Popular Circuits Page 138
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The comparator has an output pull-up resistor RL and is connected up to operate as a Schmitt trigger using the single rail supply Vcc. The feedback resistors Rl and R2 give upper and lower threshold levels VT+, VWxw, respectively. VT+ is easily set by....
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This alarm circuit is an anti- theft wireless alarm can be used with any vehicle having 6- to 12-volt DC supply system. The mini VHF FM radio-controlled, FM transmitter is fitted in the vehicle at night when it is parked in the car porch or car park. The....
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Whenever AC mains supply fails, this circuit alerts you by sounding an alarm. It also provides a backup light to help you find your way to the torch or the generator key in the dark. The circuit is powered directly by a 9V PP3/6F22 compact battery. Pressing....
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The schematic for controlling the motors is split up into three main parts, with each part having a unique functionality. The main parts used and seen in the schematic below are the 18F252, SN754410 and 2N2222 Transistors. Seen at the very top, the....
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No description available...
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As the speed of an electric drill is decreased by loading, its torque also drops. A compensating speed control like this one puts the oomph back into the motor. When the drill slows down, a back voltage developed across the motor—in series with the SCR....
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Displays are always nice. So far I`ve just been demonstrating how to use 7-segmented displays to display numbers using very few resources. But what if you want to display text Or pictures Or both Well in order to do that, you`re going to need a simple LCD....
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Here is a simple and easy to make heat or temperature sensor alarm circuit. A good feature of this circuit is that it will produce beep-beep sound and flashes an LED according to the temperature....
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This circuit suitable for a small office or home environment, it can also be adapted to use a combination lock or keypad to set and reset the ....
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Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world war other, simpler receiver technologies such as the TRF receiver and the regenerative receiver....
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The resistors R18 and R22 that should have been connected to pin 8 of U4 were mistakenly connected to pin 9. The present versions have been corrected. A minor error on the component layout is that there are two versions of C2, in the upper right and lower....
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This is the tuned radio frequency receiver for shortwave (25 meter band, 11. 7. 12. 1 MHz). It was created as experimental design for further experiments with the autodyne synchronous receiver (see Polyakov V. T. Autodyne synchronous regenerative receiver. -....
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Here is a schematic of a rechargeable 9-LED flashlight using two Gates SLA cells and nine LEDs. It is as bright as when the single bulb was used, and lasts 3 times longer per charge. That is about 10 hours of bright light, at a lower brightness, is available....
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The output frequency alternates between about 2100 Hz and 2200 Hz. This is a very distinctive test signal that is easily distinguished from any other signals that may be present. ..
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CMOS interface circuit with the PMOS cross-c PMOS integrated circuit high input impedance, input current can be ignored. CMOS and PMOS interface circuit shown in Figure ..
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A tapped-coil Colpitis oscillator is used at Ql to provide four tuning ranges from 1.7 to 3.131Hz, 3.0 to 5.6 MHz, 5.0 to 12 MHz and 11.5 to 31 MHz. A Zener diode (D2) is used at Ql to lower the operating voltage of the oscillator. A small value capacitor is....
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The Vinculum board is controlled using DOS commands and so every time you send a command if the command is executed successfully the board sends a D:> response that indicates its ready for the next command. If you try and send commands faster than the....
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Chinas national conditions, general living room area of more than twenty square meters, and usually doubles as a bedroom or living room listening room. If the speaker sensitivi..
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This project is probably the most ambitious so far, and can be expected to be very expensive. On the positive side, it is also capable of excellent performance, and can be tailored to suit your exact specifications. There are several different input modules....
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MP3 players are all the rage these days. The smaller ones in memory-stick format are particularly easy to take with you; your very own personal sound system` on the move! It`s when you want others to share your taste in music that you ¬nd these players to....
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This is battery charger indicator circuit diagram. When the battery charges it shows by the LED this circuit can be used with 12V battery with charging current less than 1A...
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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....
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4 simple 12Vdc power supply circuits with output voltages around 12V. First power supply circuit is built with BD139, one zener diode and a few passive components. Each of the schematic is very simple to construct and will function without problems if you....
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An economical and commercially available quartz temperature sensor, Y1 and IC1, an LTC-485 RS485 transceiver in transmitter mode, form a Pierce crystal oscillator. The sensor, an Epson HTS-206, presents a nominal frequency of 40 kHz at 25°C and a temperature....
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This i-TRIXX circuit can prevent a whole lot of trouble for those of you who go on holiday in a caravan. It would be a significant damper on your holiday spirit when you are ready to leave the camping and discover that you have used your battery too much and....
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My first project after assembling an electronic design lab was to build a flash trigger that I could use for high-speed photography. I thought it would be useful to share not only the finished product but also the reasoning that went into its design — in the....
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This free-running multivibrator uses an external current sink to discharge the timing capacitor, C. Therefore, interval ^ may easily be 1000 the pulse duration, t1( which defines a positive output. Capacitor voltage, V^, is a negative going ramp with....
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Signetics" type NE575 compander IC is intended primarily for use with battery power supplies of 3 to 7 V (max. 8 V). It..
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This pseudorandom sequencer drives a solid-state relay. If you power a low-wattage lamp from the relay, the lamp will appear to flicker like a candle"s flame in the wind; using higher-wattage lamps allows you to simulate the blaze of a fireplace or....
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This is an electrical propulsion method with no moving parts which applies to any conductive fluid including water, liquid metal or plasma. Here I am demonstrating the principle with water. Essentially two electrodes in water have a current passed between....
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4 simple 12V power supply circuits with output voltages around 12V. First power supply circuit is built with BD139, one zener diode and a few passive components. Each of the schematic is very simple to construct and will function without problems if you....
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The counter makes use of 5 cascaded CD40110 which combine a decade counter, a display latch and a 7 segment LED driver in a single chip. (The decimal points are driven by IC8x. ) The counter allows up and down counting (although only up counting is used in....
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I constructed this voltage regulator to power my two way mobile radio from the car cigarette lighter circuit. It has many other uses and the voltage can easily be adjusted by the use of a potentiometer. The voltage regulator is an LM317T, and should accept....
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A very simple 3. 25W CV/CC charger can be designed using LinKSwitch | family IC manufactured by Power Integrations. This electronic circuit project is designed to provide a 5 volts output at a maximum current of 650mA. This 3. 25W CV/CC charger, needs to be....
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The carbon dioxide (CO2) laser is the powerhouse for high tech industrial cutting and welding of metals and many other materials. Small CO2 lasers are used for marking of metal, wood, and composites, and in medicine and surgery. Even a `small` CO2 laser....
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The 555 circuit below is a flashing bicycle light powered with three C or D cells (4.5 volts). The two flashlight lamps will alternately flash at a approximate 1.5 second cycle rate. Using a 4.7K resistor for R1 and a 100K resistor for R2 and a 4.7uF....
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In operation. the alarm circuit allows a 0-47 second time delay, as determined by the Rl/Cl combination, after the switch is armed to allow the vehicle"s motion sensor to settle down. This allows you time to get a bag of groceries out of the trunk and not....
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L200 Power Supply Regulator There are applications in which it is important for the supply voltage to be largely independent of the level of the....
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I have had this project hanging around for ages and have tried to submit it for publication without much enthusiasm so I will make everything available here for the individual constructor. The complete Pascal source code for the compiler program is available....
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8 microcomputer data is 8-bit parallel output, in addition to the serial input of D -A converters, in general, have to enter the data into two groups, and to Chen whole. Requir..
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In this configuration, the display reads hertz directly. With pin 11 of the ICM7027 A connected to V00, the gating time will be 0.1 second; this will display tens of hertz as the least significant digit. ..
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To obtain such a monitor it`s enough to connect a resistor in series with the bulb and connect at a main outlet. The resistance of that resistor may vary on the type of bulb and the main voltage but it`s not critical: about 150K © for 220. 230Vac and about....
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It consisted of 16 LEDs in a circle with two touch pads. By placing your fingers on the touch pads, the circuit started and ran the LEDs in a "chaser" pattern around the display, with a beep each time a LED was illuminated.
The circuit gradually slowed down....
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The TDA7010T is a monolithic integrated circuit for mono FM portable radios, where a minimum on peripheral components is important (small dimensions and low costs). The IC has an FLL (Frequency-Locked....
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Maybe you ever use LM555 as timer project before, yes it also nice if you want to make analog timer using LM555. According datasheet LM555 this IC can use for several purpose in electronic project like to adjust timer according time needed. From figure 1....
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The circuit below will trickle charge a four cell pack of AA or AAA NiMH batteries. The circuit draws current from the +5v available a USB connection and pumps about 70ma of current into the battery. This should be enough current to fully charge a pack of....
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Using a single 7812 IC voltage regulator and multiple outboard pass transistors, this power supply can deliver output load currents of up to 30 amps....
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The Tda2005 IC has a high output power: PO=10W+10W @ RL=2ohm, d=10% (stereo) and PO=20W @ RL=4ohm, d=1% (bridge) for Vs=14. 4V. The high reliability of the IC comes from the various protections against: output DC and AC short circuit to ground, overrating....
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Ql is a pnp power transistor used in conjunction with a ferrite transformer to form a blocking-type oscillator. This oscillator is a fixed- frequency type, and the feedback to sustain oscillations is from capacitor CI. Because of the turns ratio of Tl, the....
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A cadmium sulfide photocell (LDR1, which is a light-dependent resistor) is connected to the base and collector of an npn transistor, Ql. When light hits LDR1, the internal resistance goes from a very high (dark) value to a low (light) value, supplying base....
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By using an op amp BiMOS CA3140 provides good orientation skills for high bandwidth signal input, and can quickly adjust the energy output at its terminal CA33IO WINE. The CA3140 can also lead to near the negative supply rail...
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1999 S10 2. 2L Fuse Box Quesion. There are two (what appear to be) main power terminals on the top left and top right on the Fuse Box. Which terminal is the full time power terminal and which is the RUN power terminal Vehicle was a basket case and I am....
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Using a simple 741 amplifier connected as a current-to-voltage converter with the LED as the current source, the voltage at the output is proportional to incident light. The junction is Q biased only by the difference between the output summing node junction....
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This device is a simple timer, allowing to keep on the headlights of your vehicle for about 1min. and 30sec. , e. g. when accessing some dark place, without the necessity of coming back to switch-off the lights. Pushing on P1 allows C1 charging to full 12V....
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This is a 40 meter transmitter which uses two valves, the 6AU6 and 6GV8. The construction is easy. Just be carefull due to high voltage present...
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The scheme presented delivers waveforms from any function generator producing a triangular output and a synchronized TTL square wave. A1 and A2 act as a two-phase current fectifier by inverting the negative voltage appearing at the input of Al. Positive....
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This circuit is intended for alerting purposes after a certain time is elapsed. It is suitable for table games requiring a fixed time to answer a question, or to move a piece etc. In this view it is a modern substitute for the old sandglass. Useful also for....
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The chart shows the clock for the competition, which is assembled with 555 circuit, with the features of novel circuit, reliable performance, easy making, intuitive interesting. 555 circuit has two categories of bipolar circuit (TTL) and complementary metal....
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This circuit uses two transistors and one IC (555 timer IC) to produce a pulsating ultrasonic frequency. Transistors Ql and Q2 are connected in a direct-coupled oscillator. The frequency of that oscillator is set by capacitor CI. The oscillator output is....
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I calculated the RSet resistor value at ~17k though it should probably have been 28k according to the table on the page (the MV7744 data sheet list Vf = 2. 1V and If = 20mA) but that`s for an LED matrix not individual LEDs happy for you to work out what this....
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This circuit uses small switching transistors. The maximum motor drive current is limited to about 250mA maximum at 5V. I`ve tested the circuit on voltages from 3V to 21V. With some component changes it should be usefulto 63V in a 36V PV panel system....
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Circuit shown in Figure 3-166. It uses the button control. When start forward, press SB], the motor rotor string frequency sensitive people rheostat RF operation. When the moto..
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The first version of the schematics is finished. There are still some optimizations to do, specially regarding the logic gates. The resistors in the directly connected to the 8085 are not really necessary but handy if a later expansion is needed. It is still....
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This simple circuit is a two-person game of strategy and speed - and potentially, agility and athletic fitness. Each player has a row of four LEDs before him/her. Beside each LED, there is a push-button which, when pressed, lights up the corresponding LED.....
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A 555 timer, IC1, drives a 4017 CMOS decade counter. Each of the 4017's first four outputs drives a CA3079 zero-voltage switch. Pin 9 of the CA3079 is used to inhibit output from pin 4, thereby disabling the string of pulses that IC normally delivers. Those....
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The voltage regulators from the 78xx-series are found in many analogue power supplies. It seems, then, somewhat super‚uous to say much more about them. But on the other hand, it can be very useful to highlight the important points, just because they are so....
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This approach uses a Hip-Hop, a shift register, and two gates (A). Before the one-shot pulse, the output of the NOR gate is 0. Consequently, the data input of the D-type flip-flop is equivalent to the trigger. When a trigger pulse is present, the flip-flop....
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If there are more than some 5mV, reduce this offset value by experimenting with resistors (220K a good starting point) from testpoint Z (junction of R22/R23) to +v if there is a negative voltage or to -v if there is a positive voltage until the voltage at....
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This simple circuit will oscillate with a wide range of crystals. Connect several different types of crystal holders in ..
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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 application note describes how to implement a compact size and high-speed
interrupt driven step motor controller. Step motors are typically used in applications
like camera zoom/film feeder, fax machines, printers, copying machines, paper feeders/....
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Electromagnetic brake motors from the motor and electromagnetic brake NB ordinary composition. Circuit is shown. Figure, FR is the forward run and stop command terminal; intermediate relay KA is used to control the motor started...
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The purpose of this circuit is to power a lamp or other appliance for a given time (30 minutes in this case), and then to turn it off. It is useful when reading at bed by night, turning off the bedside lamp automatically in case the reader falls asleep... 30....
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This circuit is average reading use rms calibrated AC voltmeter. Deletion of C2 removes the averaging function and provides a precision full-wave rectifier, and deletion of C1 provides an absolute value generator. Circuit operation may be understood by....
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A schematic diagram for a broadband QRP SWR metering circuit for use in a QRP antenna tuner. One could simply hold a momentary DPDT switch down and watch the LED while tuning the capacitors of the antenna tuner for minimum or zero light...
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Multiple unit radio control : How to make a multi-iunit radio control system....
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Designed for any purpose that might need a very sensitive, any-direction, do-not-tilt switch. This instruction describes construction of: 1) My initia....
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A speed closed loop control of DC motor using back emf sensing. Running a DC motor in one direction, just replace the LED with DC motor and remove the current limit resistor. Please note that motordirection reversal is not possible with this configuration.....
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As systems grow smaller, it becomes increasingly attractive to replace mechanical potentiometers with electronic potentiometers, which are smaller and less expensive silicon equivalents. A common interface for such devices comprises a Chip-Select, Increment....
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Using the superposition theorem, I need to find the current of all the 3 nodes of the circuit. Using superposition I`ve found that the current from the source: Do you mean i_1 is the current through V1 when the other voltage sources are shorted out, in line....
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How to measure water purity How to test water quality using a simple electronics project You can perform water purity measurement and water quality analysis using this water purity checker circuit. This circuit is built around a simple LDR (Light Depended....
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Strictly speaking, this simple circuit shouldn t work! How could anyone expect an ordinary light dependent resistor photo cell to ‘see through a fingerti....
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This circuit was designed as a warning flasher to alert road users to dangerous situations in the dark. Alternatively, it can act as a bicycle light (subject to traffic regulations and legislation). White LEDs only are recommended if the circuit is used as a....
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The oscillator circuit which is composed of the 1MHz quartz crystal resonator and the NAND gate is as shown in the figure, the NAND gate 3 is the output buffer stage. This circuit can be used to calibrate the standard frequency. Figure 1 The 1MHz quartz....
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Such supplies are often realised with dedicated integrated circuits nowadays but it`s still interesting to give a look at old designs to understand the basics...
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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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The diagram below illustrates the high level connections required to drive a single 7-segment display on the scoreboard. The below circuit was repeated 4 times - once for each of the four 7-segment LED displays. Each circuit takes a single data line as its....