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

learn more… | top users | synonyms

1
vote
1answer
14 views

What's the reason for power down sequencing in an SOC can you damage it in some way?

Power on sequencing I understand. But why do power off sequencing? I could understand if you had to do something before power died, or maybe you just wanted to shutdown I/O before core so that no ...
0
votes
1answer
25 views

Installing air conditioning supply

Input rating or max current? I want to install two 5 kW inverter air cons and reading the specifications I'm a bit confused. The rated power input is 1.22 kW each so together they draw approx 2.5 kW ...
0
votes
0answers
12 views

Estimate kanthal's temperature by power dissipation

I've a bare Kanthal A-1 wire, And I want to Estimate it's temperature, basically to make a °C vs W plot. In this post Thermal resistance is used to do it as: ...
-2
votes
0answers
53 views

How much time will a 900 VA UPS resist if connected to a 140 watts PS4 [on hold]

I want to buy a UPS to connect a PS4 and a LCD TV on it, I am in Lebanon and it uses 220 V. searching the internet I saw that PS4 consumes 140 Watts and a 40 inch LCD TV consumes approx 120 Watts ...
-3
votes
1answer
52 views

How to get 24v dc from 12v dc power supply [on hold]

I have a 12v power supply with 3 +12v and 3 gnd.I need that power supply to power my ramps1.4 .It needed 12v and 24v, can i get 24v from that power supply?or do I need to buy another one?
3
votes
2answers
107 views

Is DC resistance always higher than AC [on hold]

My power professor has asked us to explain why DC resistance is always higher than AC resistance. Is it? In all of my researching on the internet, I keep getting that AC resistance is higher, thanks ...
2
votes
0answers
74 views

Q: What is the power of this signal

Determinate the power of the discrete signal: $$x[n] = u[n] + (-1)^n + (\frac{-1}3) ^n * u[n]$$ where: $$u[n] = \begin{cases} \ 1, & n \ge 0 \\[2ex] 0, & n \lt 0 \end{cases}$$ The answer ...
0
votes
0answers
12 views

Solar powered portable Xiomi Powerbank [on hold]

I am using a device called myRIO which has a power requirement as shown in the image below: I was able to power this device using Xiaomi Power bank 10000 mAh together with a USB boost converter ...
0
votes
1answer
71 views

Power supply safety standards

I want to build radio/alarm clock that power itself from the wall. I live in Canada. What safety standards should I follow? And is it free to acquire the datasheet of these safety standards or does it ...
0
votes
1answer
29 views

Two power supplies for an Arduino Mega - How to handle Vin pin?

I'm using an Arduino Mega to drive 7 servos (only 3 shown in my schematic), and I'm having some problems with the power management. Worst case scenario, the servos will draw about 4 amps, so I got ...
0
votes
1answer
30 views

Power to tool vs duration of larger ah batteries

I have a Milwaukee M18 Fuel 18v LI ion cordless impact wrench. It came with a 18v 2.0 ah 27 Wh battery pack. They also sell a 18v 5.0 ah battery pack among others. When reading online some people ...
-5
votes
1answer
94 views

What does all this mean? [on hold]

So, I got all this off of an HP power supply and would like to know what it means. ...
-4
votes
0answers
50 views

PIC24 running at 4.3 V [on hold]

I provided 5v to input of voltage regulator to supply the PIC24FJ16GA004 microcontroller with 3.3V as it is desired, checked the power connections and run the code to generate pulses. After running ...
-2
votes
0answers
54 views

Solar Powered Battery Charger (AA, AAA, 9v batteries) A unique situation… [on hold]

Alright I'll first start by saying... a person would think that after 5 weeks of research on this site and countless others that I would have figured an answer to my situation by now. So here is my ...
1
vote
1answer
24 views

Significance of Linearity in RF Power Amplifiers

I have started studying the topic of "RF" Power Amplifier (PA) operation, and so far I have come across description like, if PAs are non-linear, it does not form a straight line and rather it has a ...
0
votes
1answer
70 views

Switching between two power supplies with a P channel Mosfet, Is VGS or VDS a problem?

So I am using the following circuit to switch between VIN 0-30v and USBVIN 5v. I thought I found the ideal solution until I realised the FET in the schematic only has a max VGS of 8V. But I don't ...
0
votes
3answers
89 views

Hydropower formula:

If I had a 10 kW hydro electric generator (including turbine drive), what formula would I use to calculate how much water per second would need to be pumped into the turbine at 700 kpa to generate the ...
-1
votes
0answers
19 views

Triple output power supply with sequencing to a sensor - Where to start? [on hold]

I'm looking for a triple output power supply with built-in sequencing. Are there any OTS supplies that are small in size? If not, is my only option building a circuit for it? Any hints on how to do ...
0
votes
1answer
37 views

Battery Bank - How to achieve full amp-hour ratings with simultaneous series & parallel connections?

I have four 12V batteries (all with the same watt-hour rating), and I would like to achieve dual voltages by interconnecting them, while achieving the following: 48V at the full amp-hour rating of ...
1
vote
3answers
97 views

Component with multiple VCC and GND pins. Should I connect all of them? [duplicate]

I want to make a really small arduino using the Atmega 328p and I noticed that it has 3 GND pins and 2 VCC pins. I measured the pins and it seems that all GNDs are connected and all VCCs are ...
2
votes
2answers
140 views

How do we convert price per kVA to price per kW?

I have been told that since kVA is a smaller "unit", price per kW is higher than price per kVA. I'm not entirely sure kVA and kW are not simply units as Power Factor is not really a conversion factor. ...
0
votes
0answers
17 views

Reconnecting a tip to the power supply of a Asus eeeBox PC model B202 (12v 3amps) [closed]

The power supply socket on the Asus eeeBox PC model B202 clamps down the tip of the power supply. The power supply tip is 4.8mm by 1.7mm. The reason the power supply tip is clamped down is because ...
-3
votes
0answers
28 views

How to power a HP mini desktop 200-010 using two 12V batteries? [closed]

I am aware I have to use a DC jack to do this. I don't know how. Please help me.
0
votes
3answers
79 views

Mosfet Power Dissipation

I'm trying to find power dissipation of my mosfet when I pull 17.5A. I'm using CSD18542ktt. Can anyone help me what equations can i use. I have calculated the max power using the following equation. ...
4
votes
5answers
125 views

Rules for choosing power rating of a resistor

Let's say we're designing a system, and within it we have some resistor \$R\$ with a voltage difference \$V\$ across its terminals. Then it dissipates power \$P = V^2 / R \$. Of course the resistor ...
-3
votes
0answers
20 views

2 smps adaptor 24VDC 3A on TDA7294

Can i use 2 pcs SMPS 24V 3A adaptor for TDA 7294 as split supply 24V+ and 24V-?If TDA7294 can turn on with this split supply then how much watt i get from this 24VDC +/- 3amp?Please help im ...
-5
votes
0answers
37 views

Increase Motor Speed By low Voltage (AC) [closed]

i want ask question How i can increase motor speed AC not DC ? IF i set arm from this arrange motor , gar , arm . this arm will increase this speed . if yes what is relations with it and speed ...
1
vote
2answers
76 views

Is a capacitive power supply safe?

I'm doing a home automation system which uses a RF transceiver(nRF24L01+) paired with an arduino to control the relays. Since these require low power DC to run I was researching on ac to dc when I ...
0
votes
2answers
37 views

2 state converter, from -24VDC [ON] - +5VDC [OFF] to 5VDC [ON] - 0VDC [OFF]

So as the header says, I would like to take a 2 state signal (ON/OFF) where the on state is -24VDC and it's off state is +5VDC and make that/convert to a 0-5VDC 2 state signal, where 0 is the ...
1
vote
1answer
65 views

Designing a Smaller 2000W Transformer PCB to Run 220V Heating Element on 110V

I'm trying to design a step up transformer that can run my 220V heating element on 110V outlet. I've looked for such transformers through retail, but most of them are bulky and heavy. Is there a way ...
1
vote
1answer
35 views

0-380V Dimmer Circuit using MOC series Optotriac

I want design a dimmer circuit that have output voltage of 0-380V(rms). I didnt see any application about 380 V dimmer circuits and there is no information about 380V application in MOC series opto ...
1
vote
2answers
47 views

Filter design for high power voltages Partial discharge detector

Hell all, I have a signal imposed on a 60Hz 800V AC voltage that I need to retrieve via MCU. The signal is in the range of 10KHz to 50KHz with peak to peak voltage ranging from 5 to 50 volts . The ...
2
votes
2answers
69 views

Isolation of the transformerless power supply

One of the disadvantages of transformerless power supply is the isolation problem because of the absence of the transformer. My question here is : Doesn't the capacitor in series at the input do the ...
0
votes
2answers
85 views

What kind of generator do i need to run a 1.5 or 2 ton Air Conditioner? [closed]

I am planning to purchase a single AC that would operate on my Diesel generator. My Generator is a 5kVA , 8 HP air cooled one. I want to know that If I have to run only one AC on the generator shall I ...
1
vote
1answer
63 views

how to design power for arduino and servo

I'm designing a system where an arduino (3.3v) will run continuously, and occasionally turn a MG996R servo - this servo is pretty strong and can draw more than 2 amps. The servo runs fine off 4 AA ...
4
votes
5answers
784 views

Are there any advantages to either DC barrel connector polarity?

I was putting together a fairly basic LBB at the weekend to control a handful of DC devices which got me thinking. Why are both pin-positive and pin-negative DC barrel connectors used? Are there any ...
3
votes
1answer
30 views

hot swapping battery

I have a telescope with a computerized mount and some additional controlling systems. The mount requires a 5-10 minute long calibration process (to track stars accurately) every time it is powered. I ...
1
vote
1answer
43 views

Warm/hot starting a GSM/GPS module

I am new to electronics and trying to understand how a "warm/hot start" works. I am currently working with someone to design a PCB schematic for the SIM928A, a GSM/GPS module. In the hardware design ...
0
votes
1answer
38 views

the proper way to wire up multiple supply rails

I am making a hexcopter for a shool project that is going to be powered and controlled via an arduino project. my current setup is as follows: Where the linear regulators are the 6 speed controllers' ...
-1
votes
2answers
41 views

What would happen if we supply dc as well as ac voltage in a circuit? [closed]

How the characteristics of the circuit will change if we supply some dc voltage in an ac circuit ?
0
votes
1answer
20 views

Calculate capacitance i.a. via reactive power

The ampermeter of the following circuit shows 10A (AC) and the voltmeter 220V (AC). Furthermore its known that: $$ cos\varphi=\frac{2}{3} \\ f=50Hz $$ I calculated the following: $$ ...
-1
votes
2answers
117 views

Question about amplifier design

I'm somewhat new to analog circuit design, and I have some questions about this circuit, which I came up with trying to understand how transistor amplifiers work: simulate this circuit – ...
0
votes
3answers
81 views

Is power rating of transformer determined by input or load?

Scenario: I have current carrying conductor with a current transformer around it. If the load is rated at 5V, 2A and only requires 2W of power, but the primary side conductor is carrying 100V 12A. ...
-1
votes
1answer
29 views

AC Line detection using MID400

I want to detect an AC Line Voltage (230V RMS, 50 Hz) and interface it with a microcontroller. I am aware about two solutions. Using an optocoupler like PC817 [datasheet] using MID400 ...
-3
votes
2answers
60 views

Why do RI=RL equal in maximum power transfer theorm?

I know mathematical proof I need explanation. Why this happen.That doesn't make any sense to me.I know that in series connection current (I)is same.But here  current flow is changing with different ...
0
votes
1answer
53 views

Router WiFi with solar energy

I want to create a backup system for my WiFi router (photo). I've purchased a solar panel (12V, 80W) and a battery (12V, 30Ah). How long should my router last with a full battery? Is it possible ...
0
votes
1answer
24 views

Underground bundle of wires has a/c interference, slight noises on pairs of wires

Is there a way to mask a/c interference on a pair of underground wires. They are 14 guage wires. I have slight power from a 110 circuit that is bleeding over to several other wires in this bundle. ...
-3
votes
2answers
77 views

Can a SMPS LED driver glow 6 Watt LED bulb and same Driver is able to glow 0.5 Watt LED?

LED : 150mA * 3.3v =0.5 Watt 6 Watt LED (0.5 Watt* 12) : Which one is best method to arrange LEDs Parallel or Series. At a time only one LED will glow, Either 6 watt LED or 0.5 Watt LED. ...
1
vote
2answers
75 views

Darlington-pair transistor power amplifier for cd-player

I want to build simple one-transistor power amplifier for cd-player. I found 2sd605 Darlington transistor for it. I use 8 Ohm load speaker and have a lab power supply 20V. I want to connect speaker ...
0
votes
1answer
32 views

Mimic Power Line

For a class I am making a system to remotely turn on and off a light as well as adjust the brightness through a dimmer(this one: ...