Top Circuits Page 121
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It has an audio transformer. I`m still attempting to grasp the concept of impedance and such, so can someone explain why this is necessary And how would such a transformer even work to change the impedance What would be the difference if you didn`t use an....
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It is on top labled toy car receiver. The toy car transmitter is easy enough to understand, and I suspect that the receiver is essentially working the same way, but backwards and with more filtering. I have no experience in RF except that I saw this circuit....
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The circuit for a SIM card reader is shown here. The circuit uses a CMOS hex inverter and other simple components; yet, not only does it work but it can also communicate with a PC via serial port! I am learning electronic circuits as a hobby and I was....
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This is the eye diagram for the transmit pair. The receive pair is very similar. It`s a LAN8700 PHY, and I`ve got the MII interface effectively disabled, so the PHY is transmitting IDLE code sequences. It`s forced into 100Mbit/FDX as per the datasheet.....
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Except that I`ve added a passive high-pass filter after the output of the op-amp, to eliminate DC (since I am using 0V and +12V as my V- and V+, respectively). I use Rf=500K Ohm (is this way too much ). In addition, I have an LED adjacent to the photodiode....
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I`ve built this circuit with two LT1001 s and the output of the OP-AMP saturates to +5V. I used +5V and GND for the supplies. In the page, it says that if +1V is applied to the "Servo Input", the output of the DUT will be +1V. I can understand that since the....
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For C3, the 100pF across R2. The circuit does exactly the same thing, once again with no explanation. Apparently the utility ought to be obvious, but I`m new to earnest analog electronics. I can only assume that it`s stabilizing something, but I don`tknow....
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The BC547B has Vcbo=50V, Vceo=45V, Vebo=6V, where-as the BC548 in original circuit has Vcbo=30V, Vceo=30V, Vebo=5V, rest of the parameters being pretty same as per datasheet (hFE:220-450). 1HP Water pump (220VAC, 800W) - One thought is to use higher current....
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Even thought the power was off there was AC at the handle plug and I shorted something. I pulled it apart and found a transistor blown apart. I figured it would be an easy fix. One month, twenty plus dollars in parts and many changes of components it is....
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Build a simple audio amplifier using transistors. I know there are IC designs specifically for the task. But i want to use transistors so i can learn how to use them for amplification. Amplifier Basics - How Amps Work (Intro) by Rod Elliott covers a good....
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Using the following circuit, with 12V appplied to the motor, and either high (5V) or low (0V) to each transistor through a 1k resistor. The transistors used are TIP 142 and TIP 147. The diodes I am using are 1N5817. When I apply 0V to R2, R1, and 5V to R3,....
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As far as we are concerned we are looking for a function generator or a VCO (voltage-controlled oscillator). We would love to know which specific component we need. EDIT: What we are actually trying to achieve is to make two sine sound waves. One is constant....
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The old 555 timer will certainly work given the specs you provided, and that`s the way to go if you are sure this is precisely the problem you want to solve. By the way, as Steven mentioned, the general name for this type of timing block is monostable....
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The LED blinks as intended, then stops for an arbitrary time, flashes again a different number of times, off again etc. There doesn`t seem to be any cyclic behaviour to it. It starts working without any external input (i. e. nudging it) so doesn`t seem like....
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Achieve communication between MCU and accelerometer trough I2C nor SPI. I observed that shorting PLL filter input in device causes no effect on both gyro readings and operation. My assumption is that PLL is present only in accelerometer part of the device. I....
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After doing a little research I found out that I can change voltage by either using a voltage regulator chip or resistors. I have a couple different scenarios in which I`ll have to drop the voltage for my motors and I was wondering which method to use for....
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Assuming I can get 5V in example after adjusting the pot in real use, will the 240 ohm resistor limit the current, or do I have to add something else on top of that afterwards If it does (I can have var. voltage + current limit) I assume I will need to up....
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Will LC-based oscillator be able to show performance comparable to crystals in such conditions (probably in wierd variants like LC-opamp. so that any energy loss on each stage is recovered and we are getting narrower bandwidth) Look at some of the amateur....
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BTW, I guess I should add another input cap for high frequency noise though that`s hardly relevant to this question (and the schematic is just a very rough test circuit anyhow). The goals are 0 - 12 V at up to 2 amps (1. 5 would probably be good enough,....
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A project called LED Flasher which Flashes LED`s one by one . but I have following Query about my project . if anyone can explain me it in simple words it will be great help for me . one can use Below image for reference or use this link..
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Rsense would cause Q2 to conduct if at a threshold (0. 65V assumably) and Rbias will determine how much it will be limited, however that is unclear to me, especially if Rsense will be somewhere highside and just turning on Q2 with my uC seems to not do....
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The triac should flip on and the light and it should be at nearly 100% brighness. However, this is not what`s happening. Itstead, the light doesn`t turn on at all. Can anyone explain why this might be If I change the gate to be always triggered (i. e. always....
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The PSU you`re referring to doesn`t look extraordinarily large to me.Eagle should be able to handle this kind of dimensions. I was more looking for something that may already have the components and be more suited for this kind of design (perhaps allow you....
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It takes a 32. 768 kHz IR input and outputs a logic low when the input is present. I see 3 distinct stages. everything up to U1A, everything between U1A and Q3 and everything to the right of Q3. I follow the left and the right. but not the center which is....
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That circuit allows you to adjust the resistance (with a pot) and adjust the capacitance by opening or closing switches. So, you can have any combination of switches open or closed to get a different effective capacitance. as a side note, if he does crazy....
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I`ve got a button which I use as a push to talk switch. This works for the most part, however when I press the button it takes a good 5 seconds before I hear any output...
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Designing an IR demodulator circuit to replace the one shown in this question. Basically I want to demodulate a simple IR signal modulated at 32. 678 kHz. I just need to know if the signal is present. No packets. Just IR present or not present. I have tried....
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It`s a typical AMV (Astable MultiVibrator) setup. The capacitor gets charged through both resistors until 2/3 Vcc is reached (internal comparator level). This sets a flip-flop which activates the Discharge output (DIS). Through DIS and the potentiometer, the....
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An explanation of how the thing should work. The TPS_EN line is low at first. Since it is pulled down by a 10k pull down resistor(not shown in the schematic). When the user presses S2, the mosfet Q2 turns on because ground is applied to its gate. which....
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Designing a controller PCB for a 10x10 white LED matrix clock (inspired by the tutorial here ). It`s based off an ATmega328 AVR IC and Maxim DS3234 SPI RTC. However, I`m stuck: I have no idea how to control my custom non-standard 10x10 LED matrix. Originally....
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This is a follow up to an earlier post I made here. Below is the relevant portion of the schematic for this issue (stuff to the left of Y1 is in original post if necessary). I have finally gotten this circuit working somewhat reliably with one exception. The....
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When USB present and device needs to work, VSupply is directly provided by the USB and PMOS separates the battery from the supply. (R3 ensures PMOS is on when there is no USB) Primary reason for this is not to disturb the proper charging of the battery.....
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R4 prevent the output voltage drifting towards one of the supply rails to the op amp I understand that R4 has to have a high resistance but I do not know why That looks like a Circuit Lab schematic! It would be great if you could post a link to the schematic....
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This circuit could be used as a treble control circuit with high frequency gain occuring when R3 is set so a=b (we`ll call this k=0), and high frequency attenuation occuring when R3 is 22kOhms across a and b (k=1). So therefore, depending on R3`s setting,....
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I have been given the following circuit diagram and have been asked to compute R2 and RC such that, at the Q-point, the circuit will behave as follows: VCE=5V VBE=0.7V IC=2mA β=100(where β=ic/ib)..
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Make a little buzzer for my bike to sound occasionally to warn off bears. I have a 12V buzzer from Radio Shack (Cat. No. 273-065) and was wondering if I could run it off of 18V directly (2x9V Transistor Batteries series) for 1-2 second bursts, or if I should....
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On the bottom you will see a 74AC125 which is a Quad Buffer with Tri-State Outputs. I`ve seen quite a few buffers like this on programmers. but im not exactly sure what they do Im assuming whatever "CTL" is controls the "state" of the buffers. but what....
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Using an optocoupler ( MOC3021 ) to sense the On/Off state of an electrial appliance using a microcontroller ATmega16L. How do i go about doing this My mains supply specs are 230V, 50Hz. How do I design the surrounding circuit and select component values,....
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Using the ADC on an ATtiny24 to record a AC signal. The ADC has a range from 0-3. 3V. I`m using a precision rectifier to get rid of the negative portion of the signal. I`ve attached a picture of the circuit I`m using for the rectifier. I`m using an LMC6484....
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A circuit which utilizes a photo-transistor to make a light sensitive switch that is when there is no light in room, the led connected to the photo-transistor lights up and when there is light in room, the led connected to Phototransistor turns off Any....
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I have a Nidec TA450DC B35502-35 fan which I`ve installed in a large wooden cabinet where my computer and other electronics sit. This cabinet of course gets hot from all the electronics inside of it. The fan forces air in from the room and goes out through....
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Connect a pic to an rn-41 bluetooth module. I`m not the person who designed the PCB, so I can`t answer exactly why the circuit is the way that it is instead of using the voltage divider used by some other people. Basically, the 5v logic from the pic is used....
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A reverse polarity protection circuit, similar to that in Figure 2 of SLVA139: Reverse Current/Battery Protection Circuits. Here is my circuit: My case is slightly more complex due to the possible input voltage ranging from 5-40V. Most MOSFETs seem to have a....
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Regulating ~12V from the car battery to 5V used by Atmel AVR microcontroller. Why are there two capacitors on each side of linear regulator LM7805 This answer to another question might be the answer I`m looking for, but I`m not sure about it. If this answer....
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Make a 555 timer base circuit such that O/P pin of 555 is held LOW by default at power on, and the I/P pin is held initially at HIGH at power on. The main requirement of my circuit is that until I/P pin is held LOW for say 200ms, then only the O/P pin must....
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There is a Lithium Polymer Ion Battery that comes with the Lilypad Development Board from Sparfun. Does anyone know if the battery charges if we plug in the battery to the Lilypad Arduino and connect the Lilypad Arduino using the FTDI at the same time. The....
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Although this may be a basic question but I`m still struggling with it. In this schematic, two zener diodes D1 and D2 are connected back-to back across relay coil L1. The BVds = -30V for Q1. Can I use 15V(Vz = 15V) zeners for D1 and D2 instead of 5. 1 V....
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Get my head around the headlight wiring in my car, and I`m curious what purpose the two diodes in this diagram serve. Hoping one of the clever people on here can explain it for me: Wow - thanks for editing my post and the very quick replies. Fantastic. I....
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When VOUT is very low during start-up or a short-circuit fault on the output, the switching regulator must operate at low duty cycles to maintain the power switch current within the current limit range, since the inductor current decay rate is very low....
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Color sensing with camera and sufficiently powered processor running image histogram logic (or other such algorithms) can determine presence of certain colours fairly reliably. However, are there other, significantly more cost-effective mechanisms to....
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It seems to me like the wire connected to the 5v pin is connected to the + pins of the breadboard. which are connected to nothing. There`s nothing else on the + column. I know this is a basic "google it" question, but probably due to the fact that I don`t....
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This requires expensive hardware (microphone & amplifier) and some sophisticated audio analyizig on the microcontroller. Even a complete microphone with amplyfier circuit does not provide the desired results (according to the comments on this product) I am....
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Nokia BL-4C / BL-5C are 3. 7V, 700-1000mAh ( variants ) Lithium-ion batteries, have 3 terminals, as explained here, for battery positive-terminal, ground, and a terminal (BSI) which I believe presents a fixed resistance value, that needs to be measured, to....
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A 5v power supply to act just like a switch. I will be controlling it with an Arduino like described here: You won`t be able to drive it directly from the Arduino pin, as most general purpose relays require at least 150mW to switch which is >30mA @ 5V. You....
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Interested in starting an intro electronics project using a IR sensor and am having a little trouble understand the application circuit given on the datasheet of the circuit. The value of resistor they recommend using is far less then the one I calculate I....
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Make a Oscillator circuit with a Op Amp and an crystal (7. 68 MHz) Similar to the one in the schematic below, but for a 7. 68 MHz crystal. I have the crystal, various Capacitors, Resistors and a couple of Op Amps. But no digital Logic chips. "LM111 is not an....
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The inverting input is held low through a 10K resistor when the circuit is powered on but not being used. Whenever a measurement is being made (including calibration measurements where IN is floating), that resistor is disconnected. The circuit is used to....
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Why have one resistor and transistor for each LED, instead of chaining the LEDs in series and controlling them with a single transistor which is controlled, in turn, by the arduino pin coming in through a single resistor I have no qualms about implementing....
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Make a circuit that will allow me to switch on a relay that will turn on an LED. However, the relay is rated for 12 V, and I only have an input of 5 V, so I`m using an NPN transistor. to switch the power to the relay on and off. Here`s the schematic: If my....
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A USB powered device with multiple IC`s. From what I`ve read it`s standard practice to use a combination of multiple range capacitors for decoupling each individual IC, with the smallest being as close as possible and larger capacitors not too far away.....
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Drive a small (3. 6V, <1A) brushed motor bidirectionally with a PIC MCU. My available space is extremely limited, so I`d like to use a single 3. 6V power supply for both the motor and PIC, and a minimum of drive circuitry. I haven`t found a dedicated motor....
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A circuit using a keypad, a servo and a few LED`s. This was connected to my Arduino Uno. Now I tried putting everything onto a single PCB and thus building my own custom "Arduino" into it. The red LED is supposed to shine and the servo must move to a certain....
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Instructions to put together a small project on wireless energy transfer. If anyone knows of a good schematic that is super simple and geared towards noobs could you please share, or leave instructions. The simplest one I`ve found so far is this one off of....
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I have a copper mesh (10cm x 10cm square) in a vacuum chamber connected to a BNC connector by a 24-cm-long copper wire. The goal is to switch the mesh voltage (referenced to ground) from 8 V to ~0 V quickly. (This will switch the electric field in the....
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At a T connection, it`s clear, but at a cross it`s otherwise not clear, especially if there are no junction dots elsewhere as in your schematic. It looks like the bottom of Is and the right side of R2 are supposed to be connected to ground, but your....
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I managed to program my PIC 16f627 to turn on three LEDs when push button (trigger button) is pressed and start a shut down sequence (basically each LED toggles off one after another with a 5 second delay in between) when another pushbutton is pressed (reset....
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I want to use a picMicro 5v microcontroller combined with the figure 10 circuit from Link1 (Shown below) and a circuit similar to Link2 for motor control. It has to control 2 AC motors at 4 amps each (but the programming will make sure only one motor can....
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Amplify a MG811 CO2 sensor to a range readable by an ATMEGA2560 (0-5v). I have other analog sensors, so do not want to change ref voltage on Atmega. I have found a module that scales the signal and want to replicate the circuit from the documentation, but....
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Currently using the PIC24FJ128GA010 and I am planning to use Input/Output port to connect my 4. 2 V LiPo battery and to check if the voltage value doesn`t go below 3. 7 V. You should avoid digital. You have two options, use an ADC or use an Analog....
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A useful current limiting circuit (shown below), that allows me to select a maximum current through a load. The circuit is set to give a 480 mA max current. As the load resistance increases, the SER of the limiting circuit drops away. The following plot....
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Using an inductor inline and a decoupling capacitor it`s creating essentially a series LC circuit. Now one of the properties of LC circuits is they have a resonant frequency. I modeled a LC circuit with an attached purely resistive load to simulate what the....
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The supply voltage is 5V and I am seeking to increase it to 12V with a load current of 1A, or an output power of 12W. I selected a switching frequency of 20kHz. By my math, I need a duty cycle of 0. 583 to do this, so the on time should be 29. 15 µs.....
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Design a lighting circuit for an indoor garden, and I`m not understanding things that seem like they`re really basic, so I need some help. The schematic I`m referencing is: I have a 24V input source which I`d like to limit to 20V. LA is a series array of....
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An old RC car but without the transmitter so I built my own Rx/Tx using MCU and 2. 4Ghz transceiver, however, I want to use the car`s original H-Bridge but not sure if I understood how that circuit works...
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In the process of adapting an old phone to be used as an Bluetooth phone. I am currently testing the ringer circuit, which I build using the schematics provided by Sparkfun. Now, when I hook up just the right part of the schematic to a 3. 5V source (Vcc), I....
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The goal is to be able to turn on and off the load (an 8051 based uC) by pressing both switches. When the uC turns on, it sets PWR high, and then when the switches are pressed again, pin 4 of the flip flop goes low, turning off the boost regulator and uC.....
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For a hobby project I have bread boarded, I am considering using a pair detectors that operate as a single use physical barrier. When hit by a projectile, a trace is broken allowing +5VDC to to trigger a flipflop that is part of my gate logic for a....
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The purpose of this circuit is for research and education. If anyone knows where I can get parts for simple RF circuits or even a tutorial or schematic that would be really appreciated. Honestly guys, I know you are all probably annoyed with this question....
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A transformer with 2 input leads and 3 output leads. I hooked up an LED to 2 of the output and put a dead AA battery on the input and the LED blinked for a second. I have no data on the transformer, but I am wondering if it is possible (and if so what is the....
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If I disconnect the ground of the Arduino from the negative terminal of the power supply, current flows through the MOSFET, even when the switch isn`t closed!..
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A "power button" that is actually two buttons; one on, one off. This needs to switch on the order of 15 V and up to 10 A, for a LiFePO4 battery powered device. I don`t want to use a hardwired switch where this is mechanical, because I later also want soft....
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It should at least detect 230 VAC but it would be cool/informative for future readers if the solution could work in US and EU (approximately 120 VAC to 250 VAC). I did find this (non-isolated!) circuit, but I can not get it to simulate (the simulator....