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When testing a circuit, a source of voltage that is variable and has overvoltage shutdown is veiy useful. In this circuit, Rl is adjusted to 1 to 2 V below the eventual shutdown threshold. R2 sets the trip voltage. When this voltage is reached, the circuit....
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The popularity and easy access of RS-232 ports lend them to many communication projects. You can use a port as is” or as a tiny parallel port when the exchange uses only control lines. Before the asynchronous serial-data transfer between two devices can take....
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Well the most common use is in a solaroller which is a small wheeled car that charges up and then moves in a quick burst of speed. Since you can only use motors and coils with this circuit robots built with this circuit are mainly mechanical such as my....
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This circuit is based on a preprogrammed multi-instrument melody generator IC, containing a 512-note memory capable of generating 16 tunes. The comprehensive control facilities enable playing - all tunes repeatedly or stopping at the end, - or one tune....
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1. Pressing `Roll` switch. When the switch is turned on T1 is turned off (its base is pulled high by the 3M3) and the 555 oscillator is not oscillating. Pressing the ROLL switch immediately charges the 470nF capacitor, T1 is turned ON and the 555 starts....
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The DG419looks into the high input impedance of the op amp, so the effects of Rvs(o"l are negligible. The DG441 is also connected in series with RIN and is not included in the feedback dividers, thus contributing negligibleThis is a handy companion for a digital voltmeter. Its allowed me to do a lot of things I used to use my oscilloscope for, and in addition it measures voltages to much greater precision.Using an LM324 quad op amp, this peak detector provides 2% measurement....It operates by PWM (Pulse Width Modulation) - well, actually by PFM - Pulse Frequency Modulation. At power up, C1 charges up via D1 and R1. R2 will conduct, pulling the base of the emitter follower, Tr2, up and feeding gate voltage to the MOSFET. Tr4.....A simple circuit with which we have the possibility opening and closing the RL1 contacts. He becomes touching a small metal surface. Clue of situation that is found RL1, is become by the Led D3. The supply of circuit is +12V, the IC1 is supplied with 3.9V....One section of the precision audio frequency generator uses an electret microphone element to pick up audio from the piano. That signal is then processed and sent to one channel of a dual-trace oscilloscope. The other section of the circuit is used to....This is the voltage converter to get the voltage of ±1,25-30V from the input voltage of ±35V. I am using the 3 terminal voltage regulator for the voltage to be changed in this unit. As the regulator, LM317 is used for the positive voltage and LM337 is used....It is very interesting and convenient to be able to control everything while sitting at your PC terminal. Here, a simple hardware circuit and software is used to interface a 7-segment based rolling display. The printer port of a PC provides a set of points....The CCD Array Reader project began with a free sample of the Texas Instruments TC102-1 CCD Linear Image Sensor and its rather terse data sheet. The TC102-1 provides virtually no support circuitry, only the raw CCD (with a few special pixels) and a simple....This is a simple LED flasher using two 2N3904 transistors. Classic astable multivibrator using 2 transistors. Transistor is not critical. Try these: 2N4401, 2N2222, NTE123A, NTE123AP, NTE159, TUP/TUN and those in your junk box, you may find that most of them....Many designs require FIFO elastic buffers to form a bridge between subsystems with different clock rates and access requirements. However, in some applications, you need FIFO buffers for data conversion. One example is the case in which you need to connect....The circuit uses a dual LED. When power is applied to the probe throughthe power leads, and the input is touched to a low level or ground, Ql is cut off. This will cause Q2 to conduct since the base is positive with respect to the emitter. With Ql cut off....In many applications, it`s desirable to disable LEDs used for system verification. Many options are available for the disabling function, including manual SPST (single-pole single-throw) switches, enhancement- and depletion-mode MOSFETs, bipolar-junction....The circuit in Figure 1 is a simple, economic, compact, and tricky way of using the LM723 as a programmable voltage source to drive dc micromotors. Because of the µPs` accurate positioning and control, these motors are useful in applications such as optical....The use of a switching transistor (like a 2N2222 or 2N3904) allows use of the CD4511B with a common-anode display. should be chosen to provide about 1 mA to drive Ql and Rr should provide enough current to drive the display...This is a voltage multiplier circuit acting as an Ioniser. Its calculated to feed 220V from mains and the output is about 6KV. Caution should take with the circuit as can be dangerous due to mains. You can place a needle at the output 3cm long. ..Although theIR region is free from radio interference, it is subject to interference from incandescent lamps, fluorescent lamps, stray reflections, and other sources. A simple way to overcome that problem is to create a carrier by chopping the IR radiation....The three-amplifier implementation of the state-variable filter in Figure 1 provides for second-order bandpass, highpass, and lowpass responses. The strength of the circuit, however, is in the bandpass response (VOUT/VIN), in which it`s easy to achieve high....The unit consists of rlamplifier Q1, local oscillatorQ2, and mixer Q3. The two bands are covered without a bandswitch by using an i-f or 3.5 MHz. The oscillator range is 7.5 to 14.5 MHz. Incoming signals from 4 to 11 MHz are mixed with the oscillator to....The sensor is based on the selective absorption of hydrocarbons by an n-type metal-oxide surface. The heater in the device serves to burn off the hydrocarbons once smoke or gas is no longer present in the immediate area; hence, the device is reuseable.....Two simple circuits permit Nicad charging of a battery based on temperature differences between t..Large input-to-output voltage differentials, caused by wide input voltage variations, reduce a linear regulator`s efficiency and increase its power dissipation. A switching preregulator can reduce this power dissipation by minimizing the voltage drop across....Ideal to operate 3 to 24V DC existing on-circuit lamps LED operation is also possible. 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....If the tube is level with respect to gravity, the bubble resides in the tube"s center and the electrode resistances to common are identical. As the tube shifts away from level, the resistances increase and decrease proportionally. Transducers of this type....This project describes a new economical solution of home light control systems. The presented home light control system can be used for different sophisticated home applications. The control system consists of a PC, and control circuitry and the electrical....Have you ever wondered how many different colors can illuminate a LED? One, two or maybe three? Constructing this simple circuit, you will find it much more. The key component in this design is a dual LED. One such accessory includes two inside the 'slices'....This receiver consists of an input network amplifier IC7 FSK PLL detector ICG, and output am..Figure 1 shows the typical output from a spectroscopic amplifier, where the presence of a large amount of detector noise with Gaussian distribution is a limiting factor for system performance in amplitude and timing resolution. The time-tagging of such....A shows a typical LTC 1148 surface-mount, application providing 5 V at 2 A from an input voltage of 5.5 V to 13.5 V. The operating efficiency, shown in B, peaks at 97% and exceeds 90% from 10 mA to 2 A with a 10-V input. Ql and Q2 comprise the main switch....This circuit is a 10-LED spinning wheel that "clicks" as the wheel passes each point. The rotation starts fast, then gradu..The Link circuitry is simple and efficient, employing just two ICs, half a dozen transistors, and a handful of garden variety components. It all runs on 12 volts and is easily assembled. You can have your own home intercom between the kitchen, the garage,....The 5AH will trigger when the voltage across the two 0 juF capacitors reaches the breakdown voltage of the lamp. Control can be obtained full off to 95% of the half wave RMS output voltage..Please find attached your copy of my four foot unampilfied box loop. It will tune from 525 kHz to about 1710 kHz covering the entire Broadcast Band. The umbrella stand described in the article is the type you would use for an outdoor umbrella. I fill....Here i propose a project of an AB class power amplifier, at its simplest, assembled with common compoments (not very expensive), based on traditional diagrams : a symmetrical differential input stage, a cascode stage driver and a MOSFET output stage. The....The amplifier drives a pair of loudspeakers using two LM3876 integrated power amp ICs (50 watts per channel), or a pair of headphones via a Meier crossfeed filter and an OPA2134 dual opamp. It provides four switchable line level inputs, and an unbuffered....The use of positive feedback is useful for producing oscillators. The condition for positive feedback is that a portion of the output is combined in phase with the input. For an amplifer with positive feedback the gain is given by the expression below...Programming is very straight-forward when this programmer is used in conjunction with the easy to use DOS-compatible software. No requied power supply...I have found this circuit to have better sensitivity, both in distance to a visible bat and in audio frequency, than some other published circuits using a 40kHz transducer with 4000x gain amplification, though the 40kHz transducer I used for the comparison....This self powered interface circuit electrically isolates the TxD and RxD lines from the PC serial port and protect the PC from direct connection to hazardous voltages. The isolator is intended to provide electrical isolation between a computer and the....This is a general purpose serial port infrared receiver. With the help of appropriate software (see below) you can control different functions of your pc from a distance. For example you can control your home cinema settings (volume, play, pause, stop etc),....This window comparator generates an output pulse for each event that occurs within a specified window. That is, each output pulse signifies an input voltage pulse or level change that exceeds VREFLOW. but not VREFHIGH· The monostable multivibrators, IC2A....The circuit consists of two building blocks. The first is a square wave oscillator made up of two transistors in a multivibrator arrangement and the second is a CD 4017 decade counter IC. The multivibrator contains two extra components to speed up the....Typical QRP receivers include Direct Conversion (DC) and simple Superheterodyne types. These receivers often have quite a wide AF bandwidth which can make inteligiblity somewhar restricted, especially under difficult QRM conditions. Many commercial amateur....This very simple and self-powered device was conceived to allow a person to monitor if someone has rung his home door-bell when he was out. As most door-bells use 12Vac supply, the circuit must be simply connected to the two door-bell-coil leads...This project is a self-contained serial terminal using a PIC16F84 microcontroller chip, an inexpensive LCD character display, a keypad, and very little else. It is full-duplex, meaning keypresses cause RS-232 output, and RS-232 input makes characters appear....The unit is powered directly from the 120 volt AC line, with no power transformers. Filaments are wired in series, with the total adding up to 117 volts (35 + 35 + 35 + 12). The 35W4 forms a half-wave rectifier, which is filtered by a three-stage RC network.....For back-lit LCD displays, this supply will drive a lamp. LT1072 drives Ql and Q2, and a sine wave app..Add this to the above circuit to get a programmable trigger sequencer. Includes an optional audio modulation stage...The GS4882 and GS4982 are precision sync separators for extracting timing information from NTSC, PAL, and SECAM video signals. The GS4882 generates noise immune and temperature stable composite sync, vertical sync, back porch and odd/even field signals.....Make your own Guitar Effects Pedal with an Arduino board. Bit crushing, rate reducing, weird noises. 10-bit effects/guitar pedal with an Arduino for lo-fi DSP..This audio converter circuit maintains 40 dB of isolation between the two halves of entry and exit of a four-line son, while allowing a line connecting two son. A balancing potentiometer, R, adjusts the gain of zero lC2to crossing the inlet to the outlet. ..This is a simple microphone preamplifer circuit which you can use between your microphone and stereo amplifier. This circuit amplifier microphone suitable for use with normal home stereo amplifier line/CD/aux/tape inputs. This mic preamp can take both....A TL081 op amp is used as a high impedance to low. converter and a signal mixer. The input impedance is about 1 megohm and the output impedance is about 1 kohm. Two 9 volt batteries are used as power source. ..The usual chargers of battery automotive, are simple and cheap appliances that charge continuously the battery, with a rythm of few amperes, for the time where the appliance is ON. If the holder do not close in time the charger, the battery will overcharge....This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants' pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km. and its dot is....TCP based security system using the Ethernet module offered within the contest , an ATmega16L microcontroller , a PIR as a sensor and few other peripheral devices , which is specially targeted for homes and small business owners. I have used through for my....This circuit uses constant current LEDs to adjust charging current. It makes use of LEDs that pass a constant current of about 15 mA for an applied voltage range of 2-18 V. They can be paralleled to give any multiple of 15 mA and they light up when current....A novel supply voltage monitor which uses a LED to show the status of a power supply. This simple and slightly odd circuit can clearly show the level of the supply voltage (in a larger device): as long as the indicator has good 12 volts at its input, LED1....This circuit gives a regulated output of between 5 V and 15 Vdc, adjusted and set by a preset resistor. Current output up to about 350 mA..The timing cycle is continuously reset by the input pulse train. A change in frequency, or a missing pulse, allows completion of the timing cycle which causes a change in the output level. For this application, the time delay should be set to be slightly....When power is first applied, three things happen: the light-driving transistor (Ql) is switched on because of a low output from U2, pin 3; timer Ul begins its timing cycle, with the output (pin 3) going high, inhibiting U2`s trigger (pin 2) via D2; and....The circuit in Figure 1 is similar in principle to that of a previous Design Idea (Reference 1) but offers improved, more reproducible performance. The output current is almost constant over an input-voltage range of 1.2 to 1.5V and is insensitive to....Here is the inside of the light reflectance sensor (top) and a schematic drawing of it's circuitry (bottom). First, carefully remove the phototransistor as shown. Then, attach the three wires that we will connect to the heart sensor (show in bright yellow).....A sidetone oscillator is a special audio astable multivibrator. Keying is accomplished oscillator that is turned on and off with the by applying a positive dc potential, developed transmitter. The oscillator is rf-driven and bat- from the rf signal, to the....Three new linear regulators simplify the design of batteryoperated equipment. The LT®1521 is a 300mA, positive low dropout regulator with micropower quiescent current and shutdown. The LT1175 is a 500mA negative complement with adjustable current limit.....I found this circuit in my files. I don`t know where it came from, but it looks like I photocopied it from somewhere years ago. I have been told that it came from "The Robot Builder`s Bonanza", by Gordan McComb. Anyway, I thought that it should be fairly....Figure 1 shows a block diagram for a fan speed control system using the LTC1840. The LTC1840 contains two current DACs used to gain full control over fan speed. The scaled currents individually adjust the fan-driving output voltage of a switching....This hybrid circuit uses a mixture of transistors, an IC and a relay and is used to automatically open or close a pair of curtains. Using switch S3 also allows manual control, allowing for curtains to be left only partially open or closed. The circuit....The ISD1000A is a Direct Analog Storage device which allows you to store 20 seconds worth of voice data on an IC chip which can be play backed anytime. The data stored will stay in memory even if the power is removed. To use the circuit below simple apply....IC5 generates RS-170 NTSC synch. IC1, IC2, and IC3 make up the red, green, and blue video signals that drive the video ..A simple single-transistor circuit will give approximately 15 dB boost or cut at 100 Hz and 15 kHz respectively. A low noise audio type transistor is used, and the output can be fed directly into any existing amplifier volume control to which the tone....The sensitivity of receiver it is possible to increase itself considerably, if is interfered, between this and his aerial, a amplifier RF. The amplifier of circuit, does not use in resonant circuits and for this is suitable, so much for mid waves, what for....These short-circuit protected regulators give 6, 7, and 9 V from an automobile battery supply of 13 V nominal; however, they will function just as well if connected to a smoothed dc output from a transformer/rectifier circuit. Two types are shown for both....The supply 6-66 can be used for supply output voltages from 1 to 35 V. The line transformer should be selected to give about1.4 times the desired output voltage from the positive side of filter capacitor C1 to ground. Potentiometer R2 sets the output....This circuit generates three supply voltages using a minimum of components. Diodes D2 and D3 perform full-wave rectification, alternately charging capacitor C2 on both halves of the ac cycle. On the other hand, diode D1 with capacitor C1, and diode D4 with....I designed a simple sinewave generator based on a Analog Devices AD9832 chip. It will generate a sinewave from 0.005 to 12 MHz in 0.005 Hz steps. That`s pretty good, and definitely good enough for me ! But while waiting for the AD9832 chip to arrive, I came....This circuit was designed to detect when a call is incoming in a cellular phone (even when the calling tone of the device is switched-off) by means of a flashing LED. The device must be placed a few centimeters from the cellular phone, so its sensor coil L1....The advent of new high-speed technologies and the growing computer capacity provided realistic opportunity for new cost effective technologies and realization of new methods of innovations. This technical improvement together with the need for high....The parts to the right of T1 form a simple Joule-thief ('Blocking' oscillator) circuit which boosts the 1.2v supply to 3.5v to operate the LED. C1 is used to extend the charge and discharge cycles to increase brightness and efficiency. Components R, C and....This Design Idea presents a low-cost method of generating the basic 19-kHz pilot tone. The 19-kHz pilot tone comprises a baseband signal, and the L+R and LR signals consist of DSBSC (double-sideband-suppressed-carrier) modulation centered at 38 kHz. For a....This circuit gives multiple "stop-action" photographic effects like showing a bouncing ball in up to nine locations in a single photograph. The circuit will automatically fire the bulbs sequentially with the time between each firing variable. The circuit is....A microphone preamplifier using: om CMOS op amp with its own battery, is small enough to be placed in a case of small microphone. The amplifier operates from a 1.5V battery cathode mercury low supply currents. This preamp will operate at very low power and....The current concept incorporates a wireless transmitter and receiver and is thought to be used for remote controlled airplanes or appliances with two seperate parts. In other words, we have one dedicated transmitter (acquisition, filtering) and one dedicated....A Very Low Current, High Voltage Spark, that is "Manually Triggered". Although its not easily Measured, the Peak Ouput voltage will be over 5,000 Volts. T1 is a small audio transformer and it steps up the voltage to about 500 Volts at Point "X" on the....A very small but good quality amplifier circuit that is also fairly cheap. It is based on TDA2002 which offers very low distrortion. Power should be 12-15 volt 1,2A. The amplifier frequency responce ranges from 40Hz to 15Khz. A good heatsink is required. At....If you want to try a higher voltage with your pedals, try this simple and easy voltage doubler circuit which uses an ICL7660 CMOS Voltage Converter Chip I have found that JFETs such as the J201 sound much better at 18V than they do at 9V with more clean to....It`s common knowledge that when working with single-supply op amps, implementing simple functions in a bipolar signal environment can be difficult. Sometimes additional op amps and other electronic components are required. Taking that into consideration,....When the upper or lower limit is exceeded, the LED lights up. Positive feedback to one of the nulling terminals creates 5 to 20 p,V of hysteresis on both amplifiers. This feedback changes to offset voltage of the LT1002 by less than 5 p,V. ..This is an infrared gate with two sensors planned to use in the wall in the way behind a door. It can be applied in a toilet to keep track of that someone is inside exceeding a certain amount of time. After that time elapsed, the circuit triggers the digital....This encoder can generate up to 19,683 codes from 9 address lines by detecting 1,0, or open circuit. To initiate the transmit sequence, pin 14 should be pulsed low. The encoder will now output on pin 15 a data stream representing the condition on each of the....City dwellers and other flat dwellers know the practical difficulties they encounter when they try to put up an antenna for 40 meters. Finding space enough to accommodate 67 feet of wire is a real problem for them and most of them have to be satisfied by the....The circuit consists of two stages. The first stage is a "switch" or cut-off device. It detects a voltage above 0.7v from the solar panel and the resistance between its collector-emitter terminals reduces to a very small value. The 10k resistor allows the....Output voltage great enough to jump a l-inch gap can be obtained from a 12-V power source. A 555 timer IC is connected as an astable multivibrator that produces a narrow negative pulse at pin 3. The pulse turns Ql on for the duration of the time period.....This is my reincarnation of the EH Small Clone and Roland CE-1. Unlike the Clone it has a proper depth control. It also has a switch to change between the CE-1 like 512 stage delay and the Clone's 1024 stage delay. Current consumption is very low and the....Flash-back to the 60's with this 5 channel unit with up to 100 watts per channel. This unit uses a PIC16F84 with an 8 bit A/D. The signal from both stereo channels is combined and digitized. Each of 5 frequency bands is processed using a 16 point FFT.....Feedback - This is where part of the output signal is fedback to the input BUT 180o out-of-phase (i.e. partially cancels the input). If it were in-phase feedback then we would have an oscillator - which in this case we definitely do not want. Fidelity - This....