New Circuits Page 235
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The primary advantage of this method of bridging is that no additional components are needed (which means that it is cheap), and there is no signal degradation from additional opamps in the circuit path. The results are at least as good as using an external....
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Based on the classic Baxendall tone control circuit, this provides a maximum cut and boost of around 10dB at 10K and 50Hz. As the controls are passive, the last transistor provides a slight boost. The output is designed to feed an amplifier with input....
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The RF circuit is a C-Class power amplifier . it is used in last stage of transmitters .Its maximum power output is about 1 Watt . the circuit can be used in 3 frequency range 30-100-200MHz...
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The circuit can operate lamps and buzzers from the 120 V, 60 Hz power line while maintaining positive isolation betweenthe telephone line and the power line..
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This simple circuit produces a loud trilling noise, if no valid transmitter signal is received. This frequency must correspond with the resonant frequency of the piezo element, otherwise the sound level will be very low...
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A frequency reference for tuning up the RS-232 to 100 MHz RF desktop channel adapter elsewhere on this site, when I found this Saronix crystal oscillator in my junk box. A few minutes with AVRStudio produced an ATtiny12 to make a tone - even fewer parts....
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The LTC®2400 is the industrys first No Latency TM ADC
that combines automatic offset and full-scale calibration,
an internal oscillator, a sinc4 digital filter, and serial I/O to
yield a 24-bit ADC with 1.5µVRMS input noise and singleshot
conversion time....
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A shot of direct current will instantly stop any ac power tool motor. Switch Si is a center-off, one side spring return. With Si on, ac will be fed to the motor and the motor will run. To brake the motor, simply press Si down and a quick shot of dc will....
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This sensitive sound operated switch can be used with a dynamic microphone insert as above,
or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will
need to be included. A suitable value would be between 2.2k and 10kohms...
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Figure 99-l(a)"s circuit exhibits a high-output impedance as a result of the small effective capacitance of the series-c..
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Although not intended for this application, Hall-effect switch can be used as the basis for a rather unusual oscillator. The oscillator can be reconfigured, as shown in Fig. B, to allow the circuit`s oscillating frequency to be controlled via an RC network, ..
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This circuit uses the low power ICM7555 (CMOS 555) to generate the gating, STORE and RESET signals. To provide the gating signal, the timer is configured as an astable multivibrator. The system is calibrated by using a 5 M potentiometer for Ra as a coarse....
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This new loop antenna by Graham Maynard is his best design yet and I am proud to be the first to present his work. It uses one, six foot square, six turn loop, and is aperiodic in nature, covering the frequency range 50KHz - 5000KHz...
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?? ??????? ????? ??? ???????? ?????? ????????? ??? ???????????? TDA7294 ??????????? ??????????, ?? ???? ???? ?????????????? ??? ???. ?? ?????????? ?????? ?????????? ?? ???? ??, ???????????? ?? ????? ????? ???? ?? ?????? 8? ??? 4?. ?? ???? ???? ?????????....
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The supply receives + 20 Vdc from the rectifier/filter section. This is applied to pins 11 and 12 of the uA723, as well as to the collector of the 2N3055 series-pass transistor. The output voltage is sampled through R1 and R2, providing about 7 V with....
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This circuit turns a common oscilloscope into a versatile eight-channel display for direct voltages. The trend of each of the eight input levels is readily observed, albeit that the attainable resolution is not very high. The circuit diagram shows the use....
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When the switch is closed or the FET is conducting, the circuit behaves as an inverting amplifier with a gain of R2/Rl. Since as the inverting tenninal of the op amp is a virtual ground, the capacitor is kept charged to the output voltage by the op amp.....
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Old TV tubes are used as cold cathode x-ray emitters in a simple apparatus developed by Bob Templeman of Chicago, Illinois. With selected beam power tubes of the type used in the high voltage section of TV receivers, the intensity is adequate to make x-rays....
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If R, the sensor matching resistor, is equal to the "dark" resistance of the cadmium sulfide cell, the amplifier output will range from 0 to "" 2 as the lightlevel ranges from "dark" to "bright." The circuit in Fig. B operates similarly, but use the....
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The operating voltage of white LEDs coupled with my emotional need for low cost for a given function, motivates me to make LED drivers suitable for battery operated lanterns that can run from a small number of cells. White and Ultraviolet LEDs available at....
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A touch-sensing circuit keeps the high-voltage generator cut off until something touches the fence wire. Contact with the fence sensing circuit wire starts the high-voltage generator which applies a series of 500 microsecond pulses at approximately 300 volts....
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The design uses a proximity detector rather than a pushbutton switch to eliminate the need to mount and wire any equipment outdoors. The circuit worked well in this application and other applications...
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The purpose of a motor speed controller is to take a signal representing the demanded speed, and to drive a motor at that speed. The controller may or may not actually measure the speed of the motor. If it does, it is called a Feedback Speed Controller or....
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With all DHT stages (all tubes from Svetlana 1970-s). OK, the input/splitter are not DHT`s but DHP`s - 4P1L - triode wired. Mullard 3-tube input/splitter topology, cap-coupled to cathode bias 6B4G PP. First stage uses battery bias (no cathode resistor). Only....
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Here we have three choices, with which we can make electronic switches that use our touch or pressing (push button). We thus exploit the very big resistance of entry, that present the gates CMOS. In the fig.1 we have two gates NAND or NOR (IC1), connected as....
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The D169 serves as a level detector and provides complementary outputs. The op amp is used to integrate the input signal Vin with a time constant of R1C1. The input (must be negative) causes a positive ramp at the output of the integrator which is summed....
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There are many ways to create a stereo effect. If you were miking a piano, a string section, or some other large sound source, you`d probably stick up a pair of directional mikes and assign them left and right. But what if you want to "enlarge" a lead....
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The fan employed is one of the new electrostatic type which is very reliable, because it contains no wearing parts. These devices require high-voltage drive. When power is applied, the thermistor, located in the fan"s exhaust stream, is at a high value.....
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This circuit will give provide a Good Strobe Effect for a variety of Portable Uses. Nominal current draw is "up to about" 1 amp at 12 volts. Depending on value of capacitor on pin 2 of the 555 and the particular choke that is used...
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This low-power inverter uses only 9 parts and turns 10 to 16 Vdc into 60-Hz, 115-V square-wave power to operate ac equipment up to 25 W. The first section of the 556 timer chip is wired as an astable oscillator with R2 and C1 setting the frequency. The....
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In the 556 timer, the timing is a function of the charging rate of the external capacitor. For long time delays, expensive capacitors with extremely low leakage are required. The practicality of the components involved limits the time between pulses to....
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The electronic lantern control circuit adds high-efficiency dimming and flashing to an existing battery-powered lantern or flashlight or to a custom design. For the car it makes a great lamp for changing a flat tire, back seat reading or emergency engine....
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The circuit is also an inexpensive VCO (voltage-controlled oscillator) with only five components. Many types of ceramic capacitors for surface-mount placement are on the market. The parts become continually smaller because of space problems on the board, and....
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This preamplifier was designed to cope with CD players, tuners, tape recorders etc., providing an ac voltage gain of 4, in order to drive less sensitive power amplifiers. As modern Hi-Fi home equipment is frequently fitted with small loudspeaker cabinets,....
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The circuit of AM transmitter is designed to transmit (amplitude modulated) DSB (double side band) signals. A modulated AM signal consists of a carrier and two symetrically spaced side bands. The two side bands have the same amplitude and carry the same....
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Running from a 9-V battery, this transmitter can be used as a wireless microphone with an ordinary 88- to 108-MHz FM broadcast receiver. Keep the antenna length under 12 inches to comply with FCC limits. LI is 6 turns of #24 wire wound around a pencil or a....
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This is a compact three transistor regenerative general coverage receiver with fixed feedback. It`s based on the principle of the ZN414 only much higher coverage. The sensitivity and selectivity is relative good (especially on the LF and MW bands) as can be....
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Working on live telephone circuits can be a problem. You just can't connect a normal scope probe to the circuit while it is tied to the phone line. Neather side of a phone line is ground. When a phone or other device is 'offhook', one side floats at about....
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Save fuel bills and the economy of the planet with this circuit. SW1 is a normally open press button switch which allows you to view the level of hot water in a hot water tank. When pressed the voltage difference at the junction of the thermistor and preset....
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It's basically a photovore with a couple tactile sensors. It's rather complex but can give neat behaviors with modifications to the circuit. At this point I don't have any plans to give more information on this circuit so your on your own. C1 and C2 values....
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This circuit provides a good siren noise suitable for warding off robot-predators! Change the pitch by adjusting R2, and R5...
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This circuit operates a relay each time a sound of sufficient intensity is made, thus one clap of the hands will switch it one way, a second clap will revert the circuit to the original condition. Q2 and Q3 form a Schmitt trigger. The JK flip-flop isoised as....
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If your circuits experience frequency overvoltage conditions, continually replacing blown fuses can get pretty expensive. However, this shutdown circuit overcomes that deficiency by replacing the fuse with a relay and a low-current SCR. When the input....
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This source is selected by pressing momentary-contact pushbutton switch SI. Switch SI is connected to the trigger of a 555 oscillator/timer (Ul) configured as a monostable multivibrator, wliich generates one short output pulse for each press of SI. That....
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You may wish to use a 12 to 24V battery, like a Gel Cell, since the car power or cheap power wall wart style supply is probably too noisy. You may have to adjust the resistor value (1.2K for 24V). Whatever gets the phones working and does not use more than....
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This circuit filters noise, such as glitches and contact bounce, from digital signals. You can easily adjust the circuit for a wide range of noise frequencies. The circuit"s output changes state only if the input differs from the output long enough for....
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Unijunction transistors Ql and Q2 are both connected as relaxation-type, sawtooth oscillators. Transistor Ql is the low-frequency control oscillator and Q2 is the tone generator. Sawtooth waveforms are produced at the emitter terminals. Without R4....
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A typical circuit at 20 MHz is shown. The crystal, which has an internal series resistance Rs of 14ohm, oscillates at its third harmonic. The diode clamp Dl and D2 provides a constant amplitude control. ..
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If the input frequency is known, the timer can easily be used as a frequency divider by adjusting the length of the timeing cycle. Figure shows the waveforms of the timer when used as a divide-by-three circuit...
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This circuit uses a ring counter made up of Q3, Q4 and Q5. Q2 acts as an oscillator which triggers the SCRs Q3, Q4 and Q5 in sequence. When an SCR fires, a 0.2µ¥ capacitor provides commutation, shutting off the previous stage...
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Assume first that SCR1 is on and SCR2 is off so that CI is fully charged, with its LMP2 end positive. The..
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Each time a pulse is applied to the conversion of the control input, Ql resets the 1000 pF capacitor to 0 V. This action takes 200 ns to reset the falling edge of the convert command pulse, the capacitor begins to charge linearly. In exactly 10 microseconds,....
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Time IO-bit conversion is 3.3 MHz with a p 3. Clock. This converter uses an approximation 2504 12-bit register in successive operating mode where the short-cycle end signal conversion is taken from the first bit used in the SAR (QLO)...
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Because the CS5501 16-bit-delta-sigma analog-to-digital converter lacks a start convert command, it converts continuously, outputting conversion words to its output register every 1024 cycles of its master clock. However, by incorporating a standard dual....
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This circuit uses buffer stages to prevent channel crosstalk back through the mixer resistor network. The potentiometers used for each stage allow for convenient signal strength adjustment, while maintaining input impedance matching at the 600-0 audio....
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Volt regulators such as the LM708, and LM317 series (and others) sometimes need to provide a little bit more current then they actually can handle. If that is the case, this little circuit can help out. A power transistor such as the 2N3772 or similar can be....
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This page presents information on infrared - `Across The Track` train detection circuits. The circuits are designed around the LM339 comparator chip and can use a wide assortment of matched infrared - emitter / detector pairs...
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The only SOT-23 op amps featuring Over-The-TopTM operation
the ability to operate with either or both inputs
above the positive railare the 55mA LT®1782 and the
300mA LT1783. This feature is important in many currentsensing
applications, where the inputs....
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LochMaster is a developers tool for stripboard projects. It has useful functions for designing, documenting and testing a board. Therefore you will find features like auto-generation of components lists, a connection test, an editable library with a large....
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Building ESLs involves the use of tools and materials that if handled improperly can be hazardous. Please make sure you know how to use these things before you begin. By all means, use safety glasses at all times. If would be foolish to trade your vision for....
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This bull horn uses U1 as a driver stage and U2 as an output driver. U1 is set up for a gain of 200. The microphone should have a..
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Uses the MAX641 switching controller and an external discrete charge pump to step up the input voltage. This circuit can service low loads and is efficient when the output is two, three, four times the input voltage. Adding the MAX627 MOS driver can further....
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PID-Control with 68HC11. STEPPER CONTROL. 68HC11 read encoder. High accuracy RPM-measurement with 68HC11..
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This stereo encoder is a halfway between analogue and digital processing. It combines the best from both domains to provide high-quality and easy to build device. The sampling frequency used in this stereo encoder is 97 times (!!!) higher than the pilot tone....
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This adaptor will capture plots or prints of your GPIB instrument to your PC through the USB port. It fills the need of anybody who has a test instrument with the GPIB port and likes to get the screen dump on his PC without any GPIB card or complex software.....
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Channell is wired as a conventional integrator, and channel2 as a voltage follower. When channel2 is switched on, the output will follow VJN and C will discharge to maintain 0 V across it. When channel! is then switched on, the output will initially be at....
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This circuit is a frequency meter, low cost. It covers region 1HZ until 1MHZ. The IC1 schmitt trigger that it regulates the signal of entry and him changes in reasonable level suitable for the IC2-3-4. With the tenth pulse in the entry of IC2/1, is produced....
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This lighting-control unit will fade out one lamp while simultaneously increasing the light output of another. The two loads track each other accurately without adjustments. The gate of SCRl, a silicon-controlied rectifier, is driven from a standard....
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This circuit uses a low-input-bias op amp to give a steady dc indication of light level. To reduce circuit sensitivity to light, Rl can be reduced, but should not be less than 100 K..
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This amplifier was born out of a need to use two sets headphones with my computer's sound-card. The design presented here is a 50mW power amplifier meant for phones with impedances of 32 Ohms and greater. I chose this class A topology, because it offers very....
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The amplifier operates from supplies ranging up to 12 volts, and operates (with reduced volume) from supply voltages as low as 1.8 volts without having distortion rise to unacceptable levels. (Its power requirements make it suitable for solar-cell....
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This project is a 3 or more lines mixer. For more than 3 inputs you can repeat the input parts (P=10K R=22K). It powered with 9Vdc...
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I designed this circuit for one friend of mine to be used as a small portable DJ mixer. The circuit is an audio mixer circuit so simple as it can be. There are two dual logarithmic potentiometers in the circuit to adjust the input signal levels and some....
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This is an enhanced 5 digit keypad which may be used with the Modular Alarm System...
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The circuit is capable of charging a 12 volt component selection. When the battery voltage battery at up to a six ampere rate..
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Four blacklight lamps, 15W each, emit radiation at the region of UVA, with a peak around 350nm where the thin surface above the copper of the photosensitive board, is... sensitive. The lamps are taken by two and are connected in series thus shaping two....
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When the 555 ic goes into timing mode (triggered by an output signal from the sound detector amplifier,) the timer`s output (pin 3) is set into HIGH for a duration set by C2, and R2. adjusting R1 will adjust how long it listens, from 10 seconds all the way....
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When building amplifiers, it is often necessary to test transistors, either to verify that they (still) work, or for some esoteric designs it may even be necessary to match certain characteristics.
The design featured here is just what you need, and....
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You can build an automatic gain control AGC for the superhet receiver with only a few additional components. The first AGC circuit is more universal. It is suitable for audio amplifiers with dual op amps like TL072, TL082, NE5532 and the broadband amp NE592....
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This tester is for tracing wiring on Printed Circuit Boards. Resistors below 50 ohms act as a short circuit; above 100 ohms as an open circuit. The circuit is a simple multivibrator switched on by transistor T3. The components in the base of T3 are Dl, Rl,....
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Amplify or record a telephone call with the simple circuit shown. The 8-0 secondary winding of a miniature transistor output transformer is connected in series with either of the telephone lines. ..
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The laser diode·pulser is a simple drive circuit capable of driving the laser diode with 10-A, 20-ns pulses. For a 0.1 % duty cycle, the repetition rate will be 50 kHz. A complementary emitter follower is used as a driver. Switching speed is determined by....
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A 555 and a dual 556 timer generate a rudimentary video signal, as shown in the schematic. The first timer generates 4.7-8 synch pulses operating in the astable mode with a 64-8 period. The second timer generates a delay pulse, which triggers the third....
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This new circuit uses four chips, with an option of using just three (the flip-flops and AND g..
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For other input structures see Figures 6 to 11; shown here with PC-filter (Figure ß). The micropoco capacitor has a temperature coefficient of 125.10"6i 60.10" k"1. In simplified circuits a fixed resistor (e.g. 620k) can be used for a guaranteed switching....
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When activated, the transmitter sends out a 49.890-MHz, AM rf carrier. The.receiver detects, amplifies, and decodes the rf signal, which, in turn, activates a piezo buzzer. The receiver is small enough to carry in a pocket or sit on your workbench. ..
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The LTC1063 is the first monolithic low-pass filter that simultaneously offers outstanding dc and ac performance. It features internal or external clock tunability, cutoff frequencies up to 50 kHz, 1-mV typical output dc offset, and a dynamic range in....
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By mixing an audio signal with ultrasound, you can hear the audio as if it's inside your head... even if the 'headphones' are nowhere near your ears. Patrick Flanagan invented the "Neurophone" over 40 years ago. His original patent (US3393279) was basically....
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A programmable 8 step tone sequencer using an Arduino microcontroller. Features a 2 line x 16 character backlit LCD display..
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This hookup is useful in some house wiring situations, where only two wires are available between switches, rather than..
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A J309 Siliconix FET feeds a 2N5109 in a wideband RF amplifier configuration. A relay is used to bypass the amp..
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The philosophy behind this minimalist design has been explained by Flavio Dellepiane on his highly interesting site 1. I have myself written an article about this fleapower amp from Italy in the American magazine AudioXpress 2. All relevant details are....
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The main part of this circuit is the LM386 amplifier chip. It also uses a transistor input to buffer the input signal and provide extra gain for the LM386. The little unit has helped me out on numerous occasions when trouble shooting any amplifier circuit....
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The LT1007 is capable of providing excitation current directly to bias the 350-0 bridge at 5 V. With only 5 V across the bridge, as opposed to the usuallO V, total power dissipation and bridge warm-up drift is reduced. ..
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This highly sensitive movement detector is designed from bipolar transistors and draws a curren..
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The circuit uses two general-purpose npn transistors, Ql and Q2, and a special hand-wound, dual-coil probe ferrets out the magnetism. Ql and its associated components form a simple VLF oscillator circuit, with LI, C2, and C3 setting the frequency. The VLF....
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This very simple counter can be used to measure the frequency of various wireless devices. Applies in reviving the transmitter and its operation as a control monitor frequency. It can be used as a scale to the receiver. Due to the simplicity of the counter....
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The sensor circuit is adaptable to different liquids and sensors. The constant-current source drives current through the sensing probe and a fixed resistor..
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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)...
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The two circuits di atas illustrate opening a relay contact a short time after the ignition or ligh switch is turned off. The capacitor is charged and the relay is closed when the voltage at the diode anode rises to 12 volts. The circuit on the left is a....
The primary advantage of this method of bridging is that no additional components are needed (which means that it is cheap), and there is no signal degradation from additional opamps in the circuit path. The results are at least as good as using an external....
Based on the classic Baxendall tone control circuit, this provides a maximum cut and boost of around 10dB at 10K and 50Hz. As the controls are passive, the last transistor provides a slight boost. The output is designed to feed an amplifier with input....
The RF circuit is a C-Class power amplifier . it is used in last stage of transmitters .Its maximum power output is about 1 Watt . the circuit can be used in 3 frequency range 30-100-200MHz...
The circuit can operate lamps and buzzers from the 120 V, 60 Hz power line while maintaining positive isolation betweenthe telephone line and the power line..
This simple circuit produces a loud trilling noise, if no valid transmitter signal is received. This frequency must correspond with the resonant frequency of the piezo element, otherwise the sound level will be very low...
A frequency reference for tuning up the RS-232 to 100 MHz RF desktop channel adapter elsewhere on this site, when I found this Saronix crystal oscillator in my junk box. A few minutes with AVRStudio produced an ATtiny12 to make a tone - even fewer parts....
The LTC®2400 is the industrys first No Latency TM ADC that combines automatic offset and full-scale calibration, an internal oscillator, a sinc4 digital filter, and serial I/O to yield a 24-bit ADC with 1.5µVRMS input noise and singleshot conversion time....
A shot of direct current will instantly stop any ac power tool motor. Switch Si is a center-off, one side spring return. With Si on, ac will be fed to the motor and the motor will run. To brake the motor, simply press Si down and a quick shot of dc will....
This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms...
Figure 99-l(a)"s circuit exhibits a high-output impedance as a result of the small effective capacitance of the series-c..
Although not intended for this application, Hall-effect switch can be used as the basis for a rather unusual oscillator. The oscillator can be reconfigured, as shown in Fig. B, to allow the circuit`s oscillating frequency to be controlled via an RC network, ..
This circuit uses the low power ICM7555 (CMOS 555) to generate the gating, STORE and RESET signals. To provide the gating signal, the timer is configured as an astable multivibrator. The system is calibrated by using a 5 M potentiometer for Ra as a coarse....
This new loop antenna by Graham Maynard is his best design yet and I am proud to be the first to present his work. It uses one, six foot square, six turn loop, and is aperiodic in nature, covering the frequency range 50KHz - 5000KHz...
?? ??????? ????? ??? ???????? ?????? ????????? ??? ???????????? TDA7294 ??????????? ??????????, ?? ???? ???? ?????????????? ??? ???. ?? ?????????? ?????? ?????????? ?? ???? ??, ???????????? ?? ????? ????? ???? ?? ?????? 8? ??? 4?. ?? ???? ???? ?????????....
The supply receives + 20 Vdc from the rectifier/filter section. This is applied to pins 11 and 12 of the uA723, as well as to the collector of the 2N3055 series-pass transistor. The output voltage is sampled through R1 and R2, providing about 7 V with....
This circuit turns a common oscilloscope into a versatile eight-channel display for direct voltages. The trend of each of the eight input levels is readily observed, albeit that the attainable resolution is not very high. The circuit diagram shows the use....
When the switch is closed or the FET is conducting, the circuit behaves as an inverting amplifier with a gain of R2/Rl. Since as the inverting tenninal of the op amp is a virtual ground, the capacitor is kept charged to the output voltage by the op amp.....
Old TV tubes are used as cold cathode x-ray emitters in a simple apparatus developed by Bob Templeman of Chicago, Illinois. With selected beam power tubes of the type used in the high voltage section of TV receivers, the intensity is adequate to make x-rays....
If R, the sensor matching resistor, is equal to the "dark" resistance of the cadmium sulfide cell, the amplifier output will range from 0 to "" 2 as the lightlevel ranges from "dark" to "bright." The circuit in Fig. B operates similarly, but use the....
The operating voltage of white LEDs coupled with my emotional need for low cost for a given function, motivates me to make LED drivers suitable for battery operated lanterns that can run from a small number of cells. White and Ultraviolet LEDs available at....
A touch-sensing circuit keeps the high-voltage generator cut off until something touches the fence wire. Contact with the fence sensing circuit wire starts the high-voltage generator which applies a series of 500 microsecond pulses at approximately 300 volts....
With all DHT stages (all tubes from Svetlana 1970-s). OK, the input/splitter are not DHT`s but DHP`s - 4P1L - triode wired. Mullard 3-tube input/splitter topology, cap-coupled to cathode bias 6B4G PP. First stage uses battery bias (no cathode resistor). Only....
Here we have three choices, with which we can make electronic switches that use our touch or pressing (push button). We thus exploit the very big resistance of entry, that present the gates CMOS. In the fig.1 we have two gates NAND or NOR (IC1), connected as....
The D169 serves as a level detector and provides complementary outputs. The op amp is used to integrate the input signal Vin with a time constant of R1C1. The input (must be negative) causes a positive ramp at the output of the integrator which is summed....
There are many ways to create a stereo effect. If you were miking a piano, a string section, or some other large sound source, you`d probably stick up a pair of directional mikes and assign them left and right. But what if you want to "enlarge" a lead....
The fan employed is one of the new electrostatic type which is very reliable, because it contains no wearing parts. These devices require high-voltage drive. When power is applied, the thermistor, located in the fan"s exhaust stream, is at a high value.....
This circuit will give provide a Good Strobe Effect for a variety of Portable Uses. Nominal current draw is "up to about" 1 amp at 12 volts. Depending on value of capacitor on pin 2 of the 555 and the particular choke that is used...
This low-power inverter uses only 9 parts and turns 10 to 16 Vdc into 60-Hz, 115-V square-wave power to operate ac equipment up to 25 W. The first section of the 556 timer chip is wired as an astable oscillator with R2 and C1 setting the frequency. The....
In the 556 timer, the timing is a function of the charging rate of the external capacitor. For long time delays, expensive capacitors with extremely low leakage are required. The practicality of the components involved limits the time between pulses to....
The electronic lantern control circuit adds high-efficiency dimming and flashing to an existing battery-powered lantern or flashlight or to a custom design. For the car it makes a great lamp for changing a flat tire, back seat reading or emergency engine....
The circuit is also an inexpensive VCO (voltage-controlled oscillator) with only five components. Many types of ceramic capacitors for surface-mount placement are on the market. The parts become continually smaller because of space problems on the board, and....
This preamplifier was designed to cope with CD players, tuners, tape recorders etc., providing an ac voltage gain of 4, in order to drive less sensitive power amplifiers. As modern Hi-Fi home equipment is frequently fitted with small loudspeaker cabinets,....
The circuit of AM transmitter is designed to transmit (amplitude modulated) DSB (double side band) signals. A modulated AM signal consists of a carrier and two symetrically spaced side bands. The two side bands have the same amplitude and carry the same....
Running from a 9-V battery, this transmitter can be used as a wireless microphone with an ordinary 88- to 108-MHz FM broadcast receiver. Keep the antenna length under 12 inches to comply with FCC limits. LI is 6 turns of #24 wire wound around a pencil or a....
This is a compact three transistor regenerative general coverage receiver with fixed feedback. It`s based on the principle of the ZN414 only much higher coverage. The sensitivity and selectivity is relative good (especially on the LF and MW bands) as can be....
Working on live telephone circuits can be a problem. You just can't connect a normal scope probe to the circuit while it is tied to the phone line. Neather side of a phone line is ground. When a phone or other device is 'offhook', one side floats at about....
Save fuel bills and the economy of the planet with this circuit. SW1 is a normally open press button switch which allows you to view the level of hot water in a hot water tank. When pressed the voltage difference at the junction of the thermistor and preset....
It's basically a photovore with a couple tactile sensors. It's rather complex but can give neat behaviors with modifications to the circuit. At this point I don't have any plans to give more information on this circuit so your on your own. C1 and C2 values....
This circuit provides a good siren noise suitable for warding off robot-predators! Change the pitch by adjusting R2, and R5...
This circuit operates a relay each time a sound of sufficient intensity is made, thus one clap of the hands will switch it one way, a second clap will revert the circuit to the original condition. Q2 and Q3 form a Schmitt trigger. The JK flip-flop isoised as....
If your circuits experience frequency overvoltage conditions, continually replacing blown fuses can get pretty expensive. However, this shutdown circuit overcomes that deficiency by replacing the fuse with a relay and a low-current SCR. When the input....
This source is selected by pressing momentary-contact pushbutton switch SI. Switch SI is connected to the trigger of a 555 oscillator/timer (Ul) configured as a monostable multivibrator, wliich generates one short output pulse for each press of SI. That....
This circuit filters noise, such as glitches and contact bounce, from digital signals. You can easily adjust the circuit for a wide range of noise frequencies. The circuit"s output changes state only if the input differs from the output long enough for....
Unijunction transistors Ql and Q2 are both connected as relaxation-type, sawtooth oscillators. Transistor Ql is the low-frequency control oscillator and Q2 is the tone generator. Sawtooth waveforms are produced at the emitter terminals. Without R4....
A typical circuit at 20 MHz is shown. The crystal, which has an internal series resistance Rs of 14ohm, oscillates at its third harmonic. The diode clamp Dl and D2 provides a constant amplitude control. ..
If the input frequency is known, the timer can easily be used as a frequency divider by adjusting the length of the timeing cycle. Figure shows the waveforms of the timer when used as a divide-by-three circuit...
This circuit uses a ring counter made up of Q3, Q4 and Q5. Q2 acts as an oscillator which triggers the SCRs Q3, Q4 and Q5 in sequence. When an SCR fires, a 0.2µ¥ capacitor provides commutation, shutting off the previous stage...
Assume first that SCR1 is on and SCR2 is off so that CI is fully charged, with its LMP2 end positive. The..
Each time a pulse is applied to the conversion of the control input, Ql resets the 1000 pF capacitor to 0 V. This action takes 200 ns to reset the falling edge of the convert command pulse, the capacitor begins to charge linearly. In exactly 10 microseconds,....
Time IO-bit conversion is 3.3 MHz with a p 3. Clock. This converter uses an approximation 2504 12-bit register in successive operating mode where the short-cycle end signal conversion is taken from the first bit used in the SAR (QLO)...
Because the CS5501 16-bit-delta-sigma analog-to-digital converter lacks a start convert command, it converts continuously, outputting conversion words to its output register every 1024 cycles of its master clock. However, by incorporating a standard dual....
This circuit uses buffer stages to prevent channel crosstalk back through the mixer resistor network. The potentiometers used for each stage allow for convenient signal strength adjustment, while maintaining input impedance matching at the 600-0 audio....
Volt regulators such as the LM708, and LM317 series (and others) sometimes need to provide a little bit more current then they actually can handle. If that is the case, this little circuit can help out. A power transistor such as the 2N3772 or similar can be....
This page presents information on infrared - `Across The Track` train detection circuits. The circuits are designed around the LM339 comparator chip and can use a wide assortment of matched infrared - emitter / detector pairs...
LochMaster is a developers tool for stripboard projects. It has useful functions for designing, documenting and testing a board. Therefore you will find features like auto-generation of components lists, a connection test, an editable library with a large....
Building ESLs involves the use of tools and materials that if handled improperly can be hazardous. Please make sure you know how to use these things before you begin. By all means, use safety glasses at all times. If would be foolish to trade your vision for....
This bull horn uses U1 as a driver stage and U2 as an output driver. U1 is set up for a gain of 200. The microphone should have a..
PID-Control with 68HC11. STEPPER CONTROL. 68HC11 read encoder. High accuracy RPM-measurement with 68HC11..
This stereo encoder is a halfway between analogue and digital processing. It combines the best from both domains to provide high-quality and easy to build device. The sampling frequency used in this stereo encoder is 97 times (!!!) higher than the pilot tone....
This adaptor will capture plots or prints of your GPIB instrument to your PC through the USB port. It fills the need of anybody who has a test instrument with the GPIB port and likes to get the screen dump on his PC without any GPIB card or complex software.....
Channell is wired as a conventional integrator, and channel2 as a voltage follower. When channel2 is switched on, the output will follow VJN and C will discharge to maintain 0 V across it. When channel! is then switched on, the output will initially be at....
This circuit is a frequency meter, low cost. It covers region 1HZ until 1MHZ. The IC1 schmitt trigger that it regulates the signal of entry and him changes in reasonable level suitable for the IC2-3-4. With the tenth pulse in the entry of IC2/1, is produced....
This lighting-control unit will fade out one lamp while simultaneously increasing the light output of another. The two loads track each other accurately without adjustments. The gate of SCRl, a silicon-controlied rectifier, is driven from a standard....
This circuit uses a low-input-bias op amp to give a steady dc indication of light level. To reduce circuit sensitivity to light, Rl can be reduced, but should not be less than 100 K..
This amplifier was born out of a need to use two sets headphones with my computer's sound-card. The design presented here is a 50mW power amplifier meant for phones with impedances of 32 Ohms and greater. I chose this class A topology, because it offers very....
The amplifier operates from supplies ranging up to 12 volts, and operates (with reduced volume) from supply voltages as low as 1.8 volts without having distortion rise to unacceptable levels. (Its power requirements make it suitable for solar-cell....
This project is a 3 or more lines mixer. For more than 3 inputs you can repeat the input parts (P=10K R=22K). It powered with 9Vdc...
I designed this circuit for one friend of mine to be used as a small portable DJ mixer. The circuit is an audio mixer circuit so simple as it can be. There are two dual logarithmic potentiometers in the circuit to adjust the input signal levels and some....
This is an enhanced 5 digit keypad which may be used with the Modular Alarm System...
The circuit is capable of charging a 12 volt component selection. When the battery voltage battery at up to a six ampere rate..
Four blacklight lamps, 15W each, emit radiation at the region of UVA, with a peak around 350nm where the thin surface above the copper of the photosensitive board, is... sensitive. The lamps are taken by two and are connected in series thus shaping two....
When the 555 ic goes into timing mode (triggered by an output signal from the sound detector amplifier,) the timer`s output (pin 3) is set into HIGH for a duration set by C2, and R2. adjusting R1 will adjust how long it listens, from 10 seconds all the way....
When building amplifiers, it is often necessary to test transistors, either to verify that they (still) work, or for some esoteric designs it may even be necessary to match certain characteristics. The design featured here is just what you need, and....
You can build an automatic gain control AGC for the superhet receiver with only a few additional components. The first AGC circuit is more universal. It is suitable for audio amplifiers with dual op amps like TL072, TL082, NE5532 and the broadband amp NE592....
This tester is for tracing wiring on Printed Circuit Boards. Resistors below 50 ohms act as a short circuit; above 100 ohms as an open circuit. The circuit is a simple multivibrator switched on by transistor T3. The components in the base of T3 are Dl, Rl,....
Amplify or record a telephone call with the simple circuit shown. The 8-0 secondary winding of a miniature transistor output transformer is connected in series with either of the telephone lines. ..
The laser diode·pulser is a simple drive circuit capable of driving the laser diode with 10-A, 20-ns pulses. For a 0.1 % duty cycle, the repetition rate will be 50 kHz. A complementary emitter follower is used as a driver. Switching speed is determined by....
A 555 and a dual 556 timer generate a rudimentary video signal, as shown in the schematic. The first timer generates 4.7-8 synch pulses operating in the astable mode with a 64-8 period. The second timer generates a delay pulse, which triggers the third....
This new circuit uses four chips, with an option of using just three (the flip-flops and AND g..
For other input structures see Figures 6 to 11; shown here with PC-filter (Figure ß). The micropoco capacitor has a temperature coefficient of 125.10"6i 60.10" k"1. In simplified circuits a fixed resistor (e.g. 620k) can be used for a guaranteed switching....
When activated, the transmitter sends out a 49.890-MHz, AM rf carrier. The.receiver detects, amplifies, and decodes the rf signal, which, in turn, activates a piezo buzzer. The receiver is small enough to carry in a pocket or sit on your workbench. ..
The LTC1063 is the first monolithic low-pass filter that simultaneously offers outstanding dc and ac performance. It features internal or external clock tunability, cutoff frequencies up to 50 kHz, 1-mV typical output dc offset, and a dynamic range in....
By mixing an audio signal with ultrasound, you can hear the audio as if it's inside your head... even if the 'headphones' are nowhere near your ears. Patrick Flanagan invented the "Neurophone" over 40 years ago. His original patent (US3393279) was basically....
A programmable 8 step tone sequencer using an Arduino microcontroller. Features a 2 line x 16 character backlit LCD display..
This hookup is useful in some house wiring situations, where only two wires are available between switches, rather than..
A J309 Siliconix FET feeds a 2N5109 in a wideband RF amplifier configuration. A relay is used to bypass the amp..
The philosophy behind this minimalist design has been explained by Flavio Dellepiane on his highly interesting site 1. I have myself written an article about this fleapower amp from Italy in the American magazine AudioXpress 2. All relevant details are....
The main part of this circuit is the LM386 amplifier chip. It also uses a transistor input to buffer the input signal and provide extra gain for the LM386. The little unit has helped me out on numerous occasions when trouble shooting any amplifier circuit....
The LT1007 is capable of providing excitation current directly to bias the 350-0 bridge at 5 V. With only 5 V across the bridge, as opposed to the usuallO V, total power dissipation and bridge warm-up drift is reduced. ..
This highly sensitive movement detector is designed from bipolar transistors and draws a curren..
The circuit uses two general-purpose npn transistors, Ql and Q2, and a special hand-wound, dual-coil probe ferrets out the magnetism. Ql and its associated components form a simple VLF oscillator circuit, with LI, C2, and C3 setting the frequency. The VLF....
This very simple counter can be used to measure the frequency of various wireless devices. Applies in reviving the transmitter and its operation as a control monitor frequency. It can be used as a scale to the receiver. Due to the simplicity of the counter....
The sensor circuit is adaptable to different liquids and sensors. The constant-current source drives current through the sensing probe and a fixed resistor..
The two circuits di atas illustrate opening a relay contact a short time after the ignition or ligh switch is turned off. The capacitor is charged and the relay is closed when the voltage at the diode anode rises to 12 volts. The circuit on the left is a....
