New Circuits Page 209
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The figure shows the use of a CD4016 analog multiplex to multiplex the digital outputs back to the FUNCTION input. Since the CD4016 is a digitally controlled analog transmission gate, no level shifting of the digit output is required. The CD4051's or....
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Lamp life can be extended by improving the conditions under which its filament is operated. This includes eliminating the inrush overcurrent surge and reduclog the mechanical stress (vibration) on the filament caused by an ac source. The circuit shown....
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The dynamic mixer combines two audio inputs by adding the primary signal, Input A, to a gain-controlled signal, Input B..
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The LM1036 is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected. Four control inputs provide control of....
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It came to me in a flash. A simple way to see if a fuse has blown without removing it from its holder.
Its not often you can design a circuit using just two components, but with just one resistor and an
LED this circuit provides visual indication of when a....
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You can use Microchip`s low-cost PIC16F818 microprocessor and a pair of gates to construct a digital PLL that can clean noisy digital signals over a range of 4 to 40 kHz. Featuring programmable lock range, phase differential, and loop gain, the digital-PLL....
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Figure 1 illustrates one possible approach that uses external inverter IC1 to drive D1, a red/green bidirectional LED. A logic-high output on the port pin forces current through the green (upper) LED and pulls the inverter`s input high, which drives the....
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Q1 is an npn Darlington and Q2 is a prip Darlington. MOV1 is a metal-oxide varistor and R8 is an thermistor for limiting inrush current. This circuit limits ac line current to a load. When a predetermined interval has passed, RY1 shorts out thermistor or....
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The calibrator operates on exactly 100 kHz providing a reference for calibrating the variable time base oscillator of general purpose scopes. For example, if the scope is set so that one cycle of the signal fills exactly 10 graticule divisions then each....
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Here`s a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by measuring....
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This circuit is suitable to amplify and distribute the audio signals. The input audio signal is applied to the J1 and after passing through the P1, It is buffered and amplified by the U1 prepared to redistribute. It has 3 output to drive 3 audio lines with....
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These circuits provide overvoltage protection in case of voltage regulator failure or application of an external voltage. Intended to be used with a supply offering some form of short circuit protection, either foldback, current limiting, or a simple fuse.....
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A 10 bit scanning voltmeter with a Minimum Mass Wireless Coupler, based on the ATMega8.Range to the Minimum Mass Base Unit is 10 to 15 cm. If the voltmeter is battery operated, it can be floated from ground. This project is very simple physically, intended....
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This LCD terminal provide two modes of operation by selecting jumper J1. When J1 is open the terminal operate as a normal ascii display terminal, when J1 is closed the terminal displays the input serial data in hexadecimal format. This mode is useful for....
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The Meter and other small circuit differences, gives better performance.
On the Schematic, I show Two Possible Coils.
1) The Ferrite Rod, creates an Accurate Pin Point.
But it also has a Very Narrow Detection Field.
2) The Dual Wound "Tesla Coil"....
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The circuit uses four NAND gates of a 4011 package. In each oscillator, while one gate is configured as a straightforward inverter, the other has one input that can act as a control input. Oscillator action is inhibited if this input is held low. The first....
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A very popular circuit for driving DC motors (ordinary or gearhead) is called an H-bridge. It`s called that because it looks like the capital letter `H` on classic schematics. The great ability of an H-bridge circuit is that the motor can be driven forward....
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Precision DACs are essential in many consumer, industrial, and military applications, but high-resolution DACs can be costly. Frequency-to-voltage converters have good nonlinearity specificationstypically, 0.002% for the AD650and are inherently monotonic.....
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Meter Ml, a +/-50-uA zero-center D`Arsonval meter movement is driven by Ul, a TL081 FET op amp, through R3. The gain of Ul is set at 11 by Rl and R2, while capacitor 01 is used to restrict the bandwidth of Ul to 1.6 Hz. Power for the circuit is derived from....
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Disco anyone? Actually, this strobe serves a much more useful purpose then making it look cool when you dance in the dark. You can use it to view fast moving objects, look for craks in PC boards (hold the strobe on the trace side of the board and look from....
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It is often desirable for a single doorbell to be operated by two buttons, for instance, one at the front door and the other at the back door. The additional button, S2 in series with the break contact of relay Rel, is connected in parallel with the....
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This schematic is an impruved version of the Pro Maniac Guitar tube power amplifier...
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IC2 is an audio frequency oscillator. Its frequency is primarily controlled by the resistance between pins 2 and 7. RV4-11 eontrol the oscillator frequency and by touching a stylus (connected via limiting resistor R5 to pin 2) to each preset, different notes....
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In those cases we want to measure the temperature in an area far from where it is. The imaging unit installed, you should find some way to connect the latter with the necessary sensor. The cables we use most often will have three two conductors for power....
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The circuits in Figure 1 have certain advantages over those in a previous Design Idea (Reference 1). The first-event detector with autoreset (Figure 1a) consists of N sets of monostable multivibrators, using 4001 logic circuits with LEDs attached. After any....
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When frequency stability is not of prime importance, a simple, yet reliable, digital clock oscillator can be made with the aid of relatively few components. High-speed CMOS (HCU/HCf) inverters or gates with an inverter function are eminently suitable to....
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The physical transmission medium for the 429 standard is 78Ω shielded, twisted-pair cable that uses a complementary, differential bipolar RZ (return-to-zero) waveform (Figure 2). The voltages are the net differentials that the biphase drive develops: For....
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All ATL-3 loop windings are centre tapped and balanced w.r.t. their amplifier/receiver chassis ground, and therefore electric field interference pick up tends to self cancel. Magnetic noise fields,e.g. televisions and the electric meter box, or....
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Our programmable MP3 player has an interface to an LCD with a HD44780 controller. These are alphanumeric LCDs with one to 4 lines of text and 16 to 40 characters per line. However, these LCDs (and LCDs in general) exist in two varieties: those that require a....
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A variable resistor provides a voltage input to the PIC which is converted to a digital value using the onboard Analogue to Digital convertor, this in turn is used to set the PWM duty cycle. Since the PWM duty cycle is adjusted using a voltage signal input....
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The 5-MHz track and hold shown here has a 400-kHz power bandwidth driving ±10 V. A buffered input follower drives the hold capacitor, C4, through Ql, a low resistance FET switch. The positive hold conuuand is supplied by TTL logic, with Q3Ievel shifting....
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Now-a-days Electronic voting machines are being used effectively. The confidence of the voter in its flawless working is gradually building up and these machines are thus becoming quite popular throughout the country.
Features of the electronic voting....
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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....
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Resistors Rl and R2 temperature-stabilize the NAND gates; they also ensure that the gates are in a linear region for starting. Capacitor CI is a dc block; it must have less than Vw ohm impedance at the operating frequency. The crystal runs in a....
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This design note presents a voltage controlled cable equalizer based on the LT1256 video fader. The circuit features ease of adjustment, simplicity and the capability for remote control. The amount of equalization can be adjusted continuously from the....
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Application Note 67 is a collection of circuits from the first
five years of Linear Technology, targeting data conversion,
interface and signal processing applications. This
Application Note includes circuits such as fast video
multiplexers for high....
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No description available...
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In this circuit, an HA-4900 series comparator is used in conjunction with a D/A converter to form a simple, vers..
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The heart(s) of the unit are the ETAL P3400 line modules available from Farnell. These modules mop-up all of the line interface functions like ring detection, physical hybrid, on-off hook handling etc. This means that the TBU as a whole would probably pass....
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Two low voltage, low power zeners are used to control electronically the level of an audio signal. The attenuation range is from 6 to 58dB for an input current from 0.042 to 77 mA corresponding to a control voltage from 2.7 to 7.5V. If control voltage is....
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This circuit offers open and closed loop contacts (switches 1,2,3) that triggers the alarm ON and stays ON for 5 -10 minutes. The trigering delay (entrance/exit) is 27 seconds. This simple alarm circuit Has also a cancel button for reseting the circuit to....
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The circuit is capable of providing power for portable Geiger counters, dosimeter chargers, high resistance meters, etc. The 555 timer IC is used in its multivibrator mode, the frequency adjusted to optimize the transformer characteristics. When the output....
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This dc-to-ac inverter is based on the popular 555. A 555 oscillator circuit drives a buffer amplifier consisting of Ql, Q2, and Q3. The circuit operates at 150 to 160 Hz. Tl can be a 6.3-V or 12.6-V filament transformer as applicable...
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An input signal drives both SN74 74 D-type flip-flops, which are positive edge-triggered devices. A low-to-high input signal transition triggers tbe A flip-flop, while a high-to-low input signal transition triggers the B flip-flop via tbe SN7404 inverter.....
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This amplifier was designed to be self-contained in a small loudspeaker box. It can be feed by Walkman, Mini-Disc, iPod and CD players, computers and similar devices fitted with line or headphone output. Of course, in most cases you will have to make two....
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These filters are useful for equalisation, analysis and other tasks such as the Sound to Light converter (Project 62) or even a fully functional Vocoder. For those who have not heard of the vocoder, it is a device that takes a music source as one input and....
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This 100 watt linear amplifier may be constructed using two MRF309 transistors in push-pull, requiring only 16 watts drive from 420 to 450 MHz..
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Positive output step-up and step-down de-de converters have a common limitation in that neither can handle input voltages that are both greater than or less than the output. For example, when converting a 12-V sealed lead/acid battery to a regulated +12 V....
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Here is a circuit for using the printer port of a PC, for control application using software and some interface hardware. The interface circuit along with the given software can be used with the printer port of any PC for controlling up to eight equipment .....
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A Coil Coupled Operation Metal Detector made from readily obtainable components and using an ordinary medium receiver as a detector. The metal detector shown here may well represent a new genre. At any rate, after some exposure, it is regarded as such by....
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The governor following is intended to regulate the light intensity incandescent 220 V. The components in a relatively few, which means it can easily be mounted onto a small plate. After the build, we recommend you place it inside the box which is flush....
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The remote solar powered LED light takes advantage of the current limited nature of solar photovoltaic cells. If light shines on the solar array, current will flow through the circuit. For a typical size of solar cell, there is a maximum current that can be....
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Ul (a 4046 PLL containing a voltage controlled oscillator or VCO, two phase comparators, a source follower, and a Zener diode) is used to produce a low-frequency, pulsed output of about 40 Hz. The VCO's frequency range is determined by R6 and C2, which can....
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The core of this construction is 16-Bit Stereo Digital-To-Analog Convertor with USB interface PCM2702. PCM2702 needs only few additional parts to work. The schematic is not complex. Sound card can be powered directly from USB port (jumper W1) or from....
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The power is all in the timed switching process. There are two main principles I use of switching the radiant energy the John Bedini way. First, the SG/SSG, Icehouse unidirectional circuit or John Bedini Monopole with the School Girl Circuit (SG)....
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The intention of the following application shows how the NE5517 works in connection with a DAC. In the application, the NE5118 is used—an 8-bit DAC with current output—its input register making this device fully µ-compatible. The circuit consists of....
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A low resistance ( 0.25 - 4 ohm) continuity tester for checking soldered joints and connections. This simple circuit uses a 741 op-amp in differential mode as a continuity tester. The voltage difference between the non-inverting and inverting inputs is....
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Channel 1 is wired as a voltage follower and is turned on during the track/sample time. Ifthe product of R x Cis sufficiently short compared to the period of maximum output frequency, or sample time; Cwill charge to the output level. ..
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A simple logic-analyzer design is compatible with all versions of Windows and pushes the PIC 18C252 chip to its speed limit to achieve a 1-MHz sampling rate (Figure 1). The circuit can examine three channels of relatively low-speed logic signals that have....
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This circuit will detect AC line currents of about 250 mA or more without making any electrical connections to the line. Current is detected by passing one of the AC lines through an inductive pickup (L1) made with a 1 inch diameter U-bolt wound with 800....
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The circuit is built around the LM567 tone decoder IC that requires about 100 millivolts at its operating frequency. The frequency is set by a 10 K variable resistor and can be between 700 and 1500 He..
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V_logic is connected to the power supply Vs and all ground are connected to the negative terminal of the battery. Fout is a square wave of varying frequency with a maximum amplitude of Vs. A voltage divider is needed (200k and 10k variable resistor connected....
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Involvement is a modified version of the classic circuit of automatic level control signal used in tape recorders. The purchase price of the components (using TL072) does not exceed CZK 60 for a channel. For a range of entry level audio signal may be....
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This circuit checks the reliability of appliances so that the equipment may be used safely. The test circuit must be plugged into a properly wired three terminal wall outlet. When a two-lead or three-lead appliance is plugged into circuit outlet SOI, neon....
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To simplify the following schematics and facilitate easy understanding of the principles involved, the following schematic substitution is used (Note the triac driver is of limited use at 3 f voltage levels).
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The right way to do this is with a small extra pc board to accommodate the new components, firmly secured inside the case, and wired carefully and neatly. Unfortunately, I did none of these things, but it worked reliably and if it ain't broke. I used a pot....
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This receiver is built around a uPC1373 IR remote-control preamplifier, a sensitive 30-to-40 kHz tuned detector, an automatic..
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Rectified and filtered voltage from the 24 Vac transformer is applied to the LM723 voltage regulator and the npn pass transistor set up for constant current supply. The 470 ohm resistor limits trickle current until the momentary pushbutton (S2) is depressed,....
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This Project Components tester can be used to check the electronic components such us Diode, Transistor, Capacitor, IC555, IC741 and Continuity. The whole circuit was controlled by the Microcontroller AT89C52. The circuit has an LCD display it was used to....
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A standard shaft encoder"s A and B ports generate square waves with the same frequency as the shaft turns. The phase of A will lead or lag that of B by 90°, ~depending on the direction of rotation. To obtain maximum resolution, the tachometer circuit must....
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NOR gates a and b form a low-frequency oscillator that is activated when the CDS cell, under dark conditions, causes NOR gate a to see a logic zero at one input. This low-frequency (10 Hz) gates a high-frequency oscillator (c and d) to oscillate at around....
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Due to the huge interest in this project, I have just recently finished the NEW schematics. The older schematics were scanned and pretty poor quality. These new ones should make it considerably easier to recognize the parts used for the project. The Ming....
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This circuit is the electronic emulation of the I Ching, a form of divination originating in China. In the classical form, the response is obtained by the manipulation of 50 sticks or, more practically, by tossing 3 coins. The process must be repeated 6....
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Here`s a circuit diagram (originally drawn by Wilf Rigter, I corrected it based on Bob`s on-list feedback) for Bob`s "Vore-N-More" circuit containing the SmartCap solar engine:
In this diagram, the "SmartCap" is just the 1.5 F storage capacitor,....
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This circuit was formed to create a wireless alarm from a normal magnetic contact. By fixing the magnet to the leaf of a door, or swing of a drawer, it is easy to reveal the opening. To transmit the signal to a control anti-theft we modify the circuit of a....
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The following diagram is for the main circuit of the motor driver.
A testing version is shown near the end of this page. It is laid out differently and shows the SN7474 in logic block form and LED`s are used to indicate the motor coils being switched...
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A pulse width modulator (PWM) is a device that may be used as an efficient light dimmer or DC motor speed controller. The circuit described here is for a general purpose device that can control DC devices which draw up to a few amps of current. The circuit....
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On the initial part of the positive half cycle, the voltage is changing rapidly from zero causing a large current to flow into capacitor C2. The current through C2 flows through R4, D3, and D4 into the gate of the TRIAC Q2 causing it to turn on very close to....
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Q1 & Q2 provide linear frequency operation of IC1 following P1 resistance variation.
Q3 was added in order to obtain a louder click, similar to clockwork metronomes.
A 12V micro battery was used to obtain a higher output power and more compactness...
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This circuit is fed from the earphone jack of your receiver and goes to limiter control R6 and is then amplified by Ql: a common-emitter stage that has a voltage gain of only about 10, because of the negative feedback introduced by R3. The output of Ql is....
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This panning circuit (short for panoramic control circuit) provides the ability to move the apparent position of one microphone"s input between two output channels. This effect is often required in recording studio mixing consoles..
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This amplifier has about 20dB of gain, bandwidth of 100MHz and noise figure of about 7dB. The output transformer is 8 turns bifilar wound on a ferrite core. Use a medium power UHF transistor 2N5109, 2N3866, 2N4427 or similar. The transistor will need a small....
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100 W output at 50 MHz is available from this circuit. Ul and Q2 form a T-R relay driver, switching the amplifie..
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This circuit comes from U.S. Patent 3, 778,800, granted to BRK Electronics in Aurora, IL. The circuit provides a smoke detector with an alarm for both smoke and low batteries. The R6/R7 voltage divider monitors the battery and will turn Q2 and Ql off when....
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Multi-spark ignition is very useful especially in the case of startings at low temperature and at low rpm range. Basic idea, is to apply to spark plugs instead of only one spark, a ?spark-burst? having big energy. In this case, combustion of air/fuel mixture....
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The following diagram shows the basic laser pointer circuit. It is identical to the infrared circuit except that the infrared LED`s have been replaced by the laser pointer unit.
Due to the long range of these devices this detector method can easily....
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The pull-up transistor of the totem-pole output is used-to turn on the LED and the pull-down transistor is used to turn ·off the LED. The lower impedance and higher current handling capability of the saturated pull-down transistor is used as an effective....
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Diagram shows a 50MHz oscillator operating on a third harmonic. The collector"s load resistor R1 has been increased because the quartz crystal"s internal series resistance Rs increases with frequency in the VHF range. The crystal"s internal series....
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A MW AM radio like those you buy, or used to buy. Use just BC549 trannies, with the BC559 complement being allowed in the audio output stage. Buying RF antenna coils, oscillator coils and intermediate frequency transformers would be cheating - wind your own.....
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A laser module designer can use a fixed resistor, mechanical pot, digital pot, or a digital-to-analog converter (DAC) to control the laser driver`s modulation and bias currents. The advantages of a programmable method (POT or DAC) are that the manufacturing....
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The National Physics Laboratory broadcasts a time signal, previously known as the Rugby clock but now called "Time from NPL." Its most commonly known as the MSF signal due to it originally being identified in Morse code those letters. It is broadcast from....
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This free-running TTL square-wave oscillator has a variable frequency output over a 20:1 range or better through use of four of the six inverters in an SN7404 chip and the additional components shown. Frequency of oscillation is determined by the capacitor....
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This circuit features the ZTX450/ZTX550 transistors in a push-pull output stage. The following readings were taken at maximum volume: Input: 0.4 mV rms, Output: 1.8 V rms, Voltage gain: 4500, Max. output before distortion: 2.25 V rms -supply current ~ 3.5....
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This device acts as a variable speed control for the heater blower in a car. It takes its power directly from the existing wiring and connects with just 2 wires. It will also work for any 12 volt device up to 10 amps. A PIC12F675 provides all of the....
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Although this circuit uses a 74HC74, any CMOS variant of this flip-flop will work. IC1A acts as a true/ compleme..
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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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The timer circuit shown gives independent control of the output"s on and off intervals, which can range from 0.055 seconds to 30 minutes, relatively unaffected by power-line transients. IC1 is a CMOS programmable-timer chip that includes 24 ripple-binary....
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A low-current flyback converter is used here to generate ±15 volts at 20 mA from a +5 volt regulated line. The reference generator in the SG1524 is unused with the input voltage providing the reference..
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These parameters are expected with an approximately 50% square wave up to frequencies of seveal MHz, and symmetric sine waves at higher frequencies. The primary limitation is based on the maximum clocking rate specification for the MM74HC6040 ripple counter....
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The use of a loop antenna of large size (12 18") provides a large signal pickup at AM broadcast frequencies. It has..
The figure shows the use of a CD4016 analog multiplex to multiplex the digital outputs back to the FUNCTION input. Since the CD4016 is a digitally controlled analog transmission gate, no level shifting of the digit output is required. The CD4051's or....
Lamp life can be extended by improving the conditions under which its filament is operated. This includes eliminating the inrush overcurrent surge and reduclog the mechanical stress (vibration) on the filament caused by an ac source. The circuit shown....
The dynamic mixer combines two audio inputs by adding the primary signal, Input A, to a gain-controlled signal, Input B..
The LM1036 is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected. Four control inputs provide control of....
It came to me in a flash. A simple way to see if a fuse has blown without removing it from its holder. Its not often you can design a circuit using just two components, but with just one resistor and an LED this circuit provides visual indication of when a....
You can use Microchip`s low-cost PIC16F818 microprocessor and a pair of gates to construct a digital PLL that can clean noisy digital signals over a range of 4 to 40 kHz. Featuring programmable lock range, phase differential, and loop gain, the digital-PLL....
Q1 is an npn Darlington and Q2 is a prip Darlington. MOV1 is a metal-oxide varistor and R8 is an thermistor for limiting inrush current. This circuit limits ac line current to a load. When a predetermined interval has passed, RY1 shorts out thermistor or....
The calibrator operates on exactly 100 kHz providing a reference for calibrating the variable time base oscillator of general purpose scopes. For example, if the scope is set so that one cycle of the signal fills exactly 10 graticule divisions then each....
Here`s a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by measuring....
This circuit is suitable to amplify and distribute the audio signals. The input audio signal is applied to the J1 and after passing through the P1, It is buffered and amplified by the U1 prepared to redistribute. It has 3 output to drive 3 audio lines with....
These circuits provide overvoltage protection in case of voltage regulator failure or application of an external voltage. Intended to be used with a supply offering some form of short circuit protection, either foldback, current limiting, or a simple fuse.....
A 10 bit scanning voltmeter with a Minimum Mass Wireless Coupler, based on the ATMega8.Range to the Minimum Mass Base Unit is 10 to 15 cm. If the voltmeter is battery operated, it can be floated from ground. This project is very simple physically, intended....
This LCD terminal provide two modes of operation by selecting jumper J1. When J1 is open the terminal operate as a normal ascii display terminal, when J1 is closed the terminal displays the input serial data in hexadecimal format. This mode is useful for....
The Meter and other small circuit differences, gives better performance. On the Schematic, I show Two Possible Coils. 1) The Ferrite Rod, creates an Accurate Pin Point. But it also has a Very Narrow Detection Field. 2) The Dual Wound "Tesla Coil"....
The circuit uses four NAND gates of a 4011 package. In each oscillator, while one gate is configured as a straightforward inverter, the other has one input that can act as a control input. Oscillator action is inhibited if this input is held low. The first....
A very popular circuit for driving DC motors (ordinary or gearhead) is called an H-bridge. It`s called that because it looks like the capital letter `H` on classic schematics. The great ability of an H-bridge circuit is that the motor can be driven forward....
Meter Ml, a +/-50-uA zero-center D`Arsonval meter movement is driven by Ul, a TL081 FET op amp, through R3. The gain of Ul is set at 11 by Rl and R2, while capacitor 01 is used to restrict the bandwidth of Ul to 1.6 Hz. Power for the circuit is derived from....
Disco anyone? Actually, this strobe serves a much more useful purpose then making it look cool when you dance in the dark. You can use it to view fast moving objects, look for craks in PC boards (hold the strobe on the trace side of the board and look from....
It is often desirable for a single doorbell to be operated by two buttons, for instance, one at the front door and the other at the back door. The additional button, S2 in series with the break contact of relay Rel, is connected in parallel with the....
This schematic is an impruved version of the Pro Maniac Guitar tube power amplifier...
IC2 is an audio frequency oscillator. Its frequency is primarily controlled by the resistance between pins 2 and 7. RV4-11 eontrol the oscillator frequency and by touching a stylus (connected via limiting resistor R5 to pin 2) to each preset, different notes....
In those cases we want to measure the temperature in an area far from where it is. The imaging unit installed, you should find some way to connect the latter with the necessary sensor. The cables we use most often will have three two conductors for power....
When frequency stability is not of prime importance, a simple, yet reliable, digital clock oscillator can be made with the aid of relatively few components. High-speed CMOS (HCU/HCf) inverters or gates with an inverter function are eminently suitable to....
The physical transmission medium for the 429 standard is 78Ω shielded, twisted-pair cable that uses a complementary, differential bipolar RZ (return-to-zero) waveform (Figure 2). The voltages are the net differentials that the biphase drive develops: For....
All ATL-3 loop windings are centre tapped and balanced w.r.t. their amplifier/receiver chassis ground, and therefore electric field interference pick up tends to self cancel. Magnetic noise fields,e.g. televisions and the electric meter box, or....
Our programmable MP3 player has an interface to an LCD with a HD44780 controller. These are alphanumeric LCDs with one to 4 lines of text and 16 to 40 characters per line. However, these LCDs (and LCDs in general) exist in two varieties: those that require a....
The 5-MHz track and hold shown here has a 400-kHz power bandwidth driving ±10 V. A buffered input follower drives the hold capacitor, C4, through Ql, a low resistance FET switch. The positive hold conuuand is supplied by TTL logic, with Q3Ievel shifting....
Now-a-days Electronic voting machines are being used effectively. The confidence of the voter in its flawless working is gradually building up and these machines are thus becoming quite popular throughout the country. Features of the electronic voting....
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....
Resistors Rl and R2 temperature-stabilize the NAND gates; they also ensure that the gates are in a linear region for starting. Capacitor CI is a dc block; it must have less than Vw ohm impedance at the operating frequency. The crystal runs in a....
In this circuit, an HA-4900 series comparator is used in conjunction with a D/A converter to form a simple, vers..
The heart(s) of the unit are the ETAL P3400 line modules available from Farnell. These modules mop-up all of the line interface functions like ring detection, physical hybrid, on-off hook handling etc. This means that the TBU as a whole would probably pass....
Two low voltage, low power zeners are used to control electronically the level of an audio signal. The attenuation range is from 6 to 58dB for an input current from 0.042 to 77 mA corresponding to a control voltage from 2.7 to 7.5V. If control voltage is....
This circuit offers open and closed loop contacts (switches 1,2,3) that triggers the alarm ON and stays ON for 5 -10 minutes. The trigering delay (entrance/exit) is 27 seconds. This simple alarm circuit Has also a cancel button for reseting the circuit to....
The circuit is capable of providing power for portable Geiger counters, dosimeter chargers, high resistance meters, etc. The 555 timer IC is used in its multivibrator mode, the frequency adjusted to optimize the transformer characteristics. When the output....
This dc-to-ac inverter is based on the popular 555. A 555 oscillator circuit drives a buffer amplifier consisting of Ql, Q2, and Q3. The circuit operates at 150 to 160 Hz. Tl can be a 6.3-V or 12.6-V filament transformer as applicable...
An input signal drives both SN74 74 D-type flip-flops, which are positive edge-triggered devices. A low-to-high input signal transition triggers tbe A flip-flop, while a high-to-low input signal transition triggers the B flip-flop via tbe SN7404 inverter.....
This amplifier was designed to be self-contained in a small loudspeaker box. It can be feed by Walkman, Mini-Disc, iPod and CD players, computers and similar devices fitted with line or headphone output. Of course, in most cases you will have to make two....
These filters are useful for equalisation, analysis and other tasks such as the Sound to Light converter (Project 62) or even a fully functional Vocoder. For those who have not heard of the vocoder, it is a device that takes a music source as one input and....
This 100 watt linear amplifier may be constructed using two MRF309 transistors in push-pull, requiring only 16 watts drive from 420 to 450 MHz..
Positive output step-up and step-down de-de converters have a common limitation in that neither can handle input voltages that are both greater than or less than the output. For example, when converting a 12-V sealed lead/acid battery to a regulated +12 V....
Here is a circuit for using the printer port of a PC, for control application using software and some interface hardware. The interface circuit along with the given software can be used with the printer port of any PC for controlling up to eight equipment .....
A Coil Coupled Operation Metal Detector made from readily obtainable components and using an ordinary medium receiver as a detector. The metal detector shown here may well represent a new genre. At any rate, after some exposure, it is regarded as such by....
The governor following is intended to regulate the light intensity incandescent 220 V. The components in a relatively few, which means it can easily be mounted onto a small plate. After the build, we recommend you place it inside the box which is flush....
The remote solar powered LED light takes advantage of the current limited nature of solar photovoltaic cells. If light shines on the solar array, current will flow through the circuit. For a typical size of solar cell, there is a maximum current that can be....
Ul (a 4046 PLL containing a voltage controlled oscillator or VCO, two phase comparators, a source follower, and a Zener diode) is used to produce a low-frequency, pulsed output of about 40 Hz. The VCO's frequency range is determined by R6 and C2, which can....
The core of this construction is 16-Bit Stereo Digital-To-Analog Convertor with USB interface PCM2702. PCM2702 needs only few additional parts to work. The schematic is not complex. Sound card can be powered directly from USB port (jumper W1) or from....
The power is all in the timed switching process. There are two main principles I use of switching the radiant energy the John Bedini way. First, the SG/SSG, Icehouse unidirectional circuit or John Bedini Monopole with the School Girl Circuit (SG)....
The intention of the following application shows how the NE5517 works in connection with a DAC. In the application, the NE5118 is used—an 8-bit DAC with current output—its input register making this device fully µ-compatible. The circuit consists of....
A low resistance ( 0.25 - 4 ohm) continuity tester for checking soldered joints and connections. This simple circuit uses a 741 op-amp in differential mode as a continuity tester. The voltage difference between the non-inverting and inverting inputs is....
Channel 1 is wired as a voltage follower and is turned on during the track/sample time. Ifthe product of R x Cis sufficiently short compared to the period of maximum output frequency, or sample time; Cwill charge to the output level. ..
This circuit will detect AC line currents of about 250 mA or more without making any electrical connections to the line. Current is detected by passing one of the AC lines through an inductive pickup (L1) made with a 1 inch diameter U-bolt wound with 800....
The circuit is built around the LM567 tone decoder IC that requires about 100 millivolts at its operating frequency. The frequency is set by a 10 K variable resistor and can be between 700 and 1500 He..
V_logic is connected to the power supply Vs and all ground are connected to the negative terminal of the battery. Fout is a square wave of varying frequency with a maximum amplitude of Vs. A voltage divider is needed (200k and 10k variable resistor connected....
Involvement is a modified version of the classic circuit of automatic level control signal used in tape recorders. The purchase price of the components (using TL072) does not exceed CZK 60 for a channel. For a range of entry level audio signal may be....
This circuit checks the reliability of appliances so that the equipment may be used safely. The test circuit must be plugged into a properly wired three terminal wall outlet. When a two-lead or three-lead appliance is plugged into circuit outlet SOI, neon....
To simplify the following schematics and facilitate easy understanding of the principles involved, the following schematic substitution is used (Note the triac driver is of limited use at 3 f voltage levels). ..
The right way to do this is with a small extra pc board to accommodate the new components, firmly secured inside the case, and wired carefully and neatly. Unfortunately, I did none of these things, but it worked reliably and if it ain't broke. I used a pot....
This receiver is built around a uPC1373 IR remote-control preamplifier, a sensitive 30-to-40 kHz tuned detector, an automatic..
Rectified and filtered voltage from the 24 Vac transformer is applied to the LM723 voltage regulator and the npn pass transistor set up for constant current supply. The 470 ohm resistor limits trickle current until the momentary pushbutton (S2) is depressed,....
This Project Components tester can be used to check the electronic components such us Diode, Transistor, Capacitor, IC555, IC741 and Continuity. The whole circuit was controlled by the Microcontroller AT89C52. The circuit has an LCD display it was used to....
A standard shaft encoder"s A and B ports generate square waves with the same frequency as the shaft turns. The phase of A will lead or lag that of B by 90°, ~depending on the direction of rotation. To obtain maximum resolution, the tachometer circuit must....
NOR gates a and b form a low-frequency oscillator that is activated when the CDS cell, under dark conditions, causes NOR gate a to see a logic zero at one input. This low-frequency (10 Hz) gates a high-frequency oscillator (c and d) to oscillate at around....
Due to the huge interest in this project, I have just recently finished the NEW schematics. The older schematics were scanned and pretty poor quality. These new ones should make it considerably easier to recognize the parts used for the project. The Ming....
This circuit is the electronic emulation of the I Ching, a form of divination originating in China. In the classical form, the response is obtained by the manipulation of 50 sticks or, more practically, by tossing 3 coins. The process must be repeated 6....
Here`s a circuit diagram (originally drawn by Wilf Rigter, I corrected it based on Bob`s on-list feedback) for Bob`s "Vore-N-More" circuit containing the SmartCap solar engine: In this diagram, the "SmartCap" is just the 1.5 F storage capacitor,....
This circuit was formed to create a wireless alarm from a normal magnetic contact. By fixing the magnet to the leaf of a door, or swing of a drawer, it is easy to reveal the opening. To transmit the signal to a control anti-theft we modify the circuit of a....
The following diagram is for the main circuit of the motor driver. A testing version is shown near the end of this page. It is laid out differently and shows the SN7474 in logic block form and LED`s are used to indicate the motor coils being switched...
A pulse width modulator (PWM) is a device that may be used as an efficient light dimmer or DC motor speed controller. The circuit described here is for a general purpose device that can control DC devices which draw up to a few amps of current. The circuit....
On the initial part of the positive half cycle, the voltage is changing rapidly from zero causing a large current to flow into capacitor C2. The current through C2 flows through R4, D3, and D4 into the gate of the TRIAC Q2 causing it to turn on very close to....
Q1 & Q2 provide linear frequency operation of IC1 following P1 resistance variation. Q3 was added in order to obtain a louder click, similar to clockwork metronomes. A 12V micro battery was used to obtain a higher output power and more compactness...
This circuit is fed from the earphone jack of your receiver and goes to limiter control R6 and is then amplified by Ql: a common-emitter stage that has a voltage gain of only about 10, because of the negative feedback introduced by R3. The output of Ql is....
This panning circuit (short for panoramic control circuit) provides the ability to move the apparent position of one microphone"s input between two output channels. This effect is often required in recording studio mixing consoles..
This amplifier has about 20dB of gain, bandwidth of 100MHz and noise figure of about 7dB. The output transformer is 8 turns bifilar wound on a ferrite core. Use a medium power UHF transistor 2N5109, 2N3866, 2N4427 or similar. The transistor will need a small....
100 W output at 50 MHz is available from this circuit. Ul and Q2 form a T-R relay driver, switching the amplifie..
This circuit comes from U.S. Patent 3, 778,800, granted to BRK Electronics in Aurora, IL. The circuit provides a smoke detector with an alarm for both smoke and low batteries. The R6/R7 voltage divider monitors the battery and will turn Q2 and Ql off when....
Multi-spark ignition is very useful especially in the case of startings at low temperature and at low rpm range. Basic idea, is to apply to spark plugs instead of only one spark, a ?spark-burst? having big energy. In this case, combustion of air/fuel mixture....
The following diagram shows the basic laser pointer circuit. It is identical to the infrared circuit except that the infrared LED`s have been replaced by the laser pointer unit. Due to the long range of these devices this detector method can easily....
The pull-up transistor of the totem-pole output is used-to turn on the LED and the pull-down transistor is used to turn ·off the LED. The lower impedance and higher current handling capability of the saturated pull-down transistor is used as an effective....
Diagram shows a 50MHz oscillator operating on a third harmonic. The collector"s load resistor R1 has been increased because the quartz crystal"s internal series resistance Rs increases with frequency in the VHF range. The crystal"s internal series....
A MW AM radio like those you buy, or used to buy. Use just BC549 trannies, with the BC559 complement being allowed in the audio output stage. Buying RF antenna coils, oscillator coils and intermediate frequency transformers would be cheating - wind your own.....
The National Physics Laboratory broadcasts a time signal, previously known as the Rugby clock but now called "Time from NPL." Its most commonly known as the MSF signal due to it originally being identified in Morse code those letters. It is broadcast from....
This free-running TTL square-wave oscillator has a variable frequency output over a 20:1 range or better through use of four of the six inverters in an SN7404 chip and the additional components shown. Frequency of oscillation is determined by the capacitor....
This circuit features the ZTX450/ZTX550 transistors in a push-pull output stage. The following readings were taken at maximum volume: Input: 0.4 mV rms, Output: 1.8 V rms, Voltage gain: 4500, Max. output before distortion: 2.25 V rms -supply current ~ 3.5....
This device acts as a variable speed control for the heater blower in a car. It takes its power directly from the existing wiring and connects with just 2 wires. It will also work for any 12 volt device up to 10 amps. A PIC12F675 provides all of the....
Although this circuit uses a 74HC74, any CMOS variant of this flip-flop will work. IC1A acts as a true/ compleme..
Blue VALUES replaced by values in RED. Blue COMPONENTS removed from circuit. Red components added to circuit...
The timer circuit shown gives independent control of the output"s on and off intervals, which can range from 0.055 seconds to 30 minutes, relatively unaffected by power-line transients. IC1 is a CMOS programmable-timer chip that includes 24 ripple-binary....
A low-current flyback converter is used here to generate ±15 volts at 20 mA from a +5 volt regulated line. The reference generator in the SG1524 is unused with the input voltage providing the reference..
These parameters are expected with an approximately 50% square wave up to frequencies of seveal MHz, and symmetric sine waves at higher frequencies. The primary limitation is based on the maximum clocking rate specification for the MM74HC6040 ripple counter....
The use of a loop antenna of large size (12 18") provides a large signal pickup at AM broadcast frequencies. It has..
