# All Questions

114,592 questions
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### Vdc in ripple factor

V_p(rect) is the rectified unfiltered peak voltage V_r(pp) is the peak-to-peak voltage after filtering by a capacitor Here is a picture: V_r(pp) is given by the expression: Which I have no problem ...
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### DW01x vs AP9211

I plan to use DW01A + FS8205A for LiPo (or LiIon) battery protection. But when I searching alternatives I found AP9211 (internal Dual N-Channel Enhancement Mode Power MOSFET). Is anyone works both of ...
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### Custom IoT embedded device

I'm looking about an IoT device (computer board) to develop a system for production purposes, I have used Raspberry pi 3 for testing, and all things works fine. Now, for production, I need a board ...
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### Altium: Error on PCB Footprint Updating

I am using Altium 14.1.5 I made a change to a footprint in a non-integrated library and then wanted to update my PCB with the new footprint and it is not updating properly. I may be doing something ...
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### Cause of background buzz in my walkie talkie example?

I got a simple RF24Audio walkie talkie example working. I'm using the sketch file provided by the RF24Audio getting started example: https://github.com/nRF24/RF24Audio/blob/master/examples/...
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### How can Vo = A(V+ - V-), if V+=V-=0?

We’re considering an ideal opamp here; so does that mean that Vo is infinity ♾ * 0 (A * (V+ - V-))? Thanks!
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### What are ADC channel “map,” “max,” and “amount” used for on a Microchip ATSAML21 ARM MCU?

I'm working with a Microchip ATSAML21J18B ARM microcontroller and learning how to set up an ADC input. Coming from the AVR world, things are rather more complicated. The ADC features (datasheet pg ...
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### DAC offset error vs. output low voltage

I am looking at the datasheet for the MCP4725 DAC and trying to find the minimum voltage the DAC will output. In other words, when my code tells the DAC to output 0v, what will the output be? There ...
164 views

### Why does a single AND gate need 60 transistors?

Looking at the datasheet for the MC74VHC1G08, under the "features" section, it states Chip Complexity: FETs = 62. Why does this IC need 62 transistors, while an ...
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### Diode behavior when reverse biased with small voltage

I'm designing a simple circuit to use a lithium-metal coin battery as a backup power supply, and I'm considering something simple like this: simulate this circuit – Schematic created using ...
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### EM Vs PM Speaker

Modern Speakers have permanent magnets and are called PM speakers.Permanent magnet materials technology has improved a lot over the last 80 years .Around WW2 EM speakers were common because permanent ...
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### 2 pole single phase induction motor appears to have starting capacitor permanently connected (no centrifugal switch)

I am trying to repair and rewire an AC induction motor from a small compressor. From what I can tell it's a 24 slot, 2 pole single phase induction motor that has main coil and starting coil. The ...
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### How to control single 12V LED with 3,3v GPIO?

Heyo! I need to control single 12V LED using Raspberry's GPIO To be more exact, I need to connect 12V LED & push button to 3.3v GPIO in order to control LED (on/off) and read button push events. ...
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### Rounding up or down with Motor Overcurrent Protection

When sizing motor over-current protection, CSA 22.1 28-200 3a states that a circuit breaker can be sized up to 250% of the rated full load amperage (FLA) of the motor. E.g. 100hp, 575VAC motor ...
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### Calculating Roll Pitch and Yaw from Accelerometer Data

I found these three formula to get roll pitch and yaw angles from accelerometer but these don't work when the accelerometer is in linear motion in any axis. pitch = 180 * atan (accelerationX/sqrt(...
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### Any equivalent load circuit when an animal is connected to a current injector?

When the human body (chest, arm, etc) or an animal (limbs, belly, tail, etc) is connected to a circuit, I think this acts as a load. For instance, people simply model the connection between the AED (...
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### What does input/output resistance/impedance mean?

This keeps coming back in every single class, and I still don't have a clear idea of what it is. I keep seeing certain statements in other explanations such as "seen by X", "looking into Y" and so on. ...
38 views

### Does alcohol set off Liquid Contact Indicators?

I have a MacBook Pro PCB that has lots of yucky, gooey and sticky grime from a spill that thankfully didn't damage the board. I would like to clean it thoroughly, but I fear turning the liquid contact ...
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### Absorber effect on EM RF pattern

If I have an omnidirectional antenna and put a perfect reflector plane near it (in the near field), it will obviously change its radiation pattern in the direction opposite the reflector. ...
22 views

### Affect on C_ds in MOSFET turn off

Question boils down to whether the voltage across a capacitor can ever exceed Q/C. It relates to what happens to the drain-source capacitance when a NFET turns off. At the start of turn off V_ds and ...
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### Lt-spice switch model

I have a very simple circuit and want to see the current in the inductor. But I do not know why switch is behaving like that... Actually, I supposed to get KA range current. but it gives me very ...
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### Circuit MOSFET Pulldown Circuitry

Now, I have already made some progress, I have figured out what the W/L should be and made most of the circuit. Though I am not sure how I should put the MOSFETs ...
22 views

### Reduce AC voltage - op-amps circuit

I´m trying to reduce the amplitude of 160 VAC peak to peak to 2 VAC peak to peak using op amps with virtual ground. I've made this circuit but it isn't working. My offset voltage have to be equal to ...
36 views

### Resistor in series needed with LED string?

I have an adjustable 24VDC power supply. I have 1W LEDs that I was planning on stringing 7 or 8 in series to get approximately 24V across all of them together. They are rated 3.3-3.8V each. Do I need ...
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### What is the importance of separate power and logic ground (ie a Vss pin) in gate driver

I have 2 different versions of a high and low side driver; IRS2186 AND IRS2186. I have attached the typical connections, taken from the data sheet (data sheet: https://www.infineon.com/dgdl/irs2186pbf....
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### Passing usb data traces underneath of DCDC converter

RKZ0505D is a DCDC converter which has maximum 85kHz internal switching frequency. It is placed as large surface of it placed directly on PCB. If USB data lines pass under plastic package of DCDC ...
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### Read RFID correctly with multiple cards stacked?

This may sound like a stupid question, but I'm curios about weither this works and how. Is a RFID reader (for example when paying contactless at the supermarket) able to read my credit card correctly ...
38 views

### Voltage in an RC Circuit

I made an RC curcuit on a breadboard gave it a of 25V measured the voltage across it with an oscilloscope. During my experiment it has come to my attention that the peak voltage level was getting over ...
53 views

### High PWM frequency weird shape

Using a STM32F407 if I generate a 200 Hz signal it looks like this: If I want a higher frequency, for instance 10 kHz I get this: I am using a PicoScope 2205A, resolution 8 bits at 200Ms/s, ...
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### Liberate - Custom Cell Characterization

Tools and Tech: ST 65nm | LIBERATE Library Characterization Platform (x86_64) 12.1.4 (altos 121) | Cadence Virtuoso 6.1.5-64b | Calibre Interactive - PEX v2012.4_16.11 I am trying to characterize a ...
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### Finding equivalent capacitance and resistance from DC circuit with combinations of R and C

In order to get the simplest RC circuit and get equivalent circuit tau: I would like to know if it is possible to reduce the next circuit to another one with an equivalent C and equivalent R? How ...
24 views

### Phase shift between the winding of a three winding transformer [on hold]

What is the phase shift of the output voltage of a three phase three winding transformer connected as follows: Primary: Delta1. Secondary: Delta11. Tertiary:Wye. Is there a 15 degrees phase shift ...
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### Use lithium ion car jumpstarter to charge netbook?

I have a Gooloo car jump starter pack. https://www.amazon.ca/gp/product/B06X9R8QSY Can I use it to charge a small Gateway Nav50 netbook? What kind of adapter would I need? I suppose I could use ...
27 views

### Wiring Connection from RS-485 to RJ-45 Port

I want to connect/wire from RS-485 A and B (only 2 pin) to RJ-45 port, anyone has the schematic diagram that show hows the wiring?
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### Some questions on inductance measurement of a solenoid

I'm planning to measure the inductance L of roughly this solenoid-valve roughly by using the following setup: I measured the resistance of the solenoid RL as 55 Ohm. L is unknown. I think I can ...
58 views

### What happens when switch is open

In a simple circuit, composed only of a lamp, a generator and a switch that connects the generator to the lamp. What happens with electric current when the switch is open? Electrons turn around? They ...
54 views

### Voltage regulator not outputing desired voltage and extremely hot

Now that I have understood how to connect my transformer to output 18V, I now have a huge problem with heat and wrong output voltage. I also smells and you can feel the heat. Here is my design ...
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### USB 3.1 Gen 1 Transfer Speed Through Hub

If I have a USB Host Controller that supports USB 3.1 Gen 1 plugged into a hub, and 2 storage devices connected to the downstream ports, if I transfer data from one storage device to the other through ...
23 views

### Nand Flash Memory Chips [on hold]

How would I program a Nand Flash Memory chips to read and write? I have an FPGA, a Nand flash memory, a socket, and some cables. I just want to know the procedures or step by step by doing this! How ...
28 views

### Microcontroller resets with motor driver (L293D)

I am making a simple robot with 2 BO motors driven by L293D on ATmega328P (took out from Arduino Uno). The robot when tested on Uno works fine. But when I put it on the board that I have designed (as ...
84 views

### Could someone explain what is clock data recovery?

I have read that clock data recovery is essential for decoding signals, for instance decoding output of rotary encoders But I don't know how it helps to decode signals. Any hint or reference would ...
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### Definition of Field Wiring Terminals as in UL 499

I'm wondering if anyone can tell me where I can find the definition for "field wiring terminals" as referenced in UL 499 "Standard for Safety Electric Heating Appliances" table 27.1 "Minimum ...
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### Using Character Match functionality in a STM32F7 chip

I'm trying to implement a UART receiver that works by finding a '\0' in the datastream, OR when it receives 256 characters at which point the data should be processed by an interrupt. The point is to ...
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### How to take resistance reading when value is effected by measurement?

Context I am trying to measure the wiper resistance of a potentiometer. This is performed by leaving the potentiometer wiper in one position, and measuring from each terminal to the wiper ($R_1$ ...
617 views

### What really causes series inductance of capacitors?

Doing some research in selecting capacitors for high frequency applications, concept of equivalent series inductance comes up a lot. Apparently all capacitors have this parasitic inductance which ...
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### BLDC hoverboard motor with no specifications

I have this kind of motor but I can not find any electrical specifications about it. All I know is that is a 36V,250W BLDC motor. How can I determine the number of poles, the coil resistance/...
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### ili9341 using 3 wire with stm32f030

I am working with ili9341 TFT Display with STM32F0 MCU. And TFT display was connected with 3 configuration. I am confused between sending the "command" and "data" using spi communication. So can ...