Involving or pertaining to a circuit or device that is intended to be operated with cells or batteries (as opposed to mains power, for example).

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48 views

Power micro LED's from 5 Volt USB

simulate this circuit – Schematic created using CircuitLab I'm working with this set of LED's: Link here: 30 Ft Led wire I measured the draw for the entire string at about 170 ...
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1answer
37 views

Microcontroller self-shutdown with MAX682

I have read How to implement a soft power switch controllable by microcontroller? and am wondering if something similar would be possible with a MAX682. What I want, is a device that is turned on by ...
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37 views

Difference in self discharge rate between Lithium iron phosphate battery vs Lithium Polymer Battery

What is the difference in self discharge rate between lithium iron phosphate battery and lithium polymer battery? I have a remote application in which the self discharge rate matters a lot.
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2answers
61 views

Capacitor leakage and design for low energy battery powered devices

For the design of a portable battery operated device, I have some power circuitry which requires a DC-DC converter and some other regulators, battery charger IC etc. While in the process of ...
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3answers
136 views

Boost regulator from 3V to 14V; then two LDO to make a +5/-5 power supply?

I am designing a mixed signal circuit and I need +5/-5 dual supply for my opamps. Could the following configuration work, else what are my alternatives? ...
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4answers
141 views

Battery-Operated Mobile Charger

I want to build a mobile charger that is battery operated and found this diagram. At first glance, this diagram looks kinda simple and I thought that this won't work. I'm a newbie on making this kind ...
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2answers
97 views

How to actuate 24V solenoids from 3.6V batteries

I want to build a battery-powered device that actuates a 24 V solenoid when a button is pressed. How could I power it from a 18650-sized lithium-ion cell? It should work down to about 3 V, when it's ...
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1answer
49 views

Lead Acid max discharge rate?

I am building a flashlight using a large(ish) 35W HID headlamp from a car, and I'm having troubles choosing a good battery technology. The inverter draws about 3.5A - 4A at 12V, tested on a large ...
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44 views

Battery backed RAM for access by the OS

I apologize if this is the wrong place to ask this (just let me know where to go, if that's the case). I want to know if anyone has an idea how to set up battery backed RAM, like in an old S/NES ...
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3answers
166 views

How to keep circuit powered when battery disconnected for short time

In an assembly, I'm using spring loaded pins to connect a battery to a circuit board. It's possible from dropping the assembly that power may become disconnected for milliseconds at a time from the ...
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1answer
72 views

How create a low-voltage boost (~4v to 5v)

I am looking for a circuit that will go from a Li battery that has a voltage between 3.6v and 4.3v up to 5v - and I have seen similar questions such as this and this, but those just recommend ...
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1answer
76 views

Toggle battery powered LEDs

I am helping to build a costume prop that has four LEDs lights on it (1 white and 3 amber). This device is worn on the wrist, so space for power is limited- a 9V battery or something that will fit in ...
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66 views

L293D causing motors to move slowly

I'm modifying an RC car to use bluetooth. I use the L293D chip, and when I connect the motor to the chip, the car barely moves. If I connect the 9V battery directly to the motor, it moves the car ...
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46 views

Lengthen charge times with batteries

Would replacing a 3.7v 1000mAh lithium ion battery with a 3.7v 5000mAh lithium ion batter make my projects last longer between charges?
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1answer
104 views

Finding the right battery?

I have a 5v circuit that's running on a 3.7v 1000mAh battery. I got it changing just right and the circuit is running fine but it doesn't last as long as I want it too. So how can I find the right ...
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2answers
572 views

How does this mosquito zapper circuit work?

For the purpose of learning, I have tear down a small mosquito zapper racket. I am now trying to understand how the circuit is working (which goal is to produce high voltage). (yellow = ...
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1answer
163 views

nRF24L01+ RX in pulsed operation to save power?

I'm considering building a handheld radio receiver based on an nRF24L01+ and an ATtiny chip. It needs to receive "continuously", to receive a control signal that might operate some attached LEDs or ...
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1answer
108 views

How does the nRF24L01+ performance degrade with supply voltage?

I'm looking at building a small handheld unit based on an nRF24L01+ in PRX mode. It needs to be able to receive "continuously" to receive control signals that would cause an attached Atmel ATtiny to ...
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2answers
136 views

How to get 12v 5amps battery setup for LED strip

I'm building an LED lightbox but I really want to avoid using a power supply/cable so I'm trying to figure out a way to do it with batteries. The strip I'm using is ...
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1answer
112 views

Arduino Battery Over-Discharge Protection (O-DP)

I am getting an Arduino Uno soon, and am planning to run off a 8-cell NiMH battery pack (through the power jack). Assuming a .9V cut-off per cell, that'll mean a 7.2 cut-off voltage. How would I wire ...
3
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2answers
126 views

RF Wakeup - Battling power consumption

I am currently using two nRF24L01+ (2.4 GHz RF transceivers) together with two AVRs to create a keyless entry system. My problem is battery lifetime when using a CR2032 battery to power the key. The ...
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2answers
92 views

Alternatives to relay/contactors in DC circuits

I wanted to switch a 60Vdc line to ON/OFF using a 60Vdc controlling signal for some kind of a feedback system (yes both are 60Vdc). Presently I have two options visible: Solid State 60Vdc input ...
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1answer
99 views

On button press, use battery if no power is provided via USB

I'm making a binary clock that is normally powered using USB 5V. I already have a battery (CR2032) for the RTC chip. So I want to also use this battery to power the board, when a button is pressed ...
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3answers
202 views

Using timer to power on/off a high current circuit

I'm working on a Arduino project that takes measurements from the environment and sends them to a remote server over WiFi. The circuit should be battery powered and I've measured that what I have at ...
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2answers
163 views

How do I use an adjustable LDO regulator to power devices with USB that usually use AA/AAA batteries (or should I)?

I want to use USB to power devices designed to work with one, two, or three AA/AAA batteries. Three seems to be the trickiest, because it involves dropping the voltage only ~0.5 V from 5±0.25 V to 4.5 ...
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1answer
67 views

What is this most efficient way to power a high powered 6 V and a low powered 12 V device from a battery?

I'm looking to power two devices (two amplifiers, an Akai - EIE Pro and a Behringer - MICROAMP HA400) from a battery source (a big 12 or 6 V sealed lead-acid battery). Unfortunately they require ...
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1answer
102 views

Backward measurement of AVcc against reference voltage connected to ADC input

what you think about ADC backward measuring supply voltage in microcontroller? It looks interesting for battery-powered devices. The idea is: Connect constant voltage (some voltage reference IC) to ...
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0answers
48 views

BMS: Comparator using TLV1702

I was asked by my boss to develop a system to manage an automatic door battery system. The goal is for when, for example, the power goes out, you get home and want to open your garage door, with this ...
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1answer
896 views

LED needs a minimum current or minimum voltage to operate in forward bias

I want to wire up an IR LED on a battery. I've seen many tutorials telling me that I should add a resistor, but none says what resistor to use to maximize battery life. So a 680ohm resistor will do ...
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2answers
111 views

How can I regulate a 5V battery?

I am trying to use this 5V RAVPower battery pack to drive some electronics and a high-current load: ...
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1answer
49 views

Led head light - preventing Battery contacts from rusting

I have a cheapo Asda headlight who'sbattery contacts keep rusting over. Even if you leave the bloody thing indoors it rusts after awhile. Is there any chemicals I can put on it to stop this from ...
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1answer
155 views

Decoupling a power supply

I'm building my first biped robot, using a Raspberry Pi as the brain. My problem is, I want to decouple the battery before I use it to power the Pi. The reason I want to decouple the battery is ...
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1answer
140 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 ...
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1answer
147 views

24 Hr A Day Powered Aquatic Pump

I am looking to install a DC 12V 6W submersible aquatic pool pump for use in a small scale hydroponic setup. The location of the beds will be too far away from mains electrical, and I would like to ...
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1answer
179 views

Power Arduino Mini with 3 AA batteries

The arduino mini consumes 5V. The Voltage input is min. 7V. Is it possible to ignore that and attach 3 AA batteries (4.5V) or 4AA Batteries 6V between the GND and 5V pin of an arduino mini for long ...
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1answer
88 views

Wireless “Arduino” sensors - what is at least needed on circuit?

When I finished my Master Unit for Home Control, I want to attach some Wireless sensors via 433MHz Protocol. (At least 2 ones, 1 for Measuring the outdoor Temperature/Humidity with an DHT22 and ...
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53 views

Designing battery circuit for a custom tablet

I am designing a tablet with SOC computer. I am trying to figure out how the battery will interface with this. I know that I will need to use some Charging IC that can supply constant current and ...
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3answers
310 views

2xAAA battery => 3.3v/250mA step-up converter with logic-driven power control [superseded]

EDIT: The requirements in the question below appear to be practically unsolvable, but happily after a bit of digging I actually found an alternative equivalent RS232 device which runs off a 3.7V Li-Po ...
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3answers
822 views

Smallest, simplest possible (randomly) flashing 2-3 LED circuit

I am trying to randomly flash 2-3 LEDs using the smallest possible circuit using 1 or 2 CR2032 batteries. Can I power 2-3 3mm (3-3.4v, 20mA)(amber, white) flashing (slow 1Hz) LEDs using one CR2032 ...
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1answer
301 views

Switching Arduino/ATMega to sleep mode when on battery

I'm trying to make a small clock but want to ditch the need for a separate RTC chip with battery backup. What I would like to do, instead, is keep track of the time completely on the ATMega using the ...
5
votes
1answer
297 views

How good is the advice to run the car headlights before starting the car in cold weather?

I'll do my best to formulate this as a purely electrical problem so that it isn't claimed to be belonging to Vehicle Maintenance SE. We have a lead-acid starter battery (not a deep cycle fashion) ...
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1answer
961 views

switch between battery and usb power no microcontroller circuit

Following an earlier question about how to switch between battery and USB power, I would love to implement the TC2014 LDO as suggested by Russell McMahon. That way I could switch between 4AA ...
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1answer
151 views

Modding a charger into a power supply + charger?

I am making a handheld radio telescope which needs 13-18v to power and currently runs off 2 9V batteries. However it eats power like mad, drains them so hard that it actually needs to be recalibrated ...
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2answers
171 views

Convert Plugin Christmas decoration to a battery operated light

I have an old ceramic Christmas tree that I would like to convert to a battery powered source in order to get rid of the cord. Ideally I'd love to add a timer to it as well. I'm not sure what ...
1
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1answer
98 views

Power rail design from Li-Polymer battery chip output

Case: I am building a battery driven device and so far it seems like I will be using the MCP73871 to provide my device with battery power and charging via USB. I need to regulate the output from the ...
2
votes
2answers
634 views

Arduino: How can one control a 2-wire DC motor with PWM?

I want to control the speed of a two-wire DC motor using PWM. I already managed to control a 4-wire motor, but now I need to use a two-wire motor. I would connect it to the Arduino directly, but the ...
2
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3answers
390 views

Best way to reduce battery consumption for LED device?

I'm building a device that needs to "light up" to indicate status to the user. I of course want to use LEDs to light the device up, but I'm worried about battery consumption since I would like it to ...
3
votes
1answer
422 views

Battery powered device hardware design tips

I'm working on a prototype product(Wifi motion sensor) that will be powered from a battery source, it has a mega328(arduino bootloader, with sleep mode on and wake on interrupt,and WDT in case it ...
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1answer
304 views

How to hack a battery powered device to use 1 Li-ion cell instead of 2 NiMH cells?

I want to hack a cordless computer mouse, so it can be used with 1 lithium ion cell (standard cobalt cathode to be extra precise) instead of the intended 2 nickel metal hydride cells. The main reason ...
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1answer
231 views

How to measure battery charge and depletion over time

When using my various electronic devices, they always seem to know how much charge is left in the battery. They also know when the battery is completely charged. Not exactly sure how this is ...