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

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2
votes
2answers
66 views

Limiting amplifier output power

I am about to use this TPA0211 chip to amplify my audio signal. Supply voltage will 5V and load resistor is 4Ω. According to figure 6 page 6, Output power will be around 2W. However, I need 1.5W as ...
1
vote
2answers
57 views

Which Contacts this RC Snubber is protecting?

Hello. I want to know which contacts are this Snubber Protecting. and usually where the arcs will be happen. i read something that tells the arcs will happen when we have an Inductive Load For ...
1
vote
1answer
78 views

Wiring a Key Switch to Control USB Power?

So I'm working on a project, and I'm a bit stumped on this problem I ran into. Brief explanation, I have wired a key switch into the power pin of a USB extension cable, which will allow the female end ...
0
votes
1answer
50 views

What voltage should power requirements be listed as?

I am listing the power requirements for a culmination of multiple devices for the US and the EU. For 120 volt mains, it appears most list the requirements (amperage) relative to 115 volt. Should I do ...
0
votes
1answer
57 views

How can I avoid using different batteries to power different components in a circuit board?

I am looking to use MOSFETs as a switch to run a motor and we ran into a slight problem with the power supply to the circuit board. The main batteries we would like to use output 14.4 V nominally. ...
0
votes
1answer
69 views

How does this pulse maker work? [on hold]

Below is an image of a 555 timer producing a pulse towards an N Channel MOSFET. Can someone please explain to me why tapping into the positive terminal of the battery (RED JACK) allows us to create a ...
1
vote
2answers
34 views

how phase frequency matches in reverse power flow situation

I have a question regarding smart energy systems. Consider a reverse power flow (where the power flows from household to grid) situation, A household has a solar installation and the energy obtained ...
1
vote
2answers
98 views

Solenoid to launch tennis ball [on hold]

I am interested in putting together a tennis ball launcher. It's accuracy/precision are not important. Even varying distance by ~50% or more per shot doesn't matter (it's for my dogs). What type ...
0
votes
5answers
180 views

I need to run a 12v fan (440w) from a 240v supply - what would be the best way?

I need to run a 12v fan (440w) from a 240v supply - what would be the best way? Should of mentioned that this fan is attached to a car conditioning rad and therefore dc. - Sorry. Thanks to those who ...
-1
votes
0answers
48 views

What kind of circuit would allow power above a certain limit to switch to another pathway? [on hold]

For example, if a sensor receives all of the voltage from a solar panel, what circuitry would send the voltage into the home once the sensor has been activated? Would this be a switch?
1
vote
0answers
35 views

What determines the actual power consumption of writing to a microSD card?

I'm currently working a project that will feature writing data to a microSD card. Because my project will be battery powered with a 125mA power regulator, I'm concerned that my write operations will ...
1
vote
1answer
93 views

Will this AC-AC SSR work for a safety start / stop switch for a power tool

I'm modernising an old bench saw, and I want to replace the switch it has with a safer one, so that the tool will not start if the power is disconnected and then reconnected. The usual way to do this ...
1
vote
2answers
33 views

Total power from 2 different solar panels

I was thinking about solar panels for a while and a question popped into my head which i still can't answer nor test it, and i want to know if this would actually work: If I get a 2x12v solar panels ...
3
votes
4answers
95 views

Why aren't there any 3-phase domestic power-outlets, or any interest in 3-phase for household (mains) power or anything relatively low-power?

Since I discovered what 3-phase electrical power is on Wikipedia, I have noticed that it's associated with very high-power applications. I have not been able to find anything on the subject of 3-...
0
votes
1answer
70 views

Laser power necessary to cut/etch paper

I want to cut/etch (would be satisfied with just etching, though prefer both) paper with a laser. I have on hand several laser diodes salvaged from various disk drives and a 633 nm 10 mW CO2 laser. I ...
-3
votes
1answer
64 views

Can I use a 12v battery to power a class 2 transformer (120v input 15v output )? [closed]

I'm attempting to use old computer speakers ( Altec Lansing) and make a mobile speaker system,but I'm unsure if I can connect the transformer that came with it to power it using a 12 v ( small, like ...
-1
votes
0answers
27 views

what power supply should be used with 6 computer fans? [duplicate]

All of my computer fans in this setup are 12 volt and .38 amps. Am not sure what power supply would be good for these guys. I can get a 48 volt, 3 amp for a good deal. I would need 72 volts, which is ...
0
votes
3answers
17 views

Strange behaviour of a LED bulb via SSR Relay: it's EMI?

I've just discovered a strange behaviour of a LED bulb (E27, 220v/AC) that I'm currently turning on/off via an 8-channel SSR relay. Such a relay module is powered with a switching power-supply, ...
0
votes
0answers
39 views

Wall-wart blade design [closed]

I am in the process of designing the Bridge Module that updates the time and allows users to control the system remotely. This enclosure will be plugged into a standard 120V power receptacle. I am ...
1
vote
1answer
75 views

Ni-MH battery voltage [duplicate]

I have a battery pack of 8 Ni-MH 2400 mAh cells connected to a load that draws ~700 mAh (a Raspberry Pi Zero, display, WiFi dongle, USB hub, and a wireless keyboard dongle). I want to add a led that ...
0
votes
2answers
75 views

Use of relay 5V instead of 3.3V

We are currently designing a system which will use a relay, a MCU and a sensor (powered in 3.3V with 100mA max current consumption) + a few LED (2.2V type). it will be powered by a 9V battery After ...
1
vote
3answers
123 views

How do I compute the average and RMS of a series of triangular pulses?

I'm trying to calculate the Average and RMS values of the current through a diode with the waveform image attached. I'm struggling to work out which equations to use. Any feedback would be appreciated....
0
votes
1answer
83 views

A problem on Relay Power loss

On our quadcopter, we're carrying a switching circuit that would allow the switching between two batteries. When using the 2 Channel Relay Module, the quadcopter is having a hard time flying with it. ...
3
votes
1answer
428 views

Propagation speed of telegraph signals

Time transfer in the late 19th c was best achieved by telegraph, a major improvement in the determination of longitude for geodetic surveying. A question was posed, to acquire a high accuracy time, by ...
1
vote
1answer
49 views

How much does the power of a magnet increase voltage on electromagnetic induction?

Searching through the site i found some useful info saying that a powerful magnet means more voltage, but i'd like to know how much does the voltage increase in relation with the magnet power (Given a ...
0
votes
1answer
76 views

Maximum current through an LED

I have these LEDs for which the max current was not specified. However I know that the voltage is 3.2V-3.6V and the power is 1W. Is it correct to assume that the maximum current is therefore 0.27A ? ...
0
votes
0answers
46 views

What are the current ratings for this chip?

I've been looking at the allwinner H3 datasheet, which can be found here. But no where in the datasheet is there mention of how much current it draws. Which is annoying when your're trying to figure ...
-3
votes
0answers
43 views

why leading power factor cause rising system voltage?

why leading power factor will cause rising voltage? how can it happen in mathematical calculation? i think the voltage in power factor correction will be stable but the current will change because of ...
3
votes
0answers
74 views

Soft power, latching circuit? [closed]

I'm currently converting an arcade board into a console, and I've been using an original Xbox 360 power supply with it, as it provides 5v and 12v. I thought it would be neat to build a soft-power ...
1
vote
3answers
59 views

Upgrading my ebike battery to give more speed and longer range

I am in the early stages of trying to understand how to do this, so if you're kind enough to reply, please answer in simple terms if that's at all possible. I want to add cells to my electric bike ...
1
vote
1answer
95 views

Are resistors the only legal way to tie various power designations together?

I'm working with a schematic in Eagle and I use IC's with different types of power pins. I connect VDD to VCC to +5V and I connect GND to VSS to zero volts. When I look at the ERC, I receive warnings ...
1
vote
2answers
76 views

What is the power specification for SATA?

We are designing a product which needs to provide data and power to an SSD connected using SATA. However, we cannot find a specification of the power requirements for a SATA connector. How much power ...
0
votes
1answer
33 views

Changing the torque and excitation in an alternator

What is the effect of changing the input torque of an alternator with excitation kept constant? and what is the effect of changing its excitation with a constant torque?
1
vote
1answer
23 views

Active power output calculation of hf generator unit based on measured volt acorss a load

I have an electrosurgical hf generator unit that produces a modulated signal with duty cycle in blend mode. I have the output of this unit connected across a load. With scope connected across the load,...
2
votes
0answers
47 views

Why does my SEPIC converter output more power at higher temperatures? What are the implications of this behavior?

I have a Pololu S18V20ALV SEPIC voltage regulator board that is wired to a high-amperage 5V USB power source on the input and a DC brushless fan on the output. The output is set to about 5.5V. ...
0
votes
0answers
6 views

Combining multiple cables to increase current? (laptop charger) [migrated]

I'm looking to use a simple USB power bank as a portable charger for my laptop (just to get a little extra boost if the battery starts running low at an inopportune time). My plan is to use something ...
0
votes
2answers
69 views

Can you ruin an outlet by touching two wires together. [closed]

Recently I was switching the power cord for my dryer and before I attached it to the dryer, I plugged it in to make sure it would fit. The metals st the other end touched. They popped extremely loud ...
0
votes
1answer
103 views

why would one use a current transformer with both live and neutral lines?

Could one use this to measure the phase difference if one had the voltage measurement? I have looked at the below household power meter, and was baffled by (what seems to be) the current transformer ...
0
votes
2answers
28 views

EU power adapter for UK laptop

My laptop uses a standard clover-leaf 240v 3A UK power lead. I bought a "laptop power lead" for use in Europe. However, it seems to be rated for 16A, is this normal or is it overkill for use with my ...
0
votes
2answers
107 views

Alternatives to USB connector to supply 5V for charging battery on small circuit

I am looking for a way to get power in my recharging circuit, since my device uses a battery. The problem is the USB cable: the connector is soldered on the PCB, but with the stress of plug and ...
6
votes
3answers
513 views

Can an AND gate be used to toggle an HDMI connection?

I am looking to turn on and off the throughput of an HDMI signal via a microcontroller. Would four ICs such as the SN74LS08N AND gate be enough? Or do HDMI signals need something more complex?
-1
votes
1answer
50 views

Current and wattage overload

So, I have an extension cord reel with four outlets and current overload protection can handle a total of 2500W, 110V, 20A. Im confused about those specification because they do not add up but that's ...
3
votes
3answers
351 views

Transformer: Double primary winding?

I found the picture below on the Internet about a double primary winding transformer. I understand how a simple primary double secondary winding transformer works, but I don't see the point in making ...
0
votes
2answers
42 views

Sizing of and Type of Power-loss / Brown-Out Protection Capacitor

I found a few resources and this question here: power-loss protection I'm using an MCP16301 step down regulator to turn 12v to 3.3v I'm having trouble determining I in this equation: C=I×t/ΔV with ...
0
votes
2answers
86 views

How many LED's can a TLC5940 16-Channel LED Driver power?

A TLC5940 can sink up to 120ma per channel. I am having difficulty finding the max current for the entire chip on the Datasheet. Is there one, or is there another limiting factor for this chip? ...
4
votes
3answers
571 views

Does a dashed line mean “when energized”?

I'm having a hard time understanding this circuit diagram: I'm interested in the following component sates, and how they affect power distribution: the breakers: the buses: the AVIO MSTR ...
0
votes
2answers
39 views

Force feedback electromagnetic power requirments

i am design a force feedback system for a gun controller which will use an electromagnetic drive system to replicate gun recoil. Ive explored a range of design but all seems to require allot of power. ...
0
votes
1answer
56 views

Power strip cord length [closed]

I'm trying to avoid putting a new electrical outlet in. I need to be able to directly plug some devices into the strip which directly plugs into the wall. Is there a power strip greater than 25' that ...
0
votes
1answer
66 views

How to test insulation of an unarmored, buried cable with mega-ohmmeter?

I have 3 single 1000V rated cables that have no armor and there is no ground reference (they are in a trench in the middle of the field). Usually I do phase to phase and phase to ground for each ...
0
votes
1answer
63 views

how switch between two voltages

I have a project and I need use ISP to send codes to ATMEGA328P, the problem is that my ISP programmer works with 5V and my system works with 3.3V. I know ATMEGA328P supports 5V but other components ...