# All Questions

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### Why do they separate some parts of PCBs through making wide holes?

I have seen several PCB that they have wide holes in some their parts (especially the supply of circuits parts). for example take a look at this picture: and on the board: Not sure but I think ...
7 views

### 2.5mm Jack to USB data Cable

I was recently diagnosed with Type 1 diabetes. With the need to test my own blood upwards of 8 times a day I have a ton of data to keep track of. My testing unit has the ability to upload its data to ...
15 views

### ZigBee vs WiFi for wireless communication

I've been working on a product using WiFi. The reason I picked WiFi, is cause I essentially have 20-30 nodes communicating to a main node via a router. This all works very well, and its easy as its ...
13 views

### Use Zener diode to control an LED array?

I am trying to use an LED array to indicate a voltage level. For example, if the voltage is 3V, then 1 LED is lightened up. If 4V, 2 are lightened up. If 5V, 3 are lightened up, etc.. My previous ...
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### Reveal Agilent MSOX3034A trigger date/time

An error condition occurs once every couple of hours. I've set up my scope to trig on the condition, so I can inspect what happened. But I also need to couple the time the condition occurs with a log ...
10 views

### can I charge Mobile battery using mobile charger directly?

I want to charge mobile battery of 3.7 v directly by connecting 2 terminals of charger(5 v output) to two terminals of battery. My questions are Is IT POSSIBLE? what must be voltage adjusted to ...
16 views

### Value for feedback resistor in pierce crystal oscillator configuration

This question is partially an "understanding english" question and partially and "understanding the pierce oscillator configuration" question. Backstory I'm currently looking at using a Freescale ...
7 views

### Bitbang ATMega-328PU with CT210x using avrdude

I have made a breadboard-arduino with an ATMega-328PU and the standard components taking help from http://arduino.cc/en/Main/Standalone I interfaced the CT2102 Breakout Board with this assembly: DTR ...
22 views

### Are there other ways in which 60Hz noise can get into your system?

Are there are other ways in which 60hz can get into a system other than ground loop ?
21 views

### physical significance of group delay

What is the physical significance of the group delay of a system/filter?. Why is the slope of the phase response critical in communication systems. Thanks in advance, phani tej
12 views

### Two Sided Push Button Latch

so I have here a push button latch that is tried and tested and that works beautifully. But I need help making a variation of it that will switch between two circuits instead of just turning one ...
16 views

### VCA Using JFET and Op Amp

Just messing around with LTSpice I came up with this VCA that simulates shockingly good for what it is: I don't recall ever seeing the use of an op amp to mix the signal and control voltage in an ...
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### How should this code look like in verilog?

I am designing an ALU to add at state 000, I have to assign control signals for a mux, carry in, and operands so that it works. so, i wrote an if statement in the controller module, and the TA told me ...
26 views

### Building a +/- 150V DC power supply

I'm trying to build a +/- 150V battery powered DC power supply variable power supply. I have two of these 150V nixie power supplies: http://desmith.net/NMdS/Electronics/NixiePSU.html And was ...
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### EAGLE PCB, how to specify an out-of-board component?

This might be a very basic question. I have a schematic where some of the components are outside of the board. For example, for a power supply, I have a switch and a transformer that are on the ...
14 views

### MCP2200 - which GPIOs for DTR, DCD, DSR and RI?

Due to the recent controversy surrounding FTDI, I'm looking for a replacement for future designs. I'm looking very hard at the MCP2200. The only thing I can't figure out is that they have several GPIO ...
55 views

### Can a transistor's emitter and collector be used interchangeably?

I'm trying to understand the standard TTL NAND Gate in TTL level. But confused with the transistor Q1 operation in the diagram below: Apparently when A and B are together HIGH, the Q1 base-emitter ...
41 views

### How to find the expression for Vout?

I have that circuit and I need the equation of Vo, I've been told that I can solve it by the Kirchhoff method but I'm not sure.
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### STM32 - Multiple channel PWM input

I am using an STM32F405 based board , (OpenPilot revo ) to receive PWM signals from a joystick receiver . i have to xapture 5 PWM signals using only two timers , the timer 8 and the timer 12 . I've ...
210 views

### Do logic families use different type of transistors?

Do the logic families such as TTL and CMOS represent only different logical structure? Or do they also use different type of transistors? Latest microprocessor chips with millions of components use ...
45 views

### How to measure coils without Inductance measuring device?

I have a multimeter that can measures Capacitance, Resistors, voltage and current. If I have a known coil and unknown coil. Can I measure the ratio between the inductance of the two coils ? Is it ...
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### Hooking audio compressor to mains without chasis

I am nearing the completion of my DIY compressor project, and I have a rather seemingly basic question.. Once I hook up my toroid and everything, since I don't have my 19" 1U rack enclosure yet, but ...
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### What sampling rates will give uncorrelated samples of x(t).considering the mean of the Random Variable 'x' to be zero?

What sampling rates will give uncorrelated samples of x(t) ? Considering the mean of the Random Variable 'x' to be zero. My Thinking: Since the mean of the random variable 'x'is zero,then it will ...
41 views

### How can I convert a Mplab code into 8051 assembly code [on hold]

we have used keil software using text.a51 asm code format and the code is in mplab. can someone help me? thank you. Below is the code. ...
8 views

### Is my Arduino UNO fried? [migrated]

The title sums it all up. While testing the new proximity detector I bought off of Amazon, a spark flew from some random area and my Arduino's On LED went off while its Loop LED stayed in a dim ...
35 views

### Binary counters, homework help

When doing State Tables, in the 'Next State' column, is it always 'Present State' +1 (or if we have some arbitrary combination, the number after), even in repeating binary counters?
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### Is possible to build -168 dBm amplifer?

we know that GPS receiver can reach sensitivty of -168dBm, and also it is possible to make receivers with similar sensetitvity can operate at another bands/frequencies . but I just want to know if ...
33 views

### Conformal coating and micro SD card sockets

I have a embedded computer design which uses a low profile micro sd card socket as an extra option in addition to an on board solid state disk as storage/booting mediums. In manufacture the board is ...
37 views

### A NAND flash sector suddenly goes bad. What happens to the file using that sector?

I can read a lot about how NAND flash can be checked for bad sectors, which are flagged and won't be read/written to in the future, but happens at the moment a sector goes bad? Any file that was using ...
55 views

### Replace 12V 5A power supply with battery

I am buying a rgb led strip with the following technical details: Voltage: 12 volts Wattage: 60 watts I want to connect this strip to a battery and don't know ...
46 views

### T-flip-flop without using a clock

Is it possible to create a T flip-flop without using a clock? I really need one, but I can't use one with a clock because it requires a signal shortener.
32 views

### 2-bit branch prediction accuracy

I am trying to solve this problem, the answer should be 15/20 = 75%. However, I am not sure how this was calculated and want to understand the underlying concept. A program core consists of five ...
51 views

### Data transmission in ocean

What is the greatest depth where we can communicate with the submarine over the sonar system in ocean? Also, how can we calculate how much data can be transmitted using this method?
22 views

### Current on Easydriver stepper pin

I am using an Easydriver v4 to drive a bipolar stepper motor. The Easydriver works fine, if I wire it up and manually toggle the step pin to 5V/GND it steps as intended. Now I connected both the step ...
97 views

### Is there a non recursive formula for mixed resistors?

In equivalent resistors in multiple parallel resistors, like this simulate this circuit – Schematic created using CircuitLab I need a formula for the equivalent resistor for the whole ...
48 views

### How can the infinite reactance of either primary or secondary in an ideal transformer draw current?

Assumption 1: An "ideal" transformer is said to have very large primary, secondary, and mutual reactance.. (self-inductance/mutual-inductance tending toward infinity), has a unity coupling coefficient ...
135 views

### Convert positive square wave to positive-negative

I am looking for a way to convert a square wave coming from a microcontroller with voltage range from 0V to 5V, to a voltage range from -12V to +12V. The frequency of a square wave will vary from few ...
65 views

### Replacing capacitor from unworking TV with some other capatitors which has not the same value [on hold]

I am repairing (trying to repair) my TV. I found 1 capacitor 25V $1500\mu$F which i think is bad (it has some weird shape at top) I don't have any capacitors with that value but I have some similar ...
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### PIC12F ADC conversion has an unwanted offset

The current setup is shown below. PIC12F1822 with a 10-bit ADC. I'm using a 250R 0.05% precision resistor to get a nice 0-5V input to the analogue pin (AN2 if it matters). As far as I can tell I ...
224 views

### What is the purpose of a capacitor in the feedback path of a unity gain buffer?

First time using this site, I'm an EE student and have been studying opamps. So far in class we have only discussed 'ideal' opamps, but I saw an opamp with this layout and was wondering if anyone ...
54 views

### How to up-convert PWM frequency without using a microcontroller?

I am trying to drive a motor H-bridge, but my control system can only support a 400 Hz PWM signal (black box, can't change it) which gives the motor an extremely loud 400 Hz whine as you would expect. ...
16 views

### Virtually indexed physically tagged cache

I'm trying to understand the concept and calculations for solving this problem. I know the answer is 10 bits. ...
39 views

### when to use auto correlation and when to use fourier transform

In communication, if we don't know any prior information about the signal, we perform an auto correlation say Rx(T) and take the Fourier transform of Rx(T) to analyze the power spectrum. Supposing ...
444 views

### Limits of dead reckoning using MEMS sensors

I'm trying to track body parts relative to a person's torso. I see quite a few questions about using MEMS accelerometers and gyros for dead reckoning, and they confirm my suspicions that various ...
21 views

### VHDL indexed part select

Is there a way to do indexed part select of an array in VHDL as in Verilog? I know that you can use an array but creating a new type seems overkill to me. Moreover it's possible to slice an array ...
64 views

### Are those two filters equal?

Are those two filters equal to each other in their functionality? Of not, what is the difference between them mathematically speaking (zeros, poles, etc)? Also, what is the difference in their ...
93 views

### Is Faraday's Law not working?

Faraday-Lenz's law was easy when I was in 12th standard. But it became more complex when I jumped to Engineering. Recently when I was studying about inductors and how they oppose changes in currents, ...
35 views

### Quality Power Supply [on hold]

I m looking for a quality AC to DC power supply (5V/3A in my case), with excellent winding insulation (~ 100Mohm), universal and regulated of course, but that also is "true" relative to earth. What I ...