Popular Circuits Page 272
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When the ignition switch is on, relay K1 is energized continuously, and the headlights can be turned on. Turning off the ignition turns on timer IC1,which keeps IC1 energized for a time determined by Rl and CI. With the values shown approximately a 1 minute....
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Of particular interest to us are 12 Volt DC powered PIR sensors and associated circuits since these can be powered directly from a 12 Volt battery which is in turn charged by wind, solar, or other renewable energy sources. In this article we will look at the....
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This power supply electronic circuit is a high current 5 volts power supply circuit that use a 7805 voltage regulator and some classic electronic components. T1 acts as a current limiter. Once the voltage on R2 + R3 is greater than 0. 6 0. 7 V, the....
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The 203 Theremin utilizes Wien-bridge oscillators in a heterodyne configuration to produce an audible tone that corresponds to hand position. The instrument provides the convenience and safety of 9-volt battery operation, in a compact enclosure. It is a....
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You can get booster for fuel pumps to increase their rating, but is it possible to do anything to the wireing of an external pump to get it to flow LESS fuel Reason I ask is I am helping my brother out with an engine swap (admittidly, its not a rotary, or an....
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This is a simple temperature measurement probe circuit. This circuit measures temperature either on a PC board or at the probe tip to which contains the....
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Now, let`s re-examine the function of the TRIS registers. The TRISA and TRISB registers control the direction of data transfer on each pin of Port A and Port B, respectively. The easy way to remember the TRIS register settings is to match the numbers 0 and 1....
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The main objective of this system is to transmit message or text through ordinary Land Line Telephone from one end (source) to another end (designation). This is get achieved by the DTMF technology. It has two sections one for editing the text and to....
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A lamp provides amplitude stability while the very low noise amplifier creates a pure sine wave signal. The R an C values set the oscillator frequency and the feedback resistor sets the lamp current and output amplitude...
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Designing a high-voltage switching power supply that can produce a sustained arc can be challenging. This compact and efficient design delivers 1 kV at 20W and can withstand a continuous arcing, or short-circuit, condition (Figure 1). It uses standard,....
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This is the circuit diagram of a ding dong sound generator based on two NE555 timer ICs. The circuit is designed to toggle between two adjustable frequencies to produce the ding dong sound. The first NE555 (IC1) is wires as an astable multivibrator operating....
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Other one unit of graphic EQ. five bands. The basic difference with the other circuits is, that I use instead of IC, transistor and the power supply, go up in +/- 24V DC, ensuring low distortion and bigger margins of overloading. With switch S1, we can....
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The JFET Pierce oscillator is stable and simple. It can be the clock of a microprocessor, a digital timepiece or a calculator. With a probe at the output, it can be used as a precise injection oscillator for troubleshooting.
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As explained elsewhere in this article set, after an equipment failure I decided to replace a combination inverter/charger unit with individual components that fill the same needs. The combination unit (the "Everything Box") is an efficient way to save costs....
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Circuit shows the operation of an ultrasonic motion detector. There are two transducers, one emits an ultrasonic wave and the other picks up reflections from the different objects in the area. The reflected waves arrive at the receiver in constant phase if....
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Derating is the method of decreasing a devices operational limits as temperature is increased, in this case derating a devices operational power dissipation vs increasing ambient temperature. Ambient temperature. is the air temperature measured below a....
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The RF amplifier uses noiseless feedback through the drain-gate capacitance with an inductor in the source lead to provide the necessary 90 degree phase shift between gate voltage and channel current...
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This circuit consists of an astable multivibrator driving a push-pull pair of transistors into the transformer primary. The multivibrator frequency should~equal around 1 or 2kHz. ..
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The Pocket Programmer is a stand alone serial programmer that can program most of the PICmicro®MCU range of microprocessors. (12C6xx, 16Cxxx, 16Fxxx, 18Cxxx) It works from a single 18VDC supply or with 2 X 9 volt batteries. Combine this with 64K of on board....
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The circuit is a simple, but accurate Digital Guitar Tuner. It samples the input, which can be directly from the mics of an electric guitar, or from a microphone, it you`re using an acoustic guitar. It can ofcourse also be used for tuning other instruments.....
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I proposed a solar powered watering system for the plants to water them daily from the water butts by the greenhouse. As with all my projects, this has been work in progress for a long time now, but I have picked it up again with the intention of completion!....
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With the connections made in this order on the connector it will not matter if the connector is placed the wrong way round as GND and VCC are then applied to clock and data. If VCC and GND had been at opposite ends of the connector then there would be a....
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The light fader circuits presented here have a common idea of producing a “cool†switch ON and switch OFF effect on the connected lamps, i.e. every time these lights are switched; the outcome is gradual and not sudden, producing an interesting slow glow....
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240/24Vac(rms) transformer was used. After rectification and filtration i got about 30Vdc. Therefore the transformer and diode rating should be well chosen to meet your demand At the current limiting stage, transistor U1, Q1 and resistor R1 plays the vital....
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In these times with viruses and other threats from the Internet it would be nice to have reassurance that the PC cannot be infected. That is why this circuit was designed. It makes it possible to install multiple hard disks inside the case of a PC, which are....
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Both transistors should be low noise types. In the original circuit, I used BC650C which is an ultra low noise device. These transistors are now hard to find but BC549C or BC109C are a good replacement. The circuit is self biasing and will set its quiescent....
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If you have an application in which a MOSFET is already used to switch a load, it is relatively easy to add short-circuit or overload protection. Here we make use of the internal resistance RDS(ON), which produces a voltage drop that depends on the amount of....
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found out the hard way why the 6v EQ-5 hand controller should not be connected to 12v by accident. It only took, literally half a second to kill my hand controller. After some examination it became obvious that I had destroyed the large 40 pin micro....
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This circuit produces a ringing sound similar to that made by more recent telephones. It consists of three almost identical oscillators connected in a chain, each generating a squarewave signal. The frequency of each oscillator depends on the RC combination:....
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This is a high quality power supply with a continuously variable stabilised output adjustable at any value between 0 and 30VDC. The circuit also incorporates an electronic output current limiter that effectively controls the output current from a few....
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A four output Hall sensor combined with a few logic gates produce this digital compass. The NOR gates resolve the four Hall..
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A very simple forward and backward drive motor control electronics projects can be designed using a low saturation voltage LB1948M 2 channels, forward-reverse motor control dri..
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The aim of this design is to reproduce a Combo amplifier of the type very common in the `sixties and the `seventies of the past century. It is well suited as a guitar amplifier but it will do a good job with any kind of electronic musical instrument or....
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If you want to do the ground loop elimination in audio path, you have to cut the galvanic connection but pass the whole audio range. The simplest and most common way to do the isolation is use audio transformer which is ment for audio use. Transformers for....
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The SLA battery is charged from the vehicle s battery. When the engine is running, the voltage remains fairly constant, which greatly simplifies the charging circuit. If the SLA battery is fully charged, any further charging current from the vehicle battery....
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This article describes a 2 meter amplifier capable of running 25-30 watts output. More than 35 amplifiers have been procured at a cost of less than $50 each in these quantities. Photo A shows the final version of the circuit board; the completed amplifier is....
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Charge current: I=0,45V/R2
Power-dissipation by R2: (0,45 * 0,45 / R2) !
Please adjust 13,8V by R5 without connected battery...
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FM Telephone Bug. Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency...
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Simply you can control a relay through Pic Microcontroller. See a simple circuit for controlling a single relay with pic 16f628. When RB5 port of pic become High the relay will operate. This Circuit works with non-latching ralays(commonly used relays are....
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To complement the 60 Watt MosFet Audio Amplifier a High Quality Preamplifier design was necessary. A discrete components topology, using + and - 24V supply rails was chosen, keeping the transistor count to the minimum, but still allowing low noise, very low....
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There are only 4 parts to the circuit, including the indicator LED. There is a hand-wound coil, a 1k resistor, a 2N4401 transistor and the LED. I quickly threw this together by just wiring the component leads together and it worked right away. The coil is....
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Controlling the speed of a motor is very important in many situations especially in robotics. There are many techniques of controlling the speed of motors, each with their advantages and disadvantages. This document will show you how to build a motor....
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This simple circuit uses a 741 op-amp in differential mode as a continuity tester. The voltage difference between the non-inverting and inverting inputs is amplified by the full open loop gain of the op-amp. Ignore the 470k and the 10k control for the....
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Low-intensity ultrasonic sound waves in the 30-45 kHz frequency band repel insects and small rodents. The unit is designed to generate a swept square wave from 30 to 45 kHz. The LM555 IC is wired as an ultrasonic oscillator driving a piezoelectric speaker of....
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The circuit are suited for high precision extended temperature service if V+ is reasonably constant since IZ is dependent on V+. R1, R2, R3, and R4 are chosen to provide the proper IZ for minimum T. C. and to minimize errors due to Ibias. The circuits shown....
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The Microcontroller based Water Level Controller cum Motor Protector controls on and off conditions of the motor depending upon the level of water in the over head tank (OHT), It controls water level of tank through micro-controller so that automatically....
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A pressure sensor (IC4) is used with a dc: amplifier to convert the bridge output (IC4) to a single-ended voltage. ICld provides a reference voltage for setting barometric pressure. IC3 is an A/D converter manufactured by Intersil. This drives an LCD....
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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 555 timer IC is connected for Astable Operation, the clock pulses are fed to the 4017 IC via the 10K resistor. The 4017 is a 10 stage counter, each of the outputs is connected to the appropriate LED, as some LEDs need to be on for more than one count, we....
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The purpose of this circuit is to control the water temperature in a hot-water heating system. What it does is to lower the boiler temperature as the outside air temperature increases. The op amp is used as a comparator. Thermistor TH2 and R2 form a voltage....
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As shown, the circuit consisting of two discrete PNP Darlington transistors constituting the external PNP transistor QEXT circuit to expand output current. Here we do not advoc..
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The system described here is a four motor rotary wing aircraft with 3 inch propellers. The overall size of version one is about four inches. A 418MHz digital radio is used for communications and control and an onboard PIC17 microcontroller and L293DD mosfet....
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The microcontroller (MCU) is responsible for sending variable voltages over time (just like a traditional LFO) to an effect that can be modulated by a voltage, or a pot on a traditional analog effect that can be replaced with an optoisolator/vactrol. Here`s....
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The circuit uses a motor auto-voltage transformer start...
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Capacitor C4 couples the output of U1 to a simple attenuator, which is used to provide a loss of 0 dB, 20 dB, or 40 dB, depending on the setting of range switch Sl. The circuits sensitivity is 10-V rms for fullscale deflection, so the attenuator gives....
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This is the eye diagram for the transmit pair. The receive pair is very similar. It`s a LAN8700 PHY, and I`ve got the MII interface effectively disabled, so the PHY is transmitting IDLE code sequences. It`s forced into 100Mbit/FDX as per the datasheet.....
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This self-starting fixed-frequency oscillator circuit gives excellent frequency stability. R1 and C 1 comprise the frequency-determining network, while R2 provides the regenerative feedback. Diode D 1 enhances the stability by compensating for the....
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The circuit uses two LDRs which are placed one after another (separated by a distance of say half a metre) so that they may separately sense a person going into the room or coming out of the room. Outputs of the two LDR sensors, after processing, are used in....
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This is a simple - easy to build - multi-purpose alarm. Build it yourself using stripboard or veroboard and a few cheap off-the-shelf components. Fit it to a door, window, shed, garage, cupboard etc. It`ll alert you to intruders. Fit it to a shop-door - and....
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KD9562 music octave circuit is analog sound circuits can be issued rifle sound, space shots, game console sound, dual-tone door so sound, the sound of bomb explosions, machine gunfire and the sound of an ambulance. The main electrical parameters:..
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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 Transmitter can be powered by a battery 9V (not more than 12V). You can connect your music source where the microphone is or use a simple condenser microphone. The range of signal can reach 400 meters in open air. The wide range of frequency is up to....
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One v;ay to provide good negative-voltage regulation is with a low-dropout positive-voltage regulator operating from a well-isolated secondary winding of switch-mode circuit transformer. The technique works with any positive-voltage regulator, although....
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It is fairly safe to say that most Bulle clocks will need their magnet rejuvenated before they will run properly from the normal single 1. 5V cell. The first "real" magnet material was cobalt-chrome steel, in 1921 [ 1 ]. Prior to that, carbon steel was....
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The different strengths between the PMOS and NMOS transistors can be observed through a simple test of ramping up the input voltage an observing the point at which the output voltage will switch from 5V to 0V. To perform this test, click on the cell named....
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C ,. C! Composition ratio circuit. Ri. C, constituting the shift shed circuit diode VDi - VD4 constitute destroy stream bridge, electric pit C4 is used - Application Filtering ..
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Another application of FVC (frequency-to-voltage converter) is tone/frequency decoder. This circuit is used to determine the frequency band of an oscillation signal. This circuit is used in many application like determines the frequency band in the signal....
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Blind when they go out to bring a total crutches to Pathfinder to avoid obstacles. Due to hand battle not be too long, the detection distance is very limited. Using ultrasonic ..
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This high voltage source is formed by an inverter, around the transistor, which provides pulses of 150V to the inverter formed by the thyristor and capacitor in series with the transformer 2. This pulse output of 4. 5kV to be multiplied with the network so....
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S1 is a power switch. U2 drives counter U3 by producing a pulse when S2 is depressed. U4 and DISP1 read the count of counter IC U3. S3 is a reset to zero switch. The counter is a basic one-digit circuit useful as a holding block or by itself. ..
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The output goes high when the supply falls below a value determined by zener diode Dl. If Dl is a 5.6-V zener, the op..
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This circuit is a two-channel baseband video switcher. Buffer amps Ul/Ql, U4/Q4, and associated components produce a b..
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Circuit shown in Figure, when the phototransistor VT1 receives infrared light-emitting diode to the infrared light emitted, VT1 conduction, the inverting input of the comparato..
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It is a hansom battery portable radio with a roll top and even today it looks beautiful. When I was first given the radio it didn`t work. It had a burned out detector tube and I had no idea where I`d get a replacement for it. Most importantly, the radio....
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The project described here is one that you can just build and have working straight away (although it is entirely possible that you will want to experiment a bit), and requires only a small handful of parts. In its simplest form, there are no active....
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Without any USB to phone battery charger circuit we can charging phone battery using port on USB computer, but it will quickly damage the phone battery, and the battery will bulge. Because the voltage which was issued on usb is 5 volts, while the....
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This multitone electronic siren is useful for burglar alarms, reverse horns, etc. It produces five different audio tones and is much more earcatching than a single-tone siren. The circuit is built around popular CMOS oscillator-cum-divider IC 4060 and small....
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7-Segment LED Display is a very useful component, but also a very confusing and difficult piece to use for beginners. It won`t be difficult once you get it working for the first time. It basically consists of 7 LEDs, (8 if include decimal point). Just like....
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This was used on a Linear actuator for a variable geometry turbine used for more power to compensate for all the armor they started putting on HumVees. I forget the current rating, where ARE my old design notebooks ! The four darlingtons are the driver....
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The logic probe can indicate four input states, as follows: floating input—all LEDs off..
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I like the circuit, because it is good and enjoy. It just the signal status ""1"" and ""0"" only. And frequency generator is....
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This circuit is designed to output both a sine wave and cosine wave. This particular design uses an operational amplifier. As shown in the schematic the output frequency is set by the component values as 1Hz. The first operational amplifier outputs a 1Hz....
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This circuit provides a continuous supply of regulated + 5 V, with automatic switch-over between line power and battery backup. When the line-powered input voltage is a + 5 V, it provides 4A V to the MAX630 and trickle charges the battery, If the....
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AD7714 circuit constituted by a pressure measurement system is shown in Fig. BP01 is Sensym companys pressure sensors. The BP01 connected into a bridge circuit, from OUT +, OUT..