Where power is a primary concern for the design under discussion. Use the "low-power" tag when that applies.

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0answers
13 views

Is possible to get very narrow beamwidth antenna?

Is possible to make 60 dBi sector or patch antenna by make its beam width 0.17°/0.17° only ? how to calculate ideal dimensions against frequency at this range of beam width ?
0
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2answers
52 views

Does a typical mobile adapter draw current when no load is attached?

Summary: I am comparing the trade off of wasting my time daily plugging and unplugging multiple chargers at multiple sockets. I need to know approximately how much Amp is my adapter drawing every ...
-1
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0answers
42 views

Voltage drop across outputs in my 4 iPad connector

Thanks for the patience i reworked my question to be as detailed as possible I designed a circuit to plug several ipads at the same time To feed from the circuit from my connector im using a ...
0
votes
1answer
38 views

Shielding not connected to USB connector causes tablet restarts

I have a custom USB cable, USB type A male on one end and a DB-9 connector on the other end (only using 4 pins). The shielding of the cable is connected to the USB connector but not the DB-9 ...
0
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0answers
13 views

SIM908 PCB Switch Current Contact Rating

I am working on a board with a SIM908 module. The board is powered from a 4.2V Li-po Battery. The user must be able to switch the board on and off with the aid of a slide switch. My problem is ...
0
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1answer
66 views

Get clean 9VDC power from 9VAC using a LM317T

I'm having trouble with this design, I have this circuit below, but I already have the 9vAC transformer, so I just need to convert the current to DC, so: If I remove the Vadj part of the LM317T on ...
-5
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0answers
36 views

heavy urban 1200 km best band ? with no sky support [on hold]

what is the best band can propagate 10 kbps of data from chicago to newyork by direct wave or groundwave "no any skywave support" ? how to calculate path loss at this long range ?
2
votes
2answers
106 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 ...
0
votes
1answer
52 views

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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2answers
103 views

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 ...
0
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2answers
75 views

High voltage power lines

Why are high voltage power lines used? Electricity is generated at 11,000V...so is that a potential at the generating station or potential difference across the ends of the power line? And if it is ...
1
vote
1answer
43 views

Inverter constructed using LDMOS transistors

I have the following question: is it possible to construct an inverter using LDMOS transistors when HV power supply is equal to 30 V and maximum VGS for LDMOS transistors is 5 V? Moreover, lower MV ...
2
votes
1answer
288 views

What is an antenna amplifier ? How does it add gain?

I don't know what exactly does antenna amplifier mean. Is it possible to increase the gain of a Tx antenna ? Where do I connect the antenna amplifier to it ? If, for example, the Tx has a power of 20 ...
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votes
2answers
45 views

Can I use a 250 VAC socket for 120V power?

I live in canada and I'm trying to build some DIY audio gear. I'm using a toroid http://www.digikey.com/product-detail/en/VPT30-830/237-1326-ND/2090064 (115, 2x15v) And this socket to go with it ...
0
votes
1answer
65 views

Just I want to understand gain, power, link budget

I am a beginner, I am confused about calculating the nessecary gain and power and sensitvity to overcome path loss at certain distances. the first thing what does gain mean ? I am not talkink ...
0
votes
1answer
46 views

If I connected N numbers of amplifiers each have X gain 'dB“ and Y power ”dBm", how to calculate total gain and power?

sorry for bad description, I am a beginner. my question is just for knowledge and I did not test anything. If I connect for example 3 amplifier , each one has 60 dB gain and 15 dBm power. can we ...
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votes
1answer
58 views

240 volt cheaper than 120 volt? [closed]

We just installed a 6' 240 volt baseboard heater (hardwired). Will electrical consumption be less that using the plug in 120 volt electric heaters we used to use?
5
votes
3answers
408 views

What should I use for powering a Raspberry Pi at near space altitudes?

I'm planning a high-altitude weather balloon project (to around 100000 feet) some time down the line to take video and pictures of near space altitudes and I have some questions I need to ask before ...
0
votes
1answer
75 views

Chattering relay on microcontroller power supply

I am working with a device that has a relay on the 12v power supply to the micro controller that runs the device. Under certain unplanned circumstances this relay can chatter. What is the potential ...
0
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0answers
26 views

Can we use magnitude of C parameter (ABCD parameter) as admittance and B parameter's angle as impedance angle in numerical problems?

I read they can be approximately treated like this in analysis because C has unit of admittance? Can we consider like this?
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vote
2answers
135 views

Where does radiated power come from?

I've had electromagnetism classes back in uni, but I'm having a hard time linking them with that matter: Take a car antenna -which I assume is simply a wire, coiled or not-, and apply a voltage ...
-1
votes
1answer
33 views

maplin xm22y power supply [closed]

I have A Maplin xm22y and the main power transistor blew. I ordered a replacement transistor (tip3055), but wonder that since the transistor is broke I now have a 23 vdc reading. Is there a way on ...
0
votes
0answers
31 views

Energy Monitor IC with built in Hall Sensor

I have looked at a couple of IC's which provide energy measurement(real power,apparent power), however these need to interfaced to a current transformer or a hall effect sensor since they cannot ...
0
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1answer
54 views

Relation between C-rate and power of a battery

I'm a non-engineer, but I need to understand the function of a battery. I hope you can help me! For example, I have two bulk storages. 5MW (power) 5 MWh (capacity) 5MW/10 MWh So the definition of ...
1
vote
1answer
85 views

Combining LDOs in an effort to increase current

Is there any way to combine 2 (or more) similar LDOs with fixed output voltage so the total output current would be increased? Buying another LDO is possible but I have a large stock of 1A LDOs and I ...
1
vote
1answer
60 views

Leakage current during sleep mode?

This is an assignment question: A system is operating at 325VDC input, what is the required static leakage current during sleep mode in order to achieve Zero power? I know there may be a lot of ...
0
votes
2answers
71 views

Do I use a 5V 2A or 3A DC adapter to power my 2m (6.5ft) WS2801 LED strip?

(Please excuse me if my English is bad) I recently purchased a 5m LED strip, but I only need to power approximately 2m (6.5ft) of the 5050 RGB LED WS2801 strip, but I'm afraid that a DC power adapter ...
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votes
4answers
85 views

Please give the simplest explanation of what electricity exactly is

Nothing technical, no mathematics. Just an explanation of what electricity is. I am having a time understanding the whole idea of how electricity works because I don't understand what electricity is. ...
0
votes
2answers
63 views

Can I use the 12V line of a computer PSU to power my circuits?

Or is there any issues I should be wary of? I need at least 7A on a 12V line, but I've found that a computer PSUs are significantly cheaper.
0
votes
2answers
79 views

Design help for my 1A variable power supply

In a 1A Variable Power Supply circuit given below is it possible to use a 2A transformer and 1A bridge diodes.
2
votes
1answer
59 views

Finding the Power developed by the Nominal Frequency in FM

Question The sinusoidal signal \$f(t) = \cos(2 \pi f_m t)\$ is applied to the input of an FM system. The corresponding modulation signal output for \$f_m = 1kHz\$, is $$Q(t)=100 \cos(2 ...
0
votes
1answer
64 views

Why monitoring power and energy in energy usage meters?

This time my question about the how power companies monitor usage. We get electric usage bill in [Kilo watt hour]/Energy. What should be looked up on for monitoring the usage the instantaneous energy ...
1
vote
1answer
27 views

What is the minimum voltage for general loads and peltier units

I am confused with "power ratings" on devices and electrical components. First, what is the power rating on a home appliance or a electrical component saying when it is 12V? Is it saying "we would ...
0
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0answers
21 views

Piranha LED board connected to USB charger [duplicate]

Can I use this Piranha Light board to connect to a 5v power source like a USB charger? Do I need something extra (more than an USB-cable)? And can I connect more boards to the same circuit? (New to ...
2
votes
1answer
78 views

Power Mosfet design issue

My schematic The components BSN20 is a N-channel enhancement mode field-effect transistor (datasheet) IRF7416 is a HEXFET power MOSFET (datasheet) This is a part of a project in which the line ...
0
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0answers
34 views

High voltage distribution line fault current

On a conventional 7,200 volt distribution line, what would be the average fault current in a scenario like the one shown in the video below? Video Specifically, I'm wondering what the power ...
3
votes
4answers
139 views

How do I find the voltage range for an unknown DC motor?

I have a small unmarked motor with a burned out speed controller board. I'm able to figure out that the motor is a DC motor because it has two wires coming out of it and there's a rectifier on the ...
0
votes
1answer
74 views

Amplify a 12 MHz sine wave

I need to take a 12MHz AC sine wave, from around 3.3V - 10V @ 10uA, output 50V, @ 1A (or more). I have the signal generator for signal input, but I am not certain what I need for a circuit to step ...
1
vote
2answers
51 views

What's a probable VA rating for this?

I bought a variac at a garage sale a few months ago and I've played with it since then with a 40W incandescent desk light. Now I want to use it for the incandescent house lights in a small theater. ...
-7
votes
1answer
97 views

How to get power/electricity when the power is cut? [closed]

My power bill is cut and power is out until someone pays it. I was wondering if there are any scientific methods available to create a source of power to charge a laptop and keep it full for at least ...
1
vote
3answers
321 views

Child-Safe setup for ESD protection environment on desk

I need to setup an anti-static workbench in my spare office, and kids sometimes get into it ever since they learned how to pick the locks. My intended approach is to: Lay out an ESD mat on the ...
0
votes
1answer
66 views

Simultaneous Buck-Boost or Flyback Regulator - Help Selecting Chip [closed]

I have been trying to find a switching DC power supply that outputs a constant voltage of 12VDC, given a variable input between 4V and 25V. It's to my understanding I'd need a buck-boost converter, ...
2
votes
1answer
72 views

Can I extrapolate the rated overload spec of a wirewound resistor to a joule rating?

I'm considering using a Vishay FVT series resistor for precharging some capacitors. Capacitance: 3300uF Voltage: 730V Resistance: 500 ohms Resistor continuous wattage: 25W This series, like many ...
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votes
2answers
94 views

I want to operate a DC 9v relay with a small power

Can a lightbulb be switched on using two mobile phones? (Make a call and the bulb switches on) I need this for a kid's school project so the questions like should the bulb keep glowing after the ...
2
votes
1answer
106 views

Boost regulator: Unexpected output voltage

I just finished setting up an LM2577 as a boost converter, and have run into some unexpected issues. For starters, here is the recommended "typical application circuit": My application circuit is ...
0
votes
1answer
77 views

Commanding a 12V DC motor with high power (~20A)

I'd like to control a 12V DC motor but it has very high power, around 20A. I was looking for H-bridges but they all support only low power (around 1A) Do I have to build my own H-bridge with high ...
0
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2answers
100 views

Does unplugging a television from the wall socket make it safer? [closed]

Does unplugging a television from the wall socket make the electronic safer (against power surge for example) compared to: Plugged in, button on wall socket is off Plugged in, button on wall socket ...
0
votes
1answer
65 views

Strategies for powering an ATtiny micro controller and 40W peltier from mains

I'm trying to power an ATtiny1634 at 5VDC and a 50W peltier element at 12VDC. The microcontroller will, amongst other things, turn on the peltier via a 5VDC non-latching relay. I want to use an ...
1
vote
2answers
70 views

What is the sign convention for generated power?

Generally speaking, generated power is denoted as negative, correct? If I understand correctly, this is just the convention. Conceptually, I think of it kind of like a force, it has a magnitude and ...
1
vote
1answer
82 views

Stable voltage at high current

I am working on robotics project. The drive chassis is powered by a 3-cell 12V 8 Amps battery (I might also go for connecting two batteries to attain speed as my drive motors work at 24V full power). ...