Questions tagged [electrical-engineering]
Study and applications of electricity, electronics, and electromagnetism. Use this tag when someone who has trained as an electrical engineer is likely to be able to answer your question.
1,468
questions
3
votes
2
answers
164
views
Trasmitting data from pressure transducer to phone/web server
I am creating a 24 hour blood pressure monitor that is designed to be sleek and comfortable, I have decided on The Honey Well Series NBP AN transducer (see more info here: Basic Board Mount Pressure ...
1
vote
1
answer
110
views
Charging a battery pack using a motor
I want to fit a Hub motor ($15kW$ BLDC motor) to my car to convert it into a hybrid vehicle.
Would it be possible for me to use the same motor (as a generator) to charge my battery pack, while the ...
2
votes
1
answer
94
views
What is a multi-standard mcu?
I was watching a video on the ti products out currently for wireless microcontrollers, and they mentioned a "multi-standard" CC2650 mcu here http://bcove.me/uekqgi7q. What makes a microcontroller "...
3
votes
1
answer
909
views
Piezoelectric matching/backing layer materials
To maximize the piezoelectric transducer reception/transmission power we must choose the correct backing/matching layer materials, I'm working on a project to measure a steel tank liquid level (non ...
1
vote
2
answers
2k
views
How to find the stability margin of a transfer function?
In the control there are two kinds of margin
Phase Margin
Gain Margin
There are plenty of examples available to find about it.
Now here is my doubt.
What is stability margin? I was studying ...
2
votes
0
answers
426
views
Make a prototype of a braille tablet using arduino [closed]
I want to basically make a pin matrix controller either by using spring, electromagnets or small motors. Spring being the most viable option. Something like what’s shown in the image. I'm pretty new ...
2
votes
0
answers
287
views
ABS Traction control / fiddle brakes
I have an 4x4 which I have heavily modified, the only thing missing is mechanical differential locks. I think it wouldn't be too hard to fit a four channel abs pump from another vehicle and produce my ...
4
votes
3
answers
4k
views
Why do these car headlights run on AC?
One night, raining, crossing a street, I noticed strange thing about one of the stopped cars: In front of that car's headlamps, it rained dashed lines. I assumed that the car used LED for lights, ...
2
votes
1
answer
124
views
Transducers in cuff-style blood pressure monitors
I have been doing research into blood pressure monitors, and I was wondering when the cuff tightens, how do the transducers actually measure the systolic/diastolic pressure in the arteries.
3
votes
2
answers
117
views
Effect of Dimensions on Plate Capacitor [closed]
We have a plate capacitor:
The picture shows this plate capacitor where the space between the electrodes is filled with a dielectric plate with dielectric constant $E_r = 8$:
Determine the length of ...
3
votes
1
answer
255
views
Electricity generation via piezoelectric roads, stairways, is it plausible?
I've been wondering if roads and stairways laced with piezoelectric generators be a viable method in clean energy generation?
I'm currently unfamiliar with all engineering aspects of ...
3
votes
1
answer
126
views
Autonomous RC car trying to stop at a point
I am doing a robotics project. The goal is to make an autonomous car start from one point and stop at another point around 10 +-1 meters away. I need to make a steering mechanism. I want to be as ...
1
vote
2
answers
165
views
Why to avoid over sizing a DC Motor?
Someone told me to avoid over-sizing when using DC Motors. Why? Is this because of sparking and higher wear (brushes) while the motor is running at a lower power rating?
Can someone explain?
-1
votes
1
answer
45
views
What tools to use for a solar powered backup? [closed]
Recently, we experienced complete outages for around 8 hours, due to construction on a nearby road. We have decided to install a backup battery and solar array to prevent this from happening in the ...
1
vote
0
answers
92
views
Signals and systems convolution problem? [closed]
hey guys I'm having trouble with a convolution problem here
A continuous-time linear system has the input/output relationship
$$\int_{-\infty}^t (t-\lambda-2) x(\lambda) d{\lambda}$$
For $1 ≤ t ≤ ...
3
votes
3
answers
861
views
Use npn (2n4401) and pnp (2n3906) connected to single microcontroller to switch
I want to use a NPN (2n4401) and PNP (2n3906) with both base connected to a single microcontroller output in order to switch voltage to two inputs off and on. I'm not sure how to create the circuit I ...
1
vote
2
answers
82
views
Help with reading resistor color codes
I'm having a difficult time identifying a resistor's value as I can't find the golden / silver tolerance line.
The problem is that I can't see a silver or gold line here! They're both brown on both ...
0
votes
1
answer
49
views
How would you measure the electrostatic field of a celestial body from its surface?
If we need to measure the Electrostatic field of a celestial body due to its interaction with space plasmas, What kind of instruments can be used to achieve this?
2
votes
1
answer
1k
views
How to determine signal strength verses distance for LTE base stations?
All mobile phones have bars or some other type of indicator displaying signal strength. As mobile devices move away from the base station the signal strength becomes weak and at some point becomes out ...
2
votes
1
answer
160
views
How can one determine the LTE base station providing service to a mobile device?
In order to have continuous service a mobile devices switches to base station with higher signal strength.
Question: Is it possible using the mobile device (Android or iPhone) to determine to LTE ...
2
votes
3
answers
223
views
Why not only GSM (3G/4G/..)? Why do we need Bluetooth, Wifi,etc...?
It is quite frustrating to have multiple adapter for connecting to desktop. For example, if I want to connect my phone to desktop I need Bluetooth/wifi; why can't I just just use the Mobile's main ...
3
votes
1
answer
797
views
How to measure transmit power level from LTE base station?
Can someone tell me what type of equipment is used to measure RF power levels transmitted by a cellular LTE base station? I would like to gain some insight into how the follow data was obtained.
...
4
votes
2
answers
150
views
Why don't cellphones use unidirectional antennas?
Why don't cellphones use unidirectional antennas instead of omnidirectional (single dipole) antennas?
This could be accomplished by using a unidirectional array of dipole antennas (specifically, a ...
4
votes
1
answer
184
views
What is that airplane headphone socket?
I recently flew on a A380 and I saw this interesting socket.
Could someone explain to me what is the purpose of these 4 golden connections?
2
votes
2
answers
177
views
Why do hairdryers use line power and beard trimmers use adapters?
Hairdryers are capable of electrocuting people and are used in generally wetter conditions and run on mains power. Trimmers are used on dry bodies and use safe DC power from an adapter. Why are ...
0
votes
1
answer
45
views
Inductor/Transformer core design - reducing losses from eddy currents
From what I know, the key to reducing losses due to eddy currents in a core is to reduce the path that they take, as is shown in this diagram illustrating solid vs. laminated cores (courtesy of ...
3
votes
0
answers
140
views
How is modulated the Primary Synchronization Signal in LTE?
PSS is based on 62 values from a Zadoff-Chu sequence. Three different sequences can be used by an LTE Cell, to represent the Physical Cell ID within the Cell ID group.
The formula is the following, $...
2
votes
2
answers
4k
views
In Control Systems Engineering, why do imaginary poles and zeros on the LHP indicate stability?
I understand that poles on the left hand complex plane (LHP) make a continuous linear dynamic system stable. What's so significant about imaginary poles on the LHP that make a system stable? What does ...
1
vote
1
answer
50
views
How small can coolers get? [closed]
Ive been wondering about how small of a cooler you can build.
Although this probably is just really low-level engineering, i have a rather particular question.
For my idea, the cooler has to be as ...
1
vote
1
answer
69
views
Will the water in a gold fish bowl signficantly abosorb Bluetooth or WiFi if transciever is at bottom of bowl?
Using WiFi or bluetooth frequencies 5.8GHz and 2.4-2.485GHz respectively, I want to place a hermetically sealed circuit at the bottom of a gold fish bowl, and want to know if the water will ...
1
vote
3
answers
168
views
Is epoxy the best way to permanently attach a small PCB to a mechanism that will be vibrating?
PCB module is about the size of a nickel and has an ARM processor and a sensor chip or two, plus a connector with 5 or 6 wires.
Module must be firmly attached to device because device will be ...
1
vote
1
answer
32
views
Is there a way to quantify or graphically represent noise immunity? Is noise immunity different than noise margin? If yes, how?
Generally, there is a talk about noise margin and noise immunity in digital circuits. Both terms seem interrelated but some texts differ from this. My query is whether these two are entirely different ...
1
vote
0
answers
195
views
am335x use gpio with pull down
I'm working with a custom made mini computer, am335x based.
It comes with 2 GPIO ports that we use to provide services to our customers.
I want to change one of those specific ports, that is already ...
1
vote
2
answers
2k
views
Looking for a current multiplier circuit - if possible
I used a very inexpensive circuit based on the TP4056 chip and built a Lithium Ion battery charger for 18650 batteries.
The problem is, the batteries I use have so much capacity that the circuit, ...
4
votes
0
answers
88
views
Technical Analysis to determine optimal Cellular to transmitter location
At a very high level what are required technical analysis to
determine the need to for a new 4G LTE cellular transmitter in US?
find find the optimal location for the transmitter in US?
Back Story: ...
1
vote
1
answer
53
views
substituting power supplies safe?
I have an old casio casitone CT-310
Rating: DC 9V 8.5W
Battery 1.5V x 6
or AC adaptor AD-5
I'm looking around the house for a power supply to use.
I found the following:
Output: 9V DC 200mA
from a ...
2
votes
1
answer
51
views
What happens if current provided to mono phase motor is less than rated power
I have a 0.5 kW single-phase AC motor. What happens if the supply is 220 V but can't supply the full current needed? Will the motor torque be lower? Or will it be slower?
Will it be any ...
4
votes
1
answer
695
views
External circuit turning on powerbank
I have a circuit that consumes enough power to keep running from a powerbank. However, to save energy I'm putting it in low energy mode at night.
Problem with powerbanks, they turn off when not ...
0
votes
1
answer
61
views
Light transmittance of acrylic with temperature
I have a 2 mm piece of UV transparent acrylic sheet. The datasheet defines it as 80% transparent at 300 nm. However, when I use it with different temperatures (4-50°C), the transmittance ...
1
vote
1
answer
130
views
Interference between direct signal and reflected signal
A laptop's antenna receives signals from a Wi-Fi router in two ways:
signal falling directly on the antenna from the router, say 1 m away
signal coming from same router but bouncing off the ...
2
votes
1
answer
349
views
Why we use GPIO for embedded systems? [closed]
I'm using an F2802x microcontroller and I saw in Embedded Coder in Simulink that I have Digital output block. When I use this block, how does it work?
1
vote
0
answers
79
views
How can I use a p-iris/autoiris lens on a camera without a connection port? [closed]
My team owns a Point Grey camera that we need to attach a wide angle lens to. The wide angle lens we have has a cable allowing for autoiris and p-iris control, but the camera doesn't have the autoiris/...
1
vote
1
answer
72
views
What can I use to calculate distance? [closed]
Please excuse my ignorance in advance, (I'm in cs not EE), I am trying to figure out how can I get the distance from a car to a wall, what form of technology could I use IR sensors, ultrasound, etc.(...
1
vote
0
answers
466
views
How can I increase my ultrasonic sensor accuracy?
I am using a long ranged ultrasonic sensor to measure milk height in milk silos. Milk is stirring.
Milk Silos Design: Shows two type of silos both are stirred in different direction
2
votes
1
answer
655
views
Constant current load under varying input voltage
I am building a battery discharge system for LiPo batteries which accepts a charged battery and discharges it at a CONSTANT CURRENT regardless of the battery voltage, until a threshold is reached. The ...
3
votes
0
answers
111
views
FM transmission exercise
I'm encountering some troubles while trying to solve this exercise.
Let us consider a radio link between a geostationary satellite and a ground station. We send a binary signal (represented by two ...
1
vote
0
answers
140
views
What are the various lumped element dynamic system models called?
What are the various lumped element dynamic system models called? By lumped element dynamic system models, I mean the various nodal models comprised of things that look like capacitors, inductors, ...
1
vote
1
answer
147
views
Does electromagnetic shielding using conductor metal sheet enclosure attenuates magnetic field as well?
Does electromagnetic shielding using conductor metal sheet enclosure attenuates magnetic field of the electromagnetic wave as well? If yes, what is the relation? I know it does attenuate electric ...
1
vote
0
answers
81
views
Can't solve the 2nd order differential equation of a stepper motor single step position
I want to assess how much time it takes for a single step of a stepper motor to settle.
Starting from
$$\tau=J\frac{d²\theta}{dt²}$$
Taking
$$\tau=K_m cos(\theta)\approx K_m \theta$$
Yields
$$K_m \...
1
vote
0
answers
759
views
How to power a large electric motor from a battery?
A question I ask myself now and again is if it is technically feasible to build battery powered construction equipment, like large excavators - say 250kW motive power at the shaft of the central ...