New Circuits Page 243
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Transient overloads are not short circuits but can push the power supply above its nominal load value. This scenario occurs with typical loads such as printer heads and small motors. When facing such a load profile, the power supply can easily trigger its....
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This de voltmeter, with high input resistance, uses a CA3130 BiMOS op amp and measures voltages from 10 m V to 300 V. Resistors R12 and Rl4 are used individually to calibrate tbe meter for full:scale deflection. ..
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The unit provides a square-wave output that is rich in harmonic content. The circuit"s output frequency can be varied from 50 Hz to 15 kHz. The heart of the circuit is a 555 astable connected in its equal mark/space mode. The frequency is controlled by....
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This is a classic divider of frequency via two. It is achieved with a classic circuit T-flipFlop, round IC1 [ 4011 ]. In the circuit, the frequency of network, after are limit the negative half-s period of sine wave and transform in square wave, are divided....
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The small 8-pin PIC12C508 is pre-programmed to generate our 38KHz carrier frequency by simply pulsing I/O-pin GP1 (shown above). The PIC will generate either 38KHz or 40KHz, depending on the state of GP3 when power is first applied. If you connect GP3 to....
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This circuit use the CA3306 a family of CMOS parallel (flash) analogue to digital converters designed for low power, high speed applications. The CA3306CE operates at sampling rates up to 10 million samples per second and the CA3306E up to 15 million samples....
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Both halves of the circuit are identical. Both inputs have a dc path to ground via the input 47k control which should be a dual log type potentiometer. The balance control is a single 47k linear potentiometer, which at center adjustment prevents even....
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Tube amplifiers designed for headphones have the principal property that they can be used as preamplifiers too. In most cases, the output impedance of a tube headphone amplifier is (or should be) less than the output impedance of a tube preamp. This....
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This circuit was submitted by Graham Maynard from Newtownabbey, Northern Ireland. It has an exceptionally good high frequency response, as demonstrated by applying an 100kHz squarewave to the input. I have produced some response graphs using Tina Pro to....
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The circuit diagram of the filter section is shown in Figure 1. It is a completely conventional filter, and the component designations are the same as for the 24dB unit described in Project 09. It is designed primarily for 2-way electronically crossed over....
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In a half-duplex system, information can flow in both directions, but only one direction at any given time. The conventional method of building a half-duplex link requires a separate emitter and detector, connected with directional couplers, at each end of....
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The circuit is capable of supplying either a trickle (50 mA) or high-current (1-A) charge. You can select either charging method or an automatic mode that will first trickle charge a battery if it is particularly low before switching to
high-current charging...
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The DS protocol was designed to provide firmware-based bidirectional host-to-slave inter processor communications for situations in which no hardware solution is available and the host and/or the slave in incapable of tending the interface in real time. The....
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The circuit in Figure 1 uses a regular, general-purpose transistor as the sensing element and a thermal-diode monitor IC to measure temperature. The ADM1021 usually connects to an on-chip thermal diode on a CPU die itself, but in this application the sensor....
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I needed a pulsating light for a certain signaling. Voltage was 230V. So I decided to make a simple circuit, consisted of a LED diode, two capacitors, two resistors, a diac and a diode. Activity of the circuit is extraordinarily simple. The capacitor charges....
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Infrared remote controls are using a 32-56 kHz modulated square wave for communication. These circuits are used to transmit a 1-4 kHz digital signal (OOK modulation) through infra light (this is the maximum attainable speed, 1000-4000 bits per sec). The....
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Me and a friend are both trying to build a millipede. Because of obvious reasons, the millipede is NOT going to have 1000 feet!!! Instead, it`s going to have 16 pager motors as feet. It will also have 3 MicroMotors to ``bend`` towards light, and a backup....
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Many systems that require a user to manually enter data feature a keyboard similar to that in Figure 1. Although early keypads comprised arrays of individually wired switches, a typical modern keypad comprises a matrix of x and y lines. Pressing a key....
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The LT®1500/LT1501 current mode step-up regulators
control both the maximum and minimum inductor current,
resulting in continuous inductor current and nearly constant
switching frequency and output ripple over a wide
load current range. The switching....
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The circuit in Figure 1 efficiently monitors common digital-audio signals. One format for such signals is the Audio Engineering Society (AES) 44.1- or 48-kHz standard. Typically, the data consists of a serial data stream with a data rate of approximately 1....
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This application note describes how to implement a compact size and high-speed
interrupt driven step motor controller. Step motors are typically used in applications
like camera zoom/film feeder, fax machines, printers, copying machines, paper feeders/....
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Traditional control-system designs use separate switches to control power and various system functions, but adding a few components to a small, microprocessor-based system can combine a control function with the system`s on/off switch. For example, you can....
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The circuit lowers this dissipation after actuation by applying less than the normal 5V operating voltage. Note that the voltage required to turn a relay on the pickup voltage is greater than the pickup voltage required to keep in on the dropout voltage. The....
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A portable FM transmitter that can be used to replace a FM microphone. This simple transmitter operates from a 9V battery as shown above. I personally built this for a purpose. This is how it happened:- "members of my singing group find it difficult to....
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I've always wanted to build an electronic led dice, but something different from what we see on the internet. Making it motion controlled... now that's new! Many new cell phones that have accelerometers built in also have dice games. These dice move when....
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This circuit produces a sound similar to the police siren.
It makes use of two 555 timer ICs used as astable multivibrators. The frequency is controlled by the pin 5 of the IC.
The first IC (left) is wired to work around 1Hz. The 47uF capacitor is....
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If you use great IC PCM2702 from BURR BROWN / Texas Instruments you can create a fully functional USB sound card. This sound card can be powered from USB port and has one stereo output. You don’t need to install any driver for Windows XP and Vista, because....
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Here is the circuit diagram of simple but highly effective TV remote jammer circuit. Most of the TV remotes have 38KHz operating frequency. A flood of IR beams in the same frequency can easily confuse the TV receiver and this is the operating principle of....
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A single op amp, one fourth of an LM324 quad op amp, is configured as a standard inverting amplifier. At power up, a positive voltage is applied to the noninverting input of Ul, via R3, forcing its output high. That high output travels along three....
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The circuit is a common form used in FM transmitters. The transistor conducts for 60-90 electrical degrees. When it turns off the LC tank `rings`, completing the sinusoidal waveform coupled to the antenna. The circuit is 77-85% effecient, compared to 40-50%....
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I designed up this circuit board because of a request from a visitor to my website. I also assemble the circuit board to Varify the board was correct. It does work, VERY NICELY, but I have no way to varify the accuracy of wind flow that is stated by the....
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This house alarm circuit has open and closed loop sensor and has self shutdown function. The delay after trigering can be adjusted from 1 minute to 12. The delay before trigering is 13 seconds. Offcourse all this timmings can be change with litle changes to....
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This is a very useful project for anyone working in electronics. It is a versatile power supply that will solve most of the supply problems arising in the everyday work of any electronics work shop. It covers a wide range of voltages being continuously....
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I constructed this voltage regulator to power my two way mobile radio from the car cigarette lighter circuit. It has many other uses and the voltage can easily be adjusted by the use of a potentiometer. The voltage regulator is an LM317T, and should accept....
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When you connect remote sensors to a central process controller, a simple, robust, and commonly used interface is the 4- to 20-mA loop. The advantages of this current loop include the simplicity of just two twisted wires that share both power and signal, the....
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Sequence detection is a common operation in many communication and security systems. Some good examples are HDLC-flag identification and signature analysis. As the complexity of the system increases, designing circuitry for sequence detection becomes tedious....
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A flashing LED signals the necessity to water a plant
Very low current consumption - 3V powered circuit. This circuit is intended to signal when a plant is needing water. A LED flashes at a low rate when the ground in the flower-pot is too dry, turning off....
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The following schematic diagram shows the design of a 100 MHz Radio Frequency RF Oscillator Circuit. The electrets microphone picks up and amplifies sound then fed it into the audio amplifier stage built around the first transistor. The output from the....
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This configuration utilizes the wide bandwidth aod speed of HA-2540. plus the output capability of HA5033. Stabilization circuitry is avoided by operating HA-2540 at a closed loop gain of 10, while maintaining an overall block gain of unity. A maximum....
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Capacitor Cl and body capacitance (C2>of the operator form the voltage divider from the hot side of the ac line to ground. The voltage across Cl is determined by the ratio of Cl to C2. The higher voltage is developed across the smaller capacitor. When no one....
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The control of electronic potentiometers in most today`s applications comes from controller-generated signals. However, a significant number of applications exist that require adjustments using manual, front-panel controls. The circuit in Figure 1 uses one....
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An op amp is used as a comparator and a sink for LED current. The output voltage of the amplifier changes about 1.4 V depending on the direction of the current. Only one transistor is on at any time. Maximum LED current is limited to 25 mA by overcurrent....
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This electronic keyer uses four ICs (five, if the optional sidetone oscillator is desired) and operates from dc sources of 9 to 15..
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Inverters Ula and Ulb form a 20-kilohertz oscillator whose square wave output-further shaped by D2, R4, and R5 and by D3, R6, and R7—drives power field-effect transistors Q2 and Q3. The p-channel and n-channel FETs conduct alternately, in al push-pull....
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The time delay, T, in seconds is: T = 1.1 x Cl x (Rl + R2). The resistances are in megohms and capacitances in microfarads. The sum of R1 and R2 should not be Jess than 1000 0 nor higher than 20 MO. Pressing S1 starts the timing cycle. A low-going pulse,....
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This circuit has been designed to alert the vehicle driver that he has reached the maximum fixed speed limit (i.e. in a motorway). It eliminates the necessity of looking at the tachometer and to be distracted from driving.
There is a strict relation between....
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The CA3080 can be used as a gain controlling device. The input signal is attenuated by R1/R2 so that a 20-mVpp..
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Optically isolated SMPS and dc-to-dc converters face the variance of output voltage owing to the change of transmission c..
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Incandescent lamp has been used to reduce harmonic distortion in sine oscillator circuit. The nonlinear resistance characteristic of the lamp filament help the circuit to shape the signal to approximate the ideal sine wave. Here is the classic Wien-bridge....
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The power output of most of these circuits are very low because no power amplifier stages were incorporated.
The transmitter circuit described here has an extra RF power amplifier stage, after the oscillator stage, to raise the power output to 200-250....
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This circuit is a phaser circuit, as used in guitar foot-pedal effects. It used 11 sections of op-amp such as LM324 but others will do. The whole circuit works of a dual rail supply: +/- 9v. The 0v rail is indicated by a chassis sign. Make sure these....
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Many applications require current sources rather than voltage sources. When you need a high-current source, using a linear regulator is inadvisable, because of the high power dissipation in the series resistor. To solve the wasted-power problem, you can use....
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A full range power controller suitable for lamp dimming and similar applications operate from a 120 volt, 60 Hz ac source, and can control up to 1000 watts of power to incandescent bulbs. The power to the bulbs is varied by controlling the conduction angle....
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The 555 Stepper Pulse Generator kit will help you with the pulse required to drive your favorite DC Servo Motor application. This kit uses the famous 555 timer IC for generating the Stepping Pulse...
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The achievable accuracy for systems with multiple ADCs depends directly on the reference voltages applied to the ADCs. Medical- ultrasound- imaging systems, for example, commonly include a large number of ADCs in the system`s beam-former electronics, with....
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This is an image Schematic. No Description available...
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Generic Digital Switches are in-circuit programmable devices made by Lattice Semiconductor that allow pin to pin routing, buffering, and inversion. Perfect for making last minute circuit changes. Don't muck around with the software provided by Lattice, do it....
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Because it uses few parts, a printed circuit board is not necessary; components can simply be soldered to one another. However, a box is desirable for operating convenience. The case and aerial from a discarded toy walkie-talkie was used in the prototype....
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This circuit operates by charging a small capacitor from a constant-current source when the pulse to be measured is present. Dual pnp transistor Q3 is the current source; its output current equals the LM329 reference voltage divided by the resistance of....
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Video-signal amplitude can be measured with this simple circuit, which is basically a modified standard peak detector. The device can verify RGB generated by video RAMDACs. Ul is a high-speed buffer and U2 is a latched comparator. CI is a hold capacitor.....
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This FM transmitter has a number of features, with a volume control to adjust the input level and a small, neat box to make it easier to attach to a guitar. The volume control is positioned at the end and when turned up fully, the transmitter provides fuzz....
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Using a Signetics NE602, this converter tunes the 9.5- to 9.8-MHz range. An AM car radio is used as a..
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The tremolo effect is generated by a repeating volume change at a rate usually between 1 and 15Hz. The timer produces a low frequency square wave that is smoothed by a simple rc integrator. This varying signal modulates the signal input from the....
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I built a PCB for a simple switching power supply, originally designed by Keith Payea of the SRS. It uses an LM393, a P-channel power MOSFET, and darn little else. Since its frequency varies based on load (and nearly everything else imaginable), you can use....
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Halloween is coming up and it's time to do some pranks. Everyone likes Halloween and I'm no exception. Every year me and my wife decorate the house with lot's of bugs, spider webs, creepy posters and of course lot's of Halloween candy. While making the....
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Lamp II is a household lamp. When the switch is in the center position, the lamp is operated on half-wave rectified ac; the ef..
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The IH5352 is a quad SPST, CMOS monolithic switch which
uses a Series/Shunt (T switch) configuration to obtain
high OFF isolation while maintaining good frequency
response in the ON condition.
Construction of remote and portable video equipment with....
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Emits a carrier that sweeps the 925-960 MHz cellular tower transmitter band (handset receive band)...
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The amplifier's gain is nominally 20 dB. Its frequency response is determined primarily by the value of just a few components—primarily Cl and Rl. The values of the schematic diagram provide a response of ±3.0 dB from about 120 Hz to better than 20,000....
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Four (or more) inputs can be mixed and produce stereo output. Gain of each stage can be boosted by adding RX, but it should be kept below 50 (RX above 2 K) to avoid poor frequency, response. If more than four stages are used, decrease RXto 6 K for six....
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This equaliser is designed as a preamp suitable for musical instruments - guitar, bass and keyboard in particular. Unlike most conventional graphic equalisers, each slider ranges from fully off to fully on, and not the more conventional +/-12dB or so that is....
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On this page three adjustable notch filters configurations are shown . They can be used in your small pre-amp or amplifier project to filter out any HUM at 50 Hz ( European ) or 60Hz . By sustituting the capacitors values in the bridge other frequencies can....
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This circuit allows you to set a limit on the maximum output current available from your PSU. It`s very useful when you power-up a project for the first time - or carry out a soak-test. By setting an upper limit on the current available from your PSU - you....
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SW3 is the on/off switch. It also lets you choose between the output with the current limit and the one without. SW2 provides a selection of three different limits. You can increase or decrease this number if you wish. The limits are fixed by R4, R5 &....
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This is a replacement power source for 1.3V mercury cells or other small batteries. It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital thermometer. This circuit takes it power from a PC. The power....
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This power-stingy combination of an audio codec and touchscreen-interface controller now comprises a differential or two-channel microphone input with automatic level control, a two-channel audio-line input, a separate monophonic-audio input, a PC-"beep"....
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This moisture detector with pump controller is built around the special purpose LM1830 IC. The LM1830 is designed to detect moisture by passing an AC current through a set of probes. An internal comparator compares the resistance of the probes to an internal....
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This is an improved version of the audio interface commonly used to connect a computer soundcard to a transceiver`s receive and transmit audio circuits. This kind of interface is used by computer programs that send and receive SSTV, RTTY, CW, PSK31 and....
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This implementation is adapted to rebroadcast the output of a CD player, television receiver, or radio receiver. I use it so that I can move about the house and listen to my favorite programs without disturbing others. Within and the house, I find that I can....
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This is the second generation of a circuit for a guitar spring reverb pedal, it has dry, wet, and drive controls for a wide variety of sounds. With a decent reverb spring (tank) in overdrive, this circuit will produce an incredibly thick and grungy sound,....
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Typically applications having LEDs and keypads also
keep track of real-time, in order to synchronize certain
related events. An Industrial Clock/Timer example has
been used in this application note as a demonstration
of these functions. The software....
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With a DPDT switch, I can switch the two data lines. I tried connecting the shields from the two computers together, the grounds two computers together, switching the D+ and D- lines with the DPDT switch, and leaving the VBus lines float, but for some reason....
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The circuit offers independent control of initial delay and pulse rate. ICIc is connected as a pulse generator whose operation is inhibited by the normally low O/P of the ICla. When the circuit input goes low i.e., by pressing PB1, IClb O/P goes high and the....
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This is a little transmitter that could be put into a plastic Easter egg. It delivers approximately 1 W of measured rf output into a 50-0 dummy load, and creates no heating problems with the circuit. The crystal is a series fundamental type, and the power....
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The author described assembling this circuit on a 1"*1" perf board, I actually laid out a small PC board with excellent results. In this era of surface mount components, I think a much smaller version can be laid out on a PC board, allowing this circuit to....
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A short-circuit-proof battery charger will provide an average charging current of about 8 A to a 12-V lead/acid storage battery. The charger circuit has an additional advantage; it will not function nor will it be damaged by improperly connecting the....
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A MAX634 inverting regulator is combined with a MAX630 to provide a dual tracking ±15 output from a 12-V battery. The reference for the -15 V output is derived from the positive output via R3 and R4. ..
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The IC is ideal for detecting the presence, absence or level of water or other conducting liquids. A detector determines the presence or absence of fluid by comparing the resistance of the fluid with the IC's internal reference resistance. An AC signal is....
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Many applications require a sinusoidal reference voltage synchronized to the ac line voltage. You cannot derive such a reference voltage directly from the ac line because the waveform of the ac line is distorted because of nonlinear loads connected to the....
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Nice small audio amplifier which use only few parts to give good quality sound. This amp can be used as a simple booster, the heart of a more complicated amplifier or used as a guitar amp. Although not perfect, this amplifier does have a wide frequency....
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Industrial control systems continue to employ standard analog signals for transmitting data between the process and the control equipment. Robust, 4-to-20mA current-loop signals that are easily transmitted over several thousand feet, ±5 and ±10V signals are....
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Transformer Tl can be any matching transistor type in the range of 500/500 to 2500/2500 ohms. No connections from the SCR or its components are connected to ground. For safety's sake, keep the 117-V line voltage from the amplifier connections— that is the....
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Combine an electrostatic transducer with an ultrasonic transceiver IC to build a ranging system that senses objects at distances from 4 inches to more than 30 feet. Transducer Yl "s broadband characteristic simplifies tuning. The secondary of T1 resonates....
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This circuit uses one of the LM389 transistors.to gate the power amplifier on and off by applying the muting technique. The other transistors form a cross-coupled multivibrator circuit that controls the rate of the square-wave oscillator. ..
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This circuit adds 120 degrees of phase shift to a 50- or 60-Hz input, regardless of the frequency and amplitude fluctuations ..
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The amplifier provides 10 dB of gain from 10-600 MHz and has a 1-to-l match at 50 ohms. The BFR91 has a 1 dB noise figures at 500 MHz, The circuit requires 13 Vdc at about 13 mA. Keep the leads on the 150 pF emitter bypass capacitor as short as possible. The....
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This is easy to install to the usual system. You have to find a wire which has a voltage in position `1` and then
You cut that wire. After that You install the "ADAPWIPE" between the break of wire
just like the circuits diagram....
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The following circuit can be used to detect those annoying piezo whistles that one can get from Radio Shack. For the Trinity Home Fire Fighting Contest, additional points accrue when the robot is started by a sound similar to a fire alarm. The actual....
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This circuit detects frequency variation above or below preset limits. IC1 is a binary counter docked at FcLK· The outputs are comparea with switch preset values by IC2 and IC3. The input signal, which must be a positive-going pulse, is used to reset IC1.....
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This continuity checker (built around an LM339 quad comparator with open-collector outputs) eliminates false r..
Transient overloads are not short circuits but can push the power supply above its nominal load value. This scenario occurs with typical loads such as printer heads and small motors. When facing such a load profile, the power supply can easily trigger its....
This de voltmeter, with high input resistance, uses a CA3130 BiMOS op amp and measures voltages from 10 m V to 300 V. Resistors R12 and Rl4 are used individually to calibrate tbe meter for full:scale deflection. ..
The unit provides a square-wave output that is rich in harmonic content. The circuit"s output frequency can be varied from 50 Hz to 15 kHz. The heart of the circuit is a 555 astable connected in its equal mark/space mode. The frequency is controlled by....
This is a classic divider of frequency via two. It is achieved with a classic circuit T-flipFlop, round IC1 [ 4011 ]. In the circuit, the frequency of network, after are limit the negative half-s period of sine wave and transform in square wave, are divided....
The small 8-pin PIC12C508 is pre-programmed to generate our 38KHz carrier frequency by simply pulsing I/O-pin GP1 (shown above). The PIC will generate either 38KHz or 40KHz, depending on the state of GP3 when power is first applied. If you connect GP3 to....
This circuit use the CA3306 a family of CMOS parallel (flash) analogue to digital converters designed for low power, high speed applications. The CA3306CE operates at sampling rates up to 10 million samples per second and the CA3306E up to 15 million samples....
Both halves of the circuit are identical. Both inputs have a dc path to ground via the input 47k control which should be a dual log type potentiometer. The balance control is a single 47k linear potentiometer, which at center adjustment prevents even....
Tube amplifiers designed for headphones have the principal property that they can be used as preamplifiers too. In most cases, the output impedance of a tube headphone amplifier is (or should be) less than the output impedance of a tube preamp. This....
This circuit was submitted by Graham Maynard from Newtownabbey, Northern Ireland. It has an exceptionally good high frequency response, as demonstrated by applying an 100kHz squarewave to the input. I have produced some response graphs using Tina Pro to....
The circuit diagram of the filter section is shown in Figure 1. It is a completely conventional filter, and the component designations are the same as for the 24dB unit described in Project 09. It is designed primarily for 2-way electronically crossed over....
In a half-duplex system, information can flow in both directions, but only one direction at any given time. The conventional method of building a half-duplex link requires a separate emitter and detector, connected with directional couplers, at each end of....
The circuit is capable of supplying either a trickle (50 mA) or high-current (1-A) charge. You can select either charging method or an automatic mode that will first trickle charge a battery if it is particularly low before switching to high-current charging...
The DS protocol was designed to provide firmware-based bidirectional host-to-slave inter processor communications for situations in which no hardware solution is available and the host and/or the slave in incapable of tending the interface in real time. The....
I needed a pulsating light for a certain signaling. Voltage was 230V. So I decided to make a simple circuit, consisted of a LED diode, two capacitors, two resistors, a diac and a diode. Activity of the circuit is extraordinarily simple. The capacitor charges....
Infrared remote controls are using a 32-56 kHz modulated square wave for communication. These circuits are used to transmit a 1-4 kHz digital signal (OOK modulation) through infra light (this is the maximum attainable speed, 1000-4000 bits per sec). The....
Me and a friend are both trying to build a millipede. Because of obvious reasons, the millipede is NOT going to have 1000 feet!!! Instead, it`s going to have 16 pager motors as feet. It will also have 3 MicroMotors to ``bend`` towards light, and a backup....
A portable FM transmitter that can be used to replace a FM microphone. This simple transmitter operates from a 9V battery as shown above. I personally built this for a purpose. This is how it happened:- "members of my singing group find it difficult to....
I've always wanted to build an electronic led dice, but something different from what we see on the internet. Making it motion controlled... now that's new! Many new cell phones that have accelerometers built in also have dice games. These dice move when....
This circuit produces a sound similar to the police siren. It makes use of two 555 timer ICs used as astable multivibrators. The frequency is controlled by the pin 5 of the IC. The first IC (left) is wired to work around 1Hz. The 47uF capacitor is....
If you use great IC PCM2702 from BURR BROWN / Texas Instruments you can create a fully functional USB sound card. This sound card can be powered from USB port and has one stereo output. You don’t need to install any driver for Windows XP and Vista, because....
Here is the circuit diagram of simple but highly effective TV remote jammer circuit. Most of the TV remotes have 38KHz operating frequency. A flood of IR beams in the same frequency can easily confuse the TV receiver and this is the operating principle of....
A single op amp, one fourth of an LM324 quad op amp, is configured as a standard inverting amplifier. At power up, a positive voltage is applied to the noninverting input of Ul, via R3, forcing its output high. That high output travels along three....
The circuit is a common form used in FM transmitters. The transistor conducts for 60-90 electrical degrees. When it turns off the LC tank `rings`, completing the sinusoidal waveform coupled to the antenna. The circuit is 77-85% effecient, compared to 40-50%....
I designed up this circuit board because of a request from a visitor to my website. I also assemble the circuit board to Varify the board was correct. It does work, VERY NICELY, but I have no way to varify the accuracy of wind flow that is stated by the....
This house alarm circuit has open and closed loop sensor and has self shutdown function. The delay after trigering can be adjusted from 1 minute to 12. The delay before trigering is 13 seconds. Offcourse all this timmings can be change with litle changes to....
This is a very useful project for anyone working in electronics. It is a versatile power supply that will solve most of the supply problems arising in the everyday work of any electronics work shop. It covers a wide range of voltages being continuously....
I constructed this voltage regulator to power my two way mobile radio from the car cigarette lighter circuit. It has many other uses and the voltage can easily be adjusted by the use of a potentiometer. The voltage regulator is an LM317T, and should accept....
A flashing LED signals the necessity to water a plant Very low current consumption - 3V powered circuit. This circuit is intended to signal when a plant is needing water. A LED flashes at a low rate when the ground in the flower-pot is too dry, turning off....
The following schematic diagram shows the design of a 100 MHz Radio Frequency RF Oscillator Circuit. The electrets microphone picks up and amplifies sound then fed it into the audio amplifier stage built around the first transistor. The output from the....
This configuration utilizes the wide bandwidth aod speed of HA-2540. plus the output capability of HA5033. Stabilization circuitry is avoided by operating HA-2540 at a closed loop gain of 10, while maintaining an overall block gain of unity. A maximum....
Capacitor Cl and body capacitance (C2>of the operator form the voltage divider from the hot side of the ac line to ground. The voltage across Cl is determined by the ratio of Cl to C2. The higher voltage is developed across the smaller capacitor. When no one....
An op amp is used as a comparator and a sink for LED current. The output voltage of the amplifier changes about 1.4 V depending on the direction of the current. Only one transistor is on at any time. Maximum LED current is limited to 25 mA by overcurrent....
This electronic keyer uses four ICs (five, if the optional sidetone oscillator is desired) and operates from dc sources of 9 to 15..
Inverters Ula and Ulb form a 20-kilohertz oscillator whose square wave output-further shaped by D2, R4, and R5 and by D3, R6, and R7—drives power field-effect transistors Q2 and Q3. The p-channel and n-channel FETs conduct alternately, in al push-pull....
The time delay, T, in seconds is: T = 1.1 x Cl x (Rl + R2). The resistances are in megohms and capacitances in microfarads. The sum of R1 and R2 should not be Jess than 1000 0 nor higher than 20 MO. Pressing S1 starts the timing cycle. A low-going pulse,....
This circuit has been designed to alert the vehicle driver that he has reached the maximum fixed speed limit (i.e. in a motorway). It eliminates the necessity of looking at the tachometer and to be distracted from driving. There is a strict relation between....
The CA3080 can be used as a gain controlling device. The input signal is attenuated by R1/R2 so that a 20-mVpp..
Optically isolated SMPS and dc-to-dc converters face the variance of output voltage owing to the change of transmission c..
Incandescent lamp has been used to reduce harmonic distortion in sine oscillator circuit. The nonlinear resistance characteristic of the lamp filament help the circuit to shape the signal to approximate the ideal sine wave. Here is the classic Wien-bridge....
The power output of most of these circuits are very low because no power amplifier stages were incorporated. The transmitter circuit described here has an extra RF power amplifier stage, after the oscillator stage, to raise the power output to 200-250....
This circuit is a phaser circuit, as used in guitar foot-pedal effects. It used 11 sections of op-amp such as LM324 but others will do. The whole circuit works of a dual rail supply: +/- 9v. The 0v rail is indicated by a chassis sign. Make sure these....
A full range power controller suitable for lamp dimming and similar applications operate from a 120 volt, 60 Hz ac source, and can control up to 1000 watts of power to incandescent bulbs. The power to the bulbs is varied by controlling the conduction angle....
The 555 Stepper Pulse Generator kit will help you with the pulse required to drive your favorite DC Servo Motor application. This kit uses the famous 555 timer IC for generating the Stepping Pulse...
Generic Digital Switches are in-circuit programmable devices made by Lattice Semiconductor that allow pin to pin routing, buffering, and inversion. Perfect for making last minute circuit changes. Don't muck around with the software provided by Lattice, do it....
Because it uses few parts, a printed circuit board is not necessary; components can simply be soldered to one another. However, a box is desirable for operating convenience. The case and aerial from a discarded toy walkie-talkie was used in the prototype....
This circuit operates by charging a small capacitor from a constant-current source when the pulse to be measured is present. Dual pnp transistor Q3 is the current source; its output current equals the LM329 reference voltage divided by the resistance of....
Video-signal amplitude can be measured with this simple circuit, which is basically a modified standard peak detector. The device can verify RGB generated by video RAMDACs. Ul is a high-speed buffer and U2 is a latched comparator. CI is a hold capacitor.....
This FM transmitter has a number of features, with a volume control to adjust the input level and a small, neat box to make it easier to attach to a guitar. The volume control is positioned at the end and when turned up fully, the transmitter provides fuzz....
Using a Signetics NE602, this converter tunes the 9.5- to 9.8-MHz range. An AM car radio is used as a..
The tremolo effect is generated by a repeating volume change at a rate usually between 1 and 15Hz. The timer produces a low frequency square wave that is smoothed by a simple rc integrator. This varying signal modulates the signal input from the....
Halloween is coming up and it's time to do some pranks. Everyone likes Halloween and I'm no exception. Every year me and my wife decorate the house with lot's of bugs, spider webs, creepy posters and of course lot's of Halloween candy. While making the....
Lamp II is a household lamp. When the switch is in the center position, the lamp is operated on half-wave rectified ac; the ef..
Emits a carrier that sweeps the 925-960 MHz cellular tower transmitter band (handset receive band)...
The amplifier's gain is nominally 20 dB. Its frequency response is determined primarily by the value of just a few components—primarily Cl and Rl. The values of the schematic diagram provide a response of ±3.0 dB from about 120 Hz to better than 20,000....
Four (or more) inputs can be mixed and produce stereo output. Gain of each stage can be boosted by adding RX, but it should be kept below 50 (RX above 2 K) to avoid poor frequency, response. If more than four stages are used, decrease RXto 6 K for six....
This equaliser is designed as a preamp suitable for musical instruments - guitar, bass and keyboard in particular. Unlike most conventional graphic equalisers, each slider ranges from fully off to fully on, and not the more conventional +/-12dB or so that is....
On this page three adjustable notch filters configurations are shown . They can be used in your small pre-amp or amplifier project to filter out any HUM at 50 Hz ( European ) or 60Hz . By sustituting the capacitors values in the bridge other frequencies can....
This circuit allows you to set a limit on the maximum output current available from your PSU. It`s very useful when you power-up a project for the first time - or carry out a soak-test. By setting an upper limit on the current available from your PSU - you....
SW3 is the on/off switch. It also lets you choose between the output with the current limit and the one without. SW2 provides a selection of three different limits. You can increase or decrease this number if you wish. The limits are fixed by R4, R5 &....
This is a replacement power source for 1.3V mercury cells or other small batteries. It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital thermometer. This circuit takes it power from a PC. The power....
This moisture detector with pump controller is built around the special purpose LM1830 IC. The LM1830 is designed to detect moisture by passing an AC current through a set of probes. An internal comparator compares the resistance of the probes to an internal....
This is an improved version of the audio interface commonly used to connect a computer soundcard to a transceiver`s receive and transmit audio circuits. This kind of interface is used by computer programs that send and receive SSTV, RTTY, CW, PSK31 and....
This implementation is adapted to rebroadcast the output of a CD player, television receiver, or radio receiver. I use it so that I can move about the house and listen to my favorite programs without disturbing others. Within and the house, I find that I can....
This is the second generation of a circuit for a guitar spring reverb pedal, it has dry, wet, and drive controls for a wide variety of sounds. With a decent reverb spring (tank) in overdrive, this circuit will produce an incredibly thick and grungy sound,....
With a DPDT switch, I can switch the two data lines. I tried connecting the shields from the two computers together, the grounds two computers together, switching the D+ and D- lines with the DPDT switch, and leaving the VBus lines float, but for some reason....
The circuit offers independent control of initial delay and pulse rate. ICIc is connected as a pulse generator whose operation is inhibited by the normally low O/P of the ICla. When the circuit input goes low i.e., by pressing PB1, IClb O/P goes high and the....
This is a little transmitter that could be put into a plastic Easter egg. It delivers approximately 1 W of measured rf output into a 50-0 dummy load, and creates no heating problems with the circuit. The crystal is a series fundamental type, and the power....
The author described assembling this circuit on a 1"*1" perf board, I actually laid out a small PC board with excellent results. In this era of surface mount components, I think a much smaller version can be laid out on a PC board, allowing this circuit to....
A short-circuit-proof battery charger will provide an average charging current of about 8 A to a 12-V lead/acid storage battery. The charger circuit has an additional advantage; it will not function nor will it be damaged by improperly connecting the....
A MAX634 inverting regulator is combined with a MAX630 to provide a dual tracking ±15 output from a 12-V battery. The reference for the -15 V output is derived from the positive output via R3 and R4. ..
The IC is ideal for detecting the presence, absence or level of water or other conducting liquids. A detector determines the presence or absence of fluid by comparing the resistance of the fluid with the IC's internal reference resistance. An AC signal is....
Nice small audio amplifier which use only few parts to give good quality sound. This amp can be used as a simple booster, the heart of a more complicated amplifier or used as a guitar amp. Although not perfect, this amplifier does have a wide frequency....
Transformer Tl can be any matching transistor type in the range of 500/500 to 2500/2500 ohms. No connections from the SCR or its components are connected to ground. For safety's sake, keep the 117-V line voltage from the amplifier connections— that is the....
Combine an electrostatic transducer with an ultrasonic transceiver IC to build a ranging system that senses objects at distances from 4 inches to more than 30 feet. Transducer Yl "s broadband characteristic simplifies tuning. The secondary of T1 resonates....
This circuit uses one of the LM389 transistors.to gate the power amplifier on and off by applying the muting technique. The other transistors form a cross-coupled multivibrator circuit that controls the rate of the square-wave oscillator. ..
This circuit adds 120 degrees of phase shift to a 50- or 60-Hz input, regardless of the frequency and amplitude fluctuations ..
The amplifier provides 10 dB of gain from 10-600 MHz and has a 1-to-l match at 50 ohms. The BFR91 has a 1 dB noise figures at 500 MHz, The circuit requires 13 Vdc at about 13 mA. Keep the leads on the 150 pF emitter bypass capacitor as short as possible. The....
The following circuit can be used to detect those annoying piezo whistles that one can get from Radio Shack. For the Trinity Home Fire Fighting Contest, additional points accrue when the robot is started by a sound similar to a fire alarm. The actual....
This circuit detects frequency variation above or below preset limits. IC1 is a binary counter docked at FcLK· The outputs are comparea with switch preset values by IC2 and IC3. The input signal, which must be a positive-going pulse, is used to reset IC1.....
This continuity checker (built around an LM339 quad comparator with open-collector outputs) eliminates false r..
