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

learn more… | top users | synonyms

0
votes
0answers
24 views

What would be some solutions to prevent system malfunction after IEC 61180 4 kV and 6 kV tests?

My team of engineers are developing an energy analyser that have to be submitted to the 6 kV transient tests of IEC 61180, Table 1 Line 8 and 4 kV fast transients tests, Table 1 Line 9. When we were ...
-1
votes
0answers
32 views

MCU Restart Problem!

I have found that AVR MCU always restarts when switching AC loads with 12V relays, parallel diode is not sufficient I think!, also i used snubber RC components outside relay where AC load is ...
3
votes
3answers
112 views

Why don't DC PSUs need a fuse?

This feels like a silly question, but after taking apart some of our 6W 12V DC power supplies I've noticed that none of them are fused. Out of curiosity more than anything else, I'm wondering why a ...
0
votes
1answer
53 views

Characterization of Power Harvester

I have chosen a power harvester to power a few things as part of a wireless system. This one is the one I have and it seems to be operational: http://www.powercastco.com/PDF/P2110-datasheet.pdf ...
-1
votes
1answer
31 views

liquid insulator by example?

can someone give me some example about liquid insulator .from some text which has been read by me it is just oil can someone told me the other one . it would be good if there is any book reference ...
0
votes
1answer
56 views

IC chip for PCB to stabilize 12v input?

Hi I'm wondering if there's any SMD IC chip to stabilize a 12v input to a stabilized output? I need something like that to regulate power on PCB. Thank you.
1
vote
1answer
74 views

Is it possible to power an LCD by radio wave?

We've all heard of crystal radios that essentially draw their power from the radio waves which induces a tiny current in order to generate the sound we hear from them. There are companies that are ...
1
vote
3answers
402 views

Is this a reasonable way to switch a circuit on and off?

I'm using optical slotted switches to detect the position of a wheel. I may have a dozen or so, and at any given time I only need to have one switched on. The device might be battery powered, so I ...
1
vote
1answer
58 views

LED and Fluorescent Lights [on hold]

With all the LED and fluorescent light bulbs being used now and much more later, do you expect power companies to raise rates because of lower power factor? Or will they just absorb the cost as they ...
-2
votes
1answer
45 views

Max frequency of a component? [closed]

For example, an SCR, is this the maximum frequency you can send a 'on' or 'off' signal from an Arduino to it, or is it the maximum frequency of say, 30V flowing through it? Please let me know, I ...
1
vote
1answer
116 views

How to Generate Light in the 10,000K Spectrum?

I need to generate a lot of light with the same spectrum as the sun - 10,000 Kelvin (10000K). I have searched around for hours, however all full spectrum lights available are either 5500K or 6500K - ...
1
vote
1answer
171 views

What is the input current of the 74HC595?

I need to calculate the power consumption of my circuit, but I can't find any information about the input current of the 74HC595. I drive the 74HC595 with the atmega8 on 5v, but what is the input ...
0
votes
1answer
56 views

how to compute power of a device

how to compute power?, energy expended in joule? the battery is 3.6V, the device has a voltage reference which keeps voltage flowing through the circuit constant at 2.5 V, average current is 0.005 A ...
0
votes
0answers
21 views

Need help with on off switch to power arduino. [migrated]

I am trying to add an on and off power switch to my arduino project. My project is running off a 9v battery and I would like to save as much power as I can. There might be a better why that I don’t ...
0
votes
0answers
35 views

Getting a 12V DC power line from an existing wall power cable [closed]

I have an existing device that I want to add functionality to. It's drawing wall power. I want to splice into the wall power line inside the device, to grab 12V DC to power the new features I'm ...
1
vote
2answers
106 views

What do you call a transformer separated from a wall plug?

I got a hold of (from a friend) a AC->DC 5v 2a power transformer - it connects to the wall with lamp cord/ figure-8 connector, and has a USB plug on the other side. I can't for the life of me find ...
2
votes
3answers
585 views

Are normally open contactors virtually safe from failing closed?

Quick question: are normally-open contactors (which I assume are simply high breaking capacity relays) virtually safe from failing closed? I want to cut off a 400V 3-phase supply using an emergency ...
-1
votes
0answers
28 views

Connect a 3.3v IC to a 5v power source using resistors [duplicate]

I need to use a 3.3v IC with an Atmel uC. the power in the system is 5v. Is using a regulator a must or can I use a resistor in series to lower the voltage going into the IC? The IC needs 3.3V on its ...
0
votes
2answers
57 views

resistive braking for induction motor?

It occurred to me that since single-phase AC induction motors can act as generators, it might be possible to brake an induction motor with a resistive load. The basic idea is that when you want to ...
0
votes
1answer
33 views

power mosfet switching basis

I have a really simple question. I have this simple circuit. This is a converter, where the power-pole is made as a power mosfet transistor plus a diode. I did not get the Turn-on behaviour as ...
0
votes
1answer
42 views

Voltage regulator VS power supply

I made a circuit with some components (arduino, wifi board, ultrasonic sensor, sound sensor, light sensor, temperature sensor, humidity sensor, some leds and other components) on a breadboard. The ...
0
votes
1answer
43 views

Buck converter efficiency Vs load current:

Can somebody explain how does the efficiency of a buck converter increases with the increasing load current?
0
votes
3answers
95 views

why does the model s use multiple batteries?

The Tesla Model S and NASA's Robonaut both use a battery pack that consists of an array of hundreds of battery cells. Why don't the engineers just create one giant cell?
0
votes
3answers
108 views

MOSFET not fully OFF when Gate Voltage is 0V

A N-channel MOSFET STP16NF06L is used to drive a 12V load. Pin 1 is connected to Arduino Uno digital pin 4. Pin 2 is connected to the negative terminal of the 12V load. Pin 3 is connected to the ...
1
vote
2answers
76 views

How to calculate a electrolytic capacitor based on current and voltage to have the smallest ripple

I have built a circuit involving LEDs powered on 230V AC. The LED current driver that is powered on 30V and contains 10 LEDs of 1W each. 10 of these modules are linked in series and are ...
0
votes
1answer
38 views

Buck converter operating frequency range:

I am looking for a buck converter IC for my project. In the data-sheet if the operating(or supporting) frequency range has not been mentioned, then how do we know about the range of frequencies it ...
0
votes
0answers
56 views

Really weird AVR issue

So the other day I was changing some fuse bits on a 324p and screwed up. Well I set up a 88A to act as a clock out. Great. Well I went through 4 different chips, including a 48A, because of some ...
0
votes
3answers
29 views

Connections for Panel Mount 12VDC Power Supply

I'm using a 12V Panel Mount Power Supply, taking a 110/220VAC input and giving a 12V/5V DC output. What is the best practice for connecting this power supply to the AC mains? And how should this ...
0
votes
0answers
16 views

How to measure & control stall position of low torque synchonous motor. 3 watt, 20 RPM 150 n.cm torque,230v AC

How do I measure & control stall position of low torque synchronous motor. Data: motor 3 watt,20 RPM, Torque approx.120 to 150 N.cm.230 V AC 50 Hz. Electronic circuit for the application. ...
0
votes
1answer
68 views

Switching power to Stepper Motor Drive using relay and arduino

1.This project involves use of stepper motor once in 5 mins to perform precise movement.I m driving the Stepper using L298N-L297 Stepper Motor Driver Board and Arduino UNO. Since the Stepper Motor ...
0
votes
0answers
62 views

transformer (no load test)

If anybody has any experience with practical transformer schematics and analysis techniques, could you please explain how to solve this question, i have looked all over multiple websites and there ...
0
votes
1answer
42 views

How to maintain equal discharging on batteries

I am currently building a robot that has one 12V battery for each drive motor. The system was originally setup so that the two motor/motorcontroller/battery systems were completely separate. After ...
1
vote
0answers
62 views

Understanding power dissapation of MOSFET's

I'm currently trying to understand how MOSFET's work in total but come across confusing information when looking into power dissipation of the mosfet; mainly how to calculate it. Say I have a circuit ...
0
votes
3answers
147 views

Power optimization for high-side switch

I'm trying to figure out a way to optimize the power consumption of a group of two high-side switches. They are not supposed to be switched more than once every minute. I don't know if my way to ...
0
votes
0answers
35 views

Expandable power supply for multiple components with different power requirements

Suppose an Arduino based project involves multiple sensors and actuators, each with its own power requirements, what are the ways to build single power supply for it ? Further is it possible to make ...
1
vote
2answers
74 views

how to compute the average power from AC generator

I would like to monitor the power produced by an AC generator in a wind turbine. The goal is to monitor how the produced power varies with wind conditions. I connected the power resistor to AC ...
1
vote
1answer
67 views

How to prevent DC motor from dropping voltage of supply when switching on

I have a circuit which uses an ATtiny85 output to a transistor (S9013), which will trigger a relay that controls a motor. The reason for the transistor to relay is because I do not have a transistor ...
1
vote
1answer
70 views

Unpowered MAX232 - input 'leaking' into Vcc

My PC is connected to a MAX232 through a USB-to-serial cable. When everything is powered, there are no issues. However, when I turn off the power, the MAX232's \$V_{cc}\$ has a voltage of -0.5 V ...
0
votes
0answers
55 views

Why does load position affect dissipation of MOSFET [duplicate]

I am trying to use two MOSFETS to pass AC through a load but i noticed uneven temperatures between the two switching devices. In the configuration Below the lower FET heats up more than the upper ...
0
votes
0answers
43 views

Noise with a MPS-200 power supply

I am testing a 24V medical power supply (Mean Well MPS-200-24) for one of ours future products. The power supply is mounted on a metal chassis connected to the ground. The following schematic shows ...
1
vote
1answer
92 views

How did the DC power stations work

I've been reading about the great War of Currents and I've been trying to find out how DC power was generated in great volumes. I can't imagine it was with dozens of chemical cells, but I can't find ...
1
vote
0answers
67 views

Current/Torque - curve for an ASM

There is this exercise where I don't have a clue how to get the solution. It's about asynchronous machines, where with the help of field coordinates the string currents (istr) are split up into ...
0
votes
2answers
66 views

What should be the coil ratio to wirelessely transmit 12V/8A?

I am doing a project on wireless charging of a 40AH battery, for that I used step down transformer of 12V/8A that works fine, But now my concern is to replace transformer with coils which can give me ...
0
votes
2answers
72 views

unexpected power supply behavior

I am using this large 24V power brick (rated for 9.2A) to power a small circuit (an arduino controlling some RGB LED strip, drawing less than 0.5A). If I physically pull the plug out of the wall, the ...
0
votes
3answers
71 views

Calculating the power of a signal

I'm trying to calculate the power of a signal and my tutor has given me this formula to do it. I've spent the past while building a program and now the foundations are there it's time to implement the ...
1
vote
0answers
49 views

Blade Nano QX Charger hacking

I've got a Blade Nano QX micro drone. It's awesome. It arrives with a USB charger for the 150mAh 1S lipo battery, that has one very annoying feature. When it's charging a red LED is on, and when it's ...
-1
votes
1answer
87 views

Need help with power resistor [closed]

I need to building application where i need to heat aluminium block. Aluminium block will be chilled with water chiller system. This application need to work ~ 2 years 24/7. All this time i need to ...
21
votes
4answers
2k views

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 ...
2
votes
1answer
49 views

How do I select the best transformer/regulator strategy?

In my project, I wish to power a Raspberry PI 2 board and a small TV display like this one (http://www.adafruit.com/products/913). The RPi will draw around 1A-1.5A at 5VDC and the spec for this screen ...
0
votes
0answers
73 views

Dual redundant 1.5V battery power system?

I'm trying to build an efficient way to connect two 1.5V alkaline batteries in a redundant configuration for my circuit. I only want one battery to be supplying power to the circuit at any given time. ...