New Circuits Page 232
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This unit is designed to interface: TV sound, videotape sound, and 5.1 dvd sound to a 4 channel home theater system. It provides the following functions/options. Mix DVD center into front left/right for Phantom Center effect with optional boost on center....
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When someone touches the touchplate (TP), the resistance of his finger across points A and is added in series to the combination of Rl and R2, the capacitor C2 begins to charge. When the voltage across Cl is finally sufficient to fire NE1, Cl will begin to....
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A circuit that offers visual indication of fluid level in a vessel, with a switchable audible alarm. Example uses would be to monitor the level of water in a bath or cold storage tank...
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The alarm uses a fixed-frequency piezoelectric buzzer in conjunction with the cadmium-sulfide (CDS) cell and the two-transistor circuit to provide a unique effect. Whenever light reaches the CDS photo-electric cell, the alarm is silent. But when no light....
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Not so much a real project as a field day for experimenters, this article describes the methods you can use to tailor an amplifier to a specific driver. Much is empirical (i.e. design by experiment, trial and error), and although formulae are possible, the....
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The IRISMPS5 is an open frame 90W Flyback power supply unit (psu) using the IRIS4015 Integrated switcher. This demo board aims to show the capability of the IRIS4015 to handle the upper level of flyback topology power range, without the strict standby power....
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The special characteristic of this regulator is that the output voltage can be adjusted down to 0 V. The regulation is pr..
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Using two 12-V filament or power transformers, an impromptu isolation transformer can be made for low-power (under 50 W) use in testing or servicing. SOI is an ordinary, duplex ac recept-able. ..
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Plumbing a laboratory with a standard frequency makes a lot of sense if the lab uses multiple frequency counters, spectrum analyzers, and other frequency-dependent test equipment. Rather than spending time keeping all of the instruments` oscillators in....
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A simple Sump Pump Control Circuit using NE555...
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This circuit provides a very low cost method of controlling light levels. Circuit power is obtained from a relatively high source impedance transformer or motor windings, normally used to drive the low-voltage lamps used in these functions. It should be....
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This is a prototype of the WA4DSY 56KB RF modem. It is intended for use on amateur packet radio networks. The modem generates RF in the 28 to 30 mhz range and requires and linear transverter to convert the signal to a UHF or microwave ham band. The digital....
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No description available...
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The 555-based bistable circuit in Figure 1 can easily generate a pseudo-trapezoidal move profile. Note that the timing string of R1 and associated components does not connect to VCC, as it would in a normal circuit, but instead receives its power through a....
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Connected in this manner, an LM317 1-A adjustable-voltage regulator can be used to control the speed of a miniature dc motor or vary the brilliance of a small lamp. The circuit does so by controlling the pulse width, and therefore the current, to the load....
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Digitally controlled potentiometers are useful for generating analog control voltages under the control of a microcontroller. In some applications, manual pushbutton switches could replace a microcontroller and simplify product design. Mechanical switches....
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Deep discharge can damage a rechargeable battery. By disconnecting the battery from its load, this circuit halts battery discharge at a predetermined level of declining terminal voltage. Transistor Ql acts as the switch...
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A composite stereo signal, as transmitted by FM radio stations, is composed of at least three parts: A base band mono signal, a double sideband channel difference signal, and a pilot carrier. The signal composition is somewhat analogous to an NTSC composite....
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Adjustable capacitor C10, and coil L1 form a tank circuit that, in combination with Q1, C2, and R1, oscillates at a frequency on the FM band. The center frequency is set by adjusting C10. An electret microphone, M1, picks up an audio signal that is....
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The op amp is connected in the inverting mode. Resistor R3 from the output to the inverting input sets the gain and current through the frequency-determining capacitor, CI. Capacitor C2 provides feedback from the output to the junction of Rl and R2. CI and....
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Variable width pulses with fast rise times are provided by Ul, and MC34060 operating at 120kHz, the optimum frequency for heating aluminum alloy containers. The pulse width is modulated by sensing the temperature of the target with a thermistor, using its....
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Using two CA3450 op amps and a CA3227 transistor array, this circuit will accurately full-wave rectify sign..
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National Semiconductor's DP8464B is primarily intended for use in disk systems as a pulse detector. However it can be easily used as a general purpose peak detector for analogue signals up to 5 MHz. The chip can handle signals between 20 and 66 mV....
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The IR transmitter connects to a telephone cir cuit, and transmits both sides of all telephone conversations to any line-of"sight location, within 40 feet. No !fOWer is taken from the central office, as long as all phones remain on-hook. The current....
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This circuit has stable threshold characteristics from its dependence on the-photo diode current in the Ll4Cl to generate a base emitter voltage drop across the sensitivity setting resistor. The double phase shift network supplying voltage to the ST-4....
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Using only an 8-pin IC and a few discrete components, you can build the infrared optical interrupter. The NE567..
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Two 555s and a quad NAND-gate IC can simulate an electrocardiograph signal and a -y-wave radioisotope signal for applications in nuclear medicine. This circuit synchronizes the radioisotope signal to the EKG signal. You can use the circuit"s outputs to....
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Almost any receiver covering 540 kHz to 1600 kHz is suitable for broadcast band DX`ing, and there are a lot of them. But the antenna is another matter. If you are new to the hobby, or if you have been having trouble DX`ing those really difficult stations,....
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A 12 Volt solar power system can provide power to a wide variety of devices. Some examples include: lighting systems, cellular phones, CB and Ham radios, car stereos, televisions, recording equipment, fans, water pumps, and other low voltage DC loads. With....
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No description available...
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My generator can produce sine- and squarewaves with frequencies between 1 Hz and 100 kHz and amplitudes ranging from zero to 1.55 Veff in 600 Ohms. Sinewave distortion is 0.1% or less between 20 Hz and 20 kHz, somewhat greater outside this region. The output....
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This little circuit can be used to dim lights up to about 350 watts. It uses a simple, standard TRIAC circuit that, in my expirience, generates very little heat. Please note that this circuit cannot be used with fluorescent lights...
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An IR-sensitive phototransistor is used to sense soldering-iron temperature. The phototransistor must see t..
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A three-way switch to control a lamp (off-dim-bright, etc.) uses an NE555 timer to generate a one-second pulse, trigge..
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This is an improved version of headphone amplifier I`ve built many years ago. I wanted so much to share it with you because this simple circuit has done a great service to me through all these years. It is very simple and reliable, hard to break, offers a....
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A single zone alarm circuit with entry and exit delay and other facilities. The circuit features automatic exit and entry delays, timed bell cut-off and system reset. It has provision for normally open and normally closed switches and will suit the usual....
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This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It`s designed to be used with the usual types of normally-closed input devices such as - magnetic reed contacts - micro....
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This over/under voltage cut-out will save your costly electrical and electronic appliances from the adverse effects of very high and very low mains voltages. The circuit features auto reset and utilises easily available components. It makes use of the....
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This adaptor lets me program 8 or 20 pin DIP devices using the In-System Programmer (ISP) described in Atmel's AVR910 application note. This circuit provides power and clocks for the part to be programmed and power to the ISP circuit. When programming 8 pin....
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Electrodes are immersed in an electrolyte that remains level while the sensor follows the tilt of the body on which it is placed, more of one outer electrode and less of the other are immersed and their resistances fall or rise, respectively. The resistance....
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This protection circuit is inserted between the reset switch and the motherboard. The earth connection of th..
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The TL082 (Or a TL072 also is OK) Creates an Adjustable Sawtooth Generator. (It also has a Square wave Output, but it isn`t used here.)
The Left and Right LED`s are Connected in Series and if this circuit is used on a 12 volt system, and if a person....
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This circuit was designed on request and can be useful to those whishing to have, say, a red LED illuminated when an appliance is on and a green LED illuminated when the same appliance is off.
Any mains operated appliance can be monitored by this circuit,....
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A recent Design Idea described a method for designing simple, high-frequency LC oscillators with few passive components (Reference 1). However, for best results, practical hardware design of a stable oscillator requires more parts and greater complexity.....
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Originally, the prime harmonics were generated with 74HC4046 PLLs which were spot-on accurate but would take some time to reach their final frequencies, especially when running at low frequencies. They also limited the useful frequency output range and I....
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I aimed to copy the sound rather than the vintage circuit. Easy to build, low current consumption, no signal level changes on bypass, quiet and, most importantly, it does that Bridge of Sighs thing...
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Figure 1 shows the LT®3439, one of several low noise
switchers available from Linear Technology. Ultralow
noise and low EMI are achieved by controlling both the
output switch voltage and current slew rates. This switching
architecture is particularly....
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This multimeter was designed to measure output voltage and current in a PSU, where the current sense shunt resistor is connected in series with load at the negative voltage rail. It needs only one supply voltage that can be acquired from main PSU. An....
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This AM receiver is working perfectly without the need of coils or even a variable capacitor. The LF356 is the basic component. P1 and P2 are the frequency selectors. Use a small telescopic antenna. The stations selectivity is not perfect but is acceptable. ..
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To amplify the small current signals as an electron collector inside a vacuum chamber, it is convenient for reasons of noise and bandwidth to have a "head-amplifier" attached to the chamber. Op N-amp 1 is a precision device with bipolar bias current and low....
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This is a very simple 5 watt CW TX based upon a TTL logic chip. There is just one "tricky" component and this is Cx. This component should have an impedance of about 10 - 50 ohms at the frequency of interest. If you wish to reduce the transmitter power,....
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The circuit has both square-wave and triangle-wave output. The left section is similar in function to a comparator circuit that uses positive feedback for hysteresis. The inverting input is biased at one-half the Vcc voltage by resistor R4 and R5. The....
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Requiring no rectifier diodes, the positive peak-detector circuits in figures 1 and 2 exploit the open-drain output of a Texas Instruments TLC372 fast comparator, IC1. Both versions of the detector are simple and inexpensive and provide a buffered,....
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A simple test circuit to fault find audio and radio equipment. Can be used to inject a square wave signal, rich in harmonics, or used with headphones as an audio tracer. A single pole double throw sitch is used to switch between inject and trace modes. The....
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The major building blocks for a white-LED driver are an oscillator, a charge pump, and a regulated current source. National Semiconductor (www.national.com) produces a device that contains all these building blocks in the highly integrated LM2791/2 IC. You....
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M1 is a stepper taken from an old disk drive. There are five pins, i.e., common, coil 1, 2, 3 and 4. Resistance measured between common pin and each coil is about 75 Ohms. Driving current for each coil is then needed about 60mA at +5V supply. A darlington....
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An on-board oscillator and a 17-stage divider compose IC1. By connecting a standard 3.58-MHz, television color-burst crystal as shown, an accurate source of 60-Hz squarewaves is generated at the IC"s output, pin 1. Those pulses are then fed to IC2, a 4024....
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Converting periodic waveforms to square waves is an integral part of extracting a clock signal from data, creating waveform generators, and making timing-pulse generators. Any square-wave-conversion circuit is more valuable when the square wave`s duty cycle....
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This highly integrated GPS receiver IC improves upon earlier-generation devices by including more components in a smaller package with a reduction in power consumption...
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This circuit uses a type 741 op amp as a voltage comparator. One input of the 7.41 is connected to a reference voltage (a 12-V battery) through a resistor voltage divider. The potential at the noninverting input of the 741 is approximately 3 V. The....
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The schematic for a monostable multivibrator is shown in figure 3-11. Like the astable multivibrator, one transistor conducts and the other cuts off when the circuit is energized...
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When you need to quickly connect a negative power supply under logic control, the negative power-side switch in Figure 1 can help. Although originally intended for driving the gates of high-current MOSFETs, the MIC4451 can assume a different role. It....
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This device uses a PIC12F615 to implement a capacitor discharge ignition system. When the switch (button) is closed, the PIC sends pulses to the IRF644 MosFet creating high voltage pulses to charge the 1.0 uf/250 volt capacitor. The voltage is read back via....
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The ProfiLab-Expert software allows you to develop your own digital or analogue measuring technology projects. It doesnt matter if you want to create analogue measurements or digital controls - you can realize it all. And for all this you dont have to write....
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A2N3819 FETprovides a solid-state VOM. The 2N3819 acts as a cathode follower in a VOM. The bias offset (meter null) is obtained with R14 and R12 sets full-scale calibration. R2 through R9 should total about 10 MO. ..
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Audio-taper pot, R1, adjusts input level into two LM386 amplifier chips. The LM386 is a low-voltage audio power amplifier, designed to operate on 4V to 12V. It has an internal 15K feedback resistor between pins 1 and 5 which would set the gain at 20 (26dB)...
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This circuit allows you to equlize the audio signals in ten band. It uses low cost op-amps to form a professional equalizer circuit. The heart of the design is a classical band-pass active filter. The U11 acts as an attenuator to prepare the signal level for....
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In the 100-kHz application from left to right, the coupling network feeds into the receiver ~section on the bottom of the chip. (The external components are summarized later.) The receive data output is pulled up via RPuLL ~ 10 K!l. A minimum current of 10....
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That Circuit is a UHF TV linear amplifier for small TV transmitters with output aroun 100-200mW. The transistor BGQ136 comes with SOT-122 case has gain of 13dB at 800MHz. So with input 100mW you get 2W output and for 200mW you get 4W...
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This project is aimed at building a small circuit that fits into a standard USB Visor cradle and that adds RS-232 capabilities. Note that Handspring sells a serial cradle but if you have more time than money, do it yourself and you will have a 2 in 1 cradle !..
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With this circuit mounted in or near every phone in the house, it will allow users to know if the phone is being used and not to pick up the phone. When a phone is taken off hook, the voltage across the tip and ring terminals drops to 10 volts or less. This....
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Whenever I`m in the car listening to my favourite CD, it always happens-my batteries go dead. To solve that problem, I built this extremely simple regulator circuit. It steps down the 12V from the lighter socket to 9V which is used by the CD player.....
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A 4V-60V to 5V DC/DC converter is shown in Figure 2. This
converter is well suited for 12V automotive battery applications,
maintaining output voltage regulation with battery
line voltages from 4V cold crank through 60V load
dump. The threshold for....
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This is a computer I built for my car, its an MP3 music system but can also do other tasks. Based around a super-small sub-micro ATX motherboard from a computer known as the BookPC BKi810, I have put the motherboard, hard drive, and a 12 volt power supply in....
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The inspiration for the VCO
in Figure 1 came from Texas Instruments
application notes of years ago, detailing
the use of unbuffered U-type inverters
for use in ring oscillators. The
application notes circuit consists of only
the inverters. The circuit....
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In the drawing he appear simple but powerful power amplifier. His difference with the classic designings, that use differential amplifier in their input, they are that this amplifier it uses a completed the NE5534, in his input. Thus it should we degrade....
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The receiver will accurately condition a wide range of light inputs at up to 10 MHz data rates. The optical signal is detected by the PIN photodiode and amplified by a broadband fed-back stage, Q1-Q3. A second, similar, stage gives further amplification. The....
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For use with low-power transmitters with a positive keying voltage. Q1/Q2/Q3 form a switching amplifier. When the key is pressed, the collector of Q3 goes to ground, turning on Q5 and activating IC1, an audio oscillator. Q4 drives the speaker...
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This circuit was designed to charge NiCad battery packs in the range of 4.8 to 15.6 V from a convenient remote power source, such as an automobile battery. When power is first applied to the circuit, a small bias current supplied by Rl via winding Wl,....
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This circuit can be used to remotely monitor a loudspeaker, alarm, or audio source for presence of an audio waveform. It can also be directly connected across loudspeaker terminals used as a peak indicator. If you need to monitor some audio signal at a....
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Connecting a LCD display to your personal computer is an easy job. Displaying data from your PC to a LCD can be proven very exiting, so give it a try and build your own today! In this article we will use a 2 lines x 16 characters LCD display with Hitachi....
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This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full.
The circuit uses the widely available CD4066, bilateral switch CMOS IC to indicate the water level through LEDs.
When the water....
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The circuit is a 0-60 second timer using timer 555 and two 4017 for LED driving...
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The purpose of this circuit is to automatically turn off any device plugged into its power outlets after a certain period of time. Shutoff is activated by an absences of an audio signal or by a standard timer function. This unit would be connected to speaker....
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The voltage to be compared is fed through diode Dl and D2 to the voltage dividers Rl and R5 where the low and high limits are present. When the voltage level of an input signal exceeds the high threshold limit set with potentiometer Rl, the diode Dl becomes....
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This is a single channel (on / off) universal switch that may be used with any Infra Red remote control using 36-38kHz. (This is a very common remote handset frequency). Any "button" of any remote control may be used to work this universal switch. The button....
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This is a simple RF receiver mainly for low-distance digital radio receiver application. The analog output of this circuit should be connected to a schmitt-trigger signal conditioning circuit with a proper value capacitor (from collector of T3). L1 for 27Mhz....
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This circuit provides a unique solution to a common system-level power distribution problem: When the su..
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A microcomputer-to-triac interface uses a phototriac optoisolator to Jet safety-isolated logic signals directly control high-power loads. Depending on the input waveforms and the load, this circuit can be used in either an on/off switch or a proportional....
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The circuit uses a synchronous-detection scheme to measure low-level resistances. Other low-resis-tance-measuring circui..
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This project involves making several modification to an early 1960s era Victoreen CDV700 or CDV600-6B geiger counter. These counters are available on E-Bay for around $50 to $100. The modifications use modern electronic parts to improve the counter`s....
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This circuit has been designed to provide a clearly visible light, formed by 13 high efficiency flashing LEDs arranged in a pseudo-rotating order. Due to low voltage, low drain battery operation and small size, the device is suitable for mounting on bicycles....
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With the component values shown, the oscillator has a frequency of 8 kHz. When an input signal is applied to the base of Ql the current flowing through Ql is varied, thus varying the time required to charge Cl. Due to the phase inversion in Ql the direction....
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The control circuit in Figure 1 senses a given load and automatically soft-starts the load by synchronously adjusting the power to that load. You can also manually adjust the power delivered to the load by controlling the phase angle of the line voltage....
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The Digital Addressable Lighting Interface (DALI), international standard prlEC929, is a communication protocol
and method to interface lighting units on a 2-wire network. The DALI protocol is 16 bits and supports addressing up
to 64 ballasts individually,....
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Both of these converters use CMOS inverters. Figure 105-1A shows a free-running circuit having both the pulse duration and pulse pause dependent on temperature of the diode D8. It can be used where a synchronization between the converter and something else....
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This handy breadboard header for ATTiny 25/45/85 microcontroller is a new design based on the original idea from Tinkerlog. Maybe the most useful feature is that it can provide power to the vertical breadboard strips while connecting all six port pins to the....
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To get a low output impedance I needed to use quite a high step-down ratio (20:1); after all, the amplifier may be used with headphones of lower impedance that the 300 Ohms of the HD600. The output valve is the 12B4A which has a anode impedance of about....
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With the P1 we regulate the intensity of sound. With the P2 we regulate the frequency of reception. Optionally: If you want to check the frequency with your PC it will be supposed you make the following energies: You assemble and the circuit that is in the....
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This is a very simple crystal reciever circuit for short wave band and can be used with headphones...
This unit is designed to interface: TV sound, videotape sound, and 5.1 dvd sound to a 4 channel home theater system. It provides the following functions/options. Mix DVD center into front left/right for Phantom Center effect with optional boost on center....
When someone touches the touchplate (TP), the resistance of his finger across points A and is added in series to the combination of Rl and R2, the capacitor C2 begins to charge. When the voltage across Cl is finally sufficient to fire NE1, Cl will begin to....
A circuit that offers visual indication of fluid level in a vessel, with a switchable audible alarm. Example uses would be to monitor the level of water in a bath or cold storage tank...
The alarm uses a fixed-frequency piezoelectric buzzer in conjunction with the cadmium-sulfide (CDS) cell and the two-transistor circuit to provide a unique effect. Whenever light reaches the CDS photo-electric cell, the alarm is silent. But when no light....
Not so much a real project as a field day for experimenters, this article describes the methods you can use to tailor an amplifier to a specific driver. Much is empirical (i.e. design by experiment, trial and error), and although formulae are possible, the....
The IRISMPS5 is an open frame 90W Flyback power supply unit (psu) using the IRIS4015 Integrated switcher. This demo board aims to show the capability of the IRIS4015 to handle the upper level of flyback topology power range, without the strict standby power....
The special characteristic of this regulator is that the output voltage can be adjusted down to 0 V. The regulation is pr..
Using two 12-V filament or power transformers, an impromptu isolation transformer can be made for low-power (under 50 W) use in testing or servicing. SOI is an ordinary, duplex ac recept-able. ..
This circuit provides a very low cost method of controlling light levels. Circuit power is obtained from a relatively high source impedance transformer or motor windings, normally used to drive the low-voltage lamps used in these functions. It should be....
Connected in this manner, an LM317 1-A adjustable-voltage regulator can be used to control the speed of a miniature dc motor or vary the brilliance of a small lamp. The circuit does so by controlling the pulse width, and therefore the current, to the load....
Deep discharge can damage a rechargeable battery. By disconnecting the battery from its load, this circuit halts battery discharge at a predetermined level of declining terminal voltage. Transistor Ql acts as the switch...
A composite stereo signal, as transmitted by FM radio stations, is composed of at least three parts: A base band mono signal, a double sideband channel difference signal, and a pilot carrier. The signal composition is somewhat analogous to an NTSC composite....
Adjustable capacitor C10, and coil L1 form a tank circuit that, in combination with Q1, C2, and R1, oscillates at a frequency on the FM band. The center frequency is set by adjusting C10. An electret microphone, M1, picks up an audio signal that is....
The op amp is connected in the inverting mode. Resistor R3 from the output to the inverting input sets the gain and current through the frequency-determining capacitor, CI. Capacitor C2 provides feedback from the output to the junction of Rl and R2. CI and....
Variable width pulses with fast rise times are provided by Ul, and MC34060 operating at 120kHz, the optimum frequency for heating aluminum alloy containers. The pulse width is modulated by sensing the temperature of the target with a thermistor, using its....
Using two CA3450 op amps and a CA3227 transistor array, this circuit will accurately full-wave rectify sign..
National Semiconductor's DP8464B is primarily intended for use in disk systems as a pulse detector. However it can be easily used as a general purpose peak detector for analogue signals up to 5 MHz. The chip can handle signals between 20 and 66 mV....
The IR transmitter connects to a telephone cir cuit, and transmits both sides of all telephone conversations to any line-of"sight location, within 40 feet. No !fOWer is taken from the central office, as long as all phones remain on-hook. The current....
This circuit has stable threshold characteristics from its dependence on the-photo diode current in the Ll4Cl to generate a base emitter voltage drop across the sensitivity setting resistor. The double phase shift network supplying voltage to the ST-4....
Using only an 8-pin IC and a few discrete components, you can build the infrared optical interrupter. The NE567..
Two 555s and a quad NAND-gate IC can simulate an electrocardiograph signal and a -y-wave radioisotope signal for applications in nuclear medicine. This circuit synchronizes the radioisotope signal to the EKG signal. You can use the circuit"s outputs to....
Almost any receiver covering 540 kHz to 1600 kHz is suitable for broadcast band DX`ing, and there are a lot of them. But the antenna is another matter. If you are new to the hobby, or if you have been having trouble DX`ing those really difficult stations,....
A 12 Volt solar power system can provide power to a wide variety of devices. Some examples include: lighting systems, cellular phones, CB and Ham radios, car stereos, televisions, recording equipment, fans, water pumps, and other low voltage DC loads. With....
My generator can produce sine- and squarewaves with frequencies between 1 Hz and 100 kHz and amplitudes ranging from zero to 1.55 Veff in 600 Ohms. Sinewave distortion is 0.1% or less between 20 Hz and 20 kHz, somewhat greater outside this region. The output....
This little circuit can be used to dim lights up to about 350 watts. It uses a simple, standard TRIAC circuit that, in my expirience, generates very little heat. Please note that this circuit cannot be used with fluorescent lights...
An IR-sensitive phototransistor is used to sense soldering-iron temperature. The phototransistor must see t..
A three-way switch to control a lamp (off-dim-bright, etc.) uses an NE555 timer to generate a one-second pulse, trigge..
This is an improved version of headphone amplifier I`ve built many years ago. I wanted so much to share it with you because this simple circuit has done a great service to me through all these years. It is very simple and reliable, hard to break, offers a....
A single zone alarm circuit with entry and exit delay and other facilities. The circuit features automatic exit and entry delays, timed bell cut-off and system reset. It has provision for normally open and normally closed switches and will suit the usual....
This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It`s designed to be used with the usual types of normally-closed input devices such as - magnetic reed contacts - micro....
This over/under voltage cut-out will save your costly electrical and electronic appliances from the adverse effects of very high and very low mains voltages. The circuit features auto reset and utilises easily available components. It makes use of the....
This adaptor lets me program 8 or 20 pin DIP devices using the In-System Programmer (ISP) described in Atmel's AVR910 application note. This circuit provides power and clocks for the part to be programmed and power to the ISP circuit. When programming 8 pin....
Electrodes are immersed in an electrolyte that remains level while the sensor follows the tilt of the body on which it is placed, more of one outer electrode and less of the other are immersed and their resistances fall or rise, respectively. The resistance....
This protection circuit is inserted between the reset switch and the motherboard. The earth connection of th..
The TL082 (Or a TL072 also is OK) Creates an Adjustable Sawtooth Generator. (It also has a Square wave Output, but it isn`t used here.) The Left and Right LED`s are Connected in Series and if this circuit is used on a 12 volt system, and if a person....
This circuit was designed on request and can be useful to those whishing to have, say, a red LED illuminated when an appliance is on and a green LED illuminated when the same appliance is off. Any mains operated appliance can be monitored by this circuit,....
Originally, the prime harmonics were generated with 74HC4046 PLLs which were spot-on accurate but would take some time to reach their final frequencies, especially when running at low frequencies. They also limited the useful frequency output range and I....
I aimed to copy the sound rather than the vintage circuit. Easy to build, low current consumption, no signal level changes on bypass, quiet and, most importantly, it does that Bridge of Sighs thing...
This multimeter was designed to measure output voltage and current in a PSU, where the current sense shunt resistor is connected in series with load at the negative voltage rail. It needs only one supply voltage that can be acquired from main PSU. An....
This AM receiver is working perfectly without the need of coils or even a variable capacitor. The LF356 is the basic component. P1 and P2 are the frequency selectors. Use a small telescopic antenna. The stations selectivity is not perfect but is acceptable. ..
To amplify the small current signals as an electron collector inside a vacuum chamber, it is convenient for reasons of noise and bandwidth to have a "head-amplifier" attached to the chamber. Op N-amp 1 is a precision device with bipolar bias current and low....
This is a very simple 5 watt CW TX based upon a TTL logic chip. There is just one "tricky" component and this is Cx. This component should have an impedance of about 10 - 50 ohms at the frequency of interest. If you wish to reduce the transmitter power,....
The circuit has both square-wave and triangle-wave output. The left section is similar in function to a comparator circuit that uses positive feedback for hysteresis. The inverting input is biased at one-half the Vcc voltage by resistor R4 and R5. The....
A simple test circuit to fault find audio and radio equipment. Can be used to inject a square wave signal, rich in harmonics, or used with headphones as an audio tracer. A single pole double throw sitch is used to switch between inject and trace modes. The....
M1 is a stepper taken from an old disk drive. There are five pins, i.e., common, coil 1, 2, 3 and 4. Resistance measured between common pin and each coil is about 75 Ohms. Driving current for each coil is then needed about 60mA at +5V supply. A darlington....
An on-board oscillator and a 17-stage divider compose IC1. By connecting a standard 3.58-MHz, television color-burst crystal as shown, an accurate source of 60-Hz squarewaves is generated at the IC"s output, pin 1. Those pulses are then fed to IC2, a 4024....
Converting periodic waveforms to square waves is an integral part of extracting a clock signal from data, creating waveform generators, and making timing-pulse generators. Any square-wave-conversion circuit is more valuable when the square wave`s duty cycle....
This circuit uses a type 741 op amp as a voltage comparator. One input of the 7.41 is connected to a reference voltage (a 12-V battery) through a resistor voltage divider. The potential at the noninverting input of the 741 is approximately 3 V. The....
The schematic for a monostable multivibrator is shown in figure 3-11. Like the astable multivibrator, one transistor conducts and the other cuts off when the circuit is energized...
This device uses a PIC12F615 to implement a capacitor discharge ignition system. When the switch (button) is closed, the PIC sends pulses to the IRF644 MosFet creating high voltage pulses to charge the 1.0 uf/250 volt capacitor. The voltage is read back via....
The ProfiLab-Expert software allows you to develop your own digital or analogue measuring technology projects. It doesnt matter if you want to create analogue measurements or digital controls - you can realize it all. And for all this you dont have to write....
A2N3819 FETprovides a solid-state VOM. The 2N3819 acts as a cathode follower in a VOM. The bias offset (meter null) is obtained with R14 and R12 sets full-scale calibration. R2 through R9 should total about 10 MO. ..
This circuit allows you to equlize the audio signals in ten band. It uses low cost op-amps to form a professional equalizer circuit. The heart of the design is a classical band-pass active filter. The U11 acts as an attenuator to prepare the signal level for....
In the 100-kHz application from left to right, the coupling network feeds into the receiver ~section on the bottom of the chip. (The external components are summarized later.) The receive data output is pulled up via RPuLL ~ 10 K!l. A minimum current of 10....
That Circuit is a UHF TV linear amplifier for small TV transmitters with output aroun 100-200mW. The transistor BGQ136 comes with SOT-122 case has gain of 13dB at 800MHz. So with input 100mW you get 2W output and for 200mW you get 4W...
This project is aimed at building a small circuit that fits into a standard USB Visor cradle and that adds RS-232 capabilities. Note that Handspring sells a serial cradle but if you have more time than money, do it yourself and you will have a 2 in 1 cradle !..
With this circuit mounted in or near every phone in the house, it will allow users to know if the phone is being used and not to pick up the phone. When a phone is taken off hook, the voltage across the tip and ring terminals drops to 10 volts or less. This....
Whenever I`m in the car listening to my favourite CD, it always happens-my batteries go dead. To solve that problem, I built this extremely simple regulator circuit. It steps down the 12V from the lighter socket to 9V which is used by the CD player.....
This is a computer I built for my car, its an MP3 music system but can also do other tasks. Based around a super-small sub-micro ATX motherboard from a computer known as the BookPC BKi810, I have put the motherboard, hard drive, and a 12 volt power supply in....
The inspiration for the VCO in Figure 1 came from Texas Instruments application notes of years ago, detailing the use of unbuffered U-type inverters for use in ring oscillators. The application notes circuit consists of only the inverters. The circuit....
In the drawing he appear simple but powerful power amplifier. His difference with the classic designings, that use differential amplifier in their input, they are that this amplifier it uses a completed the NE5534, in his input. Thus it should we degrade....
The receiver will accurately condition a wide range of light inputs at up to 10 MHz data rates. The optical signal is detected by the PIN photodiode and amplified by a broadband fed-back stage, Q1-Q3. A second, similar, stage gives further amplification. The....
For use with low-power transmitters with a positive keying voltage. Q1/Q2/Q3 form a switching amplifier. When the key is pressed, the collector of Q3 goes to ground, turning on Q5 and activating IC1, an audio oscillator. Q4 drives the speaker...
This circuit was designed to charge NiCad battery packs in the range of 4.8 to 15.6 V from a convenient remote power source, such as an automobile battery. When power is first applied to the circuit, a small bias current supplied by Rl via winding Wl,....
This circuit can be used to remotely monitor a loudspeaker, alarm, or audio source for presence of an audio waveform. It can also be directly connected across loudspeaker terminals used as a peak indicator. If you need to monitor some audio signal at a....
Connecting a LCD display to your personal computer is an easy job. Displaying data from your PC to a LCD can be proven very exiting, so give it a try and build your own today! In this article we will use a 2 lines x 16 characters LCD display with Hitachi....
This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full. The circuit uses the widely available CD4066, bilateral switch CMOS IC to indicate the water level through LEDs. When the water....
The circuit is a 0-60 second timer using timer 555 and two 4017 for LED driving...
The purpose of this circuit is to automatically turn off any device plugged into its power outlets after a certain period of time. Shutoff is activated by an absences of an audio signal or by a standard timer function. This unit would be connected to speaker....
The voltage to be compared is fed through diode Dl and D2 to the voltage dividers Rl and R5 where the low and high limits are present. When the voltage level of an input signal exceeds the high threshold limit set with potentiometer Rl, the diode Dl becomes....
This is a single channel (on / off) universal switch that may be used with any Infra Red remote control using 36-38kHz. (This is a very common remote handset frequency). Any "button" of any remote control may be used to work this universal switch. The button....
This is a simple RF receiver mainly for low-distance digital radio receiver application. The analog output of this circuit should be connected to a schmitt-trigger signal conditioning circuit with a proper value capacitor (from collector of T3). L1 for 27Mhz....
This circuit provides a unique solution to a common system-level power distribution problem: When the su..
A microcomputer-to-triac interface uses a phototriac optoisolator to Jet safety-isolated logic signals directly control high-power loads. Depending on the input waveforms and the load, this circuit can be used in either an on/off switch or a proportional....
The circuit uses a synchronous-detection scheme to measure low-level resistances. Other low-resis-tance-measuring circui..
This project involves making several modification to an early 1960s era Victoreen CDV700 or CDV600-6B geiger counter. These counters are available on E-Bay for around $50 to $100. The modifications use modern electronic parts to improve the counter`s....
This circuit has been designed to provide a clearly visible light, formed by 13 high efficiency flashing LEDs arranged in a pseudo-rotating order. Due to low voltage, low drain battery operation and small size, the device is suitable for mounting on bicycles....
With the component values shown, the oscillator has a frequency of 8 kHz. When an input signal is applied to the base of Ql the current flowing through Ql is varied, thus varying the time required to charge Cl. Due to the phase inversion in Ql the direction....
Both of these converters use CMOS inverters. Figure 105-1A shows a free-running circuit having both the pulse duration and pulse pause dependent on temperature of the diode D8. It can be used where a synchronization between the converter and something else....
This handy breadboard header for ATTiny 25/45/85 microcontroller is a new design based on the original idea from Tinkerlog. Maybe the most useful feature is that it can provide power to the vertical breadboard strips while connecting all six port pins to the....
To get a low output impedance I needed to use quite a high step-down ratio (20:1); after all, the amplifier may be used with headphones of lower impedance that the 300 Ohms of the HD600. The output valve is the 12B4A which has a anode impedance of about....
With the P1 we regulate the intensity of sound. With the P2 we regulate the frequency of reception. Optionally: If you want to check the frequency with your PC it will be supposed you make the following energies: You assemble and the circuit that is in the....
This is a very simple crystal reciever circuit for short wave band and can be used with headphones...
