New Circuits Page 255
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The MAX125 and the MAX126 are complete 14-bit data-acquisition systems in which four of eight inputs are tracked and held simultaneously (Figure 1). An on-board sequencer allows the user to program which four (or fewer) channels are to be digitized.....
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The audio amplifier shown below provides 14 watts of power, but can provide much more simply by increasing the power supply voltage. This amp was built in 1975 and has worked reliably ever since. The power amp portion was published in Popular Electronics in....
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This simple counter is useful for frequency measurements of various wireless equipments, especially transmitters, receivers and signal generators in VHF/UHF band...
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his 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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This project has been specially designed to introduce you to SMD (Surface Mount Devices). Surface Mount is really not new. It started as far back as 1940 with a hybrid circuit in a digital watch. A chip was cemented onto a slab of ceramic material having....
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The LM3914A bargraph LEDis used here as a voltmeter for battery testing. The circuit is powered by a 4.5-V battery and compares the battery under test with an internally derived reference, set by R1/R2/P1. Each LED of the 10 represent 10% of full scale...
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This is a collection of non-intelligent (at least for now) inverter circuits
for operating fluorescent or other similar devices from low voltage DC power
sources. These designs - mostly obtained by reverse engineering commercial
camping lanterns, power....
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The whole Construction : You can call the transceiver like this as "OZL type". Characteristics of the "OZL type" are as follows.
1. Single conversion super.
2. Using two DBM-s as modulator and converter.
3. Modulator DBM is used as demodulator in....
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The NE602 chip, Ul, contains oscillator and mixer stages. The mixer combines the oscillator signal with the input RF signal to produce signals whose frequencies are the sum and difference of the input frequencies. For example, an 8.5-MHz oscillator and a....
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The first stage is a simple buffer used to isolate the signal source from the attenuator stages to follow. Each of the subsequent stages is preceded by a voltage divider formed by two resistors and CMOS switch. Provided that the CMOS switch for each stage....
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The infra-red (IR) toggle switch project described here is aimed to provide control mechanism for electrical appliances that do not have remote operation features. The goal is to construct a black box where you can plug-in your 120V AC appliance and control....
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This 1 channel infrared transmitter/receiver remote control is the cheapest and simplest you can find. The transmitter transmits a sequence of pulses on 36 KHz frequency carrier. The diodes are Schottky type because of their low voltage drop (only 0.2V). The....
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The cyclic converter consists of a chain of identical stages, each of which detects the polarity of the input. Step V REF then subtracted from the double entry and the rest if the polarity is correct. The signal is full wave rectified and the rest of V IN -....
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By using an op amp BiMOS CA3140 provides good orientation skills for high bandwidth signal input, and can quickly adjust the energy output at its terminal CA33IO WINE. The CA3140 can also lead to near the negative supply rail...
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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 special category of preamplifiers, they are the preamplifiers that undertake they amplification the low exit of Moving coil head, so that its drive to a input PHONO [RIAA] of preamplifier. With the moving coil heads, exist certain problems which it should....
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The volume control in a hi-fi amp or preamp (or any other audio device, for that matter), is a truly simple concept, right? Wrong. In order to get a smooth increase in level, the potentiometer (pot) must be logarithmic to match the non-linear characteristics....
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An In Circuit Programmer is a very valuable tool. Not only does it allow you to program you AVR's with ease, you can update your program without having to remove the AVR (very use full when working with surface mount devices). Also, an ICP allows you to use....
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This firmware is intended to run on Atmel ATmega163 (499 bytes for program memory) or AT90S8515 (298 Bytes for program memory). Communications with the terminal is via RS-232 at 9600 baud. Use 8 data bits, 1 stop bit, and no parity. The RXD pin and TXD pin....
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The purpose of the circuit is to hold the peak of the input voltage on capacitor Cl, and read the value, V0, at the output of U2. Op amps Ul and U2 are connected as voltage followers. When a signal is applied to Vj, Cl will charge to this same voltage....
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As I used this probe last nigh to determine if a 384 MHz oscillator was really working or not, I remembered email I received a while ago, asking how to make a field strength indicator without the microcontroller. Thus this page. If you want the auto zero....
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A transducer senses a direct current magnetically, providing isolation between the input and the output. The detecting-and-isolating element is a saturable reactor, in which the input current, to be measured, passes through a one-tum control coil. The....
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A compact, inexpensive and low component count telecom head- set can be constructed using two readily available transistors and a few other electronic components. This circuit is very useful for hands-free operation of EPABX and pager communication. Since....
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Many modern audio recorders is now compatible with digital input S / PDIF (Sony / Philips Digital Interface). Devices like CD Changers, MiniDisc recorders, computer sound cards and the like. working with digital signal just with protocol S / PDIF. Digital....
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This circuit uses a CMOS chip and a VMOS FET amplifier for 6 W of audio output. 18 W of audio can be generated using ..
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Basically, this is a frequency-current converter. It is used as frequency meter. Calibrating it can be used as tachometer. Please be aware this is an experimental project, I didn't use it connected on any vehicle but it should work fine after calibration. It....
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A microphone amplifier that may be used with either Electret Condenser Microphone (ECM) inserts or dynamic inserts, made with discrete components. Both transistors should be low noise types. In the original circuit, I used BC650C which is an ultra low noise....
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This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can....
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Used on an amateur or experimental radio beacon, the above ID circuit will generate any callsign or message program..
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Although intended to power a 100-W low-frequency amplifier, this power supply should handle many mono or stereo amplifiers in the medium power range..
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When you need a precision peak detector, you would usually implement it with one or several op amps and a few other associated components. This technique usually works well unless your design requires operation higher than a few kilohertz. In designs....
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Keyboards can be slotted into two categories, at least as far as the manner that the switches are connected is co..
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This is an image Schematic. No Description available...
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When SI is on, power is applied to an oscillator composed of Ql, Rl, Cl, LI, and L2. Coil Ll is the primary winding of Tl, and L2 is the feedback winding. When Ql turns on, its collector current saturates Tl's ferrite core. That, in turn, removes the base....
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The generators of square pulses, are used in a lot of applications, between which the adjustment of conditions of entry in the digital circuits and the control of amplifiers acoustic frequencies. This circuit is a generator that it produces, in combination....
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You can transform a 7415124 multivibrator into a wideband VCO by replacing it conventional fixed capacitor with a variable-capacitance diode. The only disadvantage of this scheme is the 30-V biasing voltage that the diode requires. Capacitors C1 and C2....
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The probe relies on the power supply of the CUT (circuit-under-test). The input to the probe, at probe tip, is fed along two paths. One path flows to the clock inputs of U2a and U2b. The other path feeds both the inverting input of Ulc, which is set up as....
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(Almost) Trivial application of an AT90S2313 or ATtiny2313 in an alarm clock to change the alarm from "BEEP BEEP BEEP BEEP BEEP BEEP BEEP BEEP..." to "WAKE UP" in Morse code. This was designed in response to a request and is in daily use. An inexpensive....
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Many times exists the need recording some conversations from a telephone line and this it's relatively easy. If we want however to have the possibility recording from two telephone lines simultaneously in a tape recorder, we needed a circuit as what appears....
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The solar-lantern circuit in Figure 1 is a low-loss configuration that uses a 7W, four-pin CFL (compact fluorescent lamp) and a 12V, 7-Ahr, sealed, maintenance-free battery. The inverter features greater-than-85% efficiency, less-than-2-mA quiescent current,....
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This amplifier can amplify to 10dB the RF signal from antenna working as class A and is based on transistor BFQ34 of Philips. The transistor comes in case SOT122A. You may find the BFQ34T in market but better do not use it as it has different characteristics. ..
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Diode detectors are good at changing AC into DC, even at high frequencies. The main problem with diode detectors have inherent nonlinearities, particularly for small signals. To minimize the effects of the nonlinearities, a preamplifier boosts the amplitude....
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If you decide to use 2 circuits, i just connect their outputs together...neg output from first circuit to neg output of second circuit & pos output from first circuit to pos output of second circuit.
And take readings from same place....from where you....
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The VHF frequency is generated by a tuned Hartley oscillator circuit. Resistors R2, R3, and R4 bias the transistor, with tapped inductor LI and trimmer capacitor Cl forming the tank circuit. Adjusting Cl determines the frequency. Capacitor C2 provides....
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All capacitors in this circuit are disc ceramic. Fixed-value resistors are 1/.-or 1/2-W carbon. Rl controls the gain of Ul. RFCl is a miniature 2.5mH rf choke. ..
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This circuits allows you to use a cheap loudspeaker as a microphone. Sound waves reaching the speaker cone cause fluctuations in the voice coil. The voice coil moving in the speakers magnetic field will produce a small electrical signal.
The circuit is....
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No description available...
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The SD1143 transistor provides a gain of about 14 dB in this circuit. It uses the fact that a 175-MHz device has a much higher gain when used at lower frequencies. The amplifier was originally designed to be used with a transverter. ..
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The circuit is capable of supplying either a trickle (50 mA) or high-current (1-A) charge. You can select either charging method or an automatic mode that will first trickle charge a battery if it is particularly low before switching to high-current....
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An analog signal requires about 100 ns to propagate through the HA-5320. For time-varying signals, this assures a voltage dif..
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In this circuit, IC1A and IC1B act as a monostable multivibrator. Any input from the sensors SI through..
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Creating a modular, networked, home control system was greatly simplified by using common 4-wire phone cable with stake-on connectors. The cable feeds both power and network signals to the various modules. Each module is made on a single sided circuit board....
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The circuit is not frequency sensitive. Its calibration will be accurate over a wide frequency spectrum, such as the entire amateur hf spectrum, if the values of L2, the voltage divider capacitors Cl-2 and C3, and the resistances of Rl-2 are chosen properly.....
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There are several websites documenting the original Furby circuit board. I decided to replace the original circuit entirely and replace it with a PIC based controller. The mechanism of the Furby itself was designed around micro- controllers. It has one....
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The circuit provides a clean, stable square wave and it will operate on anywhere from 6 to 15 volts. The IC and color-burst crystal are the kind used in TV receivers...
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I have had this project hanging around for ages and have tried to submit it for publication without much enthusiasm so I will make everything available here for the individual constructor. The complete Pascal source code for the compiler program is available....
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The LT®6700 dual comparator incorporates features to
reduce part count in space-critical designs, including a
trimmed on-chip 400mV bandgap derived reference and
internal hysteresis mechanisms. The LT6700 also features
low voltage micropower single....
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A simple voltage-to-current converter is shown in the figure. The current out is 0t or Vjn/R. For negative currents, a pnp can be used and, for better accuracy, a Darlington pah-can be substituted for the transistor. With careful design, this circuit can be....
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This circuit sends MIDI program changes. It's useful as a guitar pedalboard remote...
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It is well know that pests like rats, mice etc are repelled by ultrasonic frequency in the range of 30 kHz to 50 kHz. Human beings can't hear these high-frequency sounds. Unfortunately, all pests do not react at the same ultrasonic frequency. While some....
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Power input is to a 7805 5 volt regulator. A pair of LEDs is connected between the 5 volt supply and ground, with current limiting resistors in series and one pin on the AT90S2313 shunts the current through one LED or the other. When one LED is on, the....
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The entire circuit is powered from a very simple regulated +-15V power supply, that is able to deliver about 2 A continuous duty, and at least 6 A on musical peaks. Two three-terminal regulators with power transistors wrapped around them do the regulating....
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This circuit illustrates some possible buffer combinations. Tbese include a differential input stage, a voltage follower as well as both noninverting and inverting stages. The allowable resistor ratios and recommended device types are also included. One....
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By inserting a high-pass filter section in the IF lead, this mixer is terminated at all frequencies, besides the IF, for oth..
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The circuit is a form of the so-called ""Americanized" version of the Baxandall negative-feedback tone control. At very low frequencies, the reactance of the capacitor is large enough that they might be considered open circuits, and the gain is controlled....
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This circuit, enclosed into a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior of the fridge is in the dark, the photo resistor R2 presents a high resistance (>200K) thus clamping IC1 by holding....
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One application is where you need a Higher Power Zener, Possibly even a 100 watt rating.
Another useful application is as a Shunt Regulator for Solar Cells that are used
to charge "Lead Acid Batteries". Simply Place it in parallel with the Solar Cell....
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ICs requiring 3 or 6 volts can be run from a battery or fixed regulated supply of a higher voltage by using the circuit shown. The transistor should be mounted on a heatsink as considerable power will be dissipated by its collector. Additional filtering can....
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As you can see, there is only one regulated 12 volt supply operating the entire circuit. I was able to do this simply by AC coupling the received signal to U3 via C10. This allowed me to adjust the offset within an operating window. By using a tantalum....
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VID2G project is an PAL/NTSC color generator & video identifier with digital sync regeneration, digital PLL, video Squelch output, predefined video pages, keyboard & full RS-232 access, etc. Dynamic and fixed ID`s, user positions, user selectable....
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Using a standard PLL circuit, such as the CMOS 4046B with some passive components, is a well-known way to design a clock multiplier. Unfortunately, using a PLL in a digital circuit has two disadvantages: It takes a long time for the circuit to reach a stable....
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1. Because there is no DTR wire (modem pin 20) from Pilot. Pilot can simulate DTR line but this is not used at this moment (needs a pull-up)
2. This way we can not dial without a known dial tone if needed (like in some areas out of USA)
3. There no....
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In operation, the TL3019 device will activate, or become low, when a south pole of a magnet comes near the chip face of the device. The example shows five doors. Each door has a magnet embedded in its edge with the south pole facing the outer surface. At....
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The circuit presented here can be used for connecting two telephones in parallel and also as a 2-line intercom.
Usually a single telephone is connected to a telephone line. If another telephone is required at some distance, a parallel line is taken for....
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This submersible sonar positioning apparatus generally consists of dual-opposed ultrasonic transducers, alternately excited, with return signals processed and displayed for observation and measurement. Typical transmitter frequencies range from 50 to....
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The SCHAER+ programmer is a programmer for PIC18 family from a PC parallel port (LPT). It is derivated from the SCHAER programmer I used to download my projects in PIC1684. The SCHAER+ programmer should be improved to use a USB connection, without any....
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Note that Tl and T2 are TOKO, including part numbers for the coils Tl and T2. The direct-con-version receiver shown uses a double-tuned input network made from readily available TOKO coils. IC1, an NE602, acts as a VFO and mixer, with the output being an IF....
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This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It`s easy to use. First check that the building is secure and that the green LED is lit. Then move SW1 to the "set"....
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This circuit will generate a smaller DC output voltage from a larger DC input voltage.It is quick and simple to make and by changing the value of the zener diode, the circuit can be universally adapted to provide other output voltages.The circuit and all....
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An isolation transformer and a variable auto transformer, very much like a Variac. Fuse 1 protects against gross overload. Lamp 1, across the Fuse 1, is a red incandescent pilot lamp and it lights up in the event of a blown fuse. Imagine how much time this....
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This project has two options. It can be a mains operated project, using a 2155 or 2156 transformer or it can be connected to a plug pack.
We recommend it be connected to a 16v AC 1 amp plug pack as these are double insulated and provide complete safety for....
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The output current is set by the resistor R in the collector of Tr2, which may be varied to offer a range of output currents from 100 mA to 2 A with fine control by means of VR3 which varies the reference voltage to the non-inverting input of the op amp...
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Power-supply designers usually like flyback converters to operate in DCM (discontinuous-conduction mode) rather than in CCM (continuous-conduction mode). In DCM, the flyback converter is a first-order system at low frequencies, which eases the feedback-loop....
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The method goes by the switching method. Making it be possible to see four kinds of the input signals at the same time by switching them at the short period. In addition to the way of introducing here, there is a method which changes the input every period.....
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The preamplifier is protected from excessive input signals of either polarity by the 2N5909 junction field-effect transistor. A nulling circuit makes it possible to set the preamplifier output voltage to zero at a fixed low level (up to + 10~8A) of the input....
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This circuit gives out an alarm when its sensor is wetted by water.
A 555 astable multivibrator is used here which gives a tone of about 1kHz upon detecting water.
The sensor when wetted by water completes the circuit and makes the 555 oscillate at about....
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Digital potentiometers are versatile devices; you can use them in many filtering and waveform-generation applications. This Design Idea describes an oscillator in which setting the resistance of two digital potentiometers independently programs the....
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For some applications it is important to have a tone decoder with narrow bandwidth and fast response time. This can be accomplished by the dual time constant tone decoder circuit shown. The circuit has two low-pass loop filter capacitors, C2 and C'2. With no....
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This circuit is a simple two transistor (2N2222) FM transmitter. No license is required for this transmitter according to FCC regulations regarding wireless microphones. If powered by a 9 volt battery and used with an antenna no longer than 12 inches, the....
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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 stage. The output of the preamp stage is sent to three places: the output mixer amp, the reverb driver amp, and the input....
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That circuit uses the MSM6322GSK which is only available in small 24 pin plastic SOP style package. A speech pitch converter IC that operates in real time and requires very few external components. It has a microphone preamplifier and line level input and....
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When power is first applied to the circuit, 02 begins to charge via LED1, R3, and R4. When the voltage across C2 reaches Ul`s input trigger level, the output of Ul at pin 6 goes positive for a period that is determined by the values of and it! r That turns....
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This siren provides a constant audio output, but alternates between two separate tones. The LM13080 is set to oscillate at one basic frequency; ..
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Many noncontact temperature-measurement systems use infrared sensors, such as thermopiles, which can detect small amounts of heat radiation. Biomedical thermometers that measure the temperature of an ear or a temple use noncontact temperature measurement, as....
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The target of this project was the design of a small portable mixer supplied by a 9V PP3 battery, keeping high quality performance.
The mixer is formed assembling three main modules that can be varied in number and/or disposition to suit everyone needs...
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The "LCD2LPT with Lirc" circuit is the compilation of two circuits found on the net on a single board. The first is LCD to LPT interface and the second an IR remote control interface using http://www.lirc.org program. The main circuit for LCD connection to....
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This project is used to communicate or transmit a text message from one place to another place through wireless. The text message is encrypted by using the Microcontroller and the encrypted message was transmitted through wireless. At the receiver end the....
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The LT®3465 white LED driver is ideal for backlight
circuits in small, battery-powered portable devices
such as cellular phones, PDAs and digital cameras. The
LT3465 includes important features such as automatic
soft-start to prevent large inrush....
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A number of single-chip VGAs variable-gain amplifiers are available today. Unfortunately, they all have drawbacks, such as high noise, 55V limit, low input impedance, or nonlinear gain/frequency characteristics. The circuit in Figure 1 is a 16-step,....
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Linear Technology introduces a new micropower DC/DC
converter designed to provide high output power from a
single cell or higher input voltage. The LT®1308 features an
onboard switch capable of handling 2A with a voltage drop
of 300mV and operates from....