# All Questions

113,052 questions
35 views

### There exists 110v/60Hz motors as well 220/50Hz ac motors rating, what determines the voltage of an electric motor?

I have seen the Toms question and answers for what determines the voltage of an electric motor? None of the answers not fulfilling. I was not able to comment to get clarify my doubt, so I’m posting ...
88 views

### What's the difference between a generated hex file and a binary file in embedded systems?

I have an STM32 project (let's call it blinky). This project is developed using Keil IDE. It blinks an LED every 1 second. When I build it, a HEX file is generated. Let's say I want to upgrade the ...
66 views

### Why is the secondary winding of a current transformer shorted?

I understand that the secondary circuit in a current transformer cannot be left open, as it will result in a very potential difference being induced in the core of the transformer and permanently ...
20 views

how to read the dimensions phi A,D,E at the pins 1+ / 1- /2+/ 2-
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### unknown circuit symbol rectangle with arrow

I've never seen this symbol before but my wiring diagram is full of it. I also have searched for lists of symbols but it isn't among them. Does anybody know what is is? It is from my wiring diagram of ...
37 views

### Confusion with 555 transistor relay driver

This is probably schoolboy stuff, but before I construct it ... A 555 will output almost the supply rail, or down to zero. A transistor attached to that, with a relay on collector can drive a 12v ...
32 views

### CLOCK USING 16F876A

I have constructed a 7-segment clock using DS1307 & PIC16F876. The clock runs well except that after some time (after 10 to 12 hours running) display freezes. After resetting, original time is ...
55 views

### Does this audio amplifier do differential filtering?

I was looking at this schematic for a two-channel audio power amplifier. The amp supports a bridged mode by means of an XLR connector and a switch. When the switch is in the XLR position, pin 2 (...
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### Help: circuito combinatorio [on hold]

How can i build a 6 inputs gate that will have output = 0 only when a one input is 0. I can use and, nand and or gates for the solution
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### Too low efficiency with “0-30V 2mA-3A DC Regulated Power Supply unit with Continuously Adjustable Current Limiting Protection” PSU kit

I ordered and assembled the kit (link and image added below). Everything works fine. But as everybody knows, it requires a great heat sink for the regulator. The ordered unit costs less than \$5, but ...
29 views

### In Circuit Debugging vs On Chip Debugging

Is there any difference or are they the same thing ? Both terms are frequently used. There is only 'one' website touches the point directly: "The ICDs (In-circuit Debugger) are additional circuitry ...
27 views

### Pixelstick device backlit LCD broken

I have a Pixelstick device which has a 128x64 backlit LCD display. The LCD backlight works but the display is gone. Apparently the LCD is broken and needs to be replaced. The LCD has no markings on ...
17 views

### PIC32MZ: Changing the I2S baud rate on the fly

I am using the I2S driver on PIC32MZ1024EFE064. I want to change the baud rate of the I2S after some timeout (say 64000Hz for 10 seconds, then switch to 16000Hz for next 10 seconds and so on...) The ...
23 views

### Output changes wildly with input voltage in photodiode circuit

I am currently analyzing a photodiode sensor input circuit (not designed by me, but schematics drawn from a commercial product). I am currently simulating the circuit on TINA TI. While experimenting ...
56 views

what is loading error in op amp? I have a voltage regulator with zener diode and op amp. why do voltage is low in lower loads for example 100 ohm but for higher loads is not it?
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### Voltage applying to cpld I/O pin while VCCio isn't connected

I have a pcb based around a coolrunner II cpld . My problem is as follows. An other ic generated at it's output a logic '1' (around 3.5V ) and the signal was driven to an input pin of the cpld while ...
38 views

### VHDL Editor with lint and intellisense

Is there a freeware VHDL editor out there that supports intellisense and lint? There are plenty for other programming languages but seems like none for HDL.
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### Can anyone help me identify this connector type?

Please Help with connector identification Can anyone help me identify this connector type? I is 2 pin, pitch I think is 0.8mm (I measure it to be 1mm between the outer part of the pins, I do not ...
858 views

### what is the purpose of having a “thru cal” on RF PCB?

I often find a thru cal on RF PCB like picture below. What is the purpose of having this thru cal thing on the board? One purpose I can think of is to test whether the designed transmission line is ...
70 views

### PNP Transistor with low base current

I designed a PCB with the following schematics. simulate this circuit – Schematic created using CircuitLab The circuit uses a MAX6369 external watchdog timer which has an open-drain output(...
52 views

### Help! How can I repair this PCB [on hold]

I have a PCB that I believe to have suffered very minor damage due to water ingress. The PCB has this LCD attached. https://www.mouser.com/datasheet/2/281/20lcd-41581.pdf Currently I am getting a ...
24 views

### Questions about stability circle and impedance matching

I'm a RF circuit beginner and got stuck in stability related issues. According to Pozar's textbook, output stability circle is a contour in the "gamma_L" plane and its arc represents the "gamma_L" ...
67 views

### Protecting against a SSR failing closed

In a project I'd like to control a heating circuit with an SSR, and I'd need a contingency plan for when the SSR fails closed, and the microcontroller cannot turn off the heating element, which would ...
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### Design SAR logic block for 10-bit SAR ADC?

I have chosen a switching scheme for my 10-bit SAR ADC. But I am stuck at designing the sar logic control for DAC switch, comparator, S/H bootstrap switch. As shown in the picture is an example of 3-...
30 views

### How to proportion hydraulic flow using potentiometer and MOSFET

I am working on solving a problem that we generally deal with in a mechanical fashion. We have a hydraulic system with a dumb controller and a dumb valve stack. We can change the valve stack solenoids ...
44 views

### Opto switch for detecting translucent polypropylene

I am building a liquid handler (a CNC machine that pipettes small quantities of liquids). The machine switches polypropylene "tips" between pipetting different fluids. Positional accuracy within 0.5mm ...
52 views

### 4 100 ohm resistors need to equal 60 ohms of resistance [on hold]

Show how to combine four 100 resistors to obtain an equivalent resistance of (a) 25 ; (b) 60 ; (c) 40
55 views

### Why did Adafruit pick a 10K resistor for this phototransistor breakout?

Adafruit has an ALS-PT19 Analog Light Sensor Breakout. It looks like it has a 10K resistor on it: The ALS-PT19 datasheet says that resistor is to convert the output current of the transistor to ...
49 views

### Determining battery run time from Ah and MJ?

I am working on the following question: Two 100 ohm resisters are in parallel across a battery. The battery can store 240 MJ of energy and is rated 240 Ah. The battery depletes fully after two hours. ...
27 views

### How do I determine the capacitor to use when converting current to voltage?

I'm trying to figure out how to use an ALS-PT19-315C/L177/TR8 phototransistor (or something like it). The datasheet has this sample circuit for converting current to voltage so that I can measure it ...
44 views

### How do current and voltage relate to load?

I think I've lost the plot somewhat on how current and voltage relate to the load in a circuit and I'm hoping for some really basic level clarification. In fact, I'm not really sure how to ask the ...
39 views

### Replacing a safety capacitor [on hold]

one of my electronic appliances has stopped working after several years of use, it is definitely beyond the warranty period however I've been unable to find any more recent appliances that beat it. ...
38 views

### UART Transmit issue in VHDL

I'm working on a UART transmit process (uart_transmit) in VHDL (115200 baud, 8 data bits, 1 stop bit and no parity). I need the transmit line ...
22 views

### Chromebook power circuit: Surface mounted diode or resistor? [on hold]

I recently enjoyed finding out a mains power short (was working onsite project) has dislodged 2 surface mounted components from my device's motherboard. Thought it would be interesting to repair ( ...
9 views

### Proteus ARES 7.9 SP1 Bug?

I am working on a layout and when I go to the track mode to make traces it is only showing inner layers and Top/Bottom copper are missing from the menu. I cant seem to get them to reappear.
36 views

### How does this high impedance circuit stage work

The current i1 flows through Q3 and current i2 flows through Q4. It looks like D5 is trying to mirror the current flowing through it via Q6. D6 is trying to mirror the current flowing through it in Q5....
19 views

I have this question with this answer for the tpg_block, it says 6x200ps. Can someone see where they are getting the 6 from?
63 views

### How does a dot matrix led driver know the voltage of an led?

I wanted to make a 7x10 led dot matrix using two 5x7 led dot matrix from lite-on (LTP757KR). I first thought of using shift registers, then I found a 12 x 8 dot matrix led driver with a bunch of ...
34 views

### Altium Clearance Constraints on USB Receptacle Footprint

I made a manual footprint for a USB micro-B receptacle that is now giving me problems on my PCB in Altium Designer 16. Here's the footprint drawing that I was going off of: And here's what my ...
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### My JTAG connection with Cyclone IV is not working

My FPGA board is not programming. I think I have followed all the guide lines for JTAG connection. Can you see any problems with this connection?
60 views

### AC motor must be run off inverted DC?

I am looking at the datasheet for a motor. This is an AC induction motor designed for use in electric vehicles. It includes the statement [my emphasis]: The motors are designed for installation in ...
19 views

### SPI problem with STM32F103

I am trying to connect blue pill board(master) to arduino nano(slave) over SPI and read what I have sent on serial monitor. However I haven't been able to get SPI working. I run a timer to generate an ...
40 views

### Boost converter output voltage error

I'm using LT3494a to generate 37v from 6v input. This is my circuit. According to the datasheet, this chip can provide up to 40v output, so it should be able to generate 37v. Also, the simulation ...
48 views

### Protecting analog pin from ESD strike

After reading some relevant questions on ESD here, I have come up with the following approach to protect some ADC GPIO pins on my lipo battery operated board that are open to external input, thus ...
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### Derivative and Integral Controllers' Form

A derivative controller $C_{d} = s-z_{d}$ adds a zero to a system, placed at $s=z_{d}$. I know that a derivative controller is not used alone but for the same of the argument let's say it is. In ...
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### SPDT relay is not switching

I have a 8 channel, 10A SPDT relay, which I'm having problems getting to work. Here are its specifications. I've attached a few images below for reference. So, initially, I connected a 6V power ...
66 views

### Delaying rising edge of input signal - 3.3v logic

I'm new here and I need help with my project. I working on my DIY home automation and I need to delay rising edge of the input signal. Trigger is faling edge. I need to delay it 100 - 500ms and I use ...
894 views

### How does an op amp integrator work?

I know there are at least two questions related to this on stackoverflow but neither really answer my question, and in any case, both questions got downvoted. What I am after is an operational ...
I have been working on a dynamic model of the PMSM with surface mounted magnets and sinusoidal stator winding. I am little bit confused by formulas for the $L_d$ and $L_q$ inductances. I have ...