New Circuits Page 212
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The first pulse motor that is used to diss it because it is the positioning control things, we decided to incorporate features that may be needed for positioning control. This does not mean that intelligent, and autonomous driving the motor in response to....
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This free-running multivibrator uses an external current sink to discharge the timing capacitor, C. Therefore, interval ^ may easily be 1000 the pulse duration, t1( which defines a positive output. Capacitor voltage, V^, is a negative going ramp with....
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With 3-V to 9-V supplies, this amplifier can provide from 100-mW to 1-W output into a 4 and bandwidth is approximately 20 kHz @ 3 dB. This circuit is useful for low-power and battery applications...
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This dual astable multivibrator provides versatility not available with single timer circuits. The duty cycle can be adjusted from 5% to 95%. The two outputs provide two phase clock signals often required in digital systems..
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The power supply is based on the LM317 and LM337 variable 3-terminal regulators ICs, and while it is no powerhouse, it is quite satisfactory for testing most power amps, as long as there is no speaker connected...
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This document describes how to construct a dual polarity linear power supply which can be configured for any positive or negative voltage between 1.2-35V. A power supply is the fundamental building block of all but the simplest of electronic devices. It....
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Useful for checking TV remote controls, IR-based alarm systems, and IR sources, this circuit causes LED1 to turn on for two sec..
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It can drive up to 128 individual relais, solenoids, motors, fireworks, pyrophones, etc. With a MIDI note-on message you may switch on one of the 128 LEDs (or relais). Outputs may be switched off by sending a note-off message, or by a note-on with zero....
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A resonance-tuned narrow-band amplifier reduces this optical object detector"s sensitivity to stray light. C1 and L1 in IC2A"s feedback loop cause tbe op amp to pass only those frequencies at or near the LED"s 5-kHz modulation rate. ..
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The circuit in Figure 1 uses a fully differential amplifier to offer an answer to this problem. Fully differential amplifiers enable you to deliver an output-voltage swing beyond the rails into the load. One of the common problems in working with operational....
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The tone burst generator supplies a tone for one-half second after the power supply is activated; its intended use is a communications network alert signal. Cessation of the tone is accomplished at the SCR, which shunts the timing capacitor CI charge current....
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This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low....
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A op amp and transistors Q1 and Q2 exponential converter to generate an exponential gain control current, which is introduced into the rectifier. A reference current of 150 pA, (15 V and RZO = lOO-k), is attenuated by a factor of two (6 dB) for each increase....
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Audio graphic equalizers are very common as commercial products (for Hi-fi, car audio and stage use) but circuits for them are very rarely published. I didn`t design this one but it`s really very simple. The details shown are for a 7 band but the principle....
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A simple 3-way crossover, intended for triamping Hi-Fi systems. This is a conventional 12dB / Octave unit, and cannot be expected to have the same performance as a Linkwitz-Riley aligned filter network. It will still be a vast improvement over nearly any....
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The driver circuit (see the complete schematic) has 4 main sections:
* the voltage definition,
* the integrator,
* the current booster, and
* the foldover. The schematic is drawn so that higher voltages are toward the top and lower....
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Linear battery chargers are typically smaller, simpler and
less expensive than their switcher-based counter parts,
but they have one major disadvantage: excessive power
dissipation when the input voltage is high and the battery
voltage is low (discharged....
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By coupling two back-to-back diodes in series with an ac power circuit, a voltage of about 1.4 Vpp can be obtained. This..
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A very sensitive pico ammeter (— 1 V/pA) employs the amplifier in the inverting or current summing mode. Care must be taken to eliminate stray currents from flowing into the current summing mode. It takes approximately 5 for the circuit to stabilize to....
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This is the basis of electronics telephone sets. You can use it to replace the talking circuit of an old telephone set with new design, better noise rejection and reliability one. Also you can use it to build a telephone set without dial circuit to answer a....
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The board has been initially developed to learn with CAN, so a CAN transceiver is available (IC4). The CAN transceiver comes from Maxim, but some other manufacturers provide some compatible CAN transceivers which can be used. An RS232 transceiver is also....
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A simple voltage-controlled oscillator (VCO), coupled to your instrumentation by an optoisolator, allows you to mea..
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This circuit takes standard 0-10V control voltage (for example from analogue light controlling desk) and outputs a standard 1-2 ms RC servo motors control pulse. Power supply: 4-5V DC (same as for RC servo), consumes 15 mA of current. Control voltage range:....
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This Design Idea provides a simple, inexpensive, portable circuit as an alternative to a microcontroller to provide a wide-range source of low-distortion sine waves for audio-circuit design and debugging. Although sine waves from DDS (direct digital....
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A microcontroller implements the proper protective action when one of the temperature monitors detects an overtemperature condition. It is sometimes easier and more cost-effective to simply disconnect the offending circuit from the power supply without....
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This circuit uses low-cost IN4148 diodes and exhibits about 1.5 dB insertion loss from 10 to 1000 MHz w..
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This circuit compares a rectified input, f."!N, with a voltage that decays exponentially across a 4. 7-KO resistor and a ·o.Ol-I"F capacitor. Comparing the exponentially decaying voltage with the rectified input provides a peak-level indication that....
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This circuit uses the +5 V reference output and the op amp to level shift and amplify the 2.1 mV/°C Tempco output into a voltage signal dependent on the ambient temperature. Different scaling can be obtained by selecting appropriate resistors from the....
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This circuit is a high-input impedance version of the so-called diode pump or staircase generator. Note that charge transfer takes place at the negative-going edge of the input signal. The most common application for staircase generators is in low-cost....
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SI is external key switch. The alarm allows a 0- to 45-s delay after SI is operated before the circuit is armed. During this per..
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This tachometer lets you measure heartbeats, respiratory rates, and other low-frequency events that recur at intervals of 0.33 to 40.96 seconds. The circuit senses the period offm, computes the equivalent pulses per minute, and updates the LCD accordingly.....
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This HF SW receiver preamplifier is comprised of a broadband toroidal transformer (LI-a and Ll-b), a complex LC network (comprised of a 1600- kHz, high-pass filter and a 32-MHz, low-pass filter), L2 and L3 (26 turns of #26 enameled wire wound on an Amidon....
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LED1 and LED2 indicators turn on and remain on, each time the circuit is triggered. During the timing cycle, U1 "s Q output at pin 10 becomes positive when the Q output at pin 11 becomes negative. ..
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Using a single 555 Timer IC and a small transformer to generate a high voltage, this circuit will test zener diodes of voltage ratings up to 50VDC. The 555 timer is used in the astable mode, the output at pin3 drives a small audio transformer such as the....
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This application note describes how LEDs (including white LEDs) work. The note also explains how to drive them in battery-powered LED applications, including lithium-ion (Li+ or Li-ion), nickel-cadmium (NiCd), and nickel metal-hydride (NiMH) rechargeable....
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This circuit uses a VFO operating from 15 to 18 MHz (Ul), which feeds a balanced mixer (U2). A fixed oscillator signal is mixed with this signal to generate an output from 0.4 to 33 MHz. FL1 and FL2 are low- and high-pass filters that are used to eliminate....
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What is the effect of digital signal bits cross-talking into the analog section of a data-conversion system? There is a lot written into the data sheets of ADCs and DACs on how to minimize it. But, when asked what is the result, most laymen have the insight....
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A 555 timer drives Ql through Q4 with a square wave. LED1 and LED2 light when an npn or pnp transistor respectively, are ..
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This electronic motor-speed control circuit is designed to operate in an electrically noisy environment. The circuit includes an optoelectronic pickup device. whichis placed inside the motor housing to provide a speed feedback signal. The circuit....
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Most standard household appliances and portable hand tools can be adapted to variable -speed operation by use of this simple half-wave SCR phase control. It can be used as the speed control unit for the following typical loads pro-videe they use series....
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The particular circuit does?t have the requirement to replace the trade decoders Surround, because this they have many more facilities and possibilities. It give however the possibility in many try with this article of decoding. The coding in Stereo Dolby....
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Using this circuit you can convert the 12V dc in to the 220V Ac. In this circuit 4047 is use to generate the square wave of 50hz and amplify the current and then amplify the voltage by using the step transformer. How to calculate transformer rating The basic....
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Transistor Q5 and the 1000 ohm resistor form the variable element needed for controlling the frequency of VCO by limiting the charging current flowing into the 0.15 timing capacitor according to the forward bias being applied to Q5. As the voltage on pins 2....
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Use of a differential capacitor allows temperature compensation of LC circuit using an NFO and N1500 ceramic. C6 is a differential capacitor that has two stators and one common rotor. When one capacitance (stator) is maximum, the other is minimum...
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This circuit turns on a relay when two buttons are pressed at the same time.The relay backs off after few seconds, then the buttons have to be released and pressed again. This feature is often required in industrial safety...
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The input stage is an LF351 op amp which provides most of the open loop gain as well as stabilizes the quiescent dc voltage. This feeds a level shift stage which references the voltage swing to the (-) rail. The transconductance stage is a darlington, to....
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This application note presents practical design considerations
for battery chargers employing Green Mode FPS
(Fairchild Power Switch). It includes designing the
transformer and output filter, selecting the components and
implementing constant current /....
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When working with electronics, you always need one basic thing; power. This power supply is great for powering all kinds of electronic projects. It produces a well filtered, variable 1.2-30 volts at 5 amps. It is easy to build and the parts are easy to find...
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Firstly, we will describe the "add-on" version for the 5x7 Display as this is the cheapest version and, quite frankly, it only deserves a few dollars as a piece of test equipment.
It`s "all the rage" to have an Electrolytic Tester for servicing equipment....
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This project is a combination Logic Probe and Logic Pulser. It is capable of testing all sorts of digital and microcomputer projects. You will find it extremely handy when designing a project as the golden rule is to test everything in steps and stages....
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Have you ever been using the modem or fax and someone else picks up the phone, breaking the connection? Well, this simple circuit should put an end to that. It signals that the phone is in use by lighting a red LED. When the phone is not in use, a green LED....
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Tones (from the DTMF) on the telephone line are detected by Ul. When a valid tone is received, pin 14 (D..
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RF based Automatic meter reading, or AMR, is the technology of automatically collecting data from energy meter and transferring that data to a central database for billing and/or analyzing. This means that billing can be based on actual consumption rather....
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This circuit modulates a light beam with voice or music from the output of an amplifier. If the 10 K pot is adjusted to slightly less than the Vbe of the transistor, the circuit forms a peak detector..
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Since standard CMOS logic operates down to 3-V supply voltages and is specified as low as 30 p.A maximum current sinking/sourcing capability, it is necessary to use a buffer transistor to provide the required current to the IRED if CMOS is to drive the....
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This circuit, which was developed to monitor the traffic of bumblebees in and out of the hive, differentiates a-to-b motion from b-to-b motion. When used with an optical decoder, the circuit distinguishes clockwise from counterclockwise rotation and....
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This is audio mixer circuit. The circuit is for one channel input, if you need, for example 5 channel mixer, then you need to build 5 similar circuits...
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This is a versatile distortion pedal. Think of it as analogue modelling, using analogue circuitry to model a wide range of analogue distortion devices. It includes the main elements found in the majority of distortion boxes. The unit comprises four sections:....
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This LED thermometer is designed for in home use, to read temperatures between about 60 and 78 degrees Fahrenheit. It is based around a precision temperature sensor IC, the LM34DZ. This sensor require no calibration and can measure temperatures of between....
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By introducing an extra transmission zero to the stopband of a low-pass filter, a sharp roll-off c..
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This circuit is a variable audio bandpass filter that has a low cutoff variable from about 25 Hz to 700 Hz and a high cutoff variable from 2.5 kHz to over 20 kHz. Rolloff is 12 dB/octave on both high and low ends...
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The monostable period is set for about 1 second, as is the usual case. The induced line hum comes through C2, providing a continuous string of trigger pulses. The output becomes low for about 10 ms per second as the monostable times out and then....
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Here's a circuit to create a buzzcoil using a standard automotive ignition coil. A 556 dual timer is used to establish the frequency and duty cycle of the coil current. One of the timers is used as an oscillator to generate the 200 Hz rectangular waveform....
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The charger is based on a charging voltage of 2.4 V per cell, in accordance with most manufacturers' recommendations. The circuit pulses the battery under charge with 14.4 V (6 cells ? 2.4 V per cell) at a rate of 120 Hz. The design provides current limiting....
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When an input voltage is positive, the output of ICA is negative and diode D does not conduct; hence the outp..
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This is a spectacular but completely useless project. It lights Ultra-Bright LEDs in a sequence and each LED flashes brightly very briefly. The LEDs light-up going around and around since they are mounted in a circle (on a CD), then they pause before chasing....
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The CIRThis article will show you how to build your own version of the Fire-Stick infrared remote control system. The Fire-Stick has been an extremely popular, and HOT selling item here at Rentron.com for quite a long time. The LITEON infrared receiver....
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This project is a piece of test equipment. It`s a square wave oscillator with 6 selectable frequencies from 1Hz to 100kHz, incrementing in decade values. It`s most useful application is as a Signal Injector for radios and TV`s. A square wave is the most....
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A 4001 CMOS Quad NORgate is set up as an astable multivibrator, which drives a simple differentiator and relay..
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The circuit charges a 9-V battery at about 30 mA per input ampere at 0.4 V. Ul, a quad Schmitt trigger, operate as an astable multivibrator to drive push-pull TMOS devices Ql and Q2. Power for Ul is derived from the 9-V battery via D4; power for Ql and Q2 is....
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The waveform of a steam whistle is a complex combination of white noise and an audio frequency oscillation. The noise generator is a transistor (Ql) biased into zener mode. The audio frequency oscillation is a straightforward mixture of two similar (but not....
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The XSV-300 board is a versatile FPGA development
board providing a 300-Kgate FPGA,
programmable clock oscillators, standard PC interface
components (e.g. a USB-Transceiver),
Flash memory, RAM and 7-segment displays...
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Each stage provides 0° to 180° phase shift. By ganging the two stages, 0° to 360° phase shift is achieved This circuit is under:, power supplies, ac dc dc dc, 0° To 360° phase shifter l12884. By ganging the two stages, 0° to 360° phase shift is achieved The....
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The broadband amplifier NE592 can be used also for building a simple selective audio amplifier. By means of the +6 V and +12 V supply voltages a DC coupling between the product detector and the AF amplifier is possible. The DC level at the differential....
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This circuit is configured for the 80m band. The 365-pF, broadcast-band variable capacitor should have a vernier drive with a six-to-one ratio, which makes tuning easier by separating the stations on the dial. A good antenna and ground are also....
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The 4047 is configured as a monostable multivibrator circuit or one shot that is set up to trigger on a negative-transition of the signal applied to its pin 6 input. The multivibrator"s on time is determined by the values of R1 and Cl. Although R1 is....
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The rechargeable Li-ion, I began to intensely interested last summer, when I managed to bring a holiday without a phone charger. After several experiments involving originated in Figure 1, which has proved. Involvement of the stage provides a limited current....
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The circuit powers the load via the regulator"s input instead of its output. Because the regulator"s output sees constant dummy load R1, it tries to consume a constant amount of current, no matter what the voltage across the actual load really is. Hence,....
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This design used to measure air or gas flow works by measuring the energy required to maintain a heated resistance wire at constant temperature. The positive temperature coefficient of a small lamp, in combination with its ready availability, makes it a good....
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The design of low-phase-noise oscillators requires careful attention to resonator unloaded Q. In the construction of a low-phase-noise, high-frequency oscillator, the goal is to achieve an unloaded-Q figure greater than 400 in a reasonable package. Also, you....
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This project is a dedicated device. It dials a single phone number when the handset is lifted. There are two different modes of operation.. A slide-switch on the PC board allows the project to operate in automatic or manual mode. If the switch is in "auto....
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Although ceramic resonators are a good choice for low-power, low-frequency clock sources (if you can stand their 30-ppm te..
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This circuit uses a dc amplifier (324) in a bar-graph circuit that uses an LM339 Quad comparator IC to sense dc levels. ..
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Few years back, I had been working on a project for solar auto lighting. The light will turn on when the the solar panel voltage drop below a set point indicating that it is dark. The detection is done by using D2 in the schematic. The zener diode value will....
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A touch switch is a switch that is turned on and off by touching a wire contact, instead of flicking a lever like a regular switch. Touch switches have no mechanical parts to wear out, so they last a lot longer than regular switches. Touch switches can be....
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For the outband decoder shown here to work, the cable company must provide at least a 1 millivolt signal. Values for C1-C5 and L1-L4 ore found In Table 1. This circuit consists of an amplifier for the synch channel and a video detector which controls an....
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The computer optimized 9 el. homebrew antenna is performing very well. I have
made many long distance contacts using the ON6MU VHF Yagi antenna. I have the antenna
located only 35 feet above the ground. (See antenna photo titled KC8VWM to
see how high it....
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The transmitter consists of an oscillator which drives a high output IR emitting diode. The oscillator is a sJire start multivibrator circuit that provides an output of 15 to 1000 mark to space ratio at a frequency of 1 kHz. This large mark to space ratio....
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This strobe light operates from standard 120-Vac power. Rl limits the amount of current applied to the voltage doubler stage, which is comprised of CI, C2, C3, Dl, D2, C4, C5, and C6. Capacitors CI, C2, and C3 are connected in parallel and form a....
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The circuit presented here is a simple audio/video transmitter with a range of 3 to 5 metres. The A/V signal source for the circuit may be a VCR, a satellite receiver or a video game etc. A mixer which also operates as an oscillator at VHF (H) channel 5 TV....
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Adding a diode, a resistor, and a capacitor to the SAW (surface-acoustic-wave) oscillator allows you to use the oscillator in FSK (frequency-shift-keying) applications. Dl, Rl, and Cl form a simple diode switch in which Dl shunts Cl to ground. When the....
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You can use this powerfull amplifier in any small audio project. It is very small (6.5 x 4.5 cm).It outputs 10W and uses a 9V battery...
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Figure 1 represents a cheap and simple Gate Alarm, that is intended to run off a small universal AC-DC power supply. IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate....
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The circuit consists of a small PIC microcontroller, assembly program,
and a few other parts to detect a switch closure from an open door, window,
or manual push button and then dial the cell phone number, and transmit a
steady tone to indicate the source....
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The value of the design lies in the use of IC1, an LM317HVK adjustable s.eries-pass voltage regulator, for broad-range performance remainder supplies voltage-setting and current-limiting functions. The input to ICI-comes from the output of BR1, which is....
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This circuit will operate a car"s headlights for a predetermined time to light up the driveway or path after the driver has left the car. SQl is pushed and Q2 is turned on closing the relay and turning on the car"s headlights. Cl begins to charge through VR1....
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The watchdog circuit in Figure 1 uses a single NAND Schmitt-trigger IC. The circuit is more cost-effective than dedicated, commercially available watchdog ICs. The circuit generates an active-high reset signal upon power-up and remains in a low state as long....
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Security is a prime concern in our day-today life. Everyone wants to be as much secure as possible. An access control for doors forms a vital link in a security chain. The Microcontroller based Home Security System can be adopted at Home it has various type....
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This circuit detects metal and also magnets. When a magnet is brought close to the 10mH choke, the output frequency changes. ..
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The oscillator delivers an output of high spectral purity without any substantial sacrifice of the usual stability of a crystal oscillator. The crystal in addition to determining the oscillator's frequency, is used also as a low-pass filter for the unwanted....
The first pulse motor that is used to diss it because it is the positioning control things, we decided to incorporate features that may be needed for positioning control. This does not mean that intelligent, and autonomous driving the motor in response to....
This free-running multivibrator uses an external current sink to discharge the timing capacitor, C. Therefore, interval ^ may easily be 1000 the pulse duration, t1( which defines a positive output. Capacitor voltage, V^, is a negative going ramp with....
With 3-V to 9-V supplies, this amplifier can provide from 100-mW to 1-W output into a 4 and bandwidth is approximately 20 kHz @ 3 dB. This circuit is useful for low-power and battery applications...
This dual astable multivibrator provides versatility not available with single timer circuits. The duty cycle can be adjusted from 5% to 95%. The two outputs provide two phase clock signals often required in digital systems..
The power supply is based on the LM317 and LM337 variable 3-terminal regulators ICs, and while it is no powerhouse, it is quite satisfactory for testing most power amps, as long as there is no speaker connected...
This document describes how to construct a dual polarity linear power supply which can be configured for any positive or negative voltage between 1.2-35V. A power supply is the fundamental building block of all but the simplest of electronic devices. It....
Useful for checking TV remote controls, IR-based alarm systems, and IR sources, this circuit causes LED1 to turn on for two sec..
It can drive up to 128 individual relais, solenoids, motors, fireworks, pyrophones, etc. With a MIDI note-on message you may switch on one of the 128 LEDs (or relais). Outputs may be switched off by sending a note-off message, or by a note-on with zero....
A resonance-tuned narrow-band amplifier reduces this optical object detector"s sensitivity to stray light. C1 and L1 in IC2A"s feedback loop cause tbe op amp to pass only those frequencies at or near the LED"s 5-kHz modulation rate. ..
The circuit in Figure 1 uses a fully differential amplifier to offer an answer to this problem. Fully differential amplifiers enable you to deliver an output-voltage swing beyond the rails into the load. One of the common problems in working with operational....
The tone burst generator supplies a tone for one-half second after the power supply is activated; its intended use is a communications network alert signal. Cessation of the tone is accomplished at the SCR, which shunts the timing capacitor CI charge current....
This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low....
A op amp and transistors Q1 and Q2 exponential converter to generate an exponential gain control current, which is introduced into the rectifier. A reference current of 150 pA, (15 V and RZO = lOO-k), is attenuated by a factor of two (6 dB) for each increase....
Audio graphic equalizers are very common as commercial products (for Hi-fi, car audio and stage use) but circuits for them are very rarely published. I didn`t design this one but it`s really very simple. The details shown are for a 7 band but the principle....
A simple 3-way crossover, intended for triamping Hi-Fi systems. This is a conventional 12dB / Octave unit, and cannot be expected to have the same performance as a Linkwitz-Riley aligned filter network. It will still be a vast improvement over nearly any....
The driver circuit (see the complete schematic) has 4 main sections: * the voltage definition, * the integrator, * the current booster, and * the foldover. The schematic is drawn so that higher voltages are toward the top and lower....
By coupling two back-to-back diodes in series with an ac power circuit, a voltage of about 1.4 Vpp can be obtained. This..
A very sensitive pico ammeter (— 1 V/pA) employs the amplifier in the inverting or current summing mode. Care must be taken to eliminate stray currents from flowing into the current summing mode. It takes approximately 5 for the circuit to stabilize to....
This is the basis of electronics telephone sets. You can use it to replace the talking circuit of an old telephone set with new design, better noise rejection and reliability one. Also you can use it to build a telephone set without dial circuit to answer a....
The board has been initially developed to learn with CAN, so a CAN transceiver is available (IC4). The CAN transceiver comes from Maxim, but some other manufacturers provide some compatible CAN transceivers which can be used. An RS232 transceiver is also....
A simple voltage-controlled oscillator (VCO), coupled to your instrumentation by an optoisolator, allows you to mea..
This circuit takes standard 0-10V control voltage (for example from analogue light controlling desk) and outputs a standard 1-2 ms RC servo motors control pulse. Power supply: 4-5V DC (same as for RC servo), consumes 15 mA of current. Control voltage range:....
This circuit uses low-cost IN4148 diodes and exhibits about 1.5 dB insertion loss from 10 to 1000 MHz w..
This circuit compares a rectified input, f."!N, with a voltage that decays exponentially across a 4. 7-KO resistor and a ·o.Ol-I"F capacitor. Comparing the exponentially decaying voltage with the rectified input provides a peak-level indication that....
This circuit uses the +5 V reference output and the op amp to level shift and amplify the 2.1 mV/°C Tempco output into a voltage signal dependent on the ambient temperature. Different scaling can be obtained by selecting appropriate resistors from the....
This circuit is a high-input impedance version of the so-called diode pump or staircase generator. Note that charge transfer takes place at the negative-going edge of the input signal. The most common application for staircase generators is in low-cost....
SI is external key switch. The alarm allows a 0- to 45-s delay after SI is operated before the circuit is armed. During this per..
This tachometer lets you measure heartbeats, respiratory rates, and other low-frequency events that recur at intervals of 0.33 to 40.96 seconds. The circuit senses the period offm, computes the equivalent pulses per minute, and updates the LCD accordingly.....
This HF SW receiver preamplifier is comprised of a broadband toroidal transformer (LI-a and Ll-b), a complex LC network (comprised of a 1600- kHz, high-pass filter and a 32-MHz, low-pass filter), L2 and L3 (26 turns of #26 enameled wire wound on an Amidon....
LED1 and LED2 indicators turn on and remain on, each time the circuit is triggered. During the timing cycle, U1 "s Q output at pin 10 becomes positive when the Q output at pin 11 becomes negative. ..
Using a single 555 Timer IC and a small transformer to generate a high voltage, this circuit will test zener diodes of voltage ratings up to 50VDC. The 555 timer is used in the astable mode, the output at pin3 drives a small audio transformer such as the....
This circuit uses a VFO operating from 15 to 18 MHz (Ul), which feeds a balanced mixer (U2). A fixed oscillator signal is mixed with this signal to generate an output from 0.4 to 33 MHz. FL1 and FL2 are low- and high-pass filters that are used to eliminate....
A 555 timer drives Ql through Q4 with a square wave. LED1 and LED2 light when an npn or pnp transistor respectively, are ..
This electronic motor-speed control circuit is designed to operate in an electrically noisy environment. The circuit includes an optoelectronic pickup device. whichis placed inside the motor housing to provide a speed feedback signal. The circuit....
Most standard household appliances and portable hand tools can be adapted to variable -speed operation by use of this simple half-wave SCR phase control. It can be used as the speed control unit for the following typical loads pro-videe they use series....
The particular circuit does?t have the requirement to replace the trade decoders Surround, because this they have many more facilities and possibilities. It give however the possibility in many try with this article of decoding. The coding in Stereo Dolby....
Using this circuit you can convert the 12V dc in to the 220V Ac. In this circuit 4047 is use to generate the square wave of 50hz and amplify the current and then amplify the voltage by using the step transformer. How to calculate transformer rating The basic....
Transistor Q5 and the 1000 ohm resistor form the variable element needed for controlling the frequency of VCO by limiting the charging current flowing into the 0.15 timing capacitor according to the forward bias being applied to Q5. As the voltage on pins 2....
Use of a differential capacitor allows temperature compensation of LC circuit using an NFO and N1500 ceramic. C6 is a differential capacitor that has two stators and one common rotor. When one capacitance (stator) is maximum, the other is minimum...
This circuit turns on a relay when two buttons are pressed at the same time.The relay backs off after few seconds, then the buttons have to be released and pressed again. This feature is often required in industrial safety...
When working with electronics, you always need one basic thing; power. This power supply is great for powering all kinds of electronic projects. It produces a well filtered, variable 1.2-30 volts at 5 amps. It is easy to build and the parts are easy to find...
Firstly, we will describe the "add-on" version for the 5x7 Display as this is the cheapest version and, quite frankly, it only deserves a few dollars as a piece of test equipment. It`s "all the rage" to have an Electrolytic Tester for servicing equipment....
This project is a combination Logic Probe and Logic Pulser. It is capable of testing all sorts of digital and microcomputer projects. You will find it extremely handy when designing a project as the golden rule is to test everything in steps and stages....
Have you ever been using the modem or fax and someone else picks up the phone, breaking the connection? Well, this simple circuit should put an end to that. It signals that the phone is in use by lighting a red LED. When the phone is not in use, a green LED....
Tones (from the DTMF) on the telephone line are detected by Ul. When a valid tone is received, pin 14 (D..
RF based Automatic meter reading, or AMR, is the technology of automatically collecting data from energy meter and transferring that data to a central database for billing and/or analyzing. This means that billing can be based on actual consumption rather....
This circuit modulates a light beam with voice or music from the output of an amplifier. If the 10 K pot is adjusted to slightly less than the Vbe of the transistor, the circuit forms a peak detector..
Since standard CMOS logic operates down to 3-V supply voltages and is specified as low as 30 p.A maximum current sinking/sourcing capability, it is necessary to use a buffer transistor to provide the required current to the IRED if CMOS is to drive the....
This circuit, which was developed to monitor the traffic of bumblebees in and out of the hive, differentiates a-to-b motion from b-to-b motion. When used with an optical decoder, the circuit distinguishes clockwise from counterclockwise rotation and....
This is audio mixer circuit. The circuit is for one channel input, if you need, for example 5 channel mixer, then you need to build 5 similar circuits...
This is a versatile distortion pedal. Think of it as analogue modelling, using analogue circuitry to model a wide range of analogue distortion devices. It includes the main elements found in the majority of distortion boxes. The unit comprises four sections:....
This LED thermometer is designed for in home use, to read temperatures between about 60 and 78 degrees Fahrenheit. It is based around a precision temperature sensor IC, the LM34DZ. This sensor require no calibration and can measure temperatures of between....
By introducing an extra transmission zero to the stopband of a low-pass filter, a sharp roll-off c..
This circuit is a variable audio bandpass filter that has a low cutoff variable from about 25 Hz to 700 Hz and a high cutoff variable from 2.5 kHz to over 20 kHz. Rolloff is 12 dB/octave on both high and low ends...
The monostable period is set for about 1 second, as is the usual case. The induced line hum comes through C2, providing a continuous string of trigger pulses. The output becomes low for about 10 ms per second as the monostable times out and then....
Here's a circuit to create a buzzcoil using a standard automotive ignition coil. A 556 dual timer is used to establish the frequency and duty cycle of the coil current. One of the timers is used as an oscillator to generate the 200 Hz rectangular waveform....
The charger is based on a charging voltage of 2.4 V per cell, in accordance with most manufacturers' recommendations. The circuit pulses the battery under charge with 14.4 V (6 cells ? 2.4 V per cell) at a rate of 120 Hz. The design provides current limiting....
When an input voltage is positive, the output of ICA is negative and diode D does not conduct; hence the outp..
This is a spectacular but completely useless project. It lights Ultra-Bright LEDs in a sequence and each LED flashes brightly very briefly. The LEDs light-up going around and around since they are mounted in a circle (on a CD), then they pause before chasing....
The CIRThis article will show you how to build your own version of the Fire-Stick infrared remote control system. The Fire-Stick has been an extremely popular, and HOT selling item here at Rentron.com for quite a long time. The LITEON infrared receiver....
This project is a piece of test equipment. It`s a square wave oscillator with 6 selectable frequencies from 1Hz to 100kHz, incrementing in decade values. It`s most useful application is as a Signal Injector for radios and TV`s. A square wave is the most....
A 4001 CMOS Quad NORgate is set up as an astable multivibrator, which drives a simple differentiator and relay..
The circuit charges a 9-V battery at about 30 mA per input ampere at 0.4 V. Ul, a quad Schmitt trigger, operate as an astable multivibrator to drive push-pull TMOS devices Ql and Q2. Power for Ul is derived from the 9-V battery via D4; power for Ql and Q2 is....
The waveform of a steam whistle is a complex combination of white noise and an audio frequency oscillation. The noise generator is a transistor (Ql) biased into zener mode. The audio frequency oscillation is a straightforward mixture of two similar (but not....
Each stage provides 0° to 180° phase shift. By ganging the two stages, 0° to 360° phase shift is achieved This circuit is under:, power supplies, ac dc dc dc, 0° To 360° phase shifter l12884. By ganging the two stages, 0° to 360° phase shift is achieved The....
The broadband amplifier NE592 can be used also for building a simple selective audio amplifier. By means of the +6 V and +12 V supply voltages a DC coupling between the product detector and the AF amplifier is possible. The DC level at the differential....
This circuit is configured for the 80m band. The 365-pF, broadcast-band variable capacitor should have a vernier drive with a six-to-one ratio, which makes tuning easier by separating the stations on the dial. A good antenna and ground are also....
The 4047 is configured as a monostable multivibrator circuit or one shot that is set up to trigger on a negative-transition of the signal applied to its pin 6 input. The multivibrator"s on time is determined by the values of R1 and Cl. Although R1 is....
The rechargeable Li-ion, I began to intensely interested last summer, when I managed to bring a holiday without a phone charger. After several experiments involving originated in Figure 1, which has proved. Involvement of the stage provides a limited current....
The circuit powers the load via the regulator"s input instead of its output. Because the regulator"s output sees constant dummy load R1, it tries to consume a constant amount of current, no matter what the voltage across the actual load really is. Hence,....
This design used to measure air or gas flow works by measuring the energy required to maintain a heated resistance wire at constant temperature. The positive temperature coefficient of a small lamp, in combination with its ready availability, makes it a good....
This project is a dedicated device. It dials a single phone number when the handset is lifted. There are two different modes of operation.. A slide-switch on the PC board allows the project to operate in automatic or manual mode. If the switch is in "auto....
Although ceramic resonators are a good choice for low-power, low-frequency clock sources (if you can stand their 30-ppm te..
This circuit uses a dc amplifier (324) in a bar-graph circuit that uses an LM339 Quad comparator IC to sense dc levels. ..
Few years back, I had been working on a project for solar auto lighting. The light will turn on when the the solar panel voltage drop below a set point indicating that it is dark. The detection is done by using D2 in the schematic. The zener diode value will....
A touch switch is a switch that is turned on and off by touching a wire contact, instead of flicking a lever like a regular switch. Touch switches have no mechanical parts to wear out, so they last a lot longer than regular switches. Touch switches can be....
For the outband decoder shown here to work, the cable company must provide at least a 1 millivolt signal. Values for C1-C5 and L1-L4 ore found In Table 1. This circuit consists of an amplifier for the synch channel and a video detector which controls an....
The computer optimized 9 el. homebrew antenna is performing very well. I have made many long distance contacts using the ON6MU VHF Yagi antenna. I have the antenna located only 35 feet above the ground. (See antenna photo titled KC8VWM to see how high it....
The transmitter consists of an oscillator which drives a high output IR emitting diode. The oscillator is a sJire start multivibrator circuit that provides an output of 15 to 1000 mark to space ratio at a frequency of 1 kHz. This large mark to space ratio....
This strobe light operates from standard 120-Vac power. Rl limits the amount of current applied to the voltage doubler stage, which is comprised of CI, C2, C3, Dl, D2, C4, C5, and C6. Capacitors CI, C2, and C3 are connected in parallel and form a....
The circuit presented here is a simple audio/video transmitter with a range of 3 to 5 metres. The A/V signal source for the circuit may be a VCR, a satellite receiver or a video game etc. A mixer which also operates as an oscillator at VHF (H) channel 5 TV....
Adding a diode, a resistor, and a capacitor to the SAW (surface-acoustic-wave) oscillator allows you to use the oscillator in FSK (frequency-shift-keying) applications. Dl, Rl, and Cl form a simple diode switch in which Dl shunts Cl to ground. When the....
You can use this powerfull amplifier in any small audio project. It is very small (6.5 x 4.5 cm).It outputs 10W and uses a 9V battery...
Figure 1 represents a cheap and simple Gate Alarm, that is intended to run off a small universal AC-DC power supply. IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate....
The circuit consists of a small PIC microcontroller, assembly program, and a few other parts to detect a switch closure from an open door, window, or manual push button and then dial the cell phone number, and transmit a steady tone to indicate the source....
The value of the design lies in the use of IC1, an LM317HVK adjustable s.eries-pass voltage regulator, for broad-range performance remainder supplies voltage-setting and current-limiting functions. The input to ICI-comes from the output of BR1, which is....
This circuit will operate a car"s headlights for a predetermined time to light up the driveway or path after the driver has left the car. SQl is pushed and Q2 is turned on closing the relay and turning on the car"s headlights. Cl begins to charge through VR1....
Security is a prime concern in our day-today life. Everyone wants to be as much secure as possible. An access control for doors forms a vital link in a security chain. The Microcontroller based Home Security System can be adopted at Home it has various type....
This circuit detects metal and also magnets. When a magnet is brought close to the 10mH choke, the output frequency changes. ..
The oscillator delivers an output of high spectral purity without any substantial sacrifice of the usual stability of a crystal oscillator. The crystal in addition to determining the oscillator's frequency, is used also as a low-pass filter for the unwanted....
