"low-power" refers to components and circuits which are designed to have a lower power consumption than their common counterparts. This is most often a requirement because of limited available power, as in battery operated devices.

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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 ...
0
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1answer
22 views

Low voltage (<3V) signalling on USB DP/DN - will it work?

I'm using a microcontroller (specifically, the STM32L1) that integrates a USB device full-speed interface. I want to supply it with just 2V VDD, which is within spec for that micro. But that means USB ...
2
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2answers
47 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 ...
0
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0answers
29 views

Design of ALU use both PTL and adiabatic Logic

Adder module of My 4 bit ALU use 6 Transistor PTL circuit,to reduce power consumption. For further reduction in power consumption can I use 2:1 and 4:1 adibatic mux or there is some kind of ...
2
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2answers
91 views

What is the tiniest, low-power, and efficient am transmitter?

Here are my constraints: I need to build an am transmitter, but it has to fit in a 1 inch diameter and ~1 inch height box. Since the box is very small, I plan to use a CR2032 battery, which is also ...
0
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1answer
42 views

Solar Charge Battery Low Voltage Disconnecting

I have a 4.2V 120mA max solar panel and 3.7V 1200mAh battery. I'm trying to make a solar power system for my arduino. I search through battery management IC's and generally understand the charge ...
6
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1answer
1k views

Replacing incandescent bulbs with LEDs, unexpected behavior

I have an over-the-stove microwave/ hood vent combo with 2 adjustable-brightness lights. The lights appear to be 12V lamps with a G4-style connector, and they burn out all the time... like every 4 or ...
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2answers
126 views

Voltage regulator help

I need help with what is probably a very simple question that I don't know. When you put 12v at 10 watts and bring it down to 5v with a regulator would the wattage change? And just say the regulator ...
2
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1answer
39 views

making sense of HCT ACT cmos “addional supply current”

I'm trying to make a low-current level shifter from low voltage (~2V) CMOS up to 5V CMOS. I had the idea to use TTL-compatible CMOS gates in the HCT or ACT families. But this line in the 74HCT04 ...
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2answers
85 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 ...
0
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1answer
73 views

Do any rotary encoders allow zero idle current

Many microcontrollers and logic devices (programmable or otherwise) are capable of drawing very little current when nothing is happening. If a double-throw switch is wired to such a device, then when ...
2
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0answers
74 views

First project, powering an IC

I am working on a RGB LED Strip controller to light the inside of my PC. I plan to use a Molex connection 12V DC to power the circuit, the LEDs I am using can run up to 12V, but it should run at about ...
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60 views

Relay needed for an input ot 0.15 V

sorry about the question but I'm a beginner here. I have a very low DC voltage of 0.15V and I want to use a relay with in a simple circuit to light a LED. I'm learning in how to build circuits. So ...
0
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0answers
70 views

Trying to use INA2128 op-amp (or INA128, a similar model) in Proteus ISIS

I'm trying to simulate an EMG-signal amplifier that I got the schematic for from one of my seniors at my university. The signal strength varies from 3mV to 10mV, and the amplifier takes it up to 5V. ...
3
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5answers
339 views

Are opamps as a voltage regulator effcient?

If I setup an opamp in a non-inverting configuration as follows: Vrail+ is 7.5V, Vrail- is GND (0 V) Vin is 2.5V, Vout = 3.3V (in other words, the gain, aka, 1+R2/R1 is 1.32 [V/V]) Iout = 100mA ...
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2answers
121 views

How can I create a theatrical spark ejector?

I'm involved with an amateur theatre company (I do lighting, audio etc...) and would like to simulate a switch short-circuiting. I have also done a bit of magic in my time and have used "spark ...
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1answer
42 views

USB Compliant Power/Charging Circuit [closed]

I am designing a device that can charge a USB device, such as a cell phone. I have a 5v DC output source from my device. I know I can just tie D+ and D- together, and connect the 5v to the power pins, ...
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1answer
57 views

Looking for a 3.3V IR sensor [closed]

I am currently using a SHARP GP2YOA21 infrared distance measuring sensor which is 5.0V. I am looking for an alternative IR sensor that would work with 3.3V. Our application involves wireless sensor ...
3
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5answers
136 views

How much current is used with a μC GPIO input and pullup resistor?

I'm trying to understand power budgets a bit better and I have a question regarding pullups. I have a input to a microcontroller that needs to be logic high at all times. The micro goes to sleep now ...
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1answer
48 views

power leaking from device via USB

In my car I have power converter for the cigarette lighter. This power converter has some 3 USB ports and 2 cigarette lighter ports. I have devices plugged into the cigarette lighter ports. One of ...
0
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1answer
197 views

Backup power for adsl modem

I want to create a circuitry for switching to backup power (small battery) in case of mains power failure for my ADSL modem (to avoid the internet going down in such scenario). This is a basic ...
3
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2answers
108 views

Checking whether two voltages are similar

I am pretty new to electronics so this may seem like a basic question, but how could I check whether two voltages are similar? For example, say I want to check whether | V1 - V2 | < 1.5V and output ...
3
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2answers
83 views

Designing a mixed signal circuit for the first time

I am designing my first mixed signal circuit. I will then have a analog and digital ground plane and my question is: To be able to have separate grounds (analog and digital) on a battery powered ...
2
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2answers
105 views

MCP73871 <=> MCU interface

I am designing a small device powered by a lithium cell and I'd like to use the Microchip's MCP73871 battery charger to enable charging it from an USB port. The charger IC has three status indicator ...
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0answers
47 views

Power conusmption equation paramaters for modern ARM processors

I have been looking through the ARM Cortex (A, R and M series) eElectrical and technical datahseets (those from ST and TI) to find the power consumption parameteres for such uP. I want to know P_idle ...
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1answer
116 views

Parameters to compare microcontrollers for low power consumption?

How do I select a microcontroller with low power consumption? -for MSP430 series we can compare using \$\mu\$A/MHz at active state. Similarly how to compare this with other MCU's like PIC and STM ...
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1answer
167 views

LM431 Reference Pin Current High?

I'm working with the LM431, and have successfully observed it regulating voltage in a series pass configuration. The goal is to regulate an input voltage of up to 0-5V to a maximum output voltage of ...
4
votes
1answer
151 views

How to calculate Snubber for different load value

We are doing home automation project in that we need snubber for both resistive and inductive load. If we connect less than 5W load(Bulb) it is keep on glowing without switch on. Whether i ...
4
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5answers
350 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
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0answers
89 views

Capturing a 16.368MHz data stream with a MCU running at 32MHz

I have a 32MHz MCU (Atmel XMEGA A4) and I need to recover a digital signal coming from a GPS front end chip which is outputting SIGN and MAGNITUDE data at 16.368MHz. Clearly this is a hell of a task ...
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1answer
83 views

Micro-controller and microphone minimal current possible

We would like to have an idea about the minimal current consumption that could be achieve. We need to have some microchip mcu, that have a microphone connected to its ADC port, and that is always ...
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3answers
122 views

Very low power: Most power-efficient way of storing charge for hours

I'm researching the feasibility of doing an art project that involves soaking up ambient RF power in a city (energy harvesting) and then playing a 1 second sound clip through a speaker as soon as ...
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3answers
308 views

Low power, seven segment display

I want to display a 4 digit number on a small device that fits in a hand. I have a CR2032 3V battery at around 230mA, my microprocessor is a 8051 (in a BLE112) usually uses about 0.9µA and I want the ...
2
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1answer
121 views

Transistor as switch in variable voltage environment

I'm using a 3.3v arduino pro mini to make a solar-powered "garden bot." All the bot does is use a capacitive moisture sensor (which can accept a supply voltage between 3 and 20v), and turn on a ...
2
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1answer
119 views

FPGA power management capabilitites

When designing ASICs, engineers may use a wide set of architectural and micro-architectural tools and approaches for management of power consumption of the chip: Retention registers - registers ...
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3answers
450 views

Can I use two Arduino digital pins in parallel to keep a higher voltage?

I'm using a digital pin as a supply to a sensor (should draw ~7mA). Unfortunately, the sensor pulls the voltage of the digital pin down from 3.3v to 3.0v, which isn't enough for the sensor. Can I ...
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2answers
163 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 ...
0
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1answer
401 views

Trigger a relay with a very low DC voltage

I want to light up a couple of LEDs using a relay to trigger this event. I have a very low DC voltage, about 0.15mV to 0.20mV and I want to somehow take this voltage to a relay, that will be also ...
2
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1answer
141 views

Shut down circuit sections

I am currently devising ways to shut off different circuit sections in an embedded circuit. Here is a breakdown of what I am doing and my initial idea. Currently I have a micro controller which is ...
2
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1answer
1k views

STM32F103 low power mode (stop)

I've got a project where I'm trying to get the power consumption down as low as possible (on an STM32F103RCT6). I looked at ST's document on getting the STM32F2 power consumption down as low as ...
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1answer
109 views

What topologies are used for ultra-low-power CMOS DACs?

What schematics, topologies or algorithms are suitable for ultra-low-power DAC design? You can assume the following design requirements (they are flexible): Full custom CMOS design (this is not a ...
3
votes
2answers
237 views

Transferring arbitrary data via Bluetooth Smart (BLE) with nRF51

I was wondering if it was possible to send arbitrary packets of data over a Bluetooth Smart (Low Energy, 4.0) link from a nRF51 (Nordic Semi, BLE compliant SoC) to a phone? Also if you don't know the ...
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3answers
395 views

Circuit to switch power when detecting current (40mA/12V)

I am looking for a way to supply power to some consumers (sensors) only while another consumer (datalogger) draws power. All consumers run from the same 12v car battery. The datalogger wakes up ...
3
votes
1answer
116 views

Designing a latch with no constant power supply

I am trying to design a latch for an energy harvesting application with a very low power system. Basically I have a setup with a 3.3V regulated output driving a circuit, which is run off a capacitor ...
3
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2answers
266 views

How to draw current from a telephone line?

My landline phone comes with a lcd display caller id and clock. Even if I remove the 2 AA 1.5V batteries, the lcd still shows time even if I'm not busy on a call. The lcd has no other source of power ...
2
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1answer
506 views

Low power timer switch circuit

Our car sharing club is working to implement a smart system in our vehicles which will allow access via RFID-cards, and which will record milage for the booking and billing system. We are using a ...
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4answers
2k views

Leading Power Factor effects on electrical System

If power factor comes in leading & showing -0.95, is there any effect on electrical system? If yes, then please tell me what would be the effects and how long we keep power factor in leading?? ...
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0answers
38 views

Measure Low Voltage Signals [duplicate]

I have a tankless hot water heater in my home that is controlled through a two wire low voltage wiring from a multi function controller. I would like to know how I can measure the signals being sent ...
2
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1answer
108 views

How do I momentarily ground a 3.3V signal (with a pull-up resistor) when power is first applied?

I need to momentarily ground a 3.3V signal that has a pull-up resistor on it when power is first applied. This is feasible using a microcontroller or a push-button, but is there a "passive" way to ...
2
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3answers
263 views

Sleep on Arm Cortex

I'm trying to put a cortex m4 processor (m3 with dsp extensions) to sleep for a little less than a second. I want to be able to tell it to sleep, then a second later, or when a button is pressed, pick ...