# All Questions

113,201 questions
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### Root Locus, Gain in Feedback Loop. Need help

So this is the system for which I have to draw a root locus if 'K' changes from 0 to infinity. The problem for me is that root locus is drawn for open loop transfer function but 'K' is in the feedback ...
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### Microcontroller overheating when sensor is plugged in

I am building a board based around an STM32L051C6 microcontroller, which will measure a hall effect sensor (AH3362Q) and count the time in between the edges the sensor sees. The sensor is powered from ...
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### Methods to measure inductance with high (1%) precision using standard equipment?

I am modeling the fine behavior of interacting oscillatory circuits. I have looked up a couple of methods for measuring inductance. I believe I am following the procedure faithfully, but the values I ...
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### Iterative CORDIC algorithm dynamic shift optimization

I've implemented the CORDIC algorithm on an FPGA using an iterative approach. The component is loaded with a set of values to calculate and then iterates as many CORDIC steps as necessary for the ...
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### How important is op amp supply cleanliness?

Say I have a simple non-inverting amplifier op amp application as shown. The input signal is far from the rails. Now say the +12 and -12 V supplies are not ideal DC, but rather have lots of ripple or ...
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### iPAQ Backup Battery Connector

I've used an H4155 on and off for about a decade now and every two years or so the backup battery begins to increase in standby voltage and fail. I prefer to replace it just for the sake of it ...
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### Noise on my oscilloscope when probing a wire

I am prototyping a NTC voltage divider circuit and I am having trouble with noise on my probe. It seems like I am constantly getting a large amount of noise (200-300mv) on my oscilloscope waveform ...
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### Detect if an electromagnet it touching metal (without a switch)

I have a simple 12V DC holding electromagnet connected to a microcontroller using a MOSFET - the once you buy on aliexpress or eBay for cheap [1]. How can I detect if the magnet is in full contact ...
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### Cascade shift registers driven by single-cycle microcontroller

I'm trying to make a unit in which 4 digits can be updated in a small amount of time from a single-cycle microcontroller (preferably all digits updated within 5uS) My circuit is setup in the ...
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### How to use a transistor to drive strings of LEDs from GPIO pins?

This is similar to How to drive a 20mA LED From a 4mA max GPIO Pin except that I need a little more hand-holding in order to understand what is happening. For background, I'm a software engineer and ...
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### Alternative to alternating relay? or help?

I'm using a littelfuse relay shown in the link to switch motor directions. I'm sending a pulse to the relay switch of 0.02s in order to switch between the L1 and L2 contacts. The pulse seems to be too ...
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### Standards for conducted EMI testing

I have some doubts to interpret the CISPR standards, one of them is in relation to the test environment for EMI conducted (150kHz up to 30MHz). The minimum size indicated for the vertical or ...
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### Light bulb LED equivalent of a CFL (Compact Fluorescent Lamp)

If I have a CFL light bulb of 100W what would be (how many watts ) its equivalent in LED. In the place where I live LEDs have taken over and CFLs are no longer available, but I need stron bright ...
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### Programmatically Controlling RGB Arcade Buttons?

At my school, we're putting together an arcade cabinet that we're going to program our own custom games for. The one thing I cannot find is an RGB LED controller that is programmable from code, ...
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### How to use Altium Multi-Board to define SODIMM board and socket connections?

I am attempting to use Altium 18.1.9's new "Multi-Board" feature to connect a 200-pin SODIMM board ---> to a SODIMM socket connector ---> on my mainboard PCB. This Altium article is just about the ...
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### Monitoring Health of VFD

Good day, Is there any method or external measuring tool that can be used to monitor the health status of a VFDs perdiodically?
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### How to send a digital signal when analog sensor (QRE1113) reaches a threshold value without resorting to wasting analog input pin?

I'm building a miniature pinball machine and I am attempting to use an infrared reflector sensor (QRE1113) to detect when the ball rolls over it (I got the original idea from Ben Heck's videos). In ...
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### DIY ATX PSU turns off when attaching load on 12V rail

I want to convert my old ATX power supply to a simple bench supply for 12V devices. On the label it says it's a 300W PSU where I can use 264W on the 12V rail (see image below). https://imgur.com/...
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### Control the RGB tape with only one output of the microcontroller

I need to control the colors of an RGB ribbon. This requires 3 PWMs. But I have only one output of my microcontroller available. So for this I need to find a circuit that stays between the ...
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### Crosstalk between AC and DC

First time asking a question but I've come across something I just can't find the answer to. Whether or not it's because a silly question I hope to find out. So I understand that with crosstalk ...
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### Germanium transistor in high voltage

I want to make one of those circuits using an old PNP germanium transistor (2SB175) what values of resistors should I chose and which circuit is good ? , if the circuits are bad, is there any better ...
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### Fixing an old fan wiring

I picked up this old fan which is apparently not working. I don't know much about electrical engineering but I can solder and connect cables and wanna hope that the problem is small enough to allow me ...
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### LiFePO4 cells - self-balancing in series or parallel?

I am building various banks / packs from individual prismatic LFP cells, nominal 3.2V each. New and pretty large, 60-400AH. I have a good power supply, charge each cell independently, Bulk stage CC ...
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### How to set mfrc522 antenna to lower frequency

I have "Electronic Hotel Door Lock" It work with NXP mfrc522 module with mifare 1K card and have work with 2*1.5v battery. with this battery "Electronic Hotel Door Lock" open door for 4 month. I ...
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### Noisy Signal over FFC

I have an FFC connector between a Raspberry Pi camera and a PCB which is in turn connected to a Raspberry Pi. The signal over this is noisy and usually causes the RPI to freeze when I try to take ...
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### Replacing lightning connector with usb-c connector in lightning earphones

I have a lightning earphones, Sennheiser ambeo smart headset. https://en-us.sennheiser.com/finalstop The cables are yellowing, and I wanted to replace them, also I got tired of using this on my ...
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### Electric Power Transferred on a Load

I got this problem: A transmission system is composed by an amplifier and the antenna. The transmit amplifier has an available power of 2mW and a resistive impedance of 10Ω. The antenna (in series ...
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### What are these black components?

One of these black things is burnt and according to the technician it have to be replaced , and when I asked him: what is this he said : IC ????!!! Well, What are these? Sorry for bad English
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### Is my radio pulling more current than it should?

I have an FT-747GX radio that I am using as a RF generator for a plasma cleaning machine. In the operating manual on page 3 it states: I have a power supply connected to this radio which outputs ...
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### The output of my verilog program is showing undefined values x?

Suppose in my verilog program I have two modules connected in hierarchical manner. the first module is used for the calculation of mean values of two data sets and the output of the mean signal is ...
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### Why is it not sensible to connect many (MOS) transistors in series?

For example a NAND-gate with 3 inputs has 3 NMOS in series and 3 PMOS in parallel. But why aren't there cmos gates with e.g. 10 inputs?
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### How to find the output voltage of a system with a computing amplifier?

I got a question regarding the following system. The only given value is the input voltage $$U_e = 8V.$$ Now the task is to find the output voltage $$U_a.$$ My question now is how do I find this ...
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### How to estimate timing contraints for FPGAs?

I try to find out how to specify the timings restrictions in FPGA designs correctly (in .sdc/.xdc files). I know what setup and hold times mean. However: How do I find out, what timing constraints my ...
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### Connect a microcontroller with Bluetooth to ssd1306 OLED

I need a small (max 15x40mm) programmable microcontroller with Bluetooth which have at least 3 GPIOs (i need 2 for display and one for a analog switch) and support I2C communication for ssd1306 OLED. ...
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### How do I get rid of switching noise from these types of DCDC converters?

I am using a lot of these types of isolated DCDC converters for measurement circuits: https://power.murata.com/data/power/ncl/kdc_nmv.pdf The problem is they introduce so much switching noise. I try ...
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### What's wrong with this schematic for powering up Cyclone IV FPGA?

I have followed all the guide lines for powering up the Cyclone IV. However, the 3.3v Regulator is heating too much and also the Cyclone IV FPGA. What's wrong with my schematic? Is there a problem in ...
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### Debugging dual LVDS display panel color issue

I'm on TI's AM5708 platform (custom board) trying to drive this Full HD panel via TI's DS90C387 Dual-Pixel Display Interface. The SoC outputs 24bit RGB into ...
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### Multiple boost converter voltage pulled down

I need to make a simulation of multiple boost converter design for different load ratios. I have designed 2 boost converter both of them have same duty cycle and same L and C values. Voltage input is ...
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### Where should I put the transistor

I have written a digital input program for an Arduino to turn on an led for 12.5 seconds. But, the light I have needs 110 V and I am using a 9v battery. I was told to use a transistor. If you can ...
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### High voltage low current PSU, newbie question

I need two different power supplies, one 600vdc with a limited current of 500uA (micro ampere), the second 300vdc - 500uA. For laboratory work that requires high voltage and low current. I do not ...
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### capacitance measurement circuit

For sensing capacitance value of sensors below circuit has common usage in literature. I want to continue talking about simulated circuit in bottom. Could be possible writing an equation similar to ...
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### CAN Module(MCP2515) interface with Arduino

I connected the Arduino with an electrical meter using MCP2515. But ever time I am getting same. . The value in the meter is 12.0. Even I tried different data register which has value 0.0 but still, I ...
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### cooktop touch buttons foam [on hold]

I have recently replaced the top glass of my induction cooktop, but some of the touch buttons don't work. When i removed the broken glass, some foam pieces came along with the glass. These pieces sit ...
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### I'm having a problem with making an SPDT relay using MOSFETs

Good Day! I'm trying to make an Electronic SPDT Relay using MOSFETS, (Normally opened, Normally Closed and COM) it works like this: if the P channel Mosfet is on, the N channel Relay must be OFF, ...
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Is is true that the magnetic field generated by a conductor conducting around 20A will not be sufficient in order to provide an EMF of around 3.3V? The frequency of the AC signal is 50Hz. Based on ...
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### AS3933 data transmission

I would like to know if there is someone working with AS3933 chip, 3D Low frequency Wake-up Receiver, to discuss about some issues I’m getting with data transmission. I contacted with AMS support and ...
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### Trying to plot input and output resistance for a single BJT in LTspice

I'm trying to plot a single NPN transistors's own input and output resistances in common emitter configuration looking into the base from input and emitter. I showed below with arrows that the plot I'...