# All Questions

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I built a driver for a pulsed laser. This required a low voltage DC source to provide a bias current through the laser and also a high voltage DC source to drive an avalanche transistor to make the ...
3 views

### Generating Large Test Cases for Power Flow Simulation

I am trying to investigate the scalability of various power flow methods for large power systems (1M+ buses). It seems however that most test cases that are readily available are generally quite ...
21 views

### Why is the red diode in my RGB led burning out?

I have been working on a simple circuit that uses a 10mm RGB led. I have had the same problem again with the red diode dying out after maybe a day. This time I thought I fixed it, but I guess I'm ...
18 views

### What does the Y capacitor in a SMPS do?

It seems that a well-designed SMPS has a capacitor connecting the ground planes of the primary and secondary sides of the transformer, such as the C13 capacitor here. What is the purpose of this ...
12 views

### How to modulate a LED to send data and recieve with a photodiode

What is the concept of modulating a light source (white led, IR led, etc) to send data and then demodulating it with a photodiode back into data? I am wanting to experiment with trying to use ...
25 views

### How does vacuum tube heating (heater voltage) affect tube performance/sound?

I have replaced a 12AX7 tube with ECC85 in my guitar amp. Seems to work great and sound great. The part that is questioning me is whether the sound is being at its best because it takes a good 20-30 ...
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### What does “capacity achieving code” mean?

I am an electrical engineer passed several courses in information theory and coding theory, however as I think now, I see that I have not understand the basic ideas in these concepts till now. We ...
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### connecting a generator with an RCCB to a service panel

Consider the following schematic : simulate this circuit – Schematic created using CircuitLab in this setup we have two power sources Main power lines and a diesel generator ( with ...
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### Output in unknown state even though specified in verilog

I am having some troubles with creating an edge detector in verilog. So far I've come up with this: ...
46 views

### Need the pinout for this noname FTDI board

I would really like to know the pinout for this FTDI board. It has no model number on it and on google picture search I couldn't find it. It has 2x4 pins on the end of the two sides soldered in. I ...
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### Can't find the right power supply - could I use something similar?

So I've just bought a Behringer MX2642A mixer off eBay, which worked for two hours then promptly shut down. After investigation, it seems that the power supply might have given up - the specs for the ...
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### MOSFET power dissipation calculations - Diodes Inc. datasheets

Looking at Diodes Inc. datasheets, I am having trouble following their power dissipation limit calculations for their MOSFETS. E.g. for DMG4496SSS http://www.diodes.com/_files/datasheets/ds32048.pdf ...
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### ngspice - Measure param

I'm trying to post-process a value computed by a measure statement in ngspice (rev 26) as described in the manual: ...
20 views

### L293DD overtemperature protection

I am using an L293DD Dual H-Bridge IC to power my DC motors. I have realized I am using inadequate heatsinks, and 1,5 times the nominal maximum current(1,8A instead of 1,2A), but the circuit is ...
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### What's the easiest way to remove the power rails of a breadboard?

All of the breadboards I get come with an adhesive backing that, while keeping the metal rows inside the breadboard in, keep the power rails connected to the breadboard. I want to remove the power ...
59 views

### Can this shift-register circuit be simplified?

I've created a circuit using a shift register to drive a 7-segment display which is all controlled by an Arduino Uno. The circuit appears to work fine, I have a sketch running which simply counts ...
21 views

### UART: no input while connecting to some hosts [on hold]

I have Android tablet with configured UART (console=ttyS0,115200 in /proc/cmdline). When I connect to it from my workstation it ...
20 views

### Maximum Achievable Current from a MOSFET Current Source \ Sink [on hold]

consider the circuit has a bias voltage VGG = 5V; and the transistor parameters are k’ = 100, W = 50 micrometer , L = l micrometer , and Vt = 0.8V
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### Communication with a database - assignment

i'm a second year student of electronics and comupter science. I was asked to implement a system which works with a web application. Application should enable displaying information about current ...
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### Thevenin Resistance and Voltage

So I've confirmed the Thevenin voltage ( between A and B ) to be .5V and a the VLoad as .3633V. I'm now supposed to verify that RLoad is 4k by redrawing the circuit as its Thevenin equivalent and ...
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### Kid car 4x4 3-6 pin foot switch

I'm wiring my son's electric car and am having trouble with the foot switch. My original plans were drawn up with a 3 pin momentary foot switch; I have since learned that it is in fact a 6 pin SPDT ...
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### Problems connecting esp8266 through HL-340 usb serial adapter on Ubuntu (Input/output error)

No matter what I try I can't seem to get a serial connection going between an esp8266 (this model: http://www.autonomii.com/wp-content/uploads/2015/04/esp8266_pinout_h-569x236.png) and my HL-340 (was ...
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### Color Coding one brushless DC motor?

I have used brushed dc motors earlier.. WHere the color coding means red(+ve),black(-), (white/yellow) signal What do the color codes on bruhless dc motor means... through several forums I came ...
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### BLDC 3 Phases Motor wiring

I have a BLDC 3 phase 8 pole motor, with hall effect sensors, most other three phases motors have 1 wire for each phase U , V , W however this motor has two for each phase(these do not include the ...
22 views

### I need some help calculating values for a variable 555 oscillator circuit

For the past few hours i have been strugling with a 555 timer. What i am trying to do is generate a square wave of variable frequency controlled by a potentiometer. At the time i have a 200KΩ ...
41 views

### Can a COTS FM Radio transmit?

This is probably a really silly question, but I still want to know... Given a standard off-the-shelf FM radio alarm clock, what is to stop it from transmitting radio waves when physical motion causes ...
25 views

### how can we make a signal out of a 2 pin mic output

ok im looking to make this type of setup so that i can use its output pin to read via analog. this is the mic i got and would like to make that 3rd pinout which as you can see it only has 2 and ...
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### How to switch micro DC motors fast?

i'm planning to make micro/nano quadcopter and ive bought all major components so far. Only thing that i cant figure out are motor drivers. I was planning to use some kind of transistor to do that for ...
204 views

### Is a half-wave rectifier particularly hard on a transformer?

In the book Practical Electronics for Inventors, 3rd Ed., the authors recommend against using half-wave rectifiers because they're inefficient and cause "...the core to become polarized and to ...
34 views

### Finding Cutoff Frequency

simulate this circuit – Schematic created using CircuitLab What is the smallest value of C that will ensure that the 3dB frequency is not greater than 100Hz? That is the question ...
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### DSP + ARM Processor For Digital Audio Mixer [on hold]

I'm currently working on a project where I have been tasked with a team to create a digital audio mixer. I need a processor that preferably has a 1 DSP core and 1 ARM core both running close to or ...
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### Reuse a microphone (formerly) wired to the digital “General Purpose Input/Output” of a Realtek sound card?

I recently repurposed an old laptop screen (from a Dell XPS L502x) as external monitor, and then made the built-in webcam work without too much fuss. The camera module also has an embedded ...
65 views

### Bad idea? Powering uC from two separate supplies?

Okay, a little background: I am designing a micro controller daughter board (uCDB) that is nominally powered at 3.3V by a voltage regulator on a mother board (MB). Also I will have a programmer board ...
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### Solve the sync. system. Up till zero, XOR the bits, from zero, I/O is same

I need to build an sync. system with single I/O that, until we reach the first zero(including that zero), the output will be XOR of the bits that were read up till that point(including the zero), ...
29 views

### How do I prove that the following function is a complete system

Here's the picture: How do I prove that {f,1} is a complete system? Well, in the answers it is written that if we apply 1 to A, then we'll be able to create NOR. and NOR is a complete system. (It ...
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### Photomultipliers in Parallel

I have a photo-multiplier going into a preamp then two stage shaping amp (PC250 and PC275 board from Amptek). The photo-multiplier is attached to a plastic scintillator and then a beta emitting ...
25 views

### Failover Management from AC to DC and DC to DC

I'm working on a project that has a high availability requirement. As such, I must maintain a power supply output of 12vdc ~1a (ideally 13.5vdc ~35a). The 1a option will sustain the core equipment, ...
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### Power factor correction consequences

From what I know so far (might be wrong), The ideal or unity power factor means that all the energy is consumed by resistive components and are converted to heat, light, etc. In this case apparent ...
34 views

### Car ignition coil power supply

I'm making a car ignition coil tester. The thing is I need a constant 12v 5A DC supply for the project, so I'm going to use a laptop power supply. The one I have is 220V AC/DC 19V 4.75A. How can I ...
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### Powering RC Servos using Switching Power Supply

I have 3 RC HV Servos (working voltage 6-8.4V) (link). I purchased a 75 Watt Switching Power Supply (link). The servos draw about 3amps at full load.Is a 75Watt supply sufficient or do I need more ...
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### Advice and critical remarks regarding the manufacturing of a DC-DC step-down converter

I'm in the third year of my electrical engineering major and I want to take things a bit further than the usual analogue electronic circuits I've studied thus far by making a DC-DC step down converter ...
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### Current flow in long channel MOSFET in saturation

Why doesn't the current in long channel nMOS decrease with drain voltage due to pinch off that takes place when gate voltage at a point in the channel is less than the threshold.
47 views

### Solve a circuit with the nodal analysis

I have the following circuit, and I have to find Vo: I solved it in this way:  \\ \begin{cases} \frac{v_1 - 40}{1} + \frac{v_1 - v_0}{2} + 5 = 0 \\ \frac{v_1 ...
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### CN Interrupt (interrupt on change) on PIC32mx not working

I attached a module which communicates with my PIC32mx via UART. I am trying to bit banging this UART communication but I am not able to see the interrupt being triggered. I am using the CN4/RB2 Port ...
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### About transconductance amplifier Capacitance direction

If I use a polarized capacitor for C_large, which side should be the positive  terminal? You have to decide this based on the total voltage across the capacitor.  I am using 330 microfarad ...
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### how to solve this problem by thevenin's theorem [on hold]

Find the voltage across the 4 Ω resistor in Fig. B. using Thévenin’s theorem. circiut diagram ...
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### PIC C program flow problem XC8

Problem: My C code is not running to the end. To test my EEPROM read and write, I decided to write a simple array and read it back to different array using a PIC. However the problem is not the ...
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### stm8s I2C Communication

I want to use I2C Communication between two stm8s208cb MCUs. I use stm8s standard peripharel library. My code: Master: ...