Top Circuits Page 122
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Building a serial servo controller to learn about electronics and assembly language as part of my hexapod robot project. Quite early on I decided that I needed more I/O channels than my ATTiny2313 that I was using at the time supported so I investigated some....
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The first problem is with the 16Mhz xtal the thing doesn`t even start to oscillate. But that`s a secondary problem. If I replace 16MHz xtal with a 11MHz one (or less) the oscillator starts. I can see with the `scope that I have a nice 11Mhz sinusoidal....
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Making a light-dimming control system for a 240V heat lamp dissipating around 250W. I need to adjust the heat output on the lamp by control from a microprocessor. I`m developing on an 8051-based SoC with RF circuitry and some sensors and actuators. Basically....
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Choose a free schematic drawing software, and like the way these two look. I`ve read related questions about circuit drawing software as well. I like Fritzing, but it lacks some components. For example, I cannot get that RS232 component into it. Hm, what`s....
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Here`s a circuit diagram for a signal response test circuit from the spec sheet for a HA-5195 op amp and looks like a non-inverting amplifier circuit with a gain of 5, plus the 200 © resistor between Vout and ground:..
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We expect oscillation at the resonant frequency at which the positive feedback is at 0 degrees (in phase) with the input. For oscillation to occur, the gain has to be at least 1 at that frequency. Kaz Oct 30 `12 at 20:39 I still think the 10u cap has wrong....
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All the capacitors are there to just block DC, but how important are the capacitance values and how does one determine the value of Co. Rin represents the source resistance it`s not actually part of the amplifier circuit however, it does interact with the....
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When connection to PC speaker is plugged in and Telephone connection(bottom-left) is plugged in, I hear humming in the headphones. When only one is plugged in I hear it without distortion. Sound files showing humming. If you criticise my circuitry, add....
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A circuit that fires a relay when it detects audio pulses from one channel of an mp3 player. I`m going to record audio pulses in sync with the music to control a motor for mouth movement. So for your stereo player, you`ll just mix music/whatever onto....
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A fingerprint door lock, and the only thing that`s stopping me from purchasing the components is knowing if my setup is going to work or not. Is this an acceptable setup For the actual fingerprint reader, I was going to use this one, , which upon receiving....
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The basic problem for me is that gates on a logic circuit appear to be creating power from nothing, which is impossible. For example imagine two NOT gates connected in sequence: To my uninitiated mind what seems to be happening is that the first NOT gate....
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This Korean SuperCap OEM has support for such use in series. Do you intend to do this manually or automatically like a smart battery charger or simply a power fail backup circuit. You need to balance the voltage and protect from reverse polarity and over....
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If you want a 1MHz square wave, I would suggest using a higher frequency crystal and dividing it down, for two reasons: (1) 4MHz crystals are apt to be cheaper and easier to find than 1MHz ones; (2) Getting a 50. 0000% duty cycle from a crystal is a bit....
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Installing a water depth OEM sensor that is a solid state, continuous fluid level sensor. The sensor provides a resistive output that is inversely proportional to the level of the liquid: the lower the liquid level, the higher the output resistance; the....
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Schematic drawn using OrCAD Capture, which is straight out of the datasheet of the flyback controller LT3748. This is a class project and we must build our own transformer. We couldn`t get the bobbin we wanted and so decided to just lay down the transformer....
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A remote control light switch that fits into the existing light switch panel. And to power up the electronics that would requires a 3. 3V DC supply. The problem is, the panel has only two wires inside - 1. Live and 2. wires that goes to the light bulb. The....
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The circuit takes Vin, passes it through a SMPS with two MOSFETS (driven by the ir2104 that dies) and into Bat+. The LM321 is just a latch that allow the MCU to control and read the ir2104). The connector in the left comes from the MCU, the right one holds....
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If I use the internal 1. 1V reference for the ADC, and my Analog input exceeds 1. 1V, lets say 2. 5V, is that harmful to my microcontroller Or will ADC value simply clip (to 0x3FF) at 1. 1V Speaking from experience alone, not from datasheet references, so be....
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The microcontroller won`t be able to drive the gate of Q1 very hard (usually GPIO pins can only source a few milliamps) so your turn-on and turn-off will be very slow. This will limit how well your high-side switch will behave. You don`t have a....
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Powering the LED with a 3V CR2032 battery and hoping I could extend the battery life by making the LED blink instead of having it on all the time. The 555 timer one, with large value resistors in the voltage divider, is probably the best. It might need an....
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A circuit that should be protected from high voltage. Is there any component other than a fuse that I don`t have to change every time Something like a switch that activates only when high voltage is supplied, diverts the flow and grounds it, and then closes.....
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A half bridge setup with strain gages and a INA126 to amplify the voltage. I can read the voltage fine when the lever is bent one way, but when beding the lever in the opposite direction I don`t get any reading. I`m guessing it`s because the voltage is....
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Ground is used as a reference for the voltage divider, and that each successive point above ground is how much voltage is dropped across the circuit. (So with a 15 volt input, and 5K ohm for each resistor the taps would be 5, 10, and 15 volts respectively. )....
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I`m trying to use a 74LS259 8 bit addressable latch. I`m trying to get it working without a micro-controller first to ensure that I understanding the wiring 100%...
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Small digital design using a Xilinx picoblaze softcore processor, and I`m finding that producing schematics of acceptable quality to be frustrating and time consuming. I`ve attempted to shoehorn previously drawn schematics (From LTSpice, or Eagle) into....
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I have an automotive relay (from a scan of a workshop manual I`m afraid) which is rather more complexly wired up than the relays I`m familiar with. In this diagram: B/G - holds high if another condition is met (engine temp too high), to prevent the relay....
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How the processor produces `3` as the output. I realise that this question may be difficult to answer in simple terms. If it is, then a link would help, perhaps to a book...
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Microcontroller design where the mcu is placed in hibernation mode, and can only be awoken by a pulse(high-low-high) signal on the reset pin. (active low) As a wake-up source i`m using an accelerometer or an external RTC. The idea is to have the....
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Building a small circuit to turn on/off a 200W heater. I am using a MOC3023 and a BT136. At the datasheet of the the optotriac, this circuit is recommended: My question is how is the 180Ohm resistor value determined. I understand that it conducts for a very....
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A ringer interface circuit, and I`m running into problems that are over my head. The purpose of the circuit is to buffer the output of a central telephone system that goes to several ringers spaced throughout the building. The reason for the circuit is that....
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Arduino Uno has a ATMEGA328P-PU microcontroller, and bunch of other stuff on the board. I`d like to program the chip without the Arduino software, and only the minimum of other components. I want to eventually create things without the cost of Arduino, and I....
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Acquired an old Eistar SJ-1 Digital pulser. However the frequency it generates is always 66% of what its supposed to produce. Turns out that the frequency coming out of the frequency stage(at Pin 11)is 66% of the 16MHz crystal or about 10. 6MHz. (The 74LS38....
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The circuit is okay (not ideal for quality but it will work), but there`s one small issue if you want to feed the output to your Arduino. As shown, the output will swing below ground (i. e. it will be biased at 0V) and your Arduinos analog input will only....
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An old ignition module from a 1978 W116 model Mercedes-Benz, and I`m trying to "reverse engineer" it. The original circuit diagram is not available to mere mortals, so I have made one based on the PCB itself. I believe it is, beside being ugly, electrically....
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A cat deterrent with an Arduino, something akin to this. I have figured out detection, and now realize that I need to use an ultrasonic transducer to produce the `blast` that I need...
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In motor control circuits, one must take precautions to keep the motor from feeding back into the power supply, causing the supply voltage to rise, consequently breaking things. But how can this be Unless some external force is accelerating the motor, the....
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Many electric cars are able to convert the momentum of the car into stored energy in batteries, rather than convert it to useless heat at the brake pads. How does this work How can I implement it myself Probably you already have it, and just didn`t know it.....
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Design a circuit in which a microcontroller produces a signal and then using an amplifier drives an 8ohm speaker. I`ve so far used LM386, but it cannot go above 1W, which turned out to be insufficient. Besides that, I wish to add an (second order) anti....
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The circuit was reverse engineered from an old equipment. The op amp stage seems to me like a comparator/oscillator, it is comparing $V_0$ which varies over time because of the capacitors against the 2. 5[V] that is a square wave generatorwith 5V amplitud.....
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An Hartley Oscillator circuit can be made from a pair of series connected coils. I had a couple of 22mH fixed inductors, which I hooked up on a breadboard with the other needed pieces. When I test the transistor amplifier independently, it seems to be....
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The heatsink on the triac is a bit unclear for me. I`ve calculated a maximum value of 10C/W, is this fine My calculation is: (max temp - room temp)/(max on stage voltage * (milli amps / voltage) - junction to base themal resistance (110-25)/(1.....
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A device which provides a USB port. If I attach it to a Windows PC it is recognized as a "CP2103 USB to UART Bridge Controller". According to the device documentation, it should communicate in serial format at 38400bps. Since the USB pinout is different from....
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To get the usual BPM range for music of between 40 and 240 BPM, that corresponds to periods of 1500 ms and 200 ms respectively. A BPM of 120 is exactly 500 ms. As it is, the circuit would require an R4 of 14. 5 Mohm to yield a period of 500 ms (120 BPM). I....
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Read the generic sound level from an Electret Microphone. I`ve seen a number of schematics with NPN transistors, that will provide an inverted output (~5V when quiet, ~0V when loud, linear operation in between). However, I would like non-inverted output....
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When ONLY VR will supply power to circuit, then MCU again will get power from +5V bus, but FTDI will ONLY get VCCIO. On middle of voltage divider R10/R11 I expect there will be 0 and MCU will not detect USB connection on (B). The question is - would it work....
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Create a simple (telephone based) intercom system in our new house. Shouting between rooms is not so good, and trying to use an IM client or Facetime doesn`t have the immediacy of a good shout down the corridor. I`ve got a box of old wired telephones that....
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Developing a battery switch-over circuit which is made of two lanes of the depicted circuit. Operation voltage range is from 3V. 12V. Only one lane should be enabled at a time which is governed by logic not included in the schematic. Each lane can....
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There is one important low-impedance node in the whole circuit. That`s the frame and the cross in the middle. Let`s call that 0v. The top voltage source is connected to the middle via that 1k resistor, that means the lower voltage source has priority. the....
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Controlling a relay with stm32 micro controller. For the isolation I have used a 4N33 opto-isolator. As my relay coil needs around 250 mA, I used a mps222 transistor. I figured that the logic gets inverted when I used the gpio as the source voltage for the....
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A project with two distance sensors that signal an Arduino to operate a servo motor when an object comes into range. This currently works well, except that the sensors are outputting a relatively high voltage all the time, so I have to set a very high cutoff....
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The reason being is that I would like to use the sensor as a force sensor. I noticed that the harder I press it, the higher a voltage it delivers (but for a very short time). This is expected behavior, of course. What I am wondering is how I would connect it....
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Drive a latching relay that needs about 70-90mA if the raspberry pi can only deliver about 40mA. I need to find a relay that can handle home appliances but can be controlled by the raspberry pi...
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Did you check if you actually see the zero crossings on your input pin You might want to write a sketch that toggles the pin13 LED every 50 or 60 or zerocrossings. You should see a visible 1Hz blink. jippie Mar 3 `13 at 11:41 Which input pin did you use for....
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Designing and building a breadboard power supply for myself, which draws power from an ATX-like SMPS (Mains in, single Molex plug out) via a 4-pin Molex connector. The design includes a switch to select either 12V or 5V output, but the only appropriate....
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Using digital IR Receiver Module and digital IR Transmitter Module connected each with different Arduino Uno. How can I transmit data like "1234" to the receiver and display data on LCD This is because most of the example that I found using IR remote code....
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The AND output will be high with both switches closed. However, nothing is guaranteeing the level of the inputs when the switches are open, so the result could be anything. Olin Lathrop Mar 6 `13 at 19:58..
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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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A SPDT switch that simply switches the relay over. Any pointers would be appreciated. When I currently energize the relay, I hear it cycling, which I would image that is not good. I simple want it to "switch" normally on and then when I energize the coil,....
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A DIY kinetic energy harvester and wish to use the electromagnetic method to generate electricity. So far I know the following materials that I`m going to use:..
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It needs 2 volts as its threshold however, that only allows a small amount of curent to flow through the transistor. How do I know how much voltage I need to make it fully on. Also, how do I determine what type of resistor to use from the 5V GPIO pin to the....
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Provide zero crossing detection to my controller. Using the schematic below, I managed to generate square wave signal, representing positive v/s negative half-period. The problem is that the resistor needs to be quite large : Quite the heater. Also, voltage....
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The device exhibits 24V at no load on pins +4, 5 and -7, 8. According to Wikipedia, this is called a passive power injector. I tried drawing 1A from the device and failed (some protection drops the voltage to 0V). @W5VO, thank you for your care of the....
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Connect the 25VAC output to diodes bridge with capacitor (3300uF - 25v) to the positive and negative pins to eventually get 25VDC. What I want is to reduce the 25VDC to 17VDC, I thought i could build voltage divider with variable resistor to get the volt I....
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Connect Relay with pic microcontroller and whenever I put Load on Relay`s Contacts PIC16f877a resets. I some time solve this problem by triggering another relay from basic relay attached to PIC. But this is not a solution. Can any one describes Why pic is....
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Using a flywheel-driven permanent magnet DC generator to charge up a bank of supercapacitors, 35 farad rated to 25V. For safety I limit the max charge to 22V via a comparator and a zener reference. Because I have no stable reference voltage at all in in this....
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Switch a water solenoid valve using two water level switches, one will be placed at the top of a tank and will be NO (when water level is between full and empty) so that it will send a signal to the relay when the water reaches the top to stop the solenoid.....
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Say you have a Vsource Resistor and Inductor all nicely in a loop. You let the voltage source run until everything reaches a happy steady state. The Inductor should have energy (1/2)L*(V2/R2). Now. what happens if I cut the wire Where does the energy go..
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The bases and emitters are tied together, so the base-emitter voltages are equal. Since we assume the transistors themselves are identical, equal Vbe means equal current into the base. And equal current into the base means equal current from collector to....
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When the reverse voltage is applied that is say 10V to Source and the drain is grounded. So now the Vgs is -10V which is well above the threshold and is good enough to keep the MOS in saturation region. So it is conducting in the opposite direction also now.....
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You would calculate power through each headphone for the given source impedance to find which is louder. Chances are that the source impedance is closer to 32 ohms than 250 ohms, and the low impedance headphone would be louder, but it isn`t a sure thing....
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Any ideas Is this circuit going to be stand alone Any other circuitry around it, perhaps a microcontroller What circuitry does the timing device contain, or does it even contain electronics abdullah kahraman Mar 22 `13 at 18:10 Since you do not want much....
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Control the state (on/off) and direction of two linear actuators that are really just DC motors. It seems easy but the problem is that the linear actuators are each 12VDC and consume 10 amps of current at full load. I bought a 25A external power supply....
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An old Nokia phone charger with 5. 6 V output, so I tried to adjust it to 12 V. By changing the Zener diode though I manged to do that, but I can`t understand its circuit (I replaced the 9v1 with 16v Zener). I would really appreciate any help to understand....
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The quality sound was terrible, and suddenly it stoped working. Can anyone explain me in which part of the circuit i did something wrong any sugestions to improve the sound quality and make it work the transistors used are both BC546, and the microphone was....
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The solenoid requires a certain amount of current to generate its magnetic field. If the solenoid was a perfect inductor, the DC current would rise above all means and would most likely damage other circuit components. However, solenoids inherently have a....
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I built this circuit and for some reason it works. FYI, the diodes are red 5mm LED`s, the transistor is 3904 NPN, and the resistors are what are shown in the schematic. Logically it should not work when you press the PBNO. The red 5mm diodes should be....
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Use a relatively high-end microcontroller ( Piccolo TMS320F28035, 12-bit resolution, +/- 4LSB offset, +/- 60 LSB gain ) to measure voltage across stacked battery cells and control associated analog electronics to equalize their charge. The microcontroller....
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WHY is the voltage at 12V after the emitter If it`s coming out of the op amp at +15V, then that would put a 3volt drop across the transistor. and why isn`t the gain 2, shouldn`t there be 8 volts coming out to the transistor In that case wouldn`t a 4volt drop....
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Considering a simple circuit like the one below. Let us say that the voltage source suddenly turns on (from 0V to 1V), then current will through through the resistor R1, correct But assuming an ideal op-amp (drawing no current) and an ideal voltmeter....
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Control a furnace using a 3. 3V microcontroller. The furnace operates by connecting a common 21V AC "hot" line to one of two AC "neutral" output lines: Fan and Heat. When connected they have relatively low current flow, ~100mA. I`ve had some success using a....
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Project to control single phase ac induction motor in which I planned to use two IGBTs, one for switching the PWM to the motor (for AC chopping, PWM frequency is fixed @16khz) and one for freewheeling the motor. A symbolic circuit is included here: I know....
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It works perfectly on the breadboard, where I can see the LED blinking at 2 Hz. However, when I try to solder it on the perfboard, it blinks much faster. I don`t have a way to measure, but I`d say something like 10 Hz. I tried to mount three times on the....
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I`ve been getting that V_A = 15 (which is wrong). Also I think V+ is = 0 since the node below 3 ohm is grounded. Any help on how to start solving this Ok! So, what I did at first was: V+ = 0, the current 5Am is going through 3 ohm resistor => Va- 0 = 3 *5 =....
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A cheaper way to build or buy something with similar functionality It doesn`t necessarily even need to be remote controlled if it could be programmed to go off at certain times...
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An Arduino Uno connected to two IR transmitters and respective receivers. Basically, when one of the receivers detects a beam break, I have a strand of LEDs display a pattern. This all works in principle, but the problem is that when the IR transmitters and....
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The leads from the transformer to the circuit are quite long (>5m). Apparently the 110V side of the transformer was switched off somewhat frequently lately which likely caused a spike on the secondary (24V) side. The input pin of the LTC3631 has a visible....
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This is my conceptual schema to use a PIC12 to control the blinking of 3 LEDs with different blinking patterns. I have a few questions that would like to ask...
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Attach a 12V fan to this circuit which draws 70mA (0. 007A), so the circuit must have at least that much current. Yes, there is something missing in the analysis. Actually there is too much in the analysis. The voltage drop across the resistor will be simply....
Building a serial servo controller to learn about electronics and assembly language as part of my hexapod robot project. Quite early on I decided that I needed more I/O channels than my ATTiny2313 that I was using at the time supported so I investigated some....
The first problem is with the 16Mhz xtal the thing doesn`t even start to oscillate. But that`s a secondary problem. If I replace 16MHz xtal with a 11MHz one (or less) the oscillator starts. I can see with the `scope that I have a nice 11Mhz sinusoidal....
Making a light-dimming control system for a 240V heat lamp dissipating around 250W. I need to adjust the heat output on the lamp by control from a microprocessor. I`m developing on an 8051-based SoC with RF circuitry and some sensors and actuators. Basically....
Choose a free schematic drawing software, and like the way these two look. I`ve read related questions about circuit drawing software as well. I like Fritzing, but it lacks some components. For example, I cannot get that RS232 component into it. Hm, what`s....
Here`s a circuit diagram for a signal response test circuit from the spec sheet for a HA-5195 op amp and looks like a non-inverting amplifier circuit with a gain of 5, plus the 200 © resistor between Vout and ground:..
We expect oscillation at the resonant frequency at which the positive feedback is at 0 degrees (in phase) with the input. For oscillation to occur, the gain has to be at least 1 at that frequency. Kaz Oct 30 `12 at 20:39 I still think the 10u cap has wrong....
All the capacitors are there to just block DC, but how important are the capacitance values and how does one determine the value of Co. Rin represents the source resistance it`s not actually part of the amplifier circuit however, it does interact with the....
When connection to PC speaker is plugged in and Telephone connection(bottom-left) is plugged in, I hear humming in the headphones. When only one is plugged in I hear it without distortion. Sound files showing humming. If you criticise my circuitry, add....
A circuit that fires a relay when it detects audio pulses from one channel of an mp3 player. I`m going to record audio pulses in sync with the music to control a motor for mouth movement. So for your stereo player, you`ll just mix music/whatever onto....
A fingerprint door lock, and the only thing that`s stopping me from purchasing the components is knowing if my setup is going to work or not. Is this an acceptable setup For the actual fingerprint reader, I was going to use this one, , which upon receiving....
The basic problem for me is that gates on a logic circuit appear to be creating power from nothing, which is impossible. For example imagine two NOT gates connected in sequence: To my uninitiated mind what seems to be happening is that the first NOT gate....
This Korean SuperCap OEM has support for such use in series. Do you intend to do this manually or automatically like a smart battery charger or simply a power fail backup circuit. You need to balance the voltage and protect from reverse polarity and over....
If you want a 1MHz square wave, I would suggest using a higher frequency crystal and dividing it down, for two reasons: (1) 4MHz crystals are apt to be cheaper and easier to find than 1MHz ones; (2) Getting a 50. 0000% duty cycle from a crystal is a bit....
Installing a water depth OEM sensor that is a solid state, continuous fluid level sensor. The sensor provides a resistive output that is inversely proportional to the level of the liquid: the lower the liquid level, the higher the output resistance; the....
Schematic drawn using OrCAD Capture, which is straight out of the datasheet of the flyback controller LT3748. This is a class project and we must build our own transformer. We couldn`t get the bobbin we wanted and so decided to just lay down the transformer....
A remote control light switch that fits into the existing light switch panel. And to power up the electronics that would requires a 3. 3V DC supply. The problem is, the panel has only two wires inside - 1. Live and 2. wires that goes to the light bulb. The....
The circuit takes Vin, passes it through a SMPS with two MOSFETS (driven by the ir2104 that dies) and into Bat+. The LM321 is just a latch that allow the MCU to control and read the ir2104). The connector in the left comes from the MCU, the right one holds....
If I use the internal 1. 1V reference for the ADC, and my Analog input exceeds 1. 1V, lets say 2. 5V, is that harmful to my microcontroller Or will ADC value simply clip (to 0x3FF) at 1. 1V Speaking from experience alone, not from datasheet references, so be....
The microcontroller won`t be able to drive the gate of Q1 very hard (usually GPIO pins can only source a few milliamps) so your turn-on and turn-off will be very slow. This will limit how well your high-side switch will behave. You don`t have a....
Powering the LED with a 3V CR2032 battery and hoping I could extend the battery life by making the LED blink instead of having it on all the time. The 555 timer one, with large value resistors in the voltage divider, is probably the best. It might need an....
A circuit that should be protected from high voltage. Is there any component other than a fuse that I don`t have to change every time Something like a switch that activates only when high voltage is supplied, diverts the flow and grounds it, and then closes.....
A half bridge setup with strain gages and a INA126 to amplify the voltage. I can read the voltage fine when the lever is bent one way, but when beding the lever in the opposite direction I don`t get any reading. I`m guessing it`s because the voltage is....
Ground is used as a reference for the voltage divider, and that each successive point above ground is how much voltage is dropped across the circuit. (So with a 15 volt input, and 5K ohm for each resistor the taps would be 5, 10, and 15 volts respectively. )....
I`m trying to use a 74LS259 8 bit addressable latch. I`m trying to get it working without a micro-controller first to ensure that I understanding the wiring 100%...
Small digital design using a Xilinx picoblaze softcore processor, and I`m finding that producing schematics of acceptable quality to be frustrating and time consuming. I`ve attempted to shoehorn previously drawn schematics (From LTSpice, or Eagle) into....
I have an automotive relay (from a scan of a workshop manual I`m afraid) which is rather more complexly wired up than the relays I`m familiar with. In this diagram: B/G - holds high if another condition is met (engine temp too high), to prevent the relay....
How the processor produces `3` as the output. I realise that this question may be difficult to answer in simple terms. If it is, then a link would help, perhaps to a book...
Microcontroller design where the mcu is placed in hibernation mode, and can only be awoken by a pulse(high-low-high) signal on the reset pin. (active low) As a wake-up source i`m using an accelerometer or an external RTC. The idea is to have the....
Building a small circuit to turn on/off a 200W heater. I am using a MOC3023 and a BT136. At the datasheet of the the optotriac, this circuit is recommended: My question is how is the 180Ohm resistor value determined. I understand that it conducts for a very....
A ringer interface circuit, and I`m running into problems that are over my head. The purpose of the circuit is to buffer the output of a central telephone system that goes to several ringers spaced throughout the building. The reason for the circuit is that....
Arduino Uno has a ATMEGA328P-PU microcontroller, and bunch of other stuff on the board. I`d like to program the chip without the Arduino software, and only the minimum of other components. I want to eventually create things without the cost of Arduino, and I....
Acquired an old Eistar SJ-1 Digital pulser. However the frequency it generates is always 66% of what its supposed to produce. Turns out that the frequency coming out of the frequency stage(at Pin 11)is 66% of the 16MHz crystal or about 10. 6MHz. (The 74LS38....
The circuit is okay (not ideal for quality but it will work), but there`s one small issue if you want to feed the output to your Arduino. As shown, the output will swing below ground (i. e. it will be biased at 0V) and your Arduinos analog input will only....
An old ignition module from a 1978 W116 model Mercedes-Benz, and I`m trying to "reverse engineer" it. The original circuit diagram is not available to mere mortals, so I have made one based on the PCB itself. I believe it is, beside being ugly, electrically....
A cat deterrent with an Arduino, something akin to this. I have figured out detection, and now realize that I need to use an ultrasonic transducer to produce the `blast` that I need...
In motor control circuits, one must take precautions to keep the motor from feeding back into the power supply, causing the supply voltage to rise, consequently breaking things. But how can this be Unless some external force is accelerating the motor, the....
Many electric cars are able to convert the momentum of the car into stored energy in batteries, rather than convert it to useless heat at the brake pads. How does this work How can I implement it myself Probably you already have it, and just didn`t know it.....
Design a circuit in which a microcontroller produces a signal and then using an amplifier drives an 8ohm speaker. I`ve so far used LM386, but it cannot go above 1W, which turned out to be insufficient. Besides that, I wish to add an (second order) anti....
The circuit was reverse engineered from an old equipment. The op amp stage seems to me like a comparator/oscillator, it is comparing $V_0$ which varies over time because of the capacitors against the 2. 5[V] that is a square wave generatorwith 5V amplitud.....
An Hartley Oscillator circuit can be made from a pair of series connected coils. I had a couple of 22mH fixed inductors, which I hooked up on a breadboard with the other needed pieces. When I test the transistor amplifier independently, it seems to be....
The heatsink on the triac is a bit unclear for me. I`ve calculated a maximum value of 10C/W, is this fine My calculation is: (max temp - room temp)/(max on stage voltage * (milli amps / voltage) - junction to base themal resistance (110-25)/(1.....
A device which provides a USB port. If I attach it to a Windows PC it is recognized as a "CP2103 USB to UART Bridge Controller". According to the device documentation, it should communicate in serial format at 38400bps. Since the USB pinout is different from....
To get the usual BPM range for music of between 40 and 240 BPM, that corresponds to periods of 1500 ms and 200 ms respectively. A BPM of 120 is exactly 500 ms. As it is, the circuit would require an R4 of 14. 5 Mohm to yield a period of 500 ms (120 BPM). I....
Read the generic sound level from an Electret Microphone. I`ve seen a number of schematics with NPN transistors, that will provide an inverted output (~5V when quiet, ~0V when loud, linear operation in between). However, I would like non-inverted output....
When ONLY VR will supply power to circuit, then MCU again will get power from +5V bus, but FTDI will ONLY get VCCIO. On middle of voltage divider R10/R11 I expect there will be 0 and MCU will not detect USB connection on (B). The question is - would it work....
Create a simple (telephone based) intercom system in our new house. Shouting between rooms is not so good, and trying to use an IM client or Facetime doesn`t have the immediacy of a good shout down the corridor. I`ve got a box of old wired telephones that....
Developing a battery switch-over circuit which is made of two lanes of the depicted circuit. Operation voltage range is from 3V. 12V. Only one lane should be enabled at a time which is governed by logic not included in the schematic. Each lane can....
There is one important low-impedance node in the whole circuit. That`s the frame and the cross in the middle. Let`s call that 0v. The top voltage source is connected to the middle via that 1k resistor, that means the lower voltage source has priority. the....
Controlling a relay with stm32 micro controller. For the isolation I have used a 4N33 opto-isolator. As my relay coil needs around 250 mA, I used a mps222 transistor. I figured that the logic gets inverted when I used the gpio as the source voltage for the....
A project with two distance sensors that signal an Arduino to operate a servo motor when an object comes into range. This currently works well, except that the sensors are outputting a relatively high voltage all the time, so I have to set a very high cutoff....
The reason being is that I would like to use the sensor as a force sensor. I noticed that the harder I press it, the higher a voltage it delivers (but for a very short time). This is expected behavior, of course. What I am wondering is how I would connect it....
Drive a latching relay that needs about 70-90mA if the raspberry pi can only deliver about 40mA. I need to find a relay that can handle home appliances but can be controlled by the raspberry pi...
Did you check if you actually see the zero crossings on your input pin You might want to write a sketch that toggles the pin13 LED every 50 or 60 or zerocrossings. You should see a visible 1Hz blink. jippie Mar 3 `13 at 11:41 Which input pin did you use for....
Designing and building a breadboard power supply for myself, which draws power from an ATX-like SMPS (Mains in, single Molex plug out) via a 4-pin Molex connector. The design includes a switch to select either 12V or 5V output, but the only appropriate....
Using digital IR Receiver Module and digital IR Transmitter Module connected each with different Arduino Uno. How can I transmit data like "1234" to the receiver and display data on LCD This is because most of the example that I found using IR remote code....
The AND output will be high with both switches closed. However, nothing is guaranteeing the level of the inputs when the switches are open, so the result could be anything. Olin Lathrop Mar 6 `13 at 19:58..
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....
A SPDT switch that simply switches the relay over. Any pointers would be appreciated. When I currently energize the relay, I hear it cycling, which I would image that is not good. I simple want it to "switch" normally on and then when I energize the coil,....
A DIY kinetic energy harvester and wish to use the electromagnetic method to generate electricity. So far I know the following materials that I`m going to use:..
It needs 2 volts as its threshold however, that only allows a small amount of curent to flow through the transistor. How do I know how much voltage I need to make it fully on. Also, how do I determine what type of resistor to use from the 5V GPIO pin to the....
Provide zero crossing detection to my controller. Using the schematic below, I managed to generate square wave signal, representing positive v/s negative half-period. The problem is that the resistor needs to be quite large : Quite the heater. Also, voltage....
The device exhibits 24V at no load on pins +4, 5 and -7, 8. According to Wikipedia, this is called a passive power injector. I tried drawing 1A from the device and failed (some protection drops the voltage to 0V). @W5VO, thank you for your care of the....
Connect the 25VAC output to diodes bridge with capacitor (3300uF - 25v) to the positive and negative pins to eventually get 25VDC. What I want is to reduce the 25VDC to 17VDC, I thought i could build voltage divider with variable resistor to get the volt I....
Connect Relay with pic microcontroller and whenever I put Load on Relay`s Contacts PIC16f877a resets. I some time solve this problem by triggering another relay from basic relay attached to PIC. But this is not a solution. Can any one describes Why pic is....
Using a flywheel-driven permanent magnet DC generator to charge up a bank of supercapacitors, 35 farad rated to 25V. For safety I limit the max charge to 22V via a comparator and a zener reference. Because I have no stable reference voltage at all in in this....
Switch a water solenoid valve using two water level switches, one will be placed at the top of a tank and will be NO (when water level is between full and empty) so that it will send a signal to the relay when the water reaches the top to stop the solenoid.....
Say you have a Vsource Resistor and Inductor all nicely in a loop. You let the voltage source run until everything reaches a happy steady state. The Inductor should have energy (1/2)L*(V2/R2). Now. what happens if I cut the wire Where does the energy go..
The bases and emitters are tied together, so the base-emitter voltages are equal. Since we assume the transistors themselves are identical, equal Vbe means equal current into the base. And equal current into the base means equal current from collector to....
When the reverse voltage is applied that is say 10V to Source and the drain is grounded. So now the Vgs is -10V which is well above the threshold and is good enough to keep the MOS in saturation region. So it is conducting in the opposite direction also now.....
You would calculate power through each headphone for the given source impedance to find which is louder. Chances are that the source impedance is closer to 32 ohms than 250 ohms, and the low impedance headphone would be louder, but it isn`t a sure thing....
Any ideas Is this circuit going to be stand alone Any other circuitry around it, perhaps a microcontroller What circuitry does the timing device contain, or does it even contain electronics abdullah kahraman Mar 22 `13 at 18:10 Since you do not want much....
Control the state (on/off) and direction of two linear actuators that are really just DC motors. It seems easy but the problem is that the linear actuators are each 12VDC and consume 10 amps of current at full load. I bought a 25A external power supply....
An old Nokia phone charger with 5. 6 V output, so I tried to adjust it to 12 V. By changing the Zener diode though I manged to do that, but I can`t understand its circuit (I replaced the 9v1 with 16v Zener). I would really appreciate any help to understand....
The quality sound was terrible, and suddenly it stoped working. Can anyone explain me in which part of the circuit i did something wrong any sugestions to improve the sound quality and make it work the transistors used are both BC546, and the microphone was....
The solenoid requires a certain amount of current to generate its magnetic field. If the solenoid was a perfect inductor, the DC current would rise above all means and would most likely damage other circuit components. However, solenoids inherently have a....
I built this circuit and for some reason it works. FYI, the diodes are red 5mm LED`s, the transistor is 3904 NPN, and the resistors are what are shown in the schematic. Logically it should not work when you press the PBNO. The red 5mm diodes should be....
Use a relatively high-end microcontroller ( Piccolo TMS320F28035, 12-bit resolution, +/- 4LSB offset, +/- 60 LSB gain ) to measure voltage across stacked battery cells and control associated analog electronics to equalize their charge. The microcontroller....
WHY is the voltage at 12V after the emitter If it`s coming out of the op amp at +15V, then that would put a 3volt drop across the transistor. and why isn`t the gain 2, shouldn`t there be 8 volts coming out to the transistor In that case wouldn`t a 4volt drop....
Considering a simple circuit like the one below. Let us say that the voltage source suddenly turns on (from 0V to 1V), then current will through through the resistor R1, correct But assuming an ideal op-amp (drawing no current) and an ideal voltmeter....
Control a furnace using a 3. 3V microcontroller. The furnace operates by connecting a common 21V AC "hot" line to one of two AC "neutral" output lines: Fan and Heat. When connected they have relatively low current flow, ~100mA. I`ve had some success using a....
Project to control single phase ac induction motor in which I planned to use two IGBTs, one for switching the PWM to the motor (for AC chopping, PWM frequency is fixed @16khz) and one for freewheeling the motor. A symbolic circuit is included here: I know....
It works perfectly on the breadboard, where I can see the LED blinking at 2 Hz. However, when I try to solder it on the perfboard, it blinks much faster. I don`t have a way to measure, but I`d say something like 10 Hz. I tried to mount three times on the....
I`ve been getting that V_A = 15 (which is wrong). Also I think V+ is = 0 since the node below 3 ohm is grounded. Any help on how to start solving this Ok! So, what I did at first was: V+ = 0, the current 5Am is going through 3 ohm resistor => Va- 0 = 3 *5 =....
A cheaper way to build or buy something with similar functionality It doesn`t necessarily even need to be remote controlled if it could be programmed to go off at certain times...
An Arduino Uno connected to two IR transmitters and respective receivers. Basically, when one of the receivers detects a beam break, I have a strand of LEDs display a pattern. This all works in principle, but the problem is that when the IR transmitters and....
The leads from the transformer to the circuit are quite long (>5m). Apparently the 110V side of the transformer was switched off somewhat frequently lately which likely caused a spike on the secondary (24V) side. The input pin of the LTC3631 has a visible....
This is my conceptual schema to use a PIC12 to control the blinking of 3 LEDs with different blinking patterns. I have a few questions that would like to ask...
Attach a 12V fan to this circuit which draws 70mA (0. 007A), so the circuit must have at least that much current. Yes, there is something missing in the analysis. Actually there is too much in the analysis. The voltage drop across the resistor will be simply....
