New Circuits Page 230
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The oscillator is a Motorola MC14410CP chip using a 1-MHz crystal. The chip generates both the high and low tones, feeding the energy to the amplifier through 1-K resistors and the 1-I"F capacitor. Values for the output resistors can vary from a few....
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This circuit uses Analog Devices` AD639 universal trigonometric function generator to convert a triangle waveform, the basic waveform of the VCO itself, into a very low-distortion sine wave. By using the AD639 in its frequency tripler mode [2], the....
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The camera rotator circuit uses a 2716 EPROM to store a table of logic values that control the motor driver (H-bridge) circuit. The EPROM data is shown in the schematic. By using the EPROM, a large number of discrete gates are eliminated. The logic table is....
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The experimenter's pot is a solid state potentiometer using Dallas semiconductor?s DS1869 and National?s LM78L05 two electrolytic capacitor two small push button switch and two optional Molex connector. this project is very useful especially in finding the....
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This circuit consists of a tri-color LED, a resistor, wire, and a coin-size test plate. You will have to build two such circuits one for each black clamp on a set of auto battery jumper cables. The author installed the circuits inside the black clamps....
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The LTC1155, dual micropower MOSFET driver, generates
12V from a 5V rail to fully enhance logic-level Nchannel
switches with no external components required
(see Figure 1). Further, the supply current is typically 85mA
with the switch fully enhanced and....
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M1 is a clamp connected to the 24V (dc or ac) power from the gate opener. The diode bridge rectifies the alternate voltage (should the opener use dc current, it merely adjust the positive and negative rail to match circuit polarity), in order to get the....
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A 555 is used as an oscillator, optimally around 15.76KHz (in North America). Power pins on the chip (pin 1 to ground, pin 8 to +12V) are not shown on the diagram. The output from the 555 is then switched by PNP transistor Q1 and by the large 2N3055 NPN....
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In this case, the NE602 is used in this superhet front-end configuration. Ul serves as a frequency conve..
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As a sensor in the design of this linear thermometer, the LM34 is used. The output is the difference between..
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The persona] message recorder is built around an ISD1016 CMOS voicc messaging system, which does away with the cumbersome and expensive analog-to-digital and digital-to-analog conversion circuits. A functional block diagram of the ISD1016 is shown. The....
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Have you ever attempted to copy a commercially produced video only to end up with a distorted and jumpy image? If so, then you have run afoul of MacroVision. MacroVision is the most popular copy protection scheme used on the majority of content distributed....
-
Simple function generators normally provide sinusoidal, rectangular, and triangular waveforms, but seldom a sawtooth. Th..
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This antenna is the result of long term development and user feedback.
All ATL-3 loop windings are centre tapped and balanced w.r.t. their amplifier/receiver chassis ground, and therefore electric field interference pick up tends to self cancel. Magnetic....
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No Description available...
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The amplifier of circuit, use negative current feedback. So, the load current depends mainly from the input signal and no so much from the impedance of loudspeaker. The inductor current of loudspeaker develop above in the R7 a voltage. This voltage is drive....
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The gain of the low-cost IC is internally fixed so that it is not less than 34 dB (50 times). A unique input stage allows input signals to be referenced to ground. The output is automatically self centering to one half the supply voltage. The output is also....
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A low-noise LT1115 (Linear Technology, Inc.) op amp is coupled to a class-A buffer amplifier to produce a variable g..
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This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source. When the test button is pressed, the Car battery voltage....
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The operating principle of the circuit is very simple. The first Led D1 is placed in series with the resistor R2 and diode D4.An only be lit this LED indicates that the battery is ypofortismeni. For this reason Led D1 is red. If the voltage is greater than....
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Digital visitor counter is a reliable circuit that takes over the task of counting Number of Persons/ Visitors in the Room very Accurately. When somebody enters into the Room then the Counter is Incremented by one and when any one leaves the room then the....
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This circuit uses a digital voltmeter (formed from IC1 and IC3) to display fuel quantity as a percentage of a full tank...
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This unit is an upgrade of the previous phone call interceptor. Instead of using an answering machine to provide the outgoing message and recording functions, it uses the ISD4004 (from Windbond Electronics). The ISD4004 records up to 8 minutes of audio. I....
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What's so special about this circuit? Well, the first third-brake light I installed I had to pull a wire from the
Third Brake Light all the way underneath the carpet to the brake-pedal-switch and I thought it would be easier to
pluck the signal of both....
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An LF356 op amp is used as a gain amplifier with the output taken across R5, When a full-scale current of 1 mA is flowing..
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I recently needed to control nine seven-segment displays for a microcontroller`s serial port. The complication I faced was the need to provide a continuous brightness adjustment for all the digitsfrom completely dark to fully bright. I couldn`t easily use....
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Twang is a guitar sound that more or less approximates a banjo or mandolin. The circuit produces unusual sounds from an ordinary electric guitar by cutting the bass, severely distorting the midband and highs, and then amplifying the distortion...
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The circuit gives a programmable bandpass where both the cut-over frequency and the gain, A, are controlled independently. In the twin-T bridge the resistors R and R/2 are replaced by two double FETs, 430, the channel resistance of the first one in the....
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The circuit"s input op amp triggers the timer, sets its flip-flop and cuts off its discharge transistor so that capacitor C can charge. When capacitor voltage reaches the timer"s control voltage of 0.33 Vee. the flip-flop resets and the transistor....
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This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low....
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This circuit functions as a wideband adjustable AGC amplifier. With an effective bandwidth of approximately 10 MHz, it is capable of handling rf input signal frequencies from 3.2 to 10 MHz at levels ranging from 40 mV up to 3 V pk-pk. AGC action is....
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This Design Idea involves a low-power motion-detector circuit that operates from battery power for extended times. Part of the design includes a solenoid-operated trip mechanism that triggers whenever it detects motion. The drive circuit for the solenoid in....
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In this circuit, a TU31 shunt regulator is used to sense the output voltage. The TU31 drives the LED of a 4N28 optocoupler which provides feedback to the MAX641 while maintaining isolation between the input, +12 V, andJhe output, +15 V. ..
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By adding a flyback winding to a buck-regulator switching converter (see the figure), wliich is essentially a 5-V supply with a 200-mA output capability, a 12-V output ) can be produced. The flyback winding on the main inductor (forming transformer Tl)....
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This regulator is for the purpose of controlling a dc generator. The field configuration is that one side of the field is grounded. D4 prevents the battery from discharging through the generator and takes the place of the mechanical cut-out relay...
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This Project is used to indicate the temperature and it is also used as controller. The system will get the temperature from the IC and it will display the temperature over the seven segment display and this temperature was compared with the value stored by....
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n the view of the dramatic drop in the price of crystals used in color TV sets, they now represent an economical way of building an SSB filter. The circuit shown in the diagram is for a filter with a 6 DB band width of roughly 2.2 KHz. By terminating the....
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This circuit uses LEDs to display logic states for high, low, rising pulse, and falling pulse, it is generally useful for debugging logic circuitry...
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The transmitter output drivers present a low impedance to inbound surges and must be able to drive sufficient current in the primary of the transmit transformer in order to produce the required output pulse at the network interface. The receiver inputs....
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The sensor is a standard TO-5 or TO-46 package. For surface or air temperature sensing. Small clip-on heat sinks can be used. A simple probe can be made using heat-shrink tubing and RTV silicon rubber. Three-leads-plus-shield cable is a good choice for wire....
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A differential amp used by the SIM, and it is a completely conventional circuit. This is adjustable by using VR1 to null out any normal variations that the amp might show when there is no distortion or other nastiness in evidence. The second stage is a....
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This project gives you a fingerprint based attendance system with 8051 microcontroller. The SM630 fingerprint module is used for fingerprint matching. It can store a max of 768 fingerprints. The admin can add/delete records from the PC through the VB....
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Digital-ProfiLab was designed for measurement and control applications, combining features like circuit and logic simulation, front panel design, and hardware control to one powerful tool. Incoming signals from external devices may be processed and....
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Two identical integrated circuits, U1 and U2, known as "hex inverters" are used for the theremin's primary functions. They are CMOS (Complimentary Symmetry Metal Oxide Semiconductor) devices, typically used in digital circuits to perform a logic function....
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The object of Quick Draw is to test your reaction time against your opponent's. A third person acts as a referee and begins the duel by pressing S1, which lights LED1. Upon seeing LED1 go on, you try to outdraw your opponent by moving S2 from "Holster"....
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The 555 is configured in the standard astable oscillator circuit designed to give a square wave cycle at a period of around 1 cycle/sec. A potentiometer is included in the design so the period can be set to exactly 1 second by timing the LED flashesc. A....
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You need free power? This schematic transforms the surrounding radio waves to usable current. The levels of power can be stepped up by using more diodes. The critical points in this device are first the type of diodes and second the antenna construction. The....
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A stereo power amp designed for use in portable players and radios. A 3V supply can be used to drive headphones providing 20mW in 32 Ohms per channel. ..
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Pure Class-A triode OTL design and only one tube for amplification. The plate voltages should be low. The output impedance should be as low as possible and the maximum output current should be as high as possible. This amplifier is a stand alone Headphone....
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The transmitter for the wireless headphones is built around a CD4046 CMOS phase-locked loop, coupled with a driver transistor, and a pair of infrared LEDs. ..
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Catalytic bead sensors are used primarily to detect combustible gases. They have been in use for more than 50 years. Initially, these sensors were used for monitoring gas in coal mines, where they replaced canaries that had been used for a long period of time...
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The Car Temperature Gauge is basically the same circuit as March's project with some minor changes to the input circuit. This circuit will display the water temperature to 1 degree resolution...
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This is a general purpose remote control project with using programmable PIC microcontrollers. Schematics are shown for using infrared (RF) or radio (RF) media. If you are not familiar with microcontroller programming, you can use fixed encoder and decoder....
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The HA7210 oscillator 10 combines with an IOL7642 quad CMOS op amp to produce a sleep-mode control circuit. The circuit is put into the sleep mode with a logic high applied to the Reset input or with an RC timer for automatic reset...
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The circuit does not present particular difficulties for somebody that has a small experience. The two circuits are the himself, with a small difference only in their input, when they have they measure voltage or current and in connection that concern....
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The circuit is frequency selective. It has been used from 2 meters through 160 meters. The telescoping antenna may be adjusted to its shortest length when working at 2 meters to keep the needle on the scale, Meter should be a 100 microamp to a 500 microamp....
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The heart of the circuit is IC1, General Instrument's AY-3-1350 melody-synthesizer IC. IC2 is a TCM1512 telephone ring detector IC that is powered by the telephone line. The circuit's operation begins when IC2 senses a ring pulse on the telephone line. The....
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The circuit described here is that of a metal detector. The opera- tion of the circuit is based on superheterodyning principle which is commonly used in superhet receivers. The circuit utilises two RF oscillators. The frequencies of both oscillators are....
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With SI open the circuit functions as a doorbell. With SI closed, rain falling on the sensor will turn on Ql, triggering Q2 and the thyristor and activating the bell, R4 provides the holding for the thyristor while Dl prevents any damage to the thyristor....
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Figure 1 shows the relative responsivity and emission spectra for an Infineon (www.infineon.com) SFH409 LED. This infrared GaAs LED has peak emission at 940 nm with a half-peak bandwidth of 50 nm. In detection mode, it peaks at 920 nm with a half-peak....
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The remote control transmits encoded signals. Each time a key is pressed, the relevant code is transmitted, usually repeating it many times to ensure reception. This encoded signals travels over a radio or infrared-light beam, to eventually get captured by....
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The LDR`s were hand-picked. Got two packages of them from Radio Shack, looking for at least two pairs of similar parts. Then added wire-wrap pin sockets, to the circuit, so that the LDR`s could be plugged in. Currently, the 0.33UF cap is not being used on my....
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In essence, the circuit is nothing more than an auto ignition coil and a set of points which accomplishes the same thing. A pulsing circuit made from a single CMOS NOR integrated circuit (Ul), opens and closes the relay contacts to simulate the action of the....
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As the speed of an electric drill is decreased by loading, its torque also drops. A compensating speed control like this one puts the oomph back into the motor. When the drill slows down, a back voltage developed across the motor—in series with the SCR....
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When the torque load on the motor increases, its current increases. This current increase is sensed across Rs, and positive feedback is applied to the noninverting terminal of the LH0101, thereby increasing the motor voltage to compensate for the increased....
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Using the fact that the VRE of a transistor shifts 59.16 mV per decade of current at 25°C. This cons..
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The circuit is designed to drive an external load. A fault condition in the external load circuit could feed excessive current or voltage back into the line drive circuit. If excessive voltage appears from the load, the two zener diodes will clamp that....
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This simple AM circuit uses a 561B. There's no inductance/capacitance tuning circuit. The 365 pF capacitor connected between pins 2 and 3 does all the tuning. The circuit needs a good outside antenna and a solid ground. And if you want to further improve....
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The test circuit gives an indication of the capacity remaining in a battery. By noting the time in seconds that the LED remains on after you depress the test switch Sl. The circuit has proven reliable in testing NiCad-, carbon-, and alkaline-type....
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This preamplifier was designed for low resistance sources like moving coil heads (MC). The circuit uses in parallel three duble transistors SSM2220 or MAT03 and by forming a diferential amplifier keeps noice low. Connecting this amplifier in front of a OP27....
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Although the 78xx series of voltage regulators are available with different current outputs, you can boost
the available current output with this circuit. A power transistor is used to supply extra current to the load
the regulator, maintaining a constant....
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A common power-supply requirement involves converting a 2.4- or 3-V battery voltage to a 5-V logic suppl..
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This simple circuit functions as a 12 LED chaser. A single illuminated LED 'walks' left and right in a repeating sequence, similar to the effect seen on KITT, the car in the Knight Rider TV series.
Fully commented source code and programmer ready HEX....
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Is it possible to use DRAM with microcontroller AVR? Yes, it is possible. Jesperh has proved it. He hooked up a DRAM to a small processor (in this case an Microcontroller Atmel 8515), and handle the RAS/CAS sequencing and refresh in software. The type of....
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This circuit, designed on request, has proven to be useful to indicate when the voltage in a power supply line is changing from 120V to 240Vac. It can be used in different circumstances and circuits, mainly when an increase in ac or dc supply voltage needs....
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We are going to build a START-STOP drive (as commonly found in professional tools), that is a circuit with one switch to run the output (an LED in this case) and one switch to stop it. Nutchip feature two kind of inputs: general purpose and fixed inputs.....
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A very simple metal detector electronic project can be designed using a simple 555 timer integrated circuit . As you can see in the schematic circuit , this electronic project requires few external electronic parts .
This circuit detects metal and also....
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This project uses a 3909 IC and a few other parts; power is 1.5 volts DC...
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This circuit makes a nice lamp that consumes little power, runs cool, and has an incredibly long lifetime. The lamp puts out a warm yellow shade of light, the color may be adjusted by changing the number of red or green LED strings. Operating Voltage: 12V DC....
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This is a simple, programmable, autonomous and extensible LED matrix with the possibility of being controlled by a computer using a RS232 connection. Its basic modules are the Controller Board, the I/O Port expander boards and the LED matrix cardboard....
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On occasion, microprocessors/microcomputers and microprocessor crystals just aren`t compatible with each other. Many microprocessor data sheets specify maximum values for a crystal`s equivalent series resistance (Rs) that aren`t met by some crystals....
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Often you can get away with running a monochrome monitor on GREEN, but this looks real crappy when viewing color images. These simple resistor networks allow you to display R+G+B on a B/W or CCTV monitor without ghosting. Be shure to set your video card for....
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This simple circuit provides a solid-state equivalent of the electromechanical latching relay (see the figure). What`s more, the switching is clean, highly resistant to vibration and shock, and isn`t sensitive to magnetic fields or position. The circuit....
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Virtually any NPN small signal transistor may be used in place of the BC 108 shown. Likewise any suitable NPN power transistor can be used in place of the 2N3055. The output transistor must be mounted on a suitable heat-sink. Short circuit protection may be....
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This simple circuit will energize and de-energize a relay at the push of a button. Any type of momentary action push-to-make switch can be used. Pushing the button once - will energize the relay. And pushing it a second time - will de-energize the relay..
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A BA1404 IC is used to generate a complete FM MPX signal. The chip contains all of the necessary circuitry. CI and R3, and R4 and C4 provide pre-emphasis. The transmitter runs on a single AA cell. L3 is 3 turns of #20 wire on a Ke drill (for a form). L3 is....
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This simple CPO is for those who want to practice Morse Code in a different way, ie with out the morse key. It can be also used as a touch operated door bell. The popular timer IC555 is wired as astable multivibrator. The frequency (tone) can be changed by....
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The circuit provides a minimum component intercom. With switch SI in the talk position, the speaker of the master station acts as the microphone with the aid of step-up transformer Tl. A turns ratio of 25 and a device gain of 50 allows a maximum loop gain of....
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In applications where the rejected signal might deviate slightly from the null on the notch network, it is advantageous to lower the Q of the network. This insures some rejection over a wider range of input frequencies. The figure shows a circuit where the Q....
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A shows a twin-T network connected to an LM102 to form a high Q, 60 Hz notch filter. The junction of R3 and C3, which is normally connected to ground, is bootstrapped to the output of the follower..
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This simple circuit is a gain-of-1000 inverting amplifier. It will amplify submillivolt signals up to signal levels suitable for further processing. In almost all system applications, it is best to use as OUTPUT much gain as possible in the MAX420, thus....
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The way that this circuit works is as follows. The AC line voltage is rectified by D1 and D2 which connects to a voltage doubler circuit made up of the two 22uf capacitors. The Flash Freq. Pot and the 10uf capacitor charge up which triggers the Diac and....
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The video master consists of a series of converters that place all your video sources on unused UHF channels, which then combines them with normal TV channels (terrestrial or cable into one cable). That one cable can then feed several TV sets for....
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This circuit uses a comparator as a Schmitt trigger (311H) and two active bandpass filters (LM318H). 3-kHz output ..
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The transmitter was designed with redundancy and cutback (reduced power mode) in mind, giving the transmitter more continuity of service. The final amplifier was divided into 3 separate modules, each using four RCA type UV-898 tubes in push-pull parallel....
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This Design Idea expands on a circuit in a previous one to configure a power-outage detector with a flashing alarm (Figure 1, Reference 1). The circuit plugs into a mains outlet and uses trickle-charged nickel-cadmium batteries. The green-LED monitors the....
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Feedback is the same as a conventional op-amp voltage follower which yields 11 unity-gain, noninverting output. This hookup also has a very high input impedance. The only difference between a track-and-hold and a sample-and-hold is the time period....
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Two integrated tone decoders, XR-567 units, can be connected (as shown in Fig. 1A) to permit decoding of simultaneous or sequential tones. Both units must be on before an output is given. R1C1 and R'IC'l are chosen, respectively, for Tones 1 and 2. If....
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A project required an inexpensive oscillator whose frequency increased step by step from 200 to 400 Hz and then decreased to 200 Hz. The first step was to design a VCO with a staircase driver. However, this approach entailed at least four ICs and many....
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This single sided proto board provides an economical solution for developing and testing the projects around Atmel 20 pin series u-controllers (89Cx051 & AVR)..
The oscillator is a Motorola MC14410CP chip using a 1-MHz crystal. The chip generates both the high and low tones, feeding the energy to the amplifier through 1-K resistors and the 1-I"F capacitor. Values for the output resistors can vary from a few....
This circuit uses Analog Devices` AD639 universal trigonometric function generator to convert a triangle waveform, the basic waveform of the VCO itself, into a very low-distortion sine wave. By using the AD639 in its frequency tripler mode [2], the....
The camera rotator circuit uses a 2716 EPROM to store a table of logic values that control the motor driver (H-bridge) circuit. The EPROM data is shown in the schematic. By using the EPROM, a large number of discrete gates are eliminated. The logic table is....
The experimenter's pot is a solid state potentiometer using Dallas semiconductor?s DS1869 and National?s LM78L05 two electrolytic capacitor two small push button switch and two optional Molex connector. this project is very useful especially in finding the....
This circuit consists of a tri-color LED, a resistor, wire, and a coin-size test plate. You will have to build two such circuits one for each black clamp on a set of auto battery jumper cables. The author installed the circuits inside the black clamps....
The LTC1155, dual micropower MOSFET driver, generates 12V from a 5V rail to fully enhance logic-level Nchannel switches with no external components required (see Figure 1). Further, the supply current is typically 85mA with the switch fully enhanced and....
M1 is a clamp connected to the 24V (dc or ac) power from the gate opener. The diode bridge rectifies the alternate voltage (should the opener use dc current, it merely adjust the positive and negative rail to match circuit polarity), in order to get the....
A 555 is used as an oscillator, optimally around 15.76KHz (in North America). Power pins on the chip (pin 1 to ground, pin 8 to +12V) are not shown on the diagram. The output from the 555 is then switched by PNP transistor Q1 and by the large 2N3055 NPN....
In this case, the NE602 is used in this superhet front-end configuration. Ul serves as a frequency conve..
As a sensor in the design of this linear thermometer, the LM34 is used. The output is the difference between..
The persona] message recorder is built around an ISD1016 CMOS voicc messaging system, which does away with the cumbersome and expensive analog-to-digital and digital-to-analog conversion circuits. A functional block diagram of the ISD1016 is shown. The....
Have you ever attempted to copy a commercially produced video only to end up with a distorted and jumpy image? If so, then you have run afoul of MacroVision. MacroVision is the most popular copy protection scheme used on the majority of content distributed....
Simple function generators normally provide sinusoidal, rectangular, and triangular waveforms, but seldom a sawtooth. Th..
This antenna is the result of long term development and user feedback. All ATL-3 loop windings are centre tapped and balanced w.r.t. their amplifier/receiver chassis ground, and therefore electric field interference pick up tends to self cancel. Magnetic....
The amplifier of circuit, use negative current feedback. So, the load current depends mainly from the input signal and no so much from the impedance of loudspeaker. The inductor current of loudspeaker develop above in the R7 a voltage. This voltage is drive....
The gain of the low-cost IC is internally fixed so that it is not less than 34 dB (50 times). A unique input stage allows input signals to be referenced to ground. The output is automatically self centering to one half the supply voltage. The output is also....
A low-noise LT1115 (Linear Technology, Inc.) op amp is coupled to a class-A buffer amplifier to produce a variable g..
This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every source. When the test button is pressed, the Car battery voltage....
The operating principle of the circuit is very simple. The first Led D1 is placed in series with the resistor R2 and diode D4.An only be lit this LED indicates that the battery is ypofortismeni. For this reason Led D1 is red. If the voltage is greater than....
Digital visitor counter is a reliable circuit that takes over the task of counting Number of Persons/ Visitors in the Room very Accurately. When somebody enters into the Room then the Counter is Incremented by one and when any one leaves the room then the....
This circuit uses a digital voltmeter (formed from IC1 and IC3) to display fuel quantity as a percentage of a full tank...
This unit is an upgrade of the previous phone call interceptor. Instead of using an answering machine to provide the outgoing message and recording functions, it uses the ISD4004 (from Windbond Electronics). The ISD4004 records up to 8 minutes of audio. I....
What's so special about this circuit? Well, the first third-brake light I installed I had to pull a wire from the Third Brake Light all the way underneath the carpet to the brake-pedal-switch and I thought it would be easier to pluck the signal of both....
An LF356 op amp is used as a gain amplifier with the output taken across R5, When a full-scale current of 1 mA is flowing..
Twang is a guitar sound that more or less approximates a banjo or mandolin. The circuit produces unusual sounds from an ordinary electric guitar by cutting the bass, severely distorting the midband and highs, and then amplifying the distortion...
The circuit gives a programmable bandpass where both the cut-over frequency and the gain, A, are controlled independently. In the twin-T bridge the resistors R and R/2 are replaced by two double FETs, 430, the channel resistance of the first one in the....
The circuit"s input op amp triggers the timer, sets its flip-flop and cuts off its discharge transistor so that capacitor C can charge. When capacitor voltage reaches the timer"s control voltage of 0.33 Vee. the flip-flop resets and the transistor....
This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low....
This circuit functions as a wideband adjustable AGC amplifier. With an effective bandwidth of approximately 10 MHz, it is capable of handling rf input signal frequencies from 3.2 to 10 MHz at levels ranging from 40 mV up to 3 V pk-pk. AGC action is....
In this circuit, a TU31 shunt regulator is used to sense the output voltage. The TU31 drives the LED of a 4N28 optocoupler which provides feedback to the MAX641 while maintaining isolation between the input, +12 V, andJhe output, +15 V. ..
By adding a flyback winding to a buck-regulator switching converter (see the figure), wliich is essentially a 5-V supply with a 200-mA output capability, a 12-V output ) can be produced. The flyback winding on the main inductor (forming transformer Tl)....
This regulator is for the purpose of controlling a dc generator. The field configuration is that one side of the field is grounded. D4 prevents the battery from discharging through the generator and takes the place of the mechanical cut-out relay...
This Project is used to indicate the temperature and it is also used as controller. The system will get the temperature from the IC and it will display the temperature over the seven segment display and this temperature was compared with the value stored by....
n the view of the dramatic drop in the price of crystals used in color TV sets, they now represent an economical way of building an SSB filter. The circuit shown in the diagram is for a filter with a 6 DB band width of roughly 2.2 KHz. By terminating the....
This circuit uses LEDs to display logic states for high, low, rising pulse, and falling pulse, it is generally useful for debugging logic circuitry...
The sensor is a standard TO-5 or TO-46 package. For surface or air temperature sensing. Small clip-on heat sinks can be used. A simple probe can be made using heat-shrink tubing and RTV silicon rubber. Three-leads-plus-shield cable is a good choice for wire....
A differential amp used by the SIM, and it is a completely conventional circuit. This is adjustable by using VR1 to null out any normal variations that the amp might show when there is no distortion or other nastiness in evidence. The second stage is a....
This project gives you a fingerprint based attendance system with 8051 microcontroller. The SM630 fingerprint module is used for fingerprint matching. It can store a max of 768 fingerprints. The admin can add/delete records from the PC through the VB....
Digital-ProfiLab was designed for measurement and control applications, combining features like circuit and logic simulation, front panel design, and hardware control to one powerful tool. Incoming signals from external devices may be processed and....
Two identical integrated circuits, U1 and U2, known as "hex inverters" are used for the theremin's primary functions. They are CMOS (Complimentary Symmetry Metal Oxide Semiconductor) devices, typically used in digital circuits to perform a logic function....
The object of Quick Draw is to test your reaction time against your opponent's. A third person acts as a referee and begins the duel by pressing S1, which lights LED1. Upon seeing LED1 go on, you try to outdraw your opponent by moving S2 from "Holster"....
The 555 is configured in the standard astable oscillator circuit designed to give a square wave cycle at a period of around 1 cycle/sec. A potentiometer is included in the design so the period can be set to exactly 1 second by timing the LED flashesc. A....
You need free power? This schematic transforms the surrounding radio waves to usable current. The levels of power can be stepped up by using more diodes. The critical points in this device are first the type of diodes and second the antenna construction. The....
A stereo power amp designed for use in portable players and radios. A 3V supply can be used to drive headphones providing 20mW in 32 Ohms per channel. ..
Pure Class-A triode OTL design and only one tube for amplification. The plate voltages should be low. The output impedance should be as low as possible and the maximum output current should be as high as possible. This amplifier is a stand alone Headphone....
The transmitter for the wireless headphones is built around a CD4046 CMOS phase-locked loop, coupled with a driver transistor, and a pair of infrared LEDs. ..
The Car Temperature Gauge is basically the same circuit as March's project with some minor changes to the input circuit. This circuit will display the water temperature to 1 degree resolution...
This is a general purpose remote control project with using programmable PIC microcontrollers. Schematics are shown for using infrared (RF) or radio (RF) media. If you are not familiar with microcontroller programming, you can use fixed encoder and decoder....
The HA7210 oscillator 10 combines with an IOL7642 quad CMOS op amp to produce a sleep-mode control circuit. The circuit is put into the sleep mode with a logic high applied to the Reset input or with an RC timer for automatic reset...
The circuit does not present particular difficulties for somebody that has a small experience. The two circuits are the himself, with a small difference only in their input, when they have they measure voltage or current and in connection that concern....
The circuit is frequency selective. It has been used from 2 meters through 160 meters. The telescoping antenna may be adjusted to its shortest length when working at 2 meters to keep the needle on the scale, Meter should be a 100 microamp to a 500 microamp....
The heart of the circuit is IC1, General Instrument's AY-3-1350 melody-synthesizer IC. IC2 is a TCM1512 telephone ring detector IC that is powered by the telephone line. The circuit's operation begins when IC2 senses a ring pulse on the telephone line. The....
The circuit described here is that of a metal detector. The opera- tion of the circuit is based on superheterodyning principle which is commonly used in superhet receivers. The circuit utilises two RF oscillators. The frequencies of both oscillators are....
With SI open the circuit functions as a doorbell. With SI closed, rain falling on the sensor will turn on Ql, triggering Q2 and the thyristor and activating the bell, R4 provides the holding for the thyristor while Dl prevents any damage to the thyristor....
The remote control transmits encoded signals. Each time a key is pressed, the relevant code is transmitted, usually repeating it many times to ensure reception. This encoded signals travels over a radio or infrared-light beam, to eventually get captured by....
The LDR`s were hand-picked. Got two packages of them from Radio Shack, looking for at least two pairs of similar parts. Then added wire-wrap pin sockets, to the circuit, so that the LDR`s could be plugged in. Currently, the 0.33UF cap is not being used on my....
In essence, the circuit is nothing more than an auto ignition coil and a set of points which accomplishes the same thing. A pulsing circuit made from a single CMOS NOR integrated circuit (Ul), opens and closes the relay contacts to simulate the action of the....
As the speed of an electric drill is decreased by loading, its torque also drops. A compensating speed control like this one puts the oomph back into the motor. When the drill slows down, a back voltage developed across the motor—in series with the SCR....
When the torque load on the motor increases, its current increases. This current increase is sensed across Rs, and positive feedback is applied to the noninverting terminal of the LH0101, thereby increasing the motor voltage to compensate for the increased....
Using the fact that the VRE of a transistor shifts 59.16 mV per decade of current at 25°C. This cons..
The circuit is designed to drive an external load. A fault condition in the external load circuit could feed excessive current or voltage back into the line drive circuit. If excessive voltage appears from the load, the two zener diodes will clamp that....
This simple AM circuit uses a 561B. There's no inductance/capacitance tuning circuit. The 365 pF capacitor connected between pins 2 and 3 does all the tuning. The circuit needs a good outside antenna and a solid ground. And if you want to further improve....
The test circuit gives an indication of the capacity remaining in a battery. By noting the time in seconds that the LED remains on after you depress the test switch Sl. The circuit has proven reliable in testing NiCad-, carbon-, and alkaline-type....
This preamplifier was designed for low resistance sources like moving coil heads (MC). The circuit uses in parallel three duble transistors SSM2220 or MAT03 and by forming a diferential amplifier keeps noice low. Connecting this amplifier in front of a OP27....
Although the 78xx series of voltage regulators are available with different current outputs, you can boost the available current output with this circuit. A power transistor is used to supply extra current to the load the regulator, maintaining a constant....
A common power-supply requirement involves converting a 2.4- or 3-V battery voltage to a 5-V logic suppl..
Is it possible to use DRAM with microcontroller AVR? Yes, it is possible. Jesperh has proved it. He hooked up a DRAM to a small processor (in this case an Microcontroller Atmel 8515), and handle the RAS/CAS sequencing and refresh in software. The type of....
This circuit, designed on request, has proven to be useful to indicate when the voltage in a power supply line is changing from 120V to 240Vac. It can be used in different circumstances and circuits, mainly when an increase in ac or dc supply voltage needs....
We are going to build a START-STOP drive (as commonly found in professional tools), that is a circuit with one switch to run the output (an LED in this case) and one switch to stop it. Nutchip feature two kind of inputs: general purpose and fixed inputs.....
A very simple metal detector electronic project can be designed using a simple 555 timer integrated circuit . As you can see in the schematic circuit , this electronic project requires few external electronic parts . This circuit detects metal and also....
This project uses a 3909 IC and a few other parts; power is 1.5 volts DC...
This circuit makes a nice lamp that consumes little power, runs cool, and has an incredibly long lifetime. The lamp puts out a warm yellow shade of light, the color may be adjusted by changing the number of red or green LED strings. Operating Voltage: 12V DC....
This is a simple, programmable, autonomous and extensible LED matrix with the possibility of being controlled by a computer using a RS232 connection. Its basic modules are the Controller Board, the I/O Port expander boards and the LED matrix cardboard....
On occasion, microprocessors/microcomputers and microprocessor crystals just aren`t compatible with each other. Many microprocessor data sheets specify maximum values for a crystal`s equivalent series resistance (Rs) that aren`t met by some crystals....
Often you can get away with running a monochrome monitor on GREEN, but this looks real crappy when viewing color images. These simple resistor networks allow you to display R+G+B on a B/W or CCTV monitor without ghosting. Be shure to set your video card for....
This simple circuit provides a solid-state equivalent of the electromechanical latching relay (see the figure). What`s more, the switching is clean, highly resistant to vibration and shock, and isn`t sensitive to magnetic fields or position. The circuit....
Virtually any NPN small signal transistor may be used in place of the BC 108 shown. Likewise any suitable NPN power transistor can be used in place of the 2N3055. The output transistor must be mounted on a suitable heat-sink. Short circuit protection may be....
This simple circuit will energize and de-energize a relay at the push of a button. Any type of momentary action push-to-make switch can be used. Pushing the button once - will energize the relay. And pushing it a second time - will de-energize the relay..
A BA1404 IC is used to generate a complete FM MPX signal. The chip contains all of the necessary circuitry. CI and R3, and R4 and C4 provide pre-emphasis. The transmitter runs on a single AA cell. L3 is 3 turns of #20 wire on a Ke drill (for a form). L3 is....
This simple CPO is for those who want to practice Morse Code in a different way, ie with out the morse key. It can be also used as a touch operated door bell. The popular timer IC555 is wired as astable multivibrator. The frequency (tone) can be changed by....
The circuit provides a minimum component intercom. With switch SI in the talk position, the speaker of the master station acts as the microphone with the aid of step-up transformer Tl. A turns ratio of 25 and a device gain of 50 allows a maximum loop gain of....
In applications where the rejected signal might deviate slightly from the null on the notch network, it is advantageous to lower the Q of the network. This insures some rejection over a wider range of input frequencies. The figure shows a circuit where the Q....
A shows a twin-T network connected to an LM102 to form a high Q, 60 Hz notch filter. The junction of R3 and C3, which is normally connected to ground, is bootstrapped to the output of the follower..
This simple circuit is a gain-of-1000 inverting amplifier. It will amplify submillivolt signals up to signal levels suitable for further processing. In almost all system applications, it is best to use as OUTPUT much gain as possible in the MAX420, thus....
The way that this circuit works is as follows. The AC line voltage is rectified by D1 and D2 which connects to a voltage doubler circuit made up of the two 22uf capacitors. The Flash Freq. Pot and the 10uf capacitor charge up which triggers the Diac and....
The video master consists of a series of converters that place all your video sources on unused UHF channels, which then combines them with normal TV channels (terrestrial or cable into one cable). That one cable can then feed several TV sets for....
This circuit uses a comparator as a Schmitt trigger (311H) and two active bandpass filters (LM318H). 3-kHz output ..
The transmitter was designed with redundancy and cutback (reduced power mode) in mind, giving the transmitter more continuity of service. The final amplifier was divided into 3 separate modules, each using four RCA type UV-898 tubes in push-pull parallel....
This Design Idea expands on a circuit in a previous one to configure a power-outage detector with a flashing alarm (Figure 1, Reference 1). The circuit plugs into a mains outlet and uses trickle-charged nickel-cadmium batteries. The green-LED monitors the....
Feedback is the same as a conventional op-amp voltage follower which yields 11 unity-gain, noninverting output. This hookup also has a very high input impedance. The only difference between a track-and-hold and a sample-and-hold is the time period....
Two integrated tone decoders, XR-567 units, can be connected (as shown in Fig. 1A) to permit decoding of simultaneous or sequential tones. Both units must be on before an output is given. R1C1 and R'IC'l are chosen, respectively, for Tones 1 and 2. If....
This single sided proto board provides an economical solution for developing and testing the projects around Atmel 20 pin series u-controllers (89Cx051 & AVR)..
