Questions tagged [low-power]

Low-power refers to electronics that are designed to use less power than their common counterparts. This is often a requirement because of limited available power, as in battery operated devices, or in cases with limited cooling capabilities, as in notebooks.

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52
votes
7answers
85k views

How can I get my atmega328 to run for a year on batteries?

Scenario I have created a nice electronic door lock for my dorm room. It is currently an Arduino Diecimila with a servo [un]locking the door. It has a numerical keypad with 3x4 buttons and 5 LED's (2 ...
21
votes
2answers
29k views

Some advice on charging circuit used in simple UPS

I have looked around for some way of having a 5 volt power supply that acts like a UPS. Basically want to use a micro usb connector for +5 have a battery and li-ion or other charging circuit that ...
9
votes
5answers
6k views

How to Measure Power Consumption on Extremely Low Power Devices?

This might be old news in a half a decade or two but by today's means, I am referring to electronic prototypes and designs which would draw in a μA (uA) and even nA range of current. Some recent MCUs,...
7
votes
5answers
12k views

simple, energy efficient circuit to make single IR LED blink

I'm using a 850nm IR LED (spec sheet), and in order to extend my battery life, I'd like to make the LED blink (UF 1.9 V, IF 100 mA). I found a couple of links 1, 2, 3 but they either a) require two ...
5
votes
2answers
3k views

Unpowered devices on I2C/SPI bus

I'm trying to develop a board that includes I2C and SPI devices that are unpowered for the majority of the time to save power. I found that for these particular devices (Honeywell HSC pressure sensors)...
2
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2answers
1k views

3V power rail from 5V

I've mistakenly ordered some 3V PIC18 L F14K22 instead of the 5V 18F14K22. 3V output is fine for the designed circuit but I need to make a 3V power rail from the available 5V rail. Since only a ...
5
votes
7answers
5k views

What is the most economical way to drive an array of single coil latching relays?

Please read the question to the end. The answer to this question may be non-trivial. Replacing a number of 2-coil latching relays with single coil latching relays ...
2
votes
1answer
446 views

Minimize current consulption for MIDI input circuit?

I'm using a MIDI input circuit like the one shown in the schematic below. R1 is not touched as driven by the input device. R2 is fed from my internal power supply. The device is very low power so I ...
26
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5answers
5k views

Making a battery last a long time in a microcontroller circuit

I'm hoping to power an ATtiny85V for a nice long time on some small battery, probably a coin cell. I've looked into the software side, and my code is watchdog timer driven, has unused analog and ...
12
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4answers
33k views

Can I use multiple 18650 batteries in parallel with a standard MicroUSB 3.7V charger board?

There is this Bluetooth Audio Reciever/Amplifier board that I'm looking to get from ebay, and according to the diagram, there's a MicroUSB 3.7V lithium battery charger component in it. With my ...
10
votes
4answers
655 views

Proper ways to disconnect ICs during low power states to avoid parasitic/backfeed supply

I’m working on a low-power battery-based AVR-based project that integrates a few different devices including a neopixel strip and an Adafruit pixie. When the overall device is quiescent, I’d like it ...
4
votes
3answers
488 views

How would you detect vampire/standby power?

Is it possible to detect when a device is consuming power in a stand-by or nominally off state? For example if I leave my charger plugged in, detect that a small amount of current is being drawn and ...
2
votes
1answer
3k views

Preventing parasitic powering of FT232RL by ATMega328P

I have a battery powered board with an ATMega328P and some other peripherals such as SD card, RTC, sensors, etc. The design of the board is to be as low power as possible, whilst keeping with the ...
1
vote
2answers
886 views

Flash an LED with an extremely low power source

Let's say I have a very low power solar cell, which is producing a couple of uA of current at 100-200 mV for an output power of a few hundred nW. What I would like to know is what is the best (most ...
28
votes
7answers
6k views

Smart ways to detect a button (less power consuming)

During a meeting for a particular project I was asked to think about the way to detect a push on a button with a MCU. The detection should consume as little power as possible. At the first glance, I ...
30
votes
5answers
14k views

Why does a faster clock require more power?

If you overclock a microcontroller, it gets hot. If you overclock a microcontroller, it needs more voltage. In some abstract way it makes sense: it is doing more computation, so it needs more energy ...
13
votes
11answers
2k views

Low power radio + microcontroller recommendation? [closed]

I'm searching for a low power system-on-chip that combines: A processor (any achitecture) A radio (any frequency/bitrate/tx power) 2 or more I/O pins (ADC would be a bonus) Can anyone recommend a ...
17
votes
3answers
21k views

Efficient low power regulation? i.e. 9 -> 5 Volts

For the sake providing as much current as possible to a small circuit, regulated down from ~9V to 5V (or 5V->1.5V), I have looked at some possible options. What I was originally going to do (maybe a ...
10
votes
2answers
767 views

Do batteries last longer with constant current draw or spiky current draw?

Do batteries last longer with constant current draw or spiky current draw? Or, as is implied by the accepted answer to "Making a battery last a long time in a microcontroller circuit", do some ...
6
votes
6answers
4k views

How to build an ultra-low power time counter?

Inspired by this question I would like to know how low power you could go with a counter + 32 kHz oscillator (possibly made by yourself). I found a nice oscillator circuit on a BJT reportedly drawing ...
24
votes
5answers
9k views

How could have Banksy kept an RF receiver running for 12 years? [closed]

I'm talking about Banksy's "Girl with balloon" painting that shredded itself at auction. I think the general consensus is that he didn't, and that it was set up before the auction (or a couple years ...
9
votes
3answers
4k views

Suggest a timer chip

I need to take voltage measurements separated by long delays (couple of hours) and beep a buzzer when voltage level is met. Power consumption is important. What I want is a simple timer chip like ...
7
votes
4answers
5k views

Efficient low-power buck (step-down) regulator IC for Li-Ion - 3.3V conversion?

It's not easy for electronics novice to find good element base, so I hope this suitable question. Requirement: Efficiently power a lean, 3.3V-based MCU design from a Li-Ion battery. "Efficient" ...
5
votes
5answers
22k views

Ultra low power/ simple flashing circuit

ideally I want this to run off coin cell batteries. I found a circuit that uses transistors and capacitors but the voltage requirements are higher than I want. Is there any way I can make this circuit ...
5
votes
3answers
2k views

Simple, efficient “breathing” LED circuit

I'm currently working on a small circuit, which I intend on running off a CR2032. The intent is to have the circuit last at least 2 weeks (the longer the better), pulsing a green LED every 3 seconds, ...
4
votes
1answer
991 views

how does a cell phone transmitter work?

I came across a question that is really puzzeling me. I did some basic calculation for a cell phone transmitter. I based on 900Mhz band and assumed a 20Km distance to a cell tower. On top of that I ...
2
votes
4answers
2k views

Measuring low current at very high speed

I have a circuit with a very-low-power Jennic JN5148 module with microcontroller and 2.4 GHz radio, and some low-power sensors. I have to measure the supply current of all these components, in an ...
9
votes
1answer
267 views

LED current while off

I have a vague recollection that while off, a LED can actually receive light and generate a small current (in uA). Is that correct? How does that work? What is the best way to prevent this?
7
votes
2answers
4k views

Bluetooth power saving mode for ArduinoBT

I'm trying to get my ArduinoBT to be a bit more power friendly, I have it running in a sensor network and it is constantly drawing power. I want to be able to turn off or put the Bluetooth module to ...
7
votes
2answers
5k views

USB / Battery Switchover Circuit

Background: I am a non-EE (an 0x11? :^) thrust into the world of embedded systems design. I started this project with a only college physics-level understanding of circuits, but I'm gradually learning....
6
votes
2answers
2k views

Low power, cheap, long timeout, watchdog circuit

I need a circuit to act as a watchdog to a micro (which is not powered (instead of in a sleep mode)most of the time). it needs to be low power (< ~4uA) and non-programmable. So no I2C RTCs or MCUs....
6
votes
4answers
2k views

Do voltage dividers waste battery?

I am attempting to make a battery powered alarm clock with an Arduino, and I would appreciate some help on the circuitry part. I am very inexperienced with electrical engineering. I am using a ...
5
votes
6answers
644 views

How to prevent sealed in product battery drain on store shelf?

How can a microcontroller-based device prevent battery drain while the product is on the store shelf? We are creating a waterproof, sealed in product without any buttons. This means the battery is ...
4
votes
1answer
5k views

What is the maximum power transmitted through NFC that can be harvested?

What is the maximum power an NFC-enabled card can draw from a contactless payment terminal? What are the determinants (i.e. card reader voltage)? What techniques are available for harvesting this ...
3
votes
3answers
808 views

Very low power voltage regulator - diode?

I'm developing a very very low power system, and it has some components that need 3.3V. These components are actually spec'd to operate anywhere between ~1.8V and 3.7V, so theres some wiggle room ...
2
votes
1answer
2k views

PIC32 sleep mode with watchdog wakeup failing

I am in the process of trying to get a PIC32MX795F512L to run with lower power consumption. I'm trying to get it to enter sleep mode and then be woken by the watchdog timer. All pretty standard ...
1
vote
3answers
8k views

Circuit with 10 LEDs with 9V battery

I know that a 9V battery can only power so many LEDs. I need a 9V battery to power 10 of them maybe less or a few more and keep brightness and im not sure where to go to make it happen. Or if i ...
1
vote
1answer
509 views

Problems when loading an Ultrasonic transducer (reflected power)

I have a very simple setup that is giving me problems I cannot understand: Apparently, the reflected power is the same as the power generated by the amplifier (both measured by the amplifier, ...
1
vote
1answer
125 views

Latching battery switch triggered by interrupts

I've got an accelerometer with a couple interrupt pins and I've figured out how to get it to fire its interrupts on any change in acceleration or lack thereof for a given duration. What I want to do ...
0
votes
2answers
748 views

Shut down regulator during sleep

I'm working on a wireless sensor network and would like to know what it would take to shut down the regulator during deep sleep. MCU: STM32L151C6T6 Regulator: TPS63001 Radio: RFM69HW LCD: some ...
0
votes
1answer
418 views

Controlling Wemos D1 power with P-Channel MOSFET

[ Note: this is the continuation of another question, the first one being my attempt to implement the same idea using an N-channel MOSFET. Based on the answers I received there, I went out, bought a P-...
0
votes
2answers
865 views

3.7v > 3.3v voltage stepdown with logic-driven on/off control [paused]

(PAUSED): This topic is currently on hold as I source necessary hardware. I need to connect a Wi-Fi/RS232 module to a low-powered monitoring device, and for maximum portability, I'd like to power the ...
7
votes
2answers
2k views

How does a bathroom scale automatically power on when I step on it?

When I step on a bathroom scale how does the circuit turn on? I've disassembled these types of weight scales looking for obvious hardware switches, but none exist. I suspect the ADC is configured to ...
7
votes
4answers
1k views

Minimum energy required for LED blink to be visible

I have a 5V schematic with 15n capacitor and I wondering if I will be able to blink an LED, powered from this capacitor. My calculations is that the capacitor will have about 0.2 uJ of energy. This I ...
4
votes
3answers
721 views

How to debug current consumption with STM32 Nucleo board?

I'm trying to configure an STM32L011-Nucleo developement board to consume about 600 uA of current or so. It uses an STM32L011K4. The datasheet states that this should be possible if I drive the MCU ...
4
votes
1answer
242 views

Are Lithium Thionyl Chloride Battery usable in my vibrating environment? Are they safe?

I have to power a circuit subject to constant vibrations (10-15 Hz with an amplitude of ca 10 millimiters) with a battery and I was thinking of a Lithium Thionyl Chloride Battery. The circuit has to ...
4
votes
4answers
4k views

Recomendation for a digital inverter made of discrete components

I have a digital circuit in which I need only one logic inverter, and both PCB size and power consumption are serious constrains. So I thought about using a pair of complementary SMD MOSFETs (the ...
3
votes
1answer
273 views

For variable voltage devices, namely SD cards, how much power do you save by using a lower voltage?

I'm designing a computer vision system and my 3 main components are microcontroller (VDD = [1.8V, 3.6V]) microSD card (4 bit mode, VDD = [2.7V, 3.6V] according to SD 2.0 standard) cheap cell phone ...
3
votes
3answers
597 views

GPS Almanac versus Sky Search

The total almanac data is transmitted in 25 navigation messages. Each navigation message takes at least 30 seconds to transmit. So, receiving the almanac data from the satellites takes at least 12.5 ...
2
votes
2answers
2k views

Low voltage drop transistor/mosfet switch - 3.3V 200mA

I need to make a switch. However p-n junction drop seems to be a problem for my use. Hence I am unable to use something like this: In this case, my load won't be getting exact 3.3V across it. ...