# All Questions

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### how to select LED protection device?

I have this simple LED configuration: Voltage source is 24VDC so with the 1k resistor and three 2V LED, current is around 20mA. I want to put a PLED device across each LED. how do I select correct ...
61 views

### Is there as way to verify a spectrum analyzer setup?

I just finished setting up my spectrum analyzer and I would like to ensure that everything is as accurate as possible. I was thinking of getting some kind of RF transmitter that transmits at a ...
39 views

### SMPS Simulation Help

Finally bit the bullet and considered getting help with a simulation I'm looking to get right. Just a heads up, I have limited experience with SMPS simulation in both LTSpice and Multisim. The circuit ...
162 views

### How can I remove noise in my preamplifier circuit? [closed]

I need a low noise microphone preamplifier for my Arduino. I used a battery and standard wire but I had noise in my circuit. I need gain 20-20kHz. Can you help me with the schematic?
40 views

### Logging and retrieving large bursts of sensor data from an Arduino

I was wondering, if I put an Arduino with a few sensors on let's say a water rocket to track acceleration and height and what not, how would I save this data? I'm assuming that I want to have a high ...
49 views

### About to start a new project I have some questions before I start

So I am going to start to build a table that will have two different stands of lights, which are linked below. I was planning on using an 18 volt Milwaukee battery, but after getting the lights, I ...
65 views

### Mains voltage measurement

Consider the schematics on the figure. The aim is to measure (sample for e.g.) mains 220V voltage. MAINS_1 is phase, ground is connected to neutral. The most obvious idea is to use a transformer, but ...
50 views

### What happens if an inverter neutral is bonded to earth

My question is similar with this question: https://physics.stackexchange.com/questions/299199/will-a-battery-connected-to-the-earth-eventually-deplete#:~:text=First%20off%2C%20every%20battery%20will,...
67 views

### How to solve this non ideal inverter opamp?

it is asked to make a non ideal inverter opamp that has an input of 2mV or and get an output of -100mV, so I think the next circuit should suffice. simulate this circuit – Schematic created ...
66 views

### What sort of oscillator topology is used in WiFi/BT transmitters?

Thinking of cheap(er) consumer wireless products. Modulator aside, how is the RF carrier signal generated? Do they use really small capacitances/inductances on a chip die to make an RLC (say, Colpitts-...
132 views

### How does this RC pulse generator circuit work?

In this video from Ben Eater, he uses an RC circuit to create a push-button "write-pulse" generator for his EEPROM (discussed around the 14 minute mark) that ensures the write pulse fits ...
40 views

### Identifying and finding a replacement audio signal transformer 50 ohm / 0.5 ohm

I am trying to identify and find a replacement for the attached transformer. The green/white leads with the red center tap have a 50 ohm resistance. The side without the center tap has a 0.5 ohm ...
14 views

### Error while simulating the speed control of a brushed DC motor using a 555 timer and a high boost convertor using Multisim simulator

Reference paper: https://ieeexplore.ieee.org/document/6183251 I'm trying to simulate the speed control for a brushed DC motor using a 555 timer (astable multivibrator) and a high boost convertor using ...
15 views

### VPC0820 Li-Ion Capacitor how to understand the 97% Self Discharge (V) parameter

Does anyone know what does the self-discharge parameter mean? I know what self-discharge is, but what does over 97% mean?
28 views

### Can I get power from my Thermostat's AC relay wires?

I have a 2-wire thermostat that activates my baseboard heater when the 2 wires are shorted. I did an experiment closing those two wires with a relay and got that working well with an ESP32 as the ...
13 views

### AC 3 phase servomotor current mode

How do i mathematically model a 3 phase ac servomotor's current control mode? someone please help me. The model of the the servomotor is BSM132C 5200AA Thanks
881 views

### 5V to 400V boost converter problem

I am trying to make a boost converter that step up 5V to 400V. I am doing it for a geiger counter. I know that it's complicated, but it should be possible. Anyway, here is my schematic: My problem is ...
29 views

### Gate noise on KA3525

I am designing a 1kHz inverter in a push-pull configuration with KA3525 and IRF540N MOSFETs. Input - 12V Output - 110Vac - square wave filtered to sine wave Power - 15W at 1000Hz When I fire it up ...
46 views

### What is the bible for electric motor design? [closed]

For engine design, there is The Fundamentals of Combustion Engines by Heywood. This is generally regarded as the bible for combustion engine design, and deeply covers almost all aspects of motor ...
21 views

### Using STM32F4 Discovery I/O PINS attached to another device on the board [duplicate]

I am trying to communicate with a device over SPI using an STM32F429 Discovery kit. I would like to use the SPI5 but according to UM1670, table 7 and STM32F429xx Datasheet, table 12, page 76, there is ...
77 views

### AC circuit voltages and currents

I have this circuit: Have I done everything correctly? I cannot find my mistake. Help appreciated.
71 views

### Keyboard USB transform

I want to press a key on my keyboard, for example "a" and a device should take the scan code of the button I pressed and transform it to something else: e.g. "b" or the scan code ...
40 views

### 200 Input Smart Multimeter Project

First off, thanks for taking the time to read this and help out. Here's a quick overview of what I am trying to design. I have a break out box that has 200 female probe inputs. Each input is numbered, ...
77 views

### Trapezoidal wave RMS value

I am calculating RMS value of trapezoidal wave. I found its formula like below: and at last the RMS value formula: u = 30degree or pi/6 --> especially pi/6 A = 12 When I calculate RMS value by ...
23 views

### Can I use 2 H-Bridge for drive a motor?

I've a 12V 80A motor, for drive this i'll use a H-bridge with mosfet, in order to divide the current per H bridge we can drive a motor with 2 H-bridge? I'll use mosfet, we cant put mosfet in parallel
63 views

### TO-247 case maximum current

I've this TO-247 MOSFET http://www.datasheet.es/PDF/203551/2SK3271-01-pdf.html how much current will support this case? I've to control a 12V 80A DC Motor
115 views

### Would a faraday cage still work if it was part of a circuit?

Faraday cages protect against EM radiation and charges. As far as I understand, this effect happens through the induction of an electric field, which produces a current inside of it, which then ...
54 views

### Voltage to GPIO pins

Interested in Embedded Systems, I'm coming from Computer Science background. There is a thing that I can't get my head around for awhile about pins of GPIO. Let's say that we have a port which is ...
93 views

### Getting glitches on GPIO using a MOSFET as a logic level converter

I need to connect an Event Detection pin (pin of the NXP NTAG 5 component) to a GPIO of the NXP i.XM6 processor. The problem is that the NTAG 5 pin has a logic level of 5V and the GPIO has a logic ...
57 views

### What is the output logic levels of this STM32?

I am struggling getting my head around the input and output logic levels, mostly the output levels of this STM32 (STM32F446xC/E). This table shows the output logic levels as dependent on if it is a ...
59 views

### Change LED blinking frequency depending on voltage

I'd like to make an LED blink with a varying frequency that depends on a voltage. I know about the 555's control pin, but I'd like the blinking to vary continuously, instead of switching between just ...
41 views

### Pulling different voltages directly from AA alkaline cells wired in series

I need to power a miniature LED light show that will draw a few hundred mA, or possibly more, and requires less than 5 Vin, and a microcontroller board that wants 7-21 Vin. I was thinking the easiest ...
15 views

### Mixed Sensitivity Problem

I have plant, $$P(s) = \frac{1-s/5}{(s^2 + s/4 +1/4)}$$ I am taking a mixed sensitivity approach for that I have chosen $V$,$W_1$ and $W_2$ as follows: For bandwidth, $\omega$ =1 so I chose M ...
54 views

### Sizing Through-hole Vias for Power Traces

I am trying to understand what size vias I should use for my 5V power traces. The trace typical runs at 0.5-3 amps and is 2mm and about 150mm in length. The width is huge, but I do have the extra ...
569 views

### Why is my low dropout voltage regulator Diodes AP7370 burning up?

I'm building a LED driver using Diodes AL8871Q IC to power a XHP70 LED powered from a 4 series protected Lithium battery pack, integrated on the board it has an Attiny85. I plan to use the Attiny85 to ...
22 views

### Thermal voltage of Ge diode

What is the thermal voltage of a Ge diode?I know for a silicon diode is about 26mV at room temperature. I have this circuit: simulate this circuit – Schematic created using CircuitLab and a set ...
36 views

### What determines the power requirements of a IC

This is more of an acquiring more knowledge question. I have used a few ICs, such as the 741 op-amp, AND, OR, NAND gates, etc. I have also used a few micro-controllers like the atmega32, atmega328, ...
49 views

### Can I wire a wall switch to my circuit?

simulate this circuit – Schematic created using CircuitLab Can a wall switch be wired to a DC circuit like these two circuits??
18 views

### Control RF controlled LED panels with a Raspberry Pi 4

I'm trying to "smartify" my LED panels by controlling them without the actual remotes. My goal is to make it possible to control the lamps from an http endpoint. I have an Raspberry Pi 4 as ...
75 views

### How to tell correctly if a circuit is pull-high type or pull-low type?

I have been giving this assignment working with Arduino that would light up a 7-segment component, when a push button is pressed. Is there an intuitive way of looking at the circuit and recognize ...
18 views

### Issue using TCC3 of microchip SAMD21J in variant file

I am writing variant files for SAMD21J/G/E. I am unable to use TCC3 of SAMD21J/G/E in Variant.cpp for arduino IDE. If it is used Arduino IDE shows error TCC3 undeclared variable whereas, all other ...
39 views

### opamp single supply output AC (audio) voltage limit

I build non-inverting op amp with single supply voltage cca 9V. The basic scheme is shown in the figure below: How to limit output AC signal if the base DC voltage is at half the supply voltage 4.5 V ...
49 views

### 400Mhz frequence HackRF One

All, Sorry but I am new to this topic and have no experience with SDR myself.First, I briefly give the hardware that I am using: HackRF One Following antenna: https://zsecurity.org/product/atheros-...
73 views

### Image recognition for PCB - is this available?

I have a populated PCB, and I want to draw a circuit diagram of it. For printed documents, you have OCR which can recognize text in an image. Is something similar available for PCBs? i.e. I provide ...
13 views

### What is the right BMS and S/P configoration

the cells are 3.2 volt at 280ah buy 32 cells what is the best 12/24/28v and the best BMS for setup I have all ready purchaced cells and am waiting on delivery to install in my rv
56 views

### Shift-register seems to read wrong input data

Here the schematic of a small board with a 74HC595 shift-register: Here the detail of each output. They are connected to QB..QE. Nothing is connected to the collectors of BJTs and the board contains ...
56 views

### What's TL431 Output voltage

I am using PSIM to simulate the TL431, and I have some questions. This is my PSIM circuit: When Vref is less than 2.5V, the TL431 doesn't conduct, it looks like an open circuit so Vo is almost 5.1V. ...
64 views

### High gate pin current leakage on a p channel mosfet

I have added a P-MOSFET before my main circuit, between the v+ of the battery, and the Vcc main power line of the circuit, so that the battery stays disconnected and doesn't drain until I am ready to ...