# All Questions

0answers
9 views

### Power line voltage out of phase with ambient 60hz electrical noise - why?

I just bought my first oscilloscope and have been tinkering with the measurement of different signals just to learn the ropes and familiarize myself with the scope. One of the first things I noticed ...
0answers
8 views

### How to monitor data exchange on single wire?

I have two modules that communicate over a single wire. Where would I even start about monitoring the data without introducing any kind of interference to both modules? One of the modules has to be ...
1answer
13 views

### Common Base Amplifier

I am thoroughly confused on this topic. How does "common base" even make sense? If the base is grounded then the transistor is turned off, so how does the input reach the output?
1answer
12 views

### Memory Problems

I've been having some problems with memory ICs, specifically Flash and EEPROM. I've had some experience with the 7400 series for some time...logic gates are pretty straightforward. Input something, ...
0answers
4 views

### vhdl recursive instantiation with packages

I have a system where a design and a subdesign inside it are different architectures of the same entity; so this is a case of recursive instantiation. First the setup : ...
0answers
21 views

### Worm Motor shafts?

I finally got a large motor for a rotary spark gap on a tesla coil from an old pool pump. The motor unusually has a screw motor shaft on the end. How can I add spark gap parts to this end, and ensure ...
4answers
45 views

### Adding indicator LED to optointerruptor circuit?

This question relates to my earlier question on how to wire an optointerruptor:Figuring out wiring of optical encoder I was able to get the optointerruptor working using the circuit below. I wanted ...
4answers
2k views

### Basic questions about transistor amplification

Can anyone explain how a transistor can amplify voltage or current? According to me, amplification means - You send in something small, it comes out bigger. Say for example, I want to amplify a sound ...
2answers
221 views

### What type of component would be required?

I apologize in advance if this is the wrong place to ask the question. Although it does in someway relate to electrical engineering, at the product level, i am sure. Basically i am trying to figure ...
1answer
9 views

### MPS430 Launchpad Keypad

I tried to use my MSP430G2553 launchpad with a keypad using http://www.pjrc.com/teensy/td_libs_Keypad.html http://bildr.org/2011/05/arduino-keypad/ ...
1answer
21 views

### BJH H-bridge going in reverse but not forward, LL transistor overheating

I've built one of this BJT H-bridge to control a DC motor in an old R/C car of mine, but I'm having problems with it and wanted a few tips to help me debug the board. The motor is a 2-wire DC with ...
2answers
15 views

### Correct Part for Connect an Two-Pin LED or Switch

Quite simply what I'd like to know is, what is the technical information for the male connector that corresponds to the following plug: The male connectors (headers?) are commonly found on computer ...
1answer
24 views

### Voltage to current ratio in a circuit

How do I find the ratio $${V_0\over I_s}$$ in the following circuit? Thanks!
0answers
20 views

### KiCad: Component outline on the soldering pad - will it disturb the soldering process?

Lots of KiCad's SMD components (including capacitors and resistors) print the component outlines over the solder pad. The pictures are shown below, please notice C25-27, R5-6 and D2-3 PCB design ...
1answer
136 views

### Intersection Turning Movement counts

Civil Traffic Engineers have a perpetual data gathering problem. They need intersection turning movement counts to do their studies. This has historically been a manual task. Someone sits by the ...
0answers
16 views

### 4-pin quartz resonators - shall the 2 ground pins be connected to ground plane of the pcb?

I am about to use a 8MHz quartz resonator that has 4 pins (http://datasheet.octopart.com/LF-XTAL026380.-IQD-Frequency-Products-datasheet-6993.pdf): pin 1 and 3 are connected to resonator while pins 2 ...
1answer
41 views

### Switching regulator for 40~80V

If I have only +-5v source, can I boost it up to +-80V ? If possible, can you recommend a part? If not possible, how should I combine multiple booster to make it to high voltages. Thanks
0answers
10 views

### Torque measurement of induction motor

what device should be used to measure the torque of 3 phase induction motor? The motor is of 3000 rpm or greater
1answer
135 views

### correct wiring of a preamplifier and a lock-in amplifier

I've got a question regarding the correct wiring. I'm operating a vibrating sample magnetometer. It uses two coils to detect the magnetisation via induction. The two signals are amplified and mixed ...
2answers
44 views

### Combination of four half-bridge load cells

I have a kitchen weight scale containing four half-bridge load cells, each cell associated to one foot of the scale. I want to hack it to use it as a pressure sensor and link it to an Arduino ...
1answer
921 views

### A problem on synchronous generators

This is part of a problem of my past examination in Electric Machines. I don't know how to solve it yet. A salient pole synchronous generator $(X_q < X_d)$ has a connected load at rated ...
3answers
133 views

### I do not understand what power actually is

I realize this is probably a super common question, but I have to put it in my own words. I try to understand ohm's law with the water analogy. Two tanks with water, one with a higher level than the ...
0answers
47 views

### Horrible noise after plugins power to my laptop plugged into effects chain

I'm using some stompbox effects with my guitar. I'm comparing them with my laptop where I have few VST effects. Everything sound clearly until I plugged power supply to the laptop. Then horrible noise ...
1answer
145 views

### Migrated from C18 to Hi-Tech C 18.. Interrupt not working

Here is my source code. This code is working perfectly fine in C18 Compiler. Not until I migrated to Hi Tech C. It does not enter the interrupt service routine. Moreover, it somehow corrupted sid ...
1answer
36 views

### Alternative to TPST Shift Registers?

So I'm building a musical sequencer that uses a shift register to close relays and pass the discharge pins of three 555 timers through a manual switch and potentiometer (acting as a variable resistor) ...
1answer
32 views

### LPC FMC to FPGA pin mapping on the Zedboard

Does anybody know anything about how to map fpga pins to actual physical pins on the FMC connector on a Zedboard? Of course I have looked into the user's hardware guide and the master constraint ...
0answers
41 views

### How do I work out what temperature to use when desoldering?

I have a temperature controlled soldering station, and know that I need to set the temperature appropriately for soldering based on the solder I use when soldering, but how do I determine what ...
6answers
4k views

### How to convert AC to DC

I am designing a circuit that needs to output 5VDC @ 1A. I'm trying to use a wall transformer to step the voltage down to 12VAC. The next step is the diode bridge and ripple capacitor. The ripple ...
2answers
37 views

### external watchdog reset for AVR required

I had a circuit with atmega644PA and use internal watchdog timer to bring the controller from a hang state to known by a reset. but still my code gets hanged in ...
2answers
85 views

### Can I use digital pots for my feedback resistors to a buck-boost regulator?

I'm working on a design, and this will be my first attempt at a buck-boost regulator. I need the output to be variable because my application calls for different voltages under certain conditions. ...
4answers
125 views

### Different answers when using two different equations to find the same unknown (BJT)

Problem 43, chapter 6 in sedra and smith microelectronics. simulate this circuit – Schematic created using CircuitLab We are asked to find the current flowing in R1 and R2 knowing that ...
1answer
36 views

### L293D outputs different in different motors. Are there different types of DC motors?

I recently picked up a used Spider King RC toy from a thrift shop (http://amax-toys.en.alibaba.com/product/337890538-212191267/rsc_9021_RC_Spider_King_car.html). It had no remote or battery charger ...
1answer
53 views

### Converting Short circuit solar cell (5v to 50mA)

How to convert solar cell short circuit current to Voltage. Because i need to display it to a 10bit micro controller. The voltage must within 0-5V. I'm using a 3V 50mA (max output) solar cell. ...
0answers
78 views

### Will this motor controller take more motors?

If I was to connect two motors in parallel instead of just the one motor it currently has on each H-Bridge,, would the transistors on the motor controller blow? I have this motor controller - here is ...
4answers
3k views

### Raspberry Pi wiring simple LED

I'm completely new to hardware in general. I just got a raspberry pi and was messing around trying to get an LED to light up. I have everything wired like the picture below. I am using a 330ohm ...
0answers
14 views

### Accelemetor wifi module

I'm looking for a module that sends data from an accelerometer over WiFi. I looked around a bit and found this: Axivity-WAX3, but this was the only module I could find, and the site doesn't provide a ...
0answers
38 views

### The relation between light electric field and light power (optical modulation)

I have been keeping thinking this question for one week. Hope could get some help from you. Light 1: Electric field = $\text{e}^{j\omega t}$; Power = $\frac{1}{2}A^2$ light 2: \\$ \alpha = ...
4answers
686 views

### Desoldering an SON package

I have recently discovered that my AVR Dragon has a busted voltage regulator (see this). I am trying to remove the voltage regulator IC so I can perform the mod specified on that page, however it is a ...
5answers
183 views

### How to build a timed audio switch?

I want to build a simple device with 2 inputs and 1 output, all TRS 1/8" audio jacks. The device picks one of the inputs to pass through to the output depending on the time of day (at night, it ...
1answer
79 views

### How to design a schematic diagram of amplifier that can drive 8 ohms 0.25 Watts speaker? [on hold]

I have here a schematic diagram for amplifier that drives a 0.025watts 8ohms speaker. But what I need is an amplifier that drives a 0.25 watts 8 ohms speaker. So, here are my concerns: How can I ...
2answers
43 views

### D/A converter with 0.4 up to 4V voltage output

I have this circuit: I want to have as output: BCD Voltage 0 0.4V 1 0.8V . . 9 4V My circuit actually doesn't work correctly.
1answer
126 views

### Connecting three led transformers

I'm a furniture maker and I built a unit which used three circuits of led lights. Each circuit's transformer has a max output of 2.5 A. I would like to use a single switch to put between the plug and ...
3answers
160 views

### Reversing direction of a motor

I need to be able to reverse the direction of a RS-360SH motor The operating voltage is 7.2 volt Current is around 5 A on normal running and around 8 A during stalling. I tried to use a 2-pole ...
1answer
49 views

### DC motor starting and stopping

I'm powering a motor, and instead of rotating at a constant rate, it rotates roughly a third revolution every half second or so; the rotation keeps starting and stopping. There's no load on the motor, ...
0answers
90 views

### How does this prototyping style work?

I'm a little puzzled about a prototyping style I've seen used recently. Here is an example picture of a circuit made in this way: Can someone explain the process of making a board like this? Why are ...
5answers
5k views

### Python serial between Arduino and Raspberry Pi: Data is modified upon reception

I'm using an Arduino for sensor readings and sending them to a Raspberry Pi via USB, using PySerial for data reception. It works great, except for the fact received data is awkwardly modified (And ...
3answers
180 views

### PIR sensor (with open collector) + Arduino - anomalous results

I'm attempting to get a PIR sensor working with an Arduino Duemilanove. Nothing fancy yet, just attempting to get accurate high or low values from it first. The PIR sensor was bought from Cool ...
1answer
64 views

### Structuring Large Quartus Projects

I'm working on a project which will contain lots of smaller modules written in VHDL, how in quartus can I make this manageable also to the point that I can test the smaller modules. I am trying to ...
1answer
77 views

### Driving high-powered LED with demanding requirements

I have just purchased this impressive looking 100W "7-band" LED multichip, apparently it's the latest innovation. My problem is the chip's voltage demands are far lower than what ordinary 100W drivers ...
4answers
3k views

### what size of copper wire can act as a 150A fuse?

If I would like to use a piece of copper wire as a 150A fuse, what size of wire should I use? It doesn't have to be 150A very accurately, the parameters I need the wire to meet are: it needs to ...

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