q3 monitor the two outputs of the stereo amplifier. If the offsets exceed 2 V, Q7 is turned off, which turns off Q8 and the normally on relay. Diodes D2 and D5, together with Q4, provide a mains voltage monitor. As soon as the ac....
The output of a video amplifier is differentiated before being fed to a Schottky comparator. The propagation delay is reduced to typically 10ns. The output pulse width is set by the value of C, lOOpf giving a pulse of about 90ns duration. ..
This DC Motor Controller circuit will control a 12V dc motor. The system will have three pushbuttons: a START button, a REVERSE button and a STOP button. Initially, the motor must not be running. When the START button is pressed, the motor will run in one....
This circuit will allow you to control the speed of an AC motor, for example an electric drill. The way that this circuit works is as follows. The bridge rectifier produces dc voltage from the 120vac line. A portion on this current passes through the 10K ohm....
This circuit outputs the maximum (or the minimum) of the four input voltages Vv V2, V3, and V4. Each of these input voltages is in the range 0 to 5 V. The output of the unit is the maximum of Vv V2, V3, and V4 if the control voltage input is 5 V (i.e.,....
CodeLock AVR electronic combination lock is realised with Atmel AVR microcontroller AT90S2313 or ATtiny2313. Program in hex code is 2 kB long. User code is consisted of 1 to 4 digits. If you buy the chip than user code is consisted of 1 to 8 digits. If the....
When button S12 (#) is pressed, a positive voltage fed through Rl appears at the base of transistor Ql, turning it on. When Ql is conducting, pin 1 of Ul is brought to ground 0ow) or the battery's negative terminal. With pin 1 low, two things occur: Pin 8 of....
The circuit shown here with RC filter (Figure T). Micropoco capacitor has a temperature coefficient of 125 10"6 60.10" 6'C" V In simplified circuits a fixed resistor (e g. 620k) can be used for a guaranteed switching level of < l6mV. ..
1. Full 5 watt output using a power MOSFET final that is resistant to high SWR and thermal runaway. This final is very efficient and runs much cooler than traditional bipolar designs. 2. Highly sensitive and selective superhetrodyne....
Transistors Ql and Q2 are connected as a free running multivibrator. The output, at the emitter of Q2, drives the base of the common emitter amplifier Q3, which controls the lamp. This circuit configuration permits the flash duration, the interval between....
The analog to digital converter (ADC) is a commonly required in most of the projects. Analog voltage measurement can be done using the ADC hardware built in together in a PIC. The picture below show a simple setup for measuring the voltage through the....
These circuits are based on TEA2025 is a monolithic integrated audio amplifier in a 16-pin plastic dual in line package manufactured by UTC .Circuit has an Internal Thermal Protector. It is designed for portable cassette players and radios. You can also use....
The SillOO series circuit input is connected to a capacitive field sensor-possibly a piece of doublesided circuit board. Any induced voltage change on the plate is fed to the input of the peak detector section of the op-amp circuit. The Schmitt trigger....
Inverters U1a and U1b are connected in a simple RC oscillator circuit. The frequency is determined by the values of R1, C1 C2 and the internal characteristics of the integrated circuit. As long as the circuit is oscillating, a positive dc voltage is....
Using the versatile L200 voltage regulator, this power supply has independent voltage and current limits. The mains transformer has a 12volt, 2 amp rated secondary, the primary winding should equal the electricity supply in your country, which is 240V here....
As is commonly the case, this supply was born of necessity. There is absolutely nothing special about the circuit, except that as shown, it is quite capable of up to 20 Amps intermittently or 10A continuous. Simply use a bigger transformer, bridge rectifier....
The dc-dc converter substitutes a voltage tripler in place of the external inductor and the diode that"s typically as..
This bridge circuit is intended for those cases where two unequal supply voltages are required. The lower voltage is obtai..
This is a simple, precise voltage-controlled current source. Bipolar supplies will permit bipolar output. Configurations featuring a grounded voltage- control source and a grounded load are usually more complex and depend upon several components for....
Measures 10mV to 50Volt RMS in eight ranges. Simply connect to your Avo-meter set to 50µA range. Connect J2 and J3 to an Avo-meter set to 50µA range. Switching SW2 the four input ranges will be multiplied by 5. Total fsd ranges are: 10mV, 50mV, 100mV,....
The given circuit, when connected in parallel to a telephone, dis- plays the number dialled from the telephone set using the DTMF mode. This circuit can also show the number dialled from the phone of the called party. This is particularly helpful for....
