New Circuits Page 223
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The 12VDC supply provides power for the camera and video modulator circuits. The video from the camera is fed into the video input of the modulator circuit. The modulated RF from the modulator is fed into a small antenna. Use of a dipole antenna that is....
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The pitch of the tone is dependent upon the resistance under test. The tester will respond to resistances of hundreds of kilohms, yet it is possible to distinguish differences of just tens of ohms in low-resistance circuits. Q1 and Q2 form a....
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This is another kit in our self-sufficiency range. We also have a 12v fluoro inverter kit for those who need to operate 20watt to 40watt fluorescent lamps from a 12v supply.
We will be introducing a number of kits for those who have opted to live with 12v....
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This will probably be one of the last transmitters for the 88MHz to 108MHz band. This particular TX is of special interest to those wishing to build low power Power Amplifiers for the VHF bands since it used impedance matching, power amplifier and antenna....
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The UJT-oscillator frequency is determined by the 100 µ¥ capacitor and the effective resistance of the 22 and 470 resistors and the potentiometer. Rate can be varied from 42 to 208 beats/minute.
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Turns-off your amplifier when idle for 15 minutes
Fed by amplifier tape-output. This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least.
Pushing P1 the device is switched-on....
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The NE604"s signal-strength indicator section is used, based on an internal logarithmic converter. This enables a linear ..
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The frequency counter is the most popular instrument in the home maid instruments. I think that the reason why it is built widely is: it can be built easily because it is digital circuit, it is generic measurement and many construction kits are available.....
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If you use an ADC to monitor a system`s power-supply voltage, you may encounter situations in which the supply voltage exceeds the ADC`s reference voltage (Figure 1). However, the ADC`s input voltage cannot exceed its reference voltage. You can use an....
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This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device...
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This circuit is very basic to build and puts out great power for your car or home. Keep all leads as short as possible...
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CW is the simplest form of modulation. The output of the transmitter is switched on and off, typically to form the characters of the Morse code.
CW transmitters are simple and inexpensive, and the transmitted CW signal doesn`t occupy much frequency space....
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Indicator provides an accurate comparison of two voltages by indicating their degree of balance (or imbalance). Detecting small variations near the null point is difficult with the basic Wheatstone bridge alone. Amplification of voltage differences near the....
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With the proliferation of dual-voltage architectures and multiprocessor boards, even simple applications can require several processor voltage rails. With each processor having its own power-up and -down requirements, power-rail sequencing and control can....
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LED 1 will light and the buzzer turns on when the coil is changing inductance. The setup is easy, VR1 is adjusted ( away from any metal objects ) so that LED 1 will light and the buzzor sounds on, and then VR1 will be trimmed until led and buzzer are off...
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The crystal element in this circuit is connected directly between the base and ground. Capacitor Cl is used to improve the feedback due to the internal capacitances of the transistor. This capacitor should be mounted as close as possible to the case of the....
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Professional schematic capture and PCB design software with automatic component placement, track routing and design validation. Includes full feature schematic capture environment...
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A thermistor (RI) is compared with a reference (R2) in a Wheatstone-bridge circuit. Comparator Ul"s output goes high..
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General There are many 9V chaser circuits that seem to waste about 7V when driving LEDs that are only about 2V. This project is unique, because it uses only two inexpensive alkaline battery cells totaling 3V for power. Since most of the waste is eliminated,....
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High power amps are not too common as projects, since they are by their nature normally difficult to build, and are expensive. A small error during assembly means that you start again - this can get very costly. I recommend that you use the PCB for this....
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This complete high quality, low noise 5-BAND GRAPHIC EQUALIZER circuit is based around Monolithic Linear integrated circuit LA3600 manufactured by SANYO. This circuit is very easy to build and has good Quality. You can use it with Portable component stereos,....
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Switch S2 is used for increasing and switch S3 is used for decreasing the volume. Similarly, switches S4 and S5 are provided for second channel (right channel) volume control. Also, pin 14 of IC2 can be connected to IC 74193 pin 14 (clear input) of the right....
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This switch will suit the Modular Burglar Alarm circuit. However, it also has other applications. The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7....
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R2 sets the output voltage. The maximum current is determined by the value of R3: the over-current protection circuitry inside the LM723 senses the voltage across R3 and starts shutting the output stage off as soon as this voltage approaches 0.65 V. This way....
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This 6V to 12V converter circuit is made with an IC from SGS with several additional components. The IC is a TDA2003 but it can be replaced with a TDA2002. The cost of building the 6volts to 12 volts converter should be low enough to justify constructing it....
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It consists only from Microchip PIC 16F84 cpu and LCD text module. Author states that this counter is capable metering frequencies from 400Hz to 50MHz. I used faster, 20MHz version of 16F84A-20I/P, and it managed to count 80MHz oscillator output...
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This remote controller can be fitted to any preamplifier for distance volume control. Basicly, Its a motor controller circuit with IR that turn the potentiometer left or right...
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The dual slope-sampling solar engine. Yet another interesting design from the fertile mind of Wilf Rigter If you had time to experiment with the ALF type SE circuit you may have discovered some of its shortcomings with regard to a Power Smart Head....
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A designer often needs to know the value of the internal resistance of a battery. Quite a few testers gi..
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A number of people have been unable to find the transformer needed for the Black Light project, so I looked around to see if I could find a fluorescent lamp driver that does not require any special components. I finally found one in Electronics Now. Here it....
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The Saver V5.0 runs simple clock emulation program, turns a night light on and off with preset time, say 19:00 to 22:00 everyday. The design features low cost, easy installation, no battery backup and no EMI. The AT89C2051 uses external oscillator generated....
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Figure 1s circuitry meets the discussed requirements. It
signal conditions a commercially available clip-on current
probe with a precision amplifier to provide 1%
measurement accuracy to 10MHz. The clip-on probe
provides convenience, even in the presence....
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The battery-operated black light uses a U-shaped, unfiltered, black-light tube, which requires approximately 250 Vac to operate. To create the 250-Vac 6-V battery, the circuit uses a one-transis-tor blocking oscillator that drives a ferrite inverter....
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An AM loop antenna is one of the true marvels of electronics. Requiring no power, it takes advantage of the resonant properties of an inductor and a capacitor connected in parallel to receive weak AM stations. The "loop" part of the antenna is the inductor,....
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This circuit will allow you to set the gain of two stereo channels to the same level. The signal across the two channel-load resistors is sampled by resistors R2. (Values of these resistors will depend upon the power level) For most 20 milliampere LED, use....
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Using this circuit will give Good Charging results to a Sealed Lead Acid Battery, like I use in the Metal Detector. This Circuit is Extremely Small in size and has a low parts count, making it ideal in some situations. It can also be adapted for Charging....
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Increased sensitivity gives field strength reading from low power transmitters. Operating range 3-30 MHz..
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This indicator senses the switching on and off of the 48-V de line voltage and transmits the pulses to logic circuitry. An Hl1A10 threshold coupler, with capacitorfiltering, gives a simple circuit which can provide dial pulse indication, and yet reject....
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The circuit can be used as a sensor that can trigger an alarm, without direct contact being made by the intruder. In this circuit, a visible or invisible light source radiates on the sensor, keeping the detection loop in what could essentially be called a....
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A bar column of LEDs is arranged so that as the audio signal level increases, more LEDs in the column light up. The LEDs are arranged vertically in 6 dB steps. A fast response time and a one second decay time give an accurate response to transients and a low....
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This transmitter sends an FM signal in the 88-to 108-MHz range, with a tone of 19 kHz. This can be used to activate the FM MPX pilot carrier indicator, which can be interfaced to external devices. L4 is for use with a 15 CM wire antenna. LI is 9 turns of....
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High-speed DACs, such as Analog Devices` AD9776/78/79 TxDAC family, offer differential outputs, but, for low-end ac applications or high-precision level-setting applications, a single-ended current-output DAC with a differential-conversion circuit provides a....
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The circuit is analogous to a voltage or a current source but delivers fixed power levels that are independent of the load resistance. A feedback loop senses load power and automatically adjusts the output voltage to maintain the desired power level. The....
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This compact tester checks cables for open-circuit or short-circuit conditions. A differential transistor pair at one end of each cable line remains balanced as long as the same clock pulse generated by timer IC appears at both ends of the line. ..
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The MPF102 (Q1) can be replaced with a NTE451 or ECG451, but still widely available. JFET-N-CHAN, UHF/VHF AMP. The 2N3565 (Q1/Q2) can be replace with a 2N2222(A), BC107, BC108, BC109(A/B/C), NTE123A, or ECG123A. The TIP31 (Q3) can be replaced with a NTE196....
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Al and A2 are two sections of a quad comparator. The first, Al, functions as an amplifier and detector. Resistors R~and R6 set the gain at 100; the output of Al is an open collector to negative-peak-rectify the output with a decay time constant determined....
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The door opener derives its power from a 9-V battery. A momentary-contact switch, 52, is provided in the event that manual opening and closing is required. Relay Kl is a 9-V type and relay K2 is a 117"Vac latching-type, which automatically latches with....
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A peak level indicator when a signal exceeds a certain maximum value. It can be quite useful, for instance, with tape recorders, mixing consoles etc. One of the most important requirements of a peak level indicator is that it should respond to very short....
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This page describes how to build this full-bandwidth single-port (one input and one output) MIDI interface. The interface is buffered (that is, if the PC gets behind you won`t lose data) and it works in Windows 3.1 and Windows 95 using a special (and very....
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The first timer is used as amonostable and determines the tone duration when triggered by a positive pulse at pin 6. The second timer is enabled by the high output of the monostable..
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Most switch-mode power supplies rely on a PWM (pulse-width-modulated) output that is controlled via voltage feedback. A 555-timer IC can inexpensively perform PWM. The circuit in Figure 1 shows how to turn a 555 PWM circuit into an switch-mode power supply....
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The meter will show volume and tone control balance between left and right stereo amplifiers. For maximum convenience the meter is a zero-center type. Resistors are five percent or better and the diodes a matched pair. Optimum stereo level and phase balance....
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A silicon-controlled rectifier is installed in parallel with the 12-V line and connected to a normally-closed 12-V relay, K1. The SCR's gate circuit is used to sample the applied voltage. As long as the applied voltage stays below a given value, SCR1 remains....
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This fixed 1-mA current source delivers a fixed current to a load connected between Ql"s collector and ground; the ..
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There`s not much to this circuit. The two RJ-11 jacks are set up to feed the telephone circuit through from the wall to the phone. The active signal for a single phone is on the red and green wires. Yellow and black are usually used for a second phone line.....
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The microcontroller used is 0822 zilog encore! 8k series (soic,28pin) as shown on the figure. Is a programmable microcontroller, the functions used are the GPIO and the UART of the chip. GPIO is used on led indicators, and the UART is used for giving and....
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This VGA to TV converter is designed to connect VGA card to a television which has suitable 21-pin AV connector for RGB input (called EURO/SCART/Peritel connector). if you Tv does not have this kind of connector, then you can`t use this circuit.
The....
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An ultra low noise audio preamplifier particularly suited to microphone preamplification including balanced microphones. The IC features wide bandwidth, low distortion only 0.007% at a gain of 100, ..
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In all the houses exist the bells in the door. All want, they have the possibility of being possible to change the intensity, the tone of sound. With this circuit we have this possibility. With the materials round the gates, we can change the sound. For the....
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Blue VALUES replaced by values in RED. Blue COMPONENTS removed from circuit. Red components added to circuit...
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M½´rklin`s signal braking module, number 72441, solves this problem by introducing a short transition track between ordinary and braking section, and additionally offers a emergency stop section with cut off power in case a loco does not brake in appropriate....
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This narrowband filter using the 741 operational amplifier can provide up to 60 dB of rejection. With resistors equal to 100 K and capacitors equal to 320 pF, the circuit will reject 50 Hz. Frequencies within the range 1 Hz to 10 kHz may be rejected by....
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Low-frequency signals produced by transducers, measurement equipment, or data loggers often appear like the first waveform in the figure. The circuit shown operates as a tracking sample-hold, and the transients are replaced in the output by the stored value....
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A rangefinder is described that uses the propagation time of a beam of infrared radiation to measure distances of up to 120 meters with errors of less than 50 µm. The instrument is capable of measuring up to five different distances per second by directing....
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Using this low-cost project one can reproduce audio from TV without disturbing others. It does not use any wire connection between TV and headphones. In place of a pair of wires, it uses invisible infrared light to transmit audio signals from TV to....
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For FM demodulation applications where the bandwidth is less than 10% of the carrier frequency, an XR-J567 can be used to detect the presence of the carrier signal. The output of the XR-567 is used to turn off the FM demodulator when no carrier is present,....
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The basic idea of the project is to make different colored bulbs light at different frequencies of music. The circuit connects to the speaker outputs of your stereo or to the back of your speaker. The music passes through the transformer and the volume....
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Using the STK4038X audio amplifier IC, can be designed a very simple high power and efficiency audio power amplifier . This circuit is manufactured by Sanyo Corporation and will provide a output power of 60 watts on a 8 ohms load or 4 ohms load with 0.008%....
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Tone control of audio systems involves altering the flat response in order to attain more low frequencies or more high ones, dependent upon listener preference...
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Using an SCR/relay combination, this circuit can be made to cut off ignition, unless a positive voltage is applied to..
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The EEprom programmer software supports the following devices 28C16, 28C256, 28C17, 29C256, 28C64. Diode D1 and resistor R1 provide the VDD isolation when programming the 24 pin devices. The jumper J3 must be shorted for 24 pin devices, and open circuit for....
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A single chip metal detecor with a range of a few inches. This is useful for decting nails or screws in walls and floors, or for locating buried mains cable. The heart of the circuit is a single IC the CS209A made by Cherry Semiconductor. The detector, is a....
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When SI is depressed, an initial positive voltage is placed on C2 and the noninverting terminal of Ul. The circuit o..
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For higher speed applications, up to 1-MHz NRZ, the Schmitt-trigger output HllL series optoisolator provides many features. The 1.6-mA drive current allows fan-in circuitry to drive the IRED, ..
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Hall-effect switches have several advantages over mechanically and optically coupled switches...
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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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These two projects , Wah and Fuzz, are the results of a modification to a Morley dual channel volume control pedal that one of my sons suggested I undertake as He had no use for the volume unit but thought I could modify the pedal into a Wah unit. I decided....
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This circuit produces the famous Big Ben sound. It produces the "ding dong" sound when switched ON.
Basically the circuit alternates between two frequencies which are adjustable. This produces the "ding-dong" sound.
The first IC(left) oscillates at about....
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Two inverters, one resistor, and one capacitor are all that is required to make a HC(T)-based oscillator that gives reliable operation up to about 10 MHz. The use of two HC inverters produces a fairly symmetrical rectangular output signal. In the same....
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Using a precision oscillator and a few CMOS counters, you can build a precise, very low dutycycle pulse generator. You can add as many counters as you desire to make the period as long as you wish. ..
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Built around a 555 timer IC, this pulse generator can be built into a probe for logic..
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This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can....
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This article describes an I-V curve tracer circuit that uses a computer for display and control. The circuit is controlled via the PC parallel port. Software is provided, written in BASIC, to control the measurement and display the results on the monitor.....
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A circuit that tailors the low end of particular items such as the bass drum and bass guitar to be used for individual tracks during mixdown, not across the entire mix. With the circuit, I can set the low end rolloff characteristic and stored energy of each....
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This project arises from the need to home-build a valid tuning control for a multi band transceiver.
It consists of a partial syntesis V.F.O. that fits to single conversion equipments with an I.F. stage
nearby 9 MHz. The circuit can cover the whole H.F.....
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A tapped transformer drives a diode bridge (D1-D4) and two 2500 µ¥ filter capacitors (Cl and C2), that provide a no-load voltage of 37 or 47 volts, depending upon the position of switch S2a. The unregulated dc is then fed to a pre-regulator stage composed....
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In the circuit, Ql and Q2 are connected in the classic SCR or thyristor configuration. Where higher input voltages or minimum component count are required, the circuit for thyristor boost can be used. The thyristor is running in a linear mode with its....
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This little instrument identifies faults in horizontal output stages by doing a `ring` test, i.e. it applies pulses to the LOPT / FBT primary circuit, and counts the number of damped oscillations or `rings` produced. For each `ring` down to about 15% of the....
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Here is a simple metal detector with TDA2822 and few NPN transistors. There is a small arrow connected from the Emitter of the T3 to the 10n Capacitor C4. That arrow is simply indicating signal flow as right to left in that particular wire, which is....
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The circuit in Figure 1 represents one method to switch a bipolar, two-color LED using an SPDT mechanical switch or relay. This circuit wastes power and does not work properly if the power-supply voltage is not substantially more than the sum of the LEDs`....
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Indicator was designed for displaying the peak level of small ac signals from a variety of transducers including microphones, strain gauges and photodiodes. The circuit responds to input signals contained within the audio frequency spectrum, i.e., 30 Hz to....
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Almost any 2x16 character LCD module with Hitachi HD44780 controller chip will work. The LCD pin numbers on the schematic are not valid for all LCD modules. Please check the actual signal names on your particular LCD module. The selected DFCW frequency....
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The circuit can be used to simulate large capacitances using small value components. With the values shown and C - 10 µ¥, an effective capacitance of 10,000 µF was obtained. The Q available is limited by the effective series resistance.
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This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. It has provision for normally open and normally closed switches and will accommodate the usual input devices such as Foil Tape, Pressure Mats, Magnetic Reed Contacts,....
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The push button and potentiometer initiate a time delay that turns a light on then automatically turns it off again after a predetermined time. The potentiometer can be set for a delay of a few seconds to just under three minutes. When the push-button switch....
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When the pushbuttons at either door are depressed, this circuit generates a different tone for each door. Tones are ge..
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No description available...
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Circuit CREATOR Electronics CAE System provides the most complete and high performance solution for electronics design using personal computers...
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This project is a digital Automatic Gain Control (AGC”) system using a PIC16F876 MCU. The ability to set the gain level in a circuit and have it control itself is a very useful function. This circuit is a building block of another project I am working on. A....
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A TDA1024 electronic thermostat senses soil temperature via thermistor R6. The circuit uses zero-crossing switching of the heater. The heater is made of elastic-coated steel wire. PI is used to set the temperature. The heater should have 2 or more....