Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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1500 questions
27
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4 answers

Can I pedal power a laptop device while the device is being used?

I want to research how easy it would be to use a small laptop device while powering it by pedaling on a stationary frame. (For example, using a tablet on an exercise bike, or using a netbook while pedaling at a desk.) I already know that it is…
Katherine Rix
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How to Convert 0 to 10V analog signal to 0 to 2.5V for ADC input?

I have an analog signal which ranges between 0V and 10V. I want to linearly scale it down to 0 to 2.5V for my ADC. I'm concerned that using a resistive voltage divider will affect signal quality. Is this true? If it's not true, what value…
lionheart
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What is this unusual LCD controller technology?

Preface: Even if you do not have a definite answer, I would greatly like feedback from anyone who has even seen an LCD using this technology. I recently took apart a Canon digital camera from the late 1990s and obtained an unusual LCD display.…
3871968
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Why are there only RGB and RGBW-LEDs, but none with more chips inside one housing?

In another thread the question emerged, where the LEDs with 5 or more dies of different colours are. (Kudos to Brian Drummond) The background is as follows: RGB LEDs are very popular for creating colourful lighting effects. In fact, due to the three…
Ariser
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Anti-static bags - safe to support powered circuit boards?

Is it generally safe to rest a low voltage powered up circuit board on an anti-static bag when debugging? A simple meter reading suggests it is a good insulator, but it must conduct to some extent? Ditto on anti-static mat on the workbench
Dirk Bruere
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Why does USB have Vcc=5V and high=3.3V?

I am thinking about adding USB support to a device of mine using V-USB. From what I read there and on other sites USB seems to have only 3.3V as a high level on the data pins, whereas the voltage supplied by USB is 5V. What is the reason behind…
Dakkaron
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Why are FPGAs used so often for HDMI video projects?

If you look through hdmi projects on a site like hackaday, you'll find that just about every one of them involves an FPGA. I don't think I have seen any DIY project with HDMI output that hasn't used an FPGA. But why? As far as I can tell, FPGAs are…
kcghost
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27
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8 answers

Why does a capacitor block DC and not AC?

If someone can explain why a capacitor blocks DC, but not AC, with some math, I will understand all of that much better. I know that there are picture animations illustrating this, but I really want to know this a little bit more detailed.
Junior
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8 answers

How bad is it to undervoltage a 12-volt lead-acid battery?

I had a heated discussion with a few colleagues today revolving around how low of a voltage was alright for 12 volt lead-acid battery; they were in the opinion that the low voltage warning buzzer and ultimate automatic shutoff was annoying and a…
MikeFoxtrot
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4 answers

std_logic or std_ulogic?

It seems that the world has decided that std_logic (and std_logic_vector) are the default way of representing bits in VHDL. The alternative would be std_ulogic, which is not resolved. This surprises me because usually, you're not describing a bus,…
Philippe
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How does an inductor store energy?

I know that the capacitors store energy by accumulating charges at their plates, similarly people say that an inductor stores energy in its magnetic field. I cannot understand this statement. I can't figure out how an inductor stores energy in its…
Andrew Flemming
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10 answers

Can a 10% resistor be used as a 1% resistor?

If my schematic calls for a 1% resistor, can I use a 10% resistor that measures to the correct resistance within 1% or is there some quality to tolerance beyond what it measures Ohm-wise? For example, my schematic calls for a 1% 1000-Ohm resistor. I…
Tyler Durden
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27
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5 answers

Good beginner book on ARM

I'm looking for a good beginner book for ARM microcontrollers. It should cover the CPU architecture and the boot sequence and ideally also assembler, C and peripherals. I have a book like this for AVRs and there seem to be several good choices for…
kwo
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27
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7 answers

Internal or external oscillator

I always use the internal oscillator that pics have as I have never found the need to run anything at higher frequency than 8 MHz (which is the fastest the pics I use tend to be able to go). Are there any reasons, beyond going above 8 MHz, that mean…
SimonBarker
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Spacecraft Power Supply Frequency

I know that aircraft sometimes employ a 400Hz AC system to save weight on transformers, so I'd imagine that spacecraft might employ a similar technique. I'm wondering if anyone in the aerospace field can confirm 400Hz or higher frequency operation…
RYS
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