# Tagged Questions

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

550 views

### 3-phase power calculation when phase to phase voltages are different

I have a 3-phase power supply rated at 230VAC per phase. However, the phase to phase voltages are not equal. Suppose $V_{RY}$, $V_{YB}$ and $V_{BR}$ be the three phase-to-phase voltages between ...
35 views

### 3 pin power adapter. 24V, GRN and COM.

Hello and thank you in anticipation for your answers. I'm trying to make a replacement power adapter (24V---3.75A) for a medical monitor. There are 3 pin connectors and the diagram on one side of ...
41 views

### Can we draw analogy between em power flow through free space and ac power flow through a transmission line?

Knowing that the free space has a characteristic impedance (which is purely resistive, measured in ohms) I was wondering if I can model the free space as an infinitely long transmission line- ...
4k views

### Are watts usually measured in watt-hours?

Pardon me, I'm a total newb to electronics. My question is, when a device is measured in watts, such as a 60-watt light bulb, is this ALWAYS supposed to be assumed to be watt-hours, i.e. 60 watts per ...
76 views

### Trying to get the most out of 48V 500mA switch

I am sorry, I don't have a lot of experience with electricity, but I'm going to give this a shot. What I'd like to do is utilize a switch, that is part of a large device. When the device turns on, the ...
2k views

### How much current can I draw from the Arduino's pins?

What's the maximum amount of current which I can draw from each of the Arduino's pins without tripping any of the internal fuses? Is there a limit per pin as well as an overall limit for the whole ...
42 views

### can 210 kw solar power plant generate 210 kw per minute with help of battery back-ups? [on hold]

can 210 kw solar power plant generate 210 kw of power per minute with help of battery back-ups? that means, 210000 watts in 1 minute, in one hour 210000*60 watts.
40 views

### Powering Several Electrical Components from Single Three-Phase 240V AC Supply

A system consisting of various electrical components is desired. Required supply voltages to power these components include the following: three-phase 240 V AC (directly through the supply), 24 V DC, ...
32 views

### Power requirements for NFC (RFID) chip

I'm new to electronics so please bear with me. I'm trying to work out what kind of battery would be required to use with the following chip: ...
201 views

### How to design a load

Requirements: I need to design a load that will be powered with 1-4 supplies at any given time. The design requirements are merely that if 1 or more supplies are 'on', there needs to be at least 1 Amp ...
193 views

### Using twisted pair for supply

Is using twisted pair for the supply in a long cable a good idea? The cable contains two twisted pairs; one twisted pair for CAN Bus, and the other twisted pair would be used for GND / Supply. What ...
35 views

### Average current (power) drawn per CPU cycle for smart phone Samsung Wonder CPU 1.4 GHz Scorpion Qualcomm MSM8255T Snapdragon [on hold]

kindly I need to know how much average current is consumed for each cycle for the above mentioned CPU
62 views

### Measuring Voltage and Curent Simultaneously with Probe?

I have very little experience with electricity, but I am doing a project in which I need to measure power output of solar cells. I am currently using this: ...
104 views

I am really stuck on this and I couldn't find any references on the internet regarding this. When a load is connected to a generator, why does the current withdrawn from the generator increases. Since ...
401 views

### Determine with Arduino if 220V AC power is on or off

What would be ways to determine with example with Arduino, is current 220V AC socket on or off state? Any other than using relay (noisy) or current sensing sensor (too big)?
38 views

### Microprocessor Power Relay

Beginning Electrical Engineering student here and had a basic question. I am researching microprocessor based relays and came upon the SEL-351 relay for differential over current. Looking at the spec ...
103 views

### Xilinx Xpower Analyzer: Expected scope definition in VCD

I use a VCD file to evaluate the power of my design. The VCD is generated using the following command in the testbench file. ...
152 views

### Will a 6 volt LED kill a 9 volt battery quickly?

I am building a little circuit and I am adding a little 6 volt LED to tell me when I have power going through. But my power source is a little 9 volt battery, will this LED kill this battery quickly? ...
55 views

### LED efficiency for IR remote

I've designed the following IR remote control circuit. I need to put 2 LEDs on it so I can physically, simultaneously point the remote at my wall mounted TV and my VCR, etc which is all situated much ...
78 views

### Determining resistance per load with only power and volts

I have a extra credit problem in my class and I'm slightly stumped as to where to go next after I determine the It, Et and Rt. I am starting with a total power of 2 watts and 32 volts. I know to get ...
79 views

### Will the relay break if the disconnected end voltage is too high

I'm trying to create a simple overvoltage protection circuit. In brief, there are times when my mains voltage goes well over 250V (normally 220) and I want to switch off the whole thing connected to ...
80 views

### High Current Battery Power

I'm looking to power about 10m of RGB LED strips (60 LEDs / meter) from a battery of some sort. Max current draw for the 10m run is 36A @ 5V. My initial thought was to get a ~12V RC Car battery and ...
106 views

### Will this circuit suffer from Shoot-Through? and is there a quick fix?

I'm considering a high-side, low-side driver using the DMG1016UDW COMPLEMENTARY PAIR ENHANCEMENT MODE MOSFET from diodes. The datasheet says The ON voltage is about 0.5V and ON the delays+rises is ...
115 views

### Does forcing a data line to a higher power make it more resistant to interference?

A device I'm working on as a hobby project requires me to transmit a HDMI signal over cat5. The TMDS lines in HDMI are balanced but in order for me to continue transmitting the DDC signal with the ...
85 views

### Can you combine two 12v DC 600mA adapters to make one 12v DC 1200mA adapter by combining the wires together and plugging both 600mA adapters in?

Can you combine two separate 12v DC 600mA adapters to make one 12v DC 1200mA adapter by simply combining the wires together and plugging both 600mA adapters in?
727 views

### Why do many electronics operate on 5 AND 3.3 Volts?

Many modern appliances use a 5V Power connection. Internally they are working with 3.3V. Wouldn't it be easier to have 5V everywhere? Examples are many USB devices or Routers (they use 5V for power ...
75 views

### How to power gate device without voltage drop [closed]

I'm designing some electronics and I want to be able to control a HC-05's power without having the 0.7V transistor drop. How could I do it? Are relays the only trick? Thank you John
99 views

### Arduino Coin Operated Appliances

As my server collection is rapidly growing so is its power consumption. I'm looking for a way to pay for the power before hand. I had something like this in mind. Although I'd use a coin acceptor such ...
128 views

### Why are capacitors used when obtaining dual power supply from a single power supply and how to know the values?

What happens if we only use 2 resistors in the figure. Why do we use capacitor if we have a DC source already? And whats the easy way to calculate capacitor capacitance for given R and Vin?
80 views

### Why are DC power supply's AC source connections interchangeable?

When we cut a power supply's DC output tips we need to be careful how we feed the circuit since one side is negative one side is positive. But why doesn't the same apply when we plug for example a ...
60 views

### Missing phase 3-quadrant TRIAC-based solid state relay for 3-phase engine

First of all, I'm a simple mechatronics technician student first time posting here, so please don't mind if I say something that seems completely stupid, since I consider myself to be a total newbie ...
823 views

### Is the 4066 appropriate for power switching?

I am building a serial interface for a GPS module. This interface will have a "traditional" DB-9 connection, a USB-to-serial connection and a 5.5V power input. The GPS module will be in a separate ...
124 views

### Frequency of fluctuations in power in an input power design circuit

I am thinking about the following power design circuit in section 6.1 : http://www.arndaleboard.org/wiki/downloads/supports/BaseBoard_Specification_Arndale_Ver1_0.pdf Is it possible to calculate how ...
108 views

### Paralleling of 2 power supplies with different voltages

I have 2 full bridge dc-dc converter from 12 to nearly 170 volts. each one are designed to 250 watts... I am designing the transformers and is very complicated to make exactly equals by homemade and ...
70 views

### Three phase rms voltage calculation

I am new in instrumentation and control. I am developing a hardware for a project and the following is my application. I have three phase stepped down voltages and stepped down currents entering my ...
295 views

### Can electric bulbs be powered by connecting the negative terminal to earth?

I have a very fundamental question, will an electric bulb glow with one point connected to the positive terminal of the electric line and the other point to earth? In my school some 10 years back I ...
253 views

### LCD screen gets hot and sucks power from Raspberry Pi

Has anyone else experienced LCD screens overheating, and drawing too much current? I was trying a GPIO project with my Raspberry Pi in an attempt to interface with an LCD screen but for some reason my ...
174 views

### Simplest 5 Volt power supply circuit design

I am doing a project related to power supply. In that i have designed 5Volt supply some what largely(using transformer,diodes, capacitors) therefore it occupies more space .So can you suggest me a ...
90 views

### Metering wiring installation

Explain the benefit to the supplier of reducing maximum demand kVa without reducing overall energy consumption? I have researched on it on the net but I need some assistance.
67 views

### Strange stepper motor behavior- moves too far

I have 3 CD drive stepper motors on a 9V 2A power supply, and they are being driven with EasyDrivers. I am using an Arduino with grbl to control the drivers. The current for the motors is at the ...
121 views

### Charging batteries directly from 117 volt wall socket

It has occurred to me that almost no battery charger would be required if the battery pack was of the same voltage as grid supplied power. I build electric bikes, and the voltage on these has been ...
70 views

Why we doing the full load and no load test for induction motor What is the purpose ? and can you provide some example? Why we doing the full load test and find power and stuff and also for no ...
11 views

### Computer sometimes doesn't boot after power failure, what should I replace? [migrated]

Hi I have a new computer that behaves strange after a power failure. When I switch off the computer it will not boot anymore. Completely unplugging the computer for about an hour cures the issue for ...
911 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 ...
1k views

### Modifying an automotive 12V power outlet to disable power when car is off?

Recently, on a business trip, I had a rental car. Now, in my car, all of my 12V power outlets are always on. On the rental car, some of them were always on, some of them were only on when the car was ...
97 views

### Heating time of an aluminum plate

I'm designing a circuit for my 3D printer's aluminium heating plate (200x200 mm) and I wanted to be sure before buying resistors. Also, I'm using a Sanguinololu 1.3a. I want it to heat at 120° fast. ...
119 views

### How to create a Power ON-Power OFF tone

I'm working on a simple alarm project and would like to build a circuit which gives a short tone when the alarm is armed and also a again once disarmed.can I do this with a 555? I am a begginer so am ...
77 views

### Why does the current still increase in CC mode in a power supply?

I use a power supply where the specs shown here: http://electronics123.net/amazon/datasheet/ps613u.pdf I want to use it as a current source but the current is not stable in cc mode. Here what I ...