New Circuits Page 231
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The timing components are Rl, R2, and C,. Cl is a bypass capacitor used to reduce the effects of noise. At start-up, the voltage across C, is less than the trigger level voltage (1/3 Vnn). causing the timer to be triggered via pin 2. The output of the....
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To "round" your square wave, you need to integrate it twice; once to produce a triangular wave, and a second time to produce a parabolic waveform. (A parabolic wave looks pretty much sinusoidal.) You can do this passively using a simple network such as the....
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1. THE INPUT CLOCK frequency fed into this circuit is divided by 2n-l. The circuit consists of clocked flip-..
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The amplifier picks up the TV"s audio output signal and amplifies it to drive a set of earphones for private listening. It is built around an LM324 quad op amp and an LM386 low-power audio amplifier. ..
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Teledyne Semiconductor"s Type TSC9402 IC is eminently suitable as an inexpensive current-to-frequency conver..
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Single programming resistor Rp provides an output-current range of about six decades.-Note that this resistor"s TC is also a potential source of error; it dissipates 125 mW when JliN ~ 5 V. The maximum deviation is typically 50 nA or 0.0002% of full scale. ..
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The LM3915 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs providing a logarithmic 3 dB/step analog display. LED current drive is regulated and programmable, eliminating the need for current limiting resistors. The IC....
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Often a circuit will be called upon to perform several functions. In these situations, the variable gain configuration of this circuit could be quite useful. This programmable gain stage depends on CMOS analog switches to alter the amount of feedback,....
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This circuit is a simple IR detector for testing IR remote controllers. The circuit is based on one phototransistor which receives the IR beam. The NPN transistor works as an amplifier which feeds current to the led. When this circuit detects IR or light,....
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This straightforward circuit uses an NE555 timer as an oscillator, a 7493 counter chain and a DAC0806 D/A conver..
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A very useful audio amp in an 8-pin DIL package. The IC features a very low minimum working supply voltage of 3V, low quiescent current, good ripple rejection, no crossover distortion and low power dissipation...
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This circuit design is a class A amplifier employing both ac and de feedback. Bias is stabilized at 15 mA of the collector current using de feedback from the collector. The ac feedback, from collector to base, and in each of the partially bypassed emitter....
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The low-cost Mini-Circuits MAR-X series of chips offer the RF builder a real advantage, with their inherent 50- input and output impedances (needed for RF systems). An MAR-1-based receiver/scanner preamplifier is shown. Ci and C2 are chip capacitors. Use....
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This Power Supply is suitable for the Modular Burglar Alarm. However, it has other applications. It is designed to provide an output of 12-volts, with a current of up to 1-amp. In the event of mains failure, the back-up battery takes over automatically. When....
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This circuit switches a tape recorder via PL2. When on-hook, D5 conducts, turns on Ql, and cuts off Q..
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This accessory connects to phone and will activate an attention-getting 120-V bell whenever a ringing voltage appears on the ph..
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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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Lamp LI stabilizes the loop gain at higher frequencies while the limiting action of R2, CRI, and CR2 prevents clipping at low frequencies and increases the frequency adjustment range from about 3:1 to greater than 10:1.
..
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Large LCD (liquid crystal display) displays designed to
replace CRTs (cathode ray tubes) in desktop computer
applications are becoming available. The LCDs reduced
size and power requirements allow much smaller product
size, a highly desirable feature...
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This divider uses a variable-length shift register, a type-D flip-flop, and an inverter. The clock feeds the..
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It seems that guitar fuzz boxes have been around since the beginning of rock, and have seen little improvement over the years. This one is somewhat different because rather than simply distorting the sound, it also pulses in step with the peaks of the....
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The circuit is completely conventional, and has been around almost forever in one guise or another. Similar circuits were used in the valve (tube) era, so there is nothing new about it. The circuit has already been published on these pages as a guitar....
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The oscillator based on IC2 is responsible for producing the sound. Its output is connected to the base of TRl, ..
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While I would have liked a 4 channel chip with about 20 Watt per channel, the local parts store didn't have any yet, so I opted for two TA8215AH stereo chips, selected by their low price in this particular store. The design? Oh well, there isn't much to it.....
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This very high quality audio amp is based on the TDA1514A, a 9-pin flat package IC. The heatsink must be insulated from ground. The amplifier will deliver 40 watt into an 8ohm load with a 27.5 volt power rail or 40 watt into 4ohm load with a 21 volt power....
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This is an image Schematic. No Description available...
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This circuit will be of interest to the radio amateur and anyone posessing two radios, (one of which must be able to transmit i.e. a transceiver). It is a self powered (audio derived) repeater circuit for receiving a signal and re-transmitting it via the....
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This amplifier operates from a 28 Vdc supply. It has a typical gain of 12 dB, and can survive operation into a 30:1 VSWR load at any phase angle with no damage. This means that with input power held constant at the level that provides 125 watts output, the....
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Using the thermistor-bridge circuit, you can detect system-cooling air losses caused by filter or inlet ..
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Germanium transistor Ql is used as a noise generator in the audio range. Ul acts as a high-gain amplifier. Ql is not ..
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This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also....
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With a single IC, you can build a simple, reliable auto burglar alarm or a similar alarm. See (a) for the timing informatio..
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An electronic scale using a pressure transducer (load cell) and an analog-digital (A/D) converter to drive a digital display is shown. The scale range depends on load cell. Display is calibrated in appropriate units. Components are on main circuit and....
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Figure 2 shows another approach that requires additional components but delivers the full magnitude of the voltage ramp to Pin 3 of IC1 and provides the approximately 1V-dc offset that Reference 1 requires. Transistors Q1 and Q2, resistors R1 and R2, and LED....
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One of the requirements that is easily overlooked is the need to identify your station during your video communications. From what I have seen, some R/C wireless video users are neglecting to broadcast their ham radio call sign. Essentially, USA hams must do....
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The logic designer is filled with features. It would not be possible to list all the possible combinations of the unit as the various building blocks on the board can be interconnected to obtain a wide variety of counting and testing stages. You will be able....
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The aim of this project was to get a digital camera into a small electric radio controlled (RC) aeroplane and still have it fly. The aeroplane shown, a park flyer, weighs between 400 and 550 grams depending on the size of battery and wing configeration that....
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This RF converter converts amateur TV signals in the 420- to 450-MHz region to VHF channel 3 or 4, allowing reception of those signals on a standard TV receiver. RF amplifier Ql feeds mixer Ml, and Q3 acts as an IF amplifier. ..
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A real analog synthesizer to build using easy to get components, capable of a wide range of sounds. The two oscillators can be detuned for that classic synth sound. Dual oscillator mono synth. Really easy to build using just 1 custom programmed PIC chip, 4....
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These two circuits are interesting from an academic point of view. Their practical implementation is rather critical and it is not easy to get steady operation. Circuit (a) requires a "cooked" zener: connect it first to a constant current generator, then....
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A Very Simple "Beat Frequency Oscillator" type of Metal Detector.
These are about the Simplest of all Metal Detector types,
But still quite useful for many Detecting applications.
And although this one is particularly simple, I find it works very well...
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The MAX104 processes analog input bandwidths that exceed 2.2GHz with 8-bit resolution. It sets a new standard for performance in high- frequency, high-bandwidth digital communications receivers, digital oscilloscopes, and high-speed data-acquisition systems.....
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it can reduce its gain. The time it takes for the compressor to recover from overload is determined by the rectifier The expander eg capacitor to complete the compressor is shown in FIG. 2-13B. Here is an external op amp is used for the high rate of ascent.....
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This 1-Wire MicroLAN [1] uses a capacitor and diode half-wave rectifier to provide parasitic power from the data line for the station's various sensors and to transfer data (see Figure 1). Each sensor has a unique serial number that identifies it to the bus.....
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An op amp is used to interface between a fiberoptic system and the MOS SCR to multi-cycle, half-wave control of a load. This receiver has two complementary outputs, one at a quiescent level of about 0.6 V and the second at 3 V. By adding a 4.7 V zener in....
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The idea behind this project is to provide some means of loading a program into a PIC that will then be able to program other PICs in a more conventional way. How do you program a PIC to be a programming device without a programmer, and why would you want to....
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From a high-volume-production point of view of the Design Idea `Test batteries without a voltmeter` (EDN, Nov 9, 2000, pg 167), it is a time-consuming and laborious task to tweak the large number of potentiometers on each of the comparator input references.....
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No Description available...
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The circuit in Figure 1 comprises IC1, a Microchip PIC12F675 microcontroller driving IC2, a Kingbright AAF5060PBESEEVG "rainbow" indicator that contains three ultrabright LED chips (red, green, and blue) within one package. Modulating each LED`s duty cycle....
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This low cost, crystal-controlled oscillator uses one TTL gate. Two factors ensure oscillator start-up: The connection of NAND gates G1, G2, and G3 into an unstable logic configuration and the high loop gain of the three inverters. Values of R1, R2, C1,....
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The SIMD1 was enhanced in the Solar Regulator version which supplies a constant 2V after triggering and permits driving LEDs without using current limiting resistors with constant brightness. Note that you can use this Low Drop Out (LDO) linear regulator for....
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A complete zero-voltage switch solid-state relay contains an input circuit, an output circuit, and the power thyristor. The circuit illustrates a triac power thyristor with snubber circuit and GE-MOVRII Vans tor transient over-voltage protection. The 22 ohm....
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This circuit provides the tum-on characteristics of an SCR, but turns off with ease. The switch is comprised of three transistors with descending current ratings: Q3 has a high-current rating and Q2 has a medium rating. The current, !1, to be switched....
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It will supply 15 watts of AC power to a device. It should power lamps, shavers, small stereos and small appliances. If you draw to much power the circuit will shut down all by itself. The output of this circuit is a square wave so there may be some....
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This Spark Can Be Very DANGEROUS, So BE CAREFUL. WARNING: FAILURE TO DO SO: WILL CAUSE THE CASE OF THE COIL TO ALSO BE ELECTRIFIED! NOTE You MUST have a LOAD on the High Voltage Output. With NO LOAD, you have a High Risk to "Damage the Ignition Coil". Either....
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This circuit was designed to provide that continuous light lamps already wired into a circuit, become flashing. Simply insert the circuit between existing lamp and negative supply.
Especially suited for car or panel pilot lights, this device can drive lamps....
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To avoid excess ripple output on a power supply feeding a heavy load, usually a large value capacitor is
chosen following the rectifier. In this circuit, C1 is only a 470uF capacitor. The gyrator principle uses the
effect that the value of input....
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Ammeter is a great addition to any Laboratory Power Supply as it will measure the current consumption and help you determine if there are any problems with the circuit that you are building or testing. This amper meter is capable of measuring the current....
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This circuit will give you a good, Accurate Watt Meter that can measure various power levels.
In the Origional Article the Shunt was a .001 Ohm Copper Shunt giving a 1000 Watt Scale. However, because Most Circuit Breakers in homes are 15 Amps, I made my....
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Use your Symbian OS mobiles to control devices through Bluetooth.
The serial to Bluetooth converter from sparkfun.com is used in this project.
The Microcontroller At89C2051 is used to receive the data from the mobile through bluetooth.
Most of the....
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By adjusting the oscillators so their frequencies are very nearly the same, the difference between them is made audible as a beat note, this beat note changes slightly when the search loop is moved over or near to a piece of metal. It has been found in....
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The circuit on this page is for a simple light detector circuit board that has 8 detectors that can be used with visible or infrared light systems. The detectors use LM339 voltage comparators as the active element.
Phototransistors or CdS photocells can be....
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This ROM emulator improves the easiness to build/use it by reducing down its function which can be used as a ROM emurator. The kind of the ROM types to be emulated, are 2764, 27128 and 27256. The debugging capability is only Load and Run, omit functions such....
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This 40W fluorescent lamp inverter allows you to run 40W fluorescent tubes from any 12V source capable of delivering 3A. This is basically a larger version of the 12VDC Fluorescent Lamp Driver and can be used to light regular or blacklight tubes...
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The circuits on this page are for motor controls using Push buttons and would typically be found in commercial and industrial installations.
The circuits do not show the wiring of the motors themselves as this depends on the particular motor type. The....
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This is a simple oscillator with multiple resistors in serie. When you press any switch, the circuit starts oscillating. You can user variable resistors instead the 1k resistors. Using variable resistors you will be able to tune the frecuency for each note.....
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The drawings and photos below are for an operating incline railway that was built by the London Model Railroad Group for its `O` scale model railway club located at London, Ontario, Canada. This is a single car model loosely based on a double car incline....
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Eight LED`s are used to indicate the pad currently selected. These LED`s are connected to a decade counter, which sequences the LED`s when it receives a clock pulse.Only one LED can be lit at a time from the decade counter, so although this circuit contains....
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This circuit measures the power -supply current of a circuit without really having a currentshunt resistor: R1 is only 3 em of #20 gauge copper wire. A length of the power distribution wiring can be used for Rl. ..
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Conversion speed of this design is the sum of the delay through the comparator and the decoding gates. Reference voltages for each bit are developed from a precision resistor ladder network. Values of R and 2R are chosen so that the threshold is 1/z of the....
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I describe a simple direct conversion receiver, thinked for QRSS and DFCW communications, as companion of ARGO or SPECTRAN programs. I don`t pretend to beat the performances of professional or commercial ham radio receiver, the scope is to suggest an easy....
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Examine a traditional Hartley oscillator circuit, and you`ll note its trademark: a tapped inductor that determines the frequency of oscillation and provides oscillation-sustaining feedback. Although you can easily calculate the total inductance required for....
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This is an add-on Over Voltage Circuit for the LM317 Regulator Circuit submitted by Matthew Hewson. It is a voltage regulator that allows a 6v portable supply to be derived from the 12v car battery. You can add a 6.2V zener diode and a LED to warn you when....
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This page describes a cheap and simple yet flexible HDMI to parallel 3.3v interface. This allows to connect most LCDs frames to the beagleboard without any further interface required. I am using this myself with some 7inch 800x480 displays which i am using....
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Use this circuit for checking fundamental oscillates, Q2 conducts and the LED lights. A3 HF crystals on a "Go-No-Go" basis. An untuned or 6V, 40mA bulb could be substituted for the Colpitts oscillator drives a voltage multiplier LED..
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A method of boosting the output current of a reference and also protecting against overloads is shown..
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Thanks to the S6986, the circuit is very simple and requires few components. D2, D3, D5 and D6 forms a bridge rectifier allowing to plug the sensor connector brick in any direction. C1 filters power supply, it must be connected near to IC1 to bypass it....
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The LTC3453 is a synchronous buck-boost DC/DC converter optimized for driving up to 4 white LEDs at a combined current of up to 500mA from a single Li-Ion battery input. The regulator operates in either synchronous buck, synchronous boost, or buck-boost....
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This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor`s output voltage, which is proportional to the measured temperature. The output frequency bursts are conveyed into the....
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This TMOS VCO operates in push-pull to produce 4 Wot 70 MHz. It consists of two MFE930 TMOS devices in a balanced VCO that generally provide better linearity than the single-ended types. Varactors are not used because the design takes advantage of the....
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The Liquid Crystal Display (LCD) is a thin layer of
Liquid Crystal Material deposited between two plates
of glass. The raw LCD is often referred to as glass.
Electrodes are attached to both sides of the glass. One
side is referred to as common or....
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A simple pulse stretcher built with two sections of an op amp uses voltage follower U1A to drive Dl and C2. ..
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Can be directly connected to CD players, tuners and tape recorders.
Tested with several headphone models of different impedance: 32, 100, 245, 300, 600 & 2000 Ohms.
Schematic shows left channel only.
B1, SW1, J1 & C3 are common to both....
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Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need. Q6 & Q7 must have a small U-shaped heatsink. Q8 & Q9 must be mounted on....
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Typically such applications
require low power from the battery. With this in mind,
every feature of the LTC4100 Smart Battery charger exists
to reduce board real estate and profile requirements. The
LTC4100 is a Level 2 (slave) Smart Battery charger that....
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A suitable pilot larnp is illuminated by a small sample of rf and energizes an inexpensive solar cell; the dc current generated by the cell is a measure of relative rf power, and may be routed to a low-current meter located at any convenient point. A....
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This circuit was designed to control a 32 channel Christmas light show from the PC serial port. Originally designed with TTL logic, it has been simplified using CMOS circuits to reduce component count. It is a fairly simple, reliable circuit that requires....
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The circuit uses one-half of a dual D flip-flop as an inverter. When the input decreases, the flip-flop resets, and its Q output increases. When the input increases, the reset line is released and Q gets clocked low. The rc delay between applying the input....
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This circuit shows a 555 with its trigger and threshold inputs connected together used to energize a relay when the light level on a photoconductive cell falls below a preset value..
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An ultralow dropout current source maintains accurate LED current at very low ILED voltages. Automatic mode switching optimizes efficiency by monitoring the voltage across the LED current source and switching modes only when ILED dropout is detected. The....
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The circuit in Figure 1 uses IC1, the integrated offline Viper22A switching regulator in a constant-current configuration to drive two to eight 1W LEDs. The circuit operates by monitoring the voltage drop across the sense resistor, R6, and uses this voltage....
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No Description available...
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Figure 1 shows a 5V to 12V boost converter ideal for USB
applications. The converter has a selectable 100mA/
500mA input current limit, allowing the device to be easily
switched between the USB low and high power modes.
Efficiency, shown in Figure 2,....
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Single transistor flyback driver caused many problems due to it's operating principle. I received e-mails from people who were unable to get it functional even when they are sure that their flyback and transistor is OK. In addition, since it's resonance....
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This inverter uses a 12.6-V to 120-V transformer to deliver a quasi-sine wave that has the same rms and peak voltage ..
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Diode Dl prevents negative spikes from occurring at the MOSFET gate, the 100 ohm resistor is a parasitic suppressor, and Z1 serves as a dissipative voltage regulator for the output and also clips the drain voltage to a level below the rated power FET....
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The 555 circuit below is a flashing bicycle light powered with three C or D cells (4.5 volts). The two flashlight lamps will alternately flash at a approximate 1.5 second cycle rate. Using a 4.7K resistor for R1 and a 100K resistor for R2 and a 4.7uF....
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These are two - easy to build - relay-based alarms. You can use them to protect your motorcycle - but they have many more applications. If you use relays with 6-volt coils - they`ll protect your "Classic Bike". Both alarms are very small. The completed....
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This circuit is used to give out a microphone preamp to a amplifier which will power the signal. The NPN transistors used are ECG123A. This circuit is also a older model to the one that now use IC's, but dont worry this will still work fine...
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The circuit in Figure 1 converts
pulse information to a clean dc voltage
by the end of a single incoming
pulse. In another technique, an RC filter
can convert a PWM signal to an averaged
dc voltage, but this method is slow in responding.
Converting....
The timing components are Rl, R2, and C,. Cl is a bypass capacitor used to reduce the effects of noise. At start-up, the voltage across C, is less than the trigger level voltage (1/3 Vnn). causing the timer to be triggered via pin 2. The output of the....
To "round" your square wave, you need to integrate it twice; once to produce a triangular wave, and a second time to produce a parabolic waveform. (A parabolic wave looks pretty much sinusoidal.) You can do this passively using a simple network such as the....
1. THE INPUT CLOCK frequency fed into this circuit is divided by 2n-l. The circuit consists of clocked flip-..
The amplifier picks up the TV"s audio output signal and amplifies it to drive a set of earphones for private listening. It is built around an LM324 quad op amp and an LM386 low-power audio amplifier. ..
Teledyne Semiconductor"s Type TSC9402 IC is eminently suitable as an inexpensive current-to-frequency conver..
Single programming resistor Rp provides an output-current range of about six decades.-Note that this resistor"s TC is also a potential source of error; it dissipates 125 mW when JliN ~ 5 V. The maximum deviation is typically 50 nA or 0.0002% of full scale. ..
The LM3915 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs providing a logarithmic 3 dB/step analog display. LED current drive is regulated and programmable, eliminating the need for current limiting resistors. The IC....
Often a circuit will be called upon to perform several functions. In these situations, the variable gain configuration of this circuit could be quite useful. This programmable gain stage depends on CMOS analog switches to alter the amount of feedback,....
This circuit is a simple IR detector for testing IR remote controllers. The circuit is based on one phototransistor which receives the IR beam. The NPN transistor works as an amplifier which feeds current to the led. When this circuit detects IR or light,....
This straightforward circuit uses an NE555 timer as an oscillator, a 7493 counter chain and a DAC0806 D/A conver..
A very useful audio amp in an 8-pin DIL package. The IC features a very low minimum working supply voltage of 3V, low quiescent current, good ripple rejection, no crossover distortion and low power dissipation...
This circuit design is a class A amplifier employing both ac and de feedback. Bias is stabilized at 15 mA of the collector current using de feedback from the collector. The ac feedback, from collector to base, and in each of the partially bypassed emitter....
The low-cost Mini-Circuits MAR-X series of chips offer the RF builder a real advantage, with their inherent 50- input and output impedances (needed for RF systems). An MAR-1-based receiver/scanner preamplifier is shown. Ci and C2 are chip capacitors. Use....
This Power Supply is suitable for the Modular Burglar Alarm. However, it has other applications. It is designed to provide an output of 12-volts, with a current of up to 1-amp. In the event of mains failure, the back-up battery takes over automatically. When....
This circuit switches a tape recorder via PL2. When on-hook, D5 conducts, turns on Ql, and cuts off Q..
This accessory connects to phone and will activate an attention-getting 120-V bell whenever a ringing voltage appears on the ph..
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....
Lamp LI stabilizes the loop gain at higher frequencies while the limiting action of R2, CRI, and CR2 prevents clipping at low frequencies and increases the frequency adjustment range from about 3:1 to greater than 10:1. ..
Large LCD (liquid crystal display) displays designed to replace CRTs (cathode ray tubes) in desktop computer applications are becoming available. The LCDs reduced size and power requirements allow much smaller product size, a highly desirable feature...
This divider uses a variable-length shift register, a type-D flip-flop, and an inverter. The clock feeds the..
It seems that guitar fuzz boxes have been around since the beginning of rock, and have seen little improvement over the years. This one is somewhat different because rather than simply distorting the sound, it also pulses in step with the peaks of the....
The circuit is completely conventional, and has been around almost forever in one guise or another. Similar circuits were used in the valve (tube) era, so there is nothing new about it. The circuit has already been published on these pages as a guitar....
The oscillator based on IC2 is responsible for producing the sound. Its output is connected to the base of TRl, ..
While I would have liked a 4 channel chip with about 20 Watt per channel, the local parts store didn't have any yet, so I opted for two TA8215AH stereo chips, selected by their low price in this particular store. The design? Oh well, there isn't much to it.....
This very high quality audio amp is based on the TDA1514A, a 9-pin flat package IC. The heatsink must be insulated from ground. The amplifier will deliver 40 watt into an 8ohm load with a 27.5 volt power rail or 40 watt into 4ohm load with a 21 volt power....
This circuit will be of interest to the radio amateur and anyone posessing two radios, (one of which must be able to transmit i.e. a transceiver). It is a self powered (audio derived) repeater circuit for receiving a signal and re-transmitting it via the....
This amplifier operates from a 28 Vdc supply. It has a typical gain of 12 dB, and can survive operation into a 30:1 VSWR load at any phase angle with no damage. This means that with input power held constant at the level that provides 125 watts output, the....
Using the thermistor-bridge circuit, you can detect system-cooling air losses caused by filter or inlet ..
Germanium transistor Ql is used as a noise generator in the audio range. Ul acts as a high-gain amplifier. Ql is not ..
This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also....
With a single IC, you can build a simple, reliable auto burglar alarm or a similar alarm. See (a) for the timing informatio..
An electronic scale using a pressure transducer (load cell) and an analog-digital (A/D) converter to drive a digital display is shown. The scale range depends on load cell. Display is calibrated in appropriate units. Components are on main circuit and....
The logic designer is filled with features. It would not be possible to list all the possible combinations of the unit as the various building blocks on the board can be interconnected to obtain a wide variety of counting and testing stages. You will be able....
The aim of this project was to get a digital camera into a small electric radio controlled (RC) aeroplane and still have it fly. The aeroplane shown, a park flyer, weighs between 400 and 550 grams depending on the size of battery and wing configeration that....
This RF converter converts amateur TV signals in the 420- to 450-MHz region to VHF channel 3 or 4, allowing reception of those signals on a standard TV receiver. RF amplifier Ql feeds mixer Ml, and Q3 acts as an IF amplifier. ..
A real analog synthesizer to build using easy to get components, capable of a wide range of sounds. The two oscillators can be detuned for that classic synth sound. Dual oscillator mono synth. Really easy to build using just 1 custom programmed PIC chip, 4....
These two circuits are interesting from an academic point of view. Their practical implementation is rather critical and it is not easy to get steady operation. Circuit (a) requires a "cooked" zener: connect it first to a constant current generator, then....
A Very Simple "Beat Frequency Oscillator" type of Metal Detector. These are about the Simplest of all Metal Detector types, But still quite useful for many Detecting applications. And although this one is particularly simple, I find it works very well...
it can reduce its gain. The time it takes for the compressor to recover from overload is determined by the rectifier The expander eg capacitor to complete the compressor is shown in FIG. 2-13B. Here is an external op amp is used for the high rate of ascent.....
This 1-Wire MicroLAN [1] uses a capacitor and diode half-wave rectifier to provide parasitic power from the data line for the station's various sensors and to transfer data (see Figure 1). Each sensor has a unique serial number that identifies it to the bus.....
An op amp is used to interface between a fiberoptic system and the MOS SCR to multi-cycle, half-wave control of a load. This receiver has two complementary outputs, one at a quiescent level of about 0.6 V and the second at 3 V. By adding a 4.7 V zener in....
The idea behind this project is to provide some means of loading a program into a PIC that will then be able to program other PICs in a more conventional way. How do you program a PIC to be a programming device without a programmer, and why would you want to....
This low cost, crystal-controlled oscillator uses one TTL gate. Two factors ensure oscillator start-up: The connection of NAND gates G1, G2, and G3 into an unstable logic configuration and the high loop gain of the three inverters. Values of R1, R2, C1,....
The SIMD1 was enhanced in the Solar Regulator version which supplies a constant 2V after triggering and permits driving LEDs without using current limiting resistors with constant brightness. Note that you can use this Low Drop Out (LDO) linear regulator for....
A complete zero-voltage switch solid-state relay contains an input circuit, an output circuit, and the power thyristor. The circuit illustrates a triac power thyristor with snubber circuit and GE-MOVRII Vans tor transient over-voltage protection. The 22 ohm....
This circuit provides the tum-on characteristics of an SCR, but turns off with ease. The switch is comprised of three transistors with descending current ratings: Q3 has a high-current rating and Q2 has a medium rating. The current, !1, to be switched....
It will supply 15 watts of AC power to a device. It should power lamps, shavers, small stereos and small appliances. If you draw to much power the circuit will shut down all by itself. The output of this circuit is a square wave so there may be some....
This Spark Can Be Very DANGEROUS, So BE CAREFUL. WARNING: FAILURE TO DO SO: WILL CAUSE THE CASE OF THE COIL TO ALSO BE ELECTRIFIED! NOTE You MUST have a LOAD on the High Voltage Output. With NO LOAD, you have a High Risk to "Damage the Ignition Coil". Either....
This circuit was designed to provide that continuous light lamps already wired into a circuit, become flashing. Simply insert the circuit between existing lamp and negative supply. Especially suited for car or panel pilot lights, this device can drive lamps....
To avoid excess ripple output on a power supply feeding a heavy load, usually a large value capacitor is chosen following the rectifier. In this circuit, C1 is only a 470uF capacitor. The gyrator principle uses the effect that the value of input....
Ammeter is a great addition to any Laboratory Power Supply as it will measure the current consumption and help you determine if there are any problems with the circuit that you are building or testing. This amper meter is capable of measuring the current....
This circuit will give you a good, Accurate Watt Meter that can measure various power levels. In the Origional Article the Shunt was a .001 Ohm Copper Shunt giving a 1000 Watt Scale. However, because Most Circuit Breakers in homes are 15 Amps, I made my....
Use your Symbian OS mobiles to control devices through Bluetooth. The serial to Bluetooth converter from sparkfun.com is used in this project. The Microcontroller At89C2051 is used to receive the data from the mobile through bluetooth. Most of the....
By adjusting the oscillators so their frequencies are very nearly the same, the difference between them is made audible as a beat note, this beat note changes slightly when the search loop is moved over or near to a piece of metal. It has been found in....
The circuit on this page is for a simple light detector circuit board that has 8 detectors that can be used with visible or infrared light systems. The detectors use LM339 voltage comparators as the active element. Phototransistors or CdS photocells can be....
This ROM emulator improves the easiness to build/use it by reducing down its function which can be used as a ROM emurator. The kind of the ROM types to be emulated, are 2764, 27128 and 27256. The debugging capability is only Load and Run, omit functions such....
This 40W fluorescent lamp inverter allows you to run 40W fluorescent tubes from any 12V source capable of delivering 3A. This is basically a larger version of the 12VDC Fluorescent Lamp Driver and can be used to light regular or blacklight tubes...
The circuits on this page are for motor controls using Push buttons and would typically be found in commercial and industrial installations. The circuits do not show the wiring of the motors themselves as this depends on the particular motor type. The....
This is a simple oscillator with multiple resistors in serie. When you press any switch, the circuit starts oscillating. You can user variable resistors instead the 1k resistors. Using variable resistors you will be able to tune the frecuency for each note.....
The drawings and photos below are for an operating incline railway that was built by the London Model Railroad Group for its `O` scale model railway club located at London, Ontario, Canada. This is a single car model loosely based on a double car incline....
Eight LED`s are used to indicate the pad currently selected. These LED`s are connected to a decade counter, which sequences the LED`s when it receives a clock pulse.Only one LED can be lit at a time from the decade counter, so although this circuit contains....
This circuit measures the power -supply current of a circuit without really having a currentshunt resistor: R1 is only 3 em of #20 gauge copper wire. A length of the power distribution wiring can be used for Rl. ..
Conversion speed of this design is the sum of the delay through the comparator and the decoding gates. Reference voltages for each bit are developed from a precision resistor ladder network. Values of R and 2R are chosen so that the threshold is 1/z of the....
I describe a simple direct conversion receiver, thinked for QRSS and DFCW communications, as companion of ARGO or SPECTRAN programs. I don`t pretend to beat the performances of professional or commercial ham radio receiver, the scope is to suggest an easy....
Examine a traditional Hartley oscillator circuit, and you`ll note its trademark: a tapped inductor that determines the frequency of oscillation and provides oscillation-sustaining feedback. Although you can easily calculate the total inductance required for....
This is an add-on Over Voltage Circuit for the LM317 Regulator Circuit submitted by Matthew Hewson. It is a voltage regulator that allows a 6v portable supply to be derived from the 12v car battery. You can add a 6.2V zener diode and a LED to warn you when....
This page describes a cheap and simple yet flexible HDMI to parallel 3.3v interface. This allows to connect most LCDs frames to the beagleboard without any further interface required. I am using this myself with some 7inch 800x480 displays which i am using....
Use this circuit for checking fundamental oscillates, Q2 conducts and the LED lights. A3 HF crystals on a "Go-No-Go" basis. An untuned or 6V, 40mA bulb could be substituted for the Colpitts oscillator drives a voltage multiplier LED..
A method of boosting the output current of a reference and also protecting against overloads is shown..
Thanks to the S6986, the circuit is very simple and requires few components. D2, D3, D5 and D6 forms a bridge rectifier allowing to plug the sensor connector brick in any direction. C1 filters power supply, it must be connected near to IC1 to bypass it....
The LTC3453 is a synchronous buck-boost DC/DC converter optimized for driving up to 4 white LEDs at a combined current of up to 500mA from a single Li-Ion battery input. The regulator operates in either synchronous buck, synchronous boost, or buck-boost....
This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor`s output voltage, which is proportional to the measured temperature. The output frequency bursts are conveyed into the....
This TMOS VCO operates in push-pull to produce 4 Wot 70 MHz. It consists of two MFE930 TMOS devices in a balanced VCO that generally provide better linearity than the single-ended types. Varactors are not used because the design takes advantage of the....
A simple pulse stretcher built with two sections of an op amp uses voltage follower U1A to drive Dl and C2. ..
Can be directly connected to CD players, tuners and tape recorders. Tested with several headphone models of different impedance: 32, 100, 245, 300, 600 & 2000 Ohms. Schematic shows left channel only. B1, SW1, J1 & C3 are common to both....
Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need. Q6 & Q7 must have a small U-shaped heatsink. Q8 & Q9 must be mounted on....
A suitable pilot larnp is illuminated by a small sample of rf and energizes an inexpensive solar cell; the dc current generated by the cell is a measure of relative rf power, and may be routed to a low-current meter located at any convenient point. A....
This circuit was designed to control a 32 channel Christmas light show from the PC serial port. Originally designed with TTL logic, it has been simplified using CMOS circuits to reduce component count. It is a fairly simple, reliable circuit that requires....
The circuit uses one-half of a dual D flip-flop as an inverter. When the input decreases, the flip-flop resets, and its Q output increases. When the input increases, the reset line is released and Q gets clocked low. The rc delay between applying the input....
This circuit shows a 555 with its trigger and threshold inputs connected together used to energize a relay when the light level on a photoconductive cell falls below a preset value..
An ultralow dropout current source maintains accurate LED current at very low ILED voltages. Automatic mode switching optimizes efficiency by monitoring the voltage across the LED current source and switching modes only when ILED dropout is detected. The....
Single transistor flyback driver caused many problems due to it's operating principle. I received e-mails from people who were unable to get it functional even when they are sure that their flyback and transistor is OK. In addition, since it's resonance....
This inverter uses a 12.6-V to 120-V transformer to deliver a quasi-sine wave that has the same rms and peak voltage ..
Diode Dl prevents negative spikes from occurring at the MOSFET gate, the 100 ohm resistor is a parasitic suppressor, and Z1 serves as a dissipative voltage regulator for the output and also clips the drain voltage to a level below the rated power FET....
The 555 circuit below is a flashing bicycle light powered with three C or D cells (4.5 volts). The two flashlight lamps will alternately flash at a approximate 1.5 second cycle rate. Using a 4.7K resistor for R1 and a 100K resistor for R2 and a 4.7uF....
These are two - easy to build - relay-based alarms. You can use them to protect your motorcycle - but they have many more applications. If you use relays with 6-volt coils - they`ll protect your "Classic Bike". Both alarms are very small. The completed....
This circuit is used to give out a microphone preamp to a amplifier which will power the signal. The NPN transistors used are ECG123A. This circuit is also a older model to the one that now use IC's, but dont worry this will still work fine...
The circuit in Figure 1 converts pulse information to a clean dc voltage by the end of a single incoming pulse. In another technique, an RC filter can convert a PWM signal to an averaged dc voltage, but this method is slow in responding. Converting....
![Video amplifier [2]](uploads/143-54d143.gif "Video amplifier [2]")
