New Circuits Page 252
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You can play this game alone or with your friends. The circuit comprises a timer IC, two decade counters and a display driver along with a 7-segment display. The game is simple. As stated above, it is a scoring game and the competitor who scores 100 points....
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In this doorphone circuit,an 8 ohm speaker is used both as a microphone and also an output device. The BC109C stage amplifies in common base mode, giving good voltage gain , whilst providing a low impedance input to match the speaker. Self DC bias is used....
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Very simple and useful circuit for communication between two person. The Q1 is used to amplify the weak output signal of speaker when one push his (her) side push-button to speak. The base-common configuration of the Q1 pre-amplifier is for matching low....
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This circuit operates in the astable mode and at the end of the first period (up to several minutes), it produces a tone. ..
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This simple rc oscillator uses a medium-speed comparator with hysteresis and feedback through Rl and Cl as timing elements. The frequency of oscillation is, at least theoretically, independent from the power supply voltage. ..
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This pulse generator can supplement a standalone pulse generator. Using a transistor and a 555 timer, pulse widths of 5 to 500 can be produced. The value of C3 is approximately found from the formula: C3 uF = 1.1 x10-5 T where T is the shortest pulse....
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The Car Voltage Gauge is based on 3 parts. The input circuit is an Analog to Digital Converter (IC2 CA3162E). The purpose of this chip is to sample an analog voltage and convert it to a decimal value which is read by a Display/Decoder Driver (IC1 CA3161E).....
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This circuit uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer. The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system...
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If you live in the frozen north, knowing your engine-block heater is working is a comfort. This device will let you know if yours is okay. Plug in PL1 to your power outlet. NE1 should light. Then, plug in the block heater. Depressing SI should cause the....
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The data separator is intended for use with 8" flexible diskettes with IBM 3870 soft sectored format. The circuit delivers data and clock (B) and clock pulses (D). These two signals must be in such a sequence that the negative edge of the clock pulse is at....
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Using a Motorola MC34118 speakerphone IC, this adapter can be used with a regular telephone to provide speaker capability. This device is powered from the phone line, but it can be powered via an external power supply if the line loop current is marginally....
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The circuit is built around a 4049 hex inverter (Ul), a pair of 555 osciliator/timers (U2 arid U3), two transistors, a Geiger-Muller tube, and a few additional support components. The first 555 (U2) is configured for astable operation. The output of U2 (a....
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The operation of the circuit is based on the difference in the primary impedance of a transformer when its secondary is loaded and when it is open-circuit. The impedance of the primary of Tl and resistor Rl are in series with the load. The triac's....
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This circuit uses LTC1043 to differentiate between a temperature sensing network and a de reference. The single-ended output biases a varactor-tuned crystal oscillator to compensate drift. ..
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You can set the interval from about 5-30 seconds. A relay operates the slide-change mechanism. Op amp Ul forms a sort of Schmitt trigger. Resistors Rl and R2 bias the noninverting input at pin 3 of Ul to half the supply voltage. Feedback resistor R3....
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Industrial applications sometimes require that power be only briefly applied to a load following the closure of a switch, such as a microswitch or foot switch. The load could be a heating element for use in sealing plastic bags, a de motor that is indexed....
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This antenna is made from 1/2" copper tubing and it is soldered together with plumbing tees, elbows, and nipples....
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The hardware is shown in the picture (might take a little while to load). Don`t be the least bit concerned if you don`t understand everything in the first few paragraphs below. Their purpose is to provide a brief description of the hardware to those who....
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Speed controllers have long exploited the reverse-EMF characteristics of dc motors to control their speed. These linear driver circuits use power op amps to create a negative resistance drive to the motor that counteracts the voltage drop in the motor`s....
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This circuit features clipping indicators on the preamp and reverb recovery stages, allowing for the optimal gain settings. The guitar input stage is a class A amplifier with adjustable bias. A 2N3906 PNP tranistor is used for a low noise design on this....
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The simple circuit of Fig.1 emulates a similar conjuring trick which sells for hundreds of Pounds. The trick seems to do the almost-impossible from an electronic point of view, let alone from the point of view of common sense.
It consists of a bank of....
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When configured as a free-running multivibrator, a 555 timer provides no more than a 50% duty cycle. By adding two transistors, however, you can obtain a variable 5 to 95% duty cycle without changing the sum of the on and off times. When VouT decreases,....
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A diode, such as a IN4148, has a typical -2m V/C temperature coefficient at a 1 mA diode current. Ql and Q2 form a constant current source. D1 is the temperature sensor. ICl-a and -b are dc amplifiers, with ICl-c a temperature reference voltage supply.....
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Receiver. Output from the transducer is amplified by Ql and Q2, and rectified by Dl. Voltage on pin 2 of ICl will go more negative as the input signal increases. ICl is used as a comparator and checks the voltage on pin 2 (i the sound level), to that on pin....
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This simple IR detector turns on a real LED when Q2 is exposed to invisible IR radiation found in fiber-optics systems, position sensors, and TV remote-control units. The device can be built on top of a 9V battery and held in place with RTV. Its power....
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The iriput signal is fed via SKI to the first active stage built around ICl. Configured as a noninverting amplifier whose gain is set by the ratio of R3 and Rl. In this case, the gain is set at unity. This initial stage is required to isolate the following....
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This circuit utilizes the MRF123 TMOS power FET. The MRF134 is a very high gain FET that is potentially unstable at both VHF and UHF frequencies. Note that a 68-0 input loading resistor has been utilized to enhance stability. ..
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This is an evaluation use of a small graphics LCD module. Last summer, SG12232C graphic LCD module has been sold sold for 1500 Yens from Akizuki Denshi and I bought it. However I could not find good application for the LCD module and it was going to go to....
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Charging current is about 100+mA, which is the internally-limited maximum current of the LP2951. For those wondering, this is compatible with just about any single-cell li-ion battery since li-ion can generally accept a charging current of up to about 1c....
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This is a replacement power source for 1.3V mercury cells or other small batteries. It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital thermometer...
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With this unique logic-power-converter design (see the figure), a switchable 3.6 or 5 V at 200 inA can be attained by using four AA cells. The supply incorporates a MOSFET switch that can switch to a lithium backup battery, providing a 3.4-V output when the....
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After (years) of mucking about with this, I finally put together a really slick tach that I`ve had in use for a long time. PCBs are available to experiment with, the source code and schematics are open, the code is well tested and mature, so what are you....
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This circuit disables the air conditioner compressor when additional engine power is required. It does so by monitoring the engine vacuum at the intake manifold. Ifthe vacuum drops to 40% of its normal level, the compressor clutch is disabled, removing the....
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The sensor is an RC oscillator in which, a water-absorbent plastic film is the insulator in the capacitive element. The capacitance of the film increases with the amount of water it absorbs from the air, and thus reduces the oscillation frequency. A....
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When the tank is cleaned the fish are removed and placed in a small amount of the tank water. The problem is that fish don’t like rapid temperature fluctuations. I guess a simple in tank or stick on thermometer would have done the trick but what is the fun....
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By using an RC oscillator and a programmable divider, this counter can run for hours. An interval osc..
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This 1 square meter antenna has radiation resistance of about 10 nanohoms, making the 0.4 Ohm resistance (including skin effect, which about doubled the resistance from the DC value) the dominant loss in the antenna. The lower the resistance, the more....
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Manufacturers have recently introduced high-performance analog-to-digital converters (ADCs) that feature outstanding static and dynamic performance. You might ask, "How do they measure this performance, and what equipment is used?" The following discussion....
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Frequently, the output current of an operational amplifier is inadequate for the application as, for instance, when a s..
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Modulation Monitor is a simple and useful circuit for hams. You can listen to on air transmission from your rig and be sure about the quality of the transmission. It requires no direct connection with the transmitter. In the prototype, headphones of 1K....
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A simple circuit measures the open-circuit voltage, such as the expanded-scale voltmeter circuit in Figure 2, which follows the curve in Figure 1.
Sealed lead-acid batteries are available in several sizes, from a single D size (2.5 Ahr) to multicell....
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The LT®1510 current mode PWM battery charger is the
simplest, most efficient solution for fast charging modern
rechargeable batteries including lithium-ion (Li-Ion), nickelmetal-
hydride (NiMH) and nickel-cadmium (NiCd) that
require constant current....
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The design delivers a regulated 400-V, 60-W output. The TL494 switching regulator governs the operating frequency and regulates output voltage. Rl and Cl determine switching frequency, which is approximately 0.SRC—100 kHz for the values shown. The TL494....
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A current source that attains a resolution as low as 10 pA is useful in applications where a precise, low-value ..
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The microphone input, MIC1, is fed through C3 and R4 to inverting amplifier U2-a; the gain of U2-a is controlled by potentiometer R5. The output of U2-a is fed through C4 to the remaining op-amps (U2-b, U2-c, U2-d), which are all configured as....
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The circuit can be used in telephone lines for speech activity detection purposes. This detection is very useful in the case of half-duplex conversation between two stations, in the case of simultaneous transmission of voice and data over the same pair of....
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This Project REMOTE CONTROLLED SWITCH BOARD is used to switch on/off the Home Appliances by using a standard Remote control. The system is used to switch on/off upto six electrical devices. All the above processes are controlled by the 8 bit Microcontroller....
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The LTC3201 contains overtemperature protection and can survive an indefinite output short to GND. Low external parts count (one small flying capacitor and three small bypass capacitors) and small MSOP-10 package size make the LTC3201 ideally suited for....
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Below is a proof of concept circuit which needs improvement. The part values shown will run a high efficiency red LED with a Vf of 1.9V from only 2 nicads, right down to 2 volts. For a white LED you will need more batteries and you must increase the 1.0K....
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In this project we'll see how to build a single-channel remote control. It 's a project easy to do : by using a radio module pre-assembled, we will get a card compact without sacrificing performance major. The insert function allows Nutchip impossible to....
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For maximum range, the receiver must be designed in the same manner as a radio receiver front end, since the received signals will be similar in both frequency component and in amplitude of the photodiode current. The major constraint on the receiver....
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A battery-powered, pushbutton-triggered TTL/CMOS-compatible source of debounced 5V logic pulses is a simple but handy piece of test equipment to have in any tool kit (Figure 1). The circuit`s battery-powered operation complicates what would otherwise be a....
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The detector will sense static charges and free ions in the air. It can be used to indicate the presence of ion emission, high voltage, static electricity, and electrostatic fields. The ground can be an earth ground or a touching metal by your hand...
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Some machines need to run for long periods and therefore may finish their work in the middle of the night or during the weekend. For the time remaining, until the operator returns, the machines stay idle, uselessly consuming power. This Design Idea allows a....
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Using two SCRs, this control circuit is designed to lock out the other SCR when one has been triggered, so only one lamp will light. Indicator lamp Il is controlled by SCRl. The operator simply presses switch Sl. Lamp I2 is similarly controlled by S2....
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This transmitter is capable of two levels of rf power. For low-power wireless video, like in a house or office, where simultaneous monitoring of program material is desirable without cumbersome hookups, 1-30 mW is available. For longer ranges up to several....
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The circuit is drawn for measurement of acceleration from 1000 mg until + 1000 mg. It can be placed in kantra'n the car and be supplied from the sheath of electric lighter. The circuit includes one indicative LED and a screen LCD. The measurement of....
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Have you ever wanted to run a TV, stereo or other appliance while on the road or camping? Well, this inverter should solve that problem. It takes 12 VDC and steps it up to 120 VAC. The wattage depends on which tansistors you use for Q1 and Q2, as well as how....
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This circuit of power supply, are very simple in the manufacture, the finding of his materials , is very easy and cost, small. The output voltage is stabilised and is regulated in the region from 0V until + 15V dc, with biggest provided current 1 A. The....
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The circuit uses (RGB) Red, Green and Blue high brightness LEDs that are pulse width modulated (PWM) to vary the intensity of each colour LED. This allows effectively any colour to be generated with rapid changing strobe effects, fast and slow colour fades....
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The residual-current circuit breaker in Figure 1 continuously monitors the supply lines for any leakage current and immediately disconnects the supply if necessary. Load-supply wires, both live and neutral, pass through the magnetic core of the CR4311-5....
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The project consists of 35 LEDs arranged as a 5x7 matrix. This may not seem very impressive but you can display all sorts of effects and treat it like a "window on a large video screen." The project comes with a series of test programs to test the operation....
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A single 6.75 V mercury battery powers the counter, which features a 1 mA count-rate meter as well as an aural output. A regulated 900 V supply provides stable operation of the counter tube. A multivibrator, built around a differential power amplifier IC2,....
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Transistor Q1-configured as a source-follower buffer stage, offering a bit under unity voltage gaingives tbe unit a high-impedance input of about 1 MO shunted by about 10 pF, which keeps only minimal loading on tbe equipment being tested. C1 serves as....
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The computer needs at least 180 millivolts peak-to-peak and the condenser microphone in my headset produces about 20 millivolts peak-to-peak into a 2.2k load with normal speech levels. There are USB ports on the machines, so I can use that for +5 volts.....
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You must be able to recognise components such as capacitors, diodes, zeners, transistors and resistors to build 5x7 Display project. This information is covered in our BASIC ELECTRONICS course and a complete set of circuit symbols can be found HERE...
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The circuit consists of a 5-V regulator, constant-current source Dl, D2, and Ql, and op amp gain stage Ul. Power is provid..
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Industrial, automotive and telecom applications pose
tough design challenges due to harsh operating environments
and large voltage transients on already high (12V
to 48V) rails. Some switching power supplies are robust
enough to provide localized low....
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An electronic siren made from discrete components. The sound produced imitates the rise and fall of an American police siren. When first switched on the 10u capacitors is discharged and both transistors are off. When the push button switch is pressed to 10u....
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This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light...
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At times, a µC must read a large number of DIP switches, such as for system identification, bus-address setup, manual configuration, or other purposes. However, the available number of I/O lines is sometimes not enough to assign a switch to each one. You can....
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In general, the transceiver switches the 4-element 1500 ohm xtal BPF ends between the inputs and outputs of the two SA602s to reverse the signal flow for R/T operation. Since no IF amplifier is used in the design, 20 dB of additional receiver gain is....
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Half of a Motorola MG14538B dual, precision, retriggerable mono stable multivibrator is used to form an extended on-time timer circuit. That type of circuit can be used as a switch debouncer. Such circuits are often used in digital circuitry, where each and....
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NiCad batteries are excellent rechargeable power sources for portable equipment, but ~care must be taken to ensure that the batteries are not damaged by overdischarge. Specifically, a NiCad battery should not be discharged to the point where the polarity....
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The Circuit shown can transmit voice to exceptionally good range. Tune trimmer to hear the signal to your near radio. Frequency range is 88-108 MHz. Max current consumption is 30mA. You can power the bug with a 9Volt Battery, or you can plug a power supply....
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The EDFET drives like a FET, but with the bias stability of bipolar. Amps of output current can be controlled by milliamps of input current. The current gain is a design choice dictated by bandwidth. Two of things you have to consider when adding a power....
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The idea behind the portable DAC is to get better sound than from the line out or headphone out of portable CD player, a pc sound card or other digital audio source. Many of us want to listen to music on the go or on PCs, and would like to get better quality....
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Built around a single 8038 waveform generator IC, this circuit produces sine, square or triangle waves from 20Hz to 200kHz in four switched ranges. There are both high and low level outputs which may be adjusted with the level control. This project makes a....
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Beeper and/or LED remotely-operated via mains supply line. Pressing the pushbutton of the transmitter, a sound and/or light alert is activated in the receiver. The system uses no wiring or radio frequencies: the transmitted signal is conveyed into the mains....
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This alarm circuit is based on two 555 timers. The alarm will sound your car horn if anyone opens the car door while the circuit is armed. The timers will allow you to leave the car without sounding the horn. To turn the circuit on S1 must be closed. To set....
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This keyer uses skin conductivity to simulate the old-fashioned mechanical CW bug keyer. When the dit paddle is touched the bias on the inverter, ICl-a is shunted to ground, and it produces a logic high, causing oscillator sections CD to generate a....
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A common need in many systems is to obtain positive and negative supplies from a single battery. Where current requirements are small, the circuit shown is a simple solution. It provides symmetrical +&- output voltages, both equal to one half the input....
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The circuit illustrates a method of interfacing a HEDS-1000 emitter-detector pair with a HA-5144 for use as a bar-code scanner circuit. The HA-5144 is used as an amplifier system which converts the bar and space widths of the printed bar code into a....
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When operating, a waveguide directs energy onto a crystal detector. The diode shown is for X-band operation. The waveguide is a 1H inch piece of plastic tubing with the ends flared. The plastic is coated with an elec-troless copper solution to provide a....
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By using the same circuit of the Digital Stopwatch 0-99sec , we can add an AND gate, and transform the 0 ? 99sec stopwatch to a 0 ? 60sec stopwatch. We must find a way to control the RESET function of the BCD counter, which is responsible for the counting of....
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The traditional frequency multiplier requires many elements: a phase comparator to detect the phase error between the input and the output signals, a lowpass filter to convert the phase error to a dc control signal, a VCO to generate the output, and a....
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The metal detector circuit is shown here that the limits represent the sake of simplicity for a metal detector, but the design works remarkably well. It only uses 40,106 Hex Schmitt inverter IC, a capacitor and a search coil and of course batteries. An....
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When the soil is moist, the LED glows. If the moisture falls below a certain predetermined level, the LED begins to flash. If there is still less moisture, the LED turns off. To calibrate, connect the battery and insert the probe into a container of dry....
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If you have access to a Lowe HF-225 shortwave receiver, then you might be interested in this page. If you don`t, then you`d probably be better off leaving now. What follows is a project I completed some time ago, which allows the Lowe HF-225 to be controlled....
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This circuit shows a typical multiplex system intended to carry one of 8 inputs into a remote location. A 5-V pulse train is sent down a separate channel to perform timing and synchronizing functions. A 15-V reset pulse is superimposed on the 5-V clock,....
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It is important to know that transistors Q1,Q2,Q3 must not work like an astable (tri-phase) multivibrator (you could verify it on scope (no square waves but NON LINEAR wave between XB, YB, ZB must be displayed on the scope)...
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If the transmitter stick-potentiometer delivers a voltage about 2 - 3 V, this circuit will be suitable. If you want to avoid using the battery cable (supplying Vcc for IC1and -2), you can use a separate 5V supply for IC1 and -2. In that case you should test....
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The circuit illustrates feedback speed regulation of a standard ac induction motor, a function difficult to accomplish other than with a costly, generator type, precision tachometer. When the apertured disc attached to the motor shaft allows the light beam....
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The EAGLE Layout Editor is an easy to use, yet powerful tool for designing printed circuit boards (PCBs). The name EAGLE is an acronym, which stands for: * online Forward- and Back-Annotation * context sensitive help function....
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The electronic gong is comprised of an oscillator (built around half of a 74COON quad 2-input NAND gate), an active twin-T filter (built around a TL081), and will drive an audio amplifier IC such as aii LM386N. Pulses from astable multivibrator ICl cause....
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This circuit is a 555 timer IC connected as a square-wave generator. Its base frequency is approximately 45kHz, as detennined by the values of Rl, R2, and Cl. The 45-kHz carrier is frequency modulated by a modified trapizoidal voltage waveform applied to....
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The purpose of D-type flip-flop IC2 is to synchronize the input signal with the clock pulse. When the clock pulse changes from low to high and the input is high, IC2 output is high. Subsequently, IC3 resets to zero and starts counting up. Until the counter....
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Most A/D-conversion techniques use dedicated hardware, usually a single-chip IC. The flexible conversion technique allows you to use successive-approximation, ramp-type, or other converters by writing the appropriate control software. The design in Figure 1....
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The LTC1980 manages both battery charging and
generaton of the regulated system bus voltage via a unique
bidirectional pulse-width modulator design (Figure 3).
When the wall adapter is present, power passes directly to
the system load DC/DC converters....
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This very simple circuit acts as a high sensitivity capacitive sensor. Lamps and/or Buzzers are operated at half the mains supply voltage when a part of the human body comes in contact with the sensor or approaches it at a close distance. The circuit can be....