# Questions tagged [power]

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

453 questions
62 views

### Power use question for a trail camera

I am trying to calculate how long that a trail camera can be deployed before the batteries run out. The trail camera in question is a Reconyx HyperFire 2. Here is a useful review of the trail camera ...
220 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 ...
2k views

### How to make your own EL Wire (electroluminescent wire) inverter

I would like to make an EL wire (electroluminescent wire) inverter because I can't seem to find a commercial inverter that can drive the right length of wire from the batteries I would like to use: ...
28 views

### Deriving the equations of power flow between buses

Can somebody please explain for me how to mathematically derive the equations of power flow between two buses? The equations I am trying to derive: Equations of power flow between buses I read the ...
40 views

### USB Type-C DRP Integrated Switch/Interface Chip

I would like to experiment with a power bank design with a single usb type-c port. The port should have dual role, source current for charging other devices as well as sink current for charging itself....
26 views

### Context of Li-Ion MnO2 “Cell Configuration” Specification

My application supports variable pack configurations: 4S4P, 4S6P and 4S8P. Each one obviously uses a different BMS profile, and other minor changes such as charge/discharge MOSFET and fuse selections....
136 views

### Overshoot/undershoot issues in load current wave form of a MOSFET

We have designed hardware circuit which validates voltage regulator maximum output current. So we designed op-amp circuitry to control gate drive of the Power MOSFET and it will work in active region ...
39 views

### Way of powering Arduino+GSM Modem+Cam off 5V powerbank

I'm trying to build a circuit, that would turn the Arduino on by a PIR sensor, take the picture by ArduCam, then transfer it onto a webserver. I got the SW site covered by now, so that is not a big ...
60 views

### Y/Y/Δ or Δ/Y/Δ transformer for a series connected 12-pulse rectifier?

I'm aware that 30° shift is needed in order to obtain a 12-pulse rectification, however, I'm a bit confused about the configuration of these transformer. In most HVDC systems that appear in Alstom - ...
130 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. ...
117 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 ...
81 views

### Audio: Camera activated external microphone

I want to build a relay circuit that turns on an external microphone (powered by an internal 9V battery) when a connected camera is turned on (a camera offering only 1V plugin power through a 3.5 mm ...
462 views

### What's necessary to properly decouple/filter a PWM-controlled fan from an Arduino?

I've got a small problem I could use some help with. I am using an Arduino to control a cooling system I am building for a DSLR. Primary goals are to use PWM and some pots to control TEC power, as ...
97 views

### Getting more than 0.5W from USB OTG

Has anyone actually measured the maximum amount of power that can be drawn from a smartphone's (say Samsung S4) USB OTG in host mode? I've read people suggest 100mA but can't find if anyone has ...
371 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 ...
20 views

### 24-60V Precharge schematic critique

I'm looking to design a soft-start precharge circuit for starting up circuits with substantial input capacitance (~1.5J @ 24V). The main requirements are: 24-60V compatible Constant current pre-...
26 views

### Changing between usb power and battery power using P-Channel MOSFETs and a CMOS Invertor

I am trying to switch between USB power and a single cell lipo using two mosfets. Would the circuit below be ideal or is there a more efficient/reliable way to do this? When the USB is connected the ...
19 views

### Is it possible to predict the operating state of a power system (using MATLAB) if I have calculated the voltages at all nodes by state estimation?

If I have calculated all the node voltages by state estimation, is it possible to predict which operating state my system is at? By operating state, I mean any of the following: ...
70 views

### Repurposing or obtaining a cheap audio signal amplifier for school physics lab

I teach highschool physics, and want to connect my smartphone (LG V20) to a Chladni plate (vibrating plate for studying interference patterns in sound in solids). I have successfully done this by ...
24 views

### What is the best way to isolate power hold-up circuit?

I an currently designing a hold up circuit for a computer and I need to keep this load isolated from other circuits that don't need to worry about a brief loss of power. The research I've done has ...
46 views

### Raspberry Pi wake-up and battery power circuit

I am working on a Raspberry Pi (3B plus) project that - at times -needs to operate on battery power, and on external power whenever available. The RPI needs to operate only when a dedicated sensor ...
35 views

### How can we make a load that has configurable power factor for 230V AC?

We are hoping to create a lab for students at our university that requires them to measure the power factor and correct for it. We are working with 230V AC and have a maximum power of 300W. We were ...
59 views

### Generate energy from waves that move my ship?

I'm currently building a small solar powered robot boat. I expect it to work fine (because why not.. :-) ), but I'm already looking for other ways than only solar panels to generate electrical power. ...
30 views

### Battery Powered System and Input Capacitance

I have a battery powered system in which the battery is connected to a buck/boost converter to derive 3.3V from two or three AA batteries. The regulator I'm using is a TI TPS63050, and it has a power ...
62 views

### What are these programming terminals for a 2 kW power supply?

Does anyone recognize the programming terminals on the real panel of this power supply? I would like to get the 50 amps out. It is an ATE1 made by Redfern radio, it is an old army surplus. Going in ...
26 views

### Reactive Power at Slack Bus

When computing the power flow solution, we find the (1) voltage angles at (a) load nodes and (b) non-slack generator nodes, and (2) voltage magnitudes at the (a) load nodes. We can then compute the ...
46 views

### Rise time and fall time issue in the power MOSFET

In our automated design due to MOSFET obsolete we have changed new MOSFET which gives us rise and fall time issue at the frequency applied from 10Khz to 500Khz. when we use the power MOSFET as Load ...
78 views

### Producing clean power with multiple switch mode power supplies

Thanks, I am new to using this site, I apologize for my vague post earlier. Here is a schematic I been working on. The project requirements are 5VDC, and 20VDC. The 5VDC is to power the ...
43 views

### Voltage drop on power bench supply for channel being off

If I measure voltage drop between terminals of my bench power supply (spec) I get -15 mV when channel output is turned off. Why it is not reading 0? I believe it's due to internal impedance of the ...
24 views

### Split Power Plane when using Load Switches?

To do power saving for a battery operated product, I am using couple of load switches to shut down peripheral power when not using that. PCB stackup - Signal(component), Gnd, Power, Signal -- 4 ...
50 views

### What factors should I consider when choosing a high amperage power supply?

I've searched around, but I haven't found an answer to this particular question yet. I'm building an elecromechanical project which requires somewhere around 60 Amps at 12 Volts. While this may not ...
100 views

### Designing a +10 V -10 V +7 V DC power supply for audio equipment

I've recently purchased a tape recorder (Tascam Midistudio 644) that was very cheap because the previous owner had lost the power supply. The PS-M1 power supply that originally came with this unit is ...
61 views

### Inrush current limiter circuit for filament bulb - comparison

Context: A 12V power supply is switching on externally connected 12V filament bulbs. The power supply's load switch implements an electronic resetable fuse (13A/τ=15ms) in case of an external short. ...
68 views

### MPU6050 hangs on ESP32 when operated using a battery on custom board

We are facing a very peculiar problem. We are designing a board based on ESP32 with various peripherals like motor drivers, sensors etc. We are using GPIO 4,5 on the ESP32 as I2C lines and have hooked ...
23 views

### Hook up an automatic transfer switch with two phases only

We have a house in Haiti connected to the shore line. The shore line isn't always working so we bought a generator. I wanted to ground one of the two phases to create one neutral, one phase and a ...
106 views

### Power consumption measurement on the bench

I've been using the Atmel Power Debugger to sort out power consumption issues on some µController based circuits... and have been pretty pleased. Unfortunately, it's limited to a maximum of 5.5 volts ...
278 views

### IGBT failure and protection

I have a 3-phase bridge rectifier (shown below). I am using an IGBT (STGE200NB60S) to limit the inrush current from the capacitors at start up. I also added the NTC thermisters to help with the inrush ...
52 views

### Is there a cost savings associated with 3 phase power at the same device power requirement (kW)?

I am a Mechanical Engineer looking into purchasing an annealing furnace and have seen that some operate on single phase power while some operate on 3 phase power. I've done some research and have seen ...
53 views

### Brick SMPS power supply issues

I'm working on a system comprised of two boards (power board, screen board) powered either via European outlet (220v 50Hz) or a LiPo battery. Power handover is achieved via an autoswitching MUX that ...
316 views

### Soldering sheet busbars to PCB concerns

Hello fellow engineers I have decided to solder busbars to a high current pcb , but i have 2 concerns : Does soldering a flat busbar (shown in left image) could cause thermal stress and deformation ...
91 views

### Are there commonly used equations for short-term overpower of wirewound resistors?

If I have a wirewound resistor rated for 250 W that might need to dissipate, say, 400 W for several seconds, is there a commonly used equation for finding its temperature rise or time to failure under ...
103 views

### aluminum anodizing power supply schmetic

It has been a long time since I played with the electrons. In my day filament transformers were common and power supply design included the number and type of tubes being used.LOL Anyway I need to ...
104 views

### Gate Driver Not Working as Expected. Why?

I am using the ADuM5230 gate driver to drive an N-channel MOSFET in a basic buck converter circuit that will convert a 12V DC input to a 5V DC output. The buck converter will operate at a 10kHz ...
50 views

### Daisy chaining power through mcu modules

I am really sorry if the following question is too obvious and basic, I am trying to understand how I can do this right. I have five 5V PIC custom modules that I am trying to power, using a daisy ...
225 views

### Which power factor is better in an industry -0.21 or -0.94 and why?

In the electrical panels , when i switched on-off the capacitor bank then power factor gets shifted from 0.89(lagging/during OFF condition) to -0.87(leading/during ON condition) , similarly on ...
197 views

I would like to create an Magsafe 1 to USB C adapter to re-use my macbook magsafe charger on my usb-c macbook. I have these components below and already tried to connect both V+ and Ground with no ...
77 views

### Power sequencing with LDO without enable pin

What is the right way to provide a power sequence using LDO (or any other power source) without the enable pin? I'm using DAC7718 from Texas Instruments and it require a quit complex power sequencing:...
62 views

### Designing Battery Power System For Robotics

I'm building a mobile robotics project for a class and I'm trying to figure out how to (or even if its necessary) to design a nice battery power system for it. I sort of wanted to learn how to build a ...
88 views

### Am I right about measuring current, and power

I have a meter that can measure: current, active power, reactive power and complex power. simulate this circuit – Schematic created using CircuitLab So, when I measure the four things: current,...
512 views

### Potential difference between DC floating power supply and earth ground

I have a question about a simple DC floating power supply: it is as simple as possible, secondary coil -> bridge rectifier -> filter cap, as shown on the figure below. If I connect the input of the ...