New Circuits Page 251
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With a handful of inexpensive components, a little creativity, and the power of PicBasic, you can build some pretty outstanding robotics creations as Rob Arnold proves with his Ruf-Bot project. RF remote control is just way too cool not to use in your....
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This is a simple servo tester which will comprehensively test the capabilities of almost any modern servo. It has two pushbuttons, CENTRE and SWEEP and a potentiometer which works as follows: CENTRE Does exactly that, centers the servo, afterwards the....
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Transistor Ql is a light-activated silicon-controlled rectifier (LASCR). The gate is tripped by light entering a small iens built into the top cap. To operate, provide a 6-in. length of stiff wire for the anode andcathodeconnections and terminate the wires....
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The circuit illustrates the usefulness of the HA-5151 as a battery-powered monostable. In this circuit, the ratio is set to .632, which allows the time constant equation to be reduced to: T=R1*C1. D2 is used to force the output to a defined state by....
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This circuit gives an output (which in this case is OV) when an input voltage lies in between two specified voltages. When it is outside this window, the output is positive. The two op amps are used as voltage comparators. When Vin is more positive than Vref....
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Analyze your circuits before you build them!
PC-ECAP has been one of the world`s best linear circuit analysis programs. The software will calculate and plot: gain, phase, group delay, impedance, VSWR and return loss. This versatile program can also....
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This simple 20 watts audio power amplifier is designed for home-brewed purpose. The L1 should be able to handle a current up to 4A to drive speaker in full load. The distortion is 0.015% @ 1KHz / 20W. This circuit is protected for AC and DC short circuits to....
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You need a power supply for a project, but only have a DC adapter available, so you can`t use my AC power adapter trick (Project 05). This little project came about because a reader had just this problem, and didn`t know what he could do..
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Ul, an LM317 adjustable regulator provides short-circuit protection and automatic current limiting at 1.5 A. The input voltage to the regulator is supplied by DBl, a 4-A 100 PIV full-wave bridge rectifier. Capacitor Cl provides initial filtering. Ul....
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Many power-factor-correction circuits use a boost converter to generate a regulated dc output voltage from the ac line inp..
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This is an image Schematic. No Description available...
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This circuit provides a digital square wave that can be viewed directly or used to drive other circuits. It used the CMOS 4047 Low-Power Monostable/Astable Multivibrator. As used in Tom Duncan's Adventures with Digital Electronic's Book, to drive CMOS Decade....
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The SCR is wired across the trigger circuit of the flash gun. Normally, the SCR is off, so the flash gun is able to cha..
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Resonant power supplies are popular because of high efficiency, low noise, and compactness. You can implement a resonant buck or boost converter using a single switch. The regulation of the output in such a converter derives from using a constant on or off....
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Designs for solar-powered applications with low-duty-cycle requirements can often rely on capacitors for energy storage in place of less reliable batteries. Typical applications include solar positioning, telemetry transmitters, chemical pumps, data loggers,....
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Agreeable, very close sound imitation
Suitable for sound effects, door-bells etc. This circuit generates a two-tone effect very much alike the cuckoo song. It can be used for door-bells or other purposes thanks to a built-in audio amplifier and loudspeaker....
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Times have changed and there is no need to keep your elaborate electronic project in an old cigar packet any longer. Today specialized dealers offer cases for almost all electronic applications you may think of. But still self-made devices often look quite....
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The circuit is that of a multiple feedback bandpass filter. A short click (pulse), makes it ring with a frequency which is its natural resonance frequency. Oscillations die away exponentially and closely resemble many naturally occuring percussive or plucked....
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Time delays from 0 milliseconds to over three minutes are possible with this circuit without using a tantalum or electrolytic capacitor. The timing interval is initiated by applying power to the circuit. At the end of the timing interval, which is determined....
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The wailing sound of a siren is generated by a VFO consisting of Q1 and Q2. Capacitor C2 provides the feedback for the oscillator. The frequency of the oscillator is varied by the voltage applied to the base of Q1 through R3. When switch S1 is closed,....
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The circuit here is a A/D converter, that consisting of A2, a flip-flop, some doors and a current sink, is based on a current balancing technique. Again, the stabilized LTC 1052 50 no drift of V input 1 ° C is necessary to eliminate the offset errors of....
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Operational amplifiers Al and A2 are connected in a noninverting configuration of their training sorties amplifier A3. The operational amplifier A3-one could call a subtractor circuit that converts the differential signal between the floating point X and Y....
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This charger will quickly and easily charge most any lead acid battery. The charger delivers full current until the current drawn by the battery falls to 150 mA. At this time, a lower voltage is applied to finish off and keep from over charging. When the....
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This circuit will allow you to connect any tape recorder that has a mic and remote input to a phone line and automatically record both sides of a conversation when ever the phone is in use. You will need to take a couple of voltage readings before connecting....
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An automatic control maintains a lamp at a constant brightness over a wide range of supply voltages. This circuit utilizes the consistency of photodiode response to control the phase angle of power line voltage applied to the lamp and can vary the power....
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This circuit determines whether more than one input in a group of digital inputs is active. It provides a digital measure of the number of active inputs, and it allows you to establish a threshold for majority-decision applications. That is, whether the....
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Each time switch S1 is closed the count on the CD4017 advances by 1 step and the coresponding LED turns on. When the maximium count plus 1 is reached for each circuit the cycle is restarted and repeats...
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74hc573 is used to store data so that the previous content on SS is not vanish when we disable LE pin. T0 select the proper latch 74hc238, 3x8 decoder is used. And to convert BCD into decimal, 74ls48 converter is used. Note that latches U1 to U4 are....
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The antenna tunning circuit can accommodate 1/2 wave length antennas or higher, for input resistances of 50 Ohms which make it suitable for CB (Citizen Band) transceivers. C1 is for fine tunning and C2 is just for tunning. Turning C3 with the help of C2....
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The LRC input network limits the anode dv/dt to a safe value—below 30 V/jus. Rl provides critical damping to prevent voltage overshoot. While a simple RC filter section could be used, the high current required by the squib would dictate a small value of....
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Observing my "Boss" pedals and how they were switched on and off I figured there must be more to it. It took me only about 4 hours to design and test this circuit, It works very well and I`m really satisfied with it so I`ll be using it in all the effect....
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The electronic circuit in the VOX Box consists of three parts: a microphone preamplifier, a Schmitt trigger, and a relay driver. Input signals (MIC INPUT terminals) to the microphone preamplifier (Ul) are amplified and fed to a THRESHOLD control (R8). When....
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LCD2USB is a open source/open hardware project. The goal of LCD2USB is to connect HD44780 based text LCD displays to various PCs via USB. LCD2USB was meant to be cheap and to be made of easily available parts. It is therefore based on the Atmel AVR Mega8 CPU....
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This was designed to flash a pair of LEDs to be mounted on the wing tips of a Parkzone Citabria R/C (remote control) airplane. The unmodified Parkzone Citabria only weights 20 grams (about 0.7 oz), so weight, and therefore the number and size of the....
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The circuit is built around two power FETs, which are configured as a simple astable multivibrator to alternately switch the two lamps on and off. The rc values given sets the flash rate to about 1/3 Hz. By varying either the resistor or capacitor....
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The circuit can be easily built to a small plastic box with telephone connectors in both ends. The circuit takes about 10-20 mA current, so if the circuit is not in use all the time it is best to use batteries. You can also use small wall transformer to....
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This is a design for a low noise microphone preamplifier, which is ideally suited to low impedance (600 Ohm nominal) microphones. One limitation is that it is not balanced, which is not a problem in a home recording environment, but will allow the mic lead....
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This mixer is built around a TL072 dual BiFET op amp with a JFET input stage, and can be powered from a single-ended 9-to 18-V power supply. The microphone input is capacitively coupled to the noninverting input of U1a. Resistors R1 and R3 set the voltage....
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In this fast-paced world, there is little time for inconveniences and a greater need for portability and adaptability. The idea for an Audio/Video transmitter stems from this need. There may have been times when you`ve wanted to hook up your VCR from one....
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This microcontroller fascinated me a lot because I wanted to see what we can do with an 8-pin microcontroller (out of which 2 pins goes to power supply, so actually just 6-pins are left for I/O). So I thought of making my own learning board for this. In this....
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This 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 siroultaneous transmission of voice and data over the same pair of....
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The System is fully controlled by the microcontroller AT89S52. It is a popular 8 bit microcontroller. The circuit consists of four switches, in which two buttons are used to increment and decrement the temperature value and the next button is to edit the....
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A standard serial interfacing for PC, RS232C, requires negative logic, i.e., logic `1` is -3V to -12V and logic `0` is +3V to +12V. To convert a TTL logic, say, TxD and RxD pins of the uC chips, thus need a converter chip. A MAX232 chip has long been using....
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In photography r a separate flash, triggered by the light of a master flash light, is often required to provide more light, fill-in shadows etc. The sensitivity of this circuit depends on the proximity of the master flash and the value of Rl..
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A fast electronic fuse designed to operate on 230V AC with an adjustable trip current. When the current through the load exceeds a level determined by the position of the wiper on the 1k wire-wound pot, this circuit cuts off the load immediately. If S1 is....
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This is an on-off control with isolated, low voltage input. Since the switching action is very rapid, compared with the response time of the lamp and the response of the eye, the effect produced with audio input is similar to a proportional control circuit..
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Any potential from 1 to 15 V can be monitored with this circuit. Two lamps alert any undesirable variation. The voltage differential from lamp tum-on to tum-off is about 0.2 Vat any setting. High and low set points are independent of each other. The SCRs....
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Up to six lights can be sequentially flashed using this circuit. LED1 through LED6 can be replaced by optocouplers (MOC3010..
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This circuit provides a short circuit protected power supply from PC 12V supply voltage. This is particularly handy when working with PC interfacing projects...
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Two soft start power supplies. The output voltage slowly increases to the desired output. The output voltage rises slowly and reaches 15 V in 5 seconds.
In order to perform this soft-start function, the LM317 voltage regulator IC requires an external....
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It has 16 timers that can be independently paused and restarted, and can run forward or backward. There are 16 alarms with configurable sounds and actions. Timers can show Earth, Mars, Jupiter, etc. times at the same time. How about sidereal time, Moon....
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The hardware block is shown in Figure 1. The MCU is 89Sxx microcontroller. And the complete hardware schematic is shown in Figure 2. Port1 is used as data-bus for LCD (4-bit interface, PCB lay-out for 16x2 character with backlight), on-board tact switch and....
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The design objective was to produce an hFE tester with switched collector currents for the DUT (Device Under Test) covering a range suitable for the selection and matching of output transistors for amplifiers such as the JLH Class-A, ESP DoZ etc. The tester....
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The LEDs are OSSV53E1A from OptoSupply and they have an 140° angle. This means that the first plane with uniform density can be obtained at a shorter distance from the LED, for a given spacing between LEDs which means smaller height for the board. Their peak....
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4 Channel Infrared (IR) Remote is a simple kit using the famous HT12A and HT12D encoder / decoder chips from Holtek...
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A nice circuit for using with audio preamplifiers, or any other circuit that use potentiometer and you need to control it from distance. The circuit includes Infrared transmitter and reciever with motor controller chip BA6418N...
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The circuit is powered by a single 1.35 V mercury cell and provides a 1 V square-wave output. As shown, the crystal is a tuned circuit between transistors Ql and Q2, which are connected in the common-emitter configuration. Positive feedback provided by means....
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To put the relay in tension the 4 buttons S1 S4 must be pressed. If anyone of the 4 butoons S5 S8 are pushed the relay donts tension ( dont receives supply voltage ).
The supply voltage must be equal to the working voltage of the relay. One transistor....
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In this circuit, CI is charged to a fixed reference level, then discharged. Integrator ICl circuit charg..
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In conventional applications, switching-regulator ICs regulate VQVT by controlling the current through an external inductor. The IC in A, however, driving a diode-capacitor network in place of the inductor, offers comparable performance for small loads. The....
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The µA2240 may easily be configured as a programmable voltage controlled timer with a minimum number of external components. The modulation input (pin 12), which allows external adjustment of the input threshold level. A variable voltage is applied from the....
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The current range in multimeters, particularly the more inexpensive ones, is restricted by the load limits of the internal..
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This Remote control Jammer device it’s useful when we need to block someone to use the remote control (children that change frequently the channels at tv). This remote control jammer it’s very simply and it use two infrared Leds which continuously transmit....
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When the carrier level is adequate to switch the cross-coupled pair of differential amplifiers, the modu· lation signal, which has been applied to the gate, will be switched at the carrier rate, between the collector loads. When switching occurs, it will....
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The circuit consists of two oscillators, both working at about 465 kHz. One uses an if transformer and the other uses an inductor (the search coil LI). The oscillators are coupled by a capacitor (10 pF). A beat note (produced if the two oscillators are....
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Real-world measurement requires the extraction of weak signals from noisy sources. High common-mode voltages are often present even in differential measurements. The usual approach to this problem is to use an op amp or an instrumentation amplifier and then....
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For many application there's no substitute for sheer power- low efficiency speakers, outdoor sound systems, or maybe you like the full flavour of the dynamic range of a high power amp. Whatever your requirement-this super power module should fit the bill.....
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This circuit is basically an op amp with an nal (±10 mV) between pin 2 and 3 and by extra input at pin 5. A current Iabc is injected controlling the current on pin 5, the level of the into this input and this controls the gain of the signal output (pin 6)....
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This is a rather unusual QRP Power Amplifier design, with a wide frequency response; within three dB's from 300KHz to 30MHz. Overall gain is in the region of 16dB and the final output power may be well over four watts. The wide bandwidth is a result of the....
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The amplifier operates across the 2 -30 MHz band with relatively flat gaio response and reaches gain saturation at approximately 210 W of output power. Both input and output transformers are 4:1 turns ratio (16:1 impedance ratio) to achieve low input....
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In Figure 1, an MC34063A switching regulator and an MC33342 NiMH battery-charger IC combine to generate from an unregulated power supply a 600-mA battery charger for one to four NiMH cells...
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Please operate caution when building this power supply. It is run on standard 117 ac current - and under the right circumstances 117 ac can kill you. Use a plastic enclosure if possible to decrease chances of short-circuiting...
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A dual-voltage circuitry both strikes and maintains the arc. The lamps require a starting voltage in excess of 1,000 volts. Once stabilized, the voltage drop across the lamp is near 20 volts. Power supply consists of two main sections. The first section, the....
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Use this circuit to test if the light coming from your 40khz IR emitter is really emitting the right frequency. The schematic says to use a GP1U5X ir module, but probably any 40khz detector module will work.. I used a GP1U26X module...
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This project is used as an electronic private exchange. It has two telephones, which have the intercom facility, and they can be connected to the telephone line. All the functions are controlled by the 8-bit microcontroller AT89C2051 which has an Program....
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The Geiger tube needs a high voltage supply which consists of Ql and its associated components. The transformer is connected in reverse; the secondary is connected as a Hartley oscillator, and Rl provides base bias. Dl, D2, C4, and C5 comprise a voltage....
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My circuit adds a transistor, to add feedback, and two resistors, to tailor the range of the control, with the result that a single-turn potentiometer gives a control range of about 2 to 30 microamps. I installed my circuit in a small plastic box, and....
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A circuit for isolating a variable resistor is shown. An optoisolator that has an LED arid a photo-conductive cell (or photoresistor) is used. The current through the LED controls its brightness, which in turn determines the resistance between terminals A....
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This project flashes eight LEDs in an apparently random manner. It uses a 4060 combined counter and display driver IC which is designed for driving 7-segment LED displays. The sequence is not really random because seven of the LEDs would normally be the....
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This simple circuit will oscillate with a wide range of crystals. Connect several different types of crystal holders in ..
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Because of the nixie-tube is a gas tube, it requires relatively high-voltage supply. Judging from archives, from 180 to 300 volts are used for supply voltage. In this project, 270 volts from rectified 100V line voltage directly is used. It is very simple but....
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This circuit can be used to check up to an eight-conductor cable. IC1, a 555 timer, drives decade counter..
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Synchronous switching is turning on only at the instant the ac supply voltage passes through zero, and turning off only when current passes through zero. This circuit provides this function in response to either a mechanical switch or a variable resistance....
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This current to voltage converter rely on the very high input impedance of the operational amplifier. The input current (I) is forced through feedback resistor (Rf), and generates an output voltage equal to (-I x Rf). This output voltage is valid for output....
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The Hot Springs tanks and circuit board should be mounted in a location that is free of ambient electro-magnetic fields. The input and output jacks are typically placed on a patch panel with other effect`s inputs and outputs. In use, the effects or aux send....
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This circuit measures temperature in Celsius scale and displays it on an alphanumeric LCD screen. When temperature rise to 40 C an alarm is activated and at the same time a relay is also activated which drives a fan to keep the temperature at a level.....
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The circuit switches the current to an electrical heater on and off to maintain the temperature of a room at 25 ±0.5°C. The temperature sensor is a thermistor which provides a differential input (for reduced noise) to an operational amplifier. A 5 kilohm....
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The circuit is basically a 555 astable circuit that divides two LEDs, LEDl and LED2. LED2 is switched on when the output of Ul is high, and LEDl is activated when its output is low. When Ul oscillates, LEDl and LED2 switch on alternately as the output....
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Under good battery conditions the LED is off. As the battery voltage falls, the LED begins to flash until, in the low battery condition, the LED lights continuously. Designed for a 9-volt battery, with the values shown the LED flashes from 7.5 to 6.5 volts.
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If this picture (above) looks a lot like the Pretty Good LC Meter also on this web site, that's because its the same meter, but with some significant improvements. At this point, its a good idea to read the Pretty Good LC Meter page because the rest of this....
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Designed to feed a low-frequency subwoofer speaker system, the amplifier is capable of up to 100 W into an 8- load. The OPA541BM op amp requires heatsinking and is manufactured by Burr-Brown Corporation. ..
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No description available...
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This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also....
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The noninvertiiig terminal of the op amp is grounded, and the circuit uses the voltage at the inverting t..
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Circ?it to close a relay when any phone extension is off-hook. Uoltage at the gate of the MOSFET sho?ld be negative (1-3 volts) with respect to the so?rce then phones are on-hook. Uoltage at the gate sho?ld be positive (8-113 volts) with respect to the....
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The circuit uses a 4011 CMOS NAND gate, a pair of diodes and an NPN power transistor to provide a variable duty-cycle dc source. Adjusting the speed control varies the average voltage applied to the motor. The peak voltage, however, is not changed. This....
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The circuit of the transmitter is shown in Figure 1, and as you can see it is quite simple. The first stage is the oscillator, and is tuned with the variable capacitor. Select an unused frequency, and carefully adjust C3 until the background noise stops (you....
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This true SSB transceiver is built around just 5 vacuum tubes, with no transistors nor ICs. Superhet receiver with AGC and S-meter drives a loudspeaker, 5W transmitter, very stable VXO uses CB crystals to cover 20m ham band. A project for skilled RF....
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A CA3240 dual MOSFET-input device is used as a white-noise source. Op amp IC2 is used as a driver stage for the push-pull output stage formed by Q5 and Q6. Transistors Q2, Q3, and Q4 form a variablefrequency multivibrator. Rll, the speed control, is used....
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If you need a timer circuit, we go after the most proven 555th However, if the delays are longer, based on timing capacitor capacity is too large. In this case, a circuit of Figure 1 After pressing the button - reset circuit - starts multivibrator. ..