Questions relating systems powered by a 12 volt supply. This may include automotive systems and lead-acid batteries that are nominally 12 volts although be aware that under many conditions the actual voltage may be several volts higher.

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1answer
26 views

How Does Connecting a Battery in Series Affect Current Flow

Background: I am creating a circuit to run electronics and motors. The some of the electronics are 5V some are 12V and the motors are 24V. I have a small universal 12V battery for the electronics I ...
0
votes
1answer
31 views

mechanical relay output voltage doesn't change

As a followup to my previous question, where a 2222 npn transistor wasn't beefy enough to handle the load I was putting on it to activate a solenoid valve, I decided to try a mechanical relay board ...
0
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2answers
39 views

transistor toggles an LED, but not a solenoid valve

I'm working on a hobby project where I'm trying to drive a solenoid valve with an arduino (for some automated plant watering). The solenoid valve takes 12v, so I've rigged up some smaller batteries ...
0
votes
1answer
58 views

momentary to on/off switch for 12v

I got some oem switches and I want to mod them into light switches. Here is my situation: I would like to use the oem switch since it has illumination and button that matches the car.I have already ...
0
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1answer
42 views

electronics voltage sensitivity

I have a 12v battery directly powering a handful of electronic devices (router, modem, hard drives). These vary from 0.5a~2a so I have breakers on the (+) lines ...
0
votes
1answer
44 views

What kind of time delay switch to choose to reverse motor for just a couple of seconds

I would like to know the following: I have a motor driving a lead screw which transports a part either up or down. When going down and something comes in the way a switch gets triggered by the ...
0
votes
1answer
63 views

Running a load off a solar panel connected to 2x 12V batteries.

I am having trouble figuring out what relay I should be using for my solar panel set up. I have a solar panel running to a solar charge controller. I then have the controller running into a relay. ...
0
votes
3answers
122 views

How to measure amperate going through a 220V cable?

Meta objective: I want to pull up a TV with a winch, when the TV is turned off. I can already move up and down the TV invoked by my controller (Arduino Nano). The physical push-sensor stops the winch ...
0
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0answers
83 views

Custom USB 7 port hub PCB dasiy-chain

I had a schematic laid out for a custom USB 2.0 7-port hub I needed to create for a project of mine. It currently uses Ethernet RJ45 sockets to provide power and data to each hub (2 Ethernet ports for ...
-2
votes
1answer
52 views

Can a 12v 27a alkaline battery damage? [closed]

I've looked inside my garage remote control and I've discovered a 12v 27a battery. The voltage is very low, but the ampere are many, can it damage a person when is fully charged? Thanks
1
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1answer
108 views

How to wire multiple 2 volt flickering LEDs to work on 12V auto system

I have tried to use the site to find an answer to this, but it seems everyone that has asked questions have different variables than I am dealing with, and I can't ever seem to grasp electrical ...
-2
votes
1answer
102 views

Connecting two power supplies with almost like voltages to an amplifier in parallel

I have recently been working on a custom sound system in my living room. For the subwoofer, I am using a 1000W amplifier. This is currently running off of a 12V computer power supply that outputs ...
3
votes
1answer
81 views

How long can I run my camera off this battery?

I have Ultramax NP7-12 12v 7ah specifications here: http://www.batterymasters.co.uk/ProductDocs/SLAUMXNP7-12-TECH.pdf My camera consumes 1.25 watts per hour and runs at 7.8 volts but can run between ...
0
votes
0answers
34 views

Emulating, tricking or faking a liquid cooling sensor

I have a specialty server board with an attached liquid cooling system, the liquid cooler has 3 pins attached to the board, pin 1 gnd, pin 2 12v+, pin3 sense. I'm assuiming this works like a cpu fan. ...
0
votes
1answer
60 views

Clock / timer activated 2 second voltage timer for wiper motor project

Ok, I need a 12 volt voltage timer using clock or timer for a wiper motor. I am working on a project in my garage. Simply put, I am wanting to use a wiper motor that will open and close a spring held ...
1
vote
2answers
385 views

Two relays for DRL on a car

I am trying to make a circuit for my newly installed DRL (Day running lights), what I am trying to do is have the DRL run all the time, turn off when using high beam, dimmed when headlights are on. I ...
2
votes
2answers
93 views

Interfacing incompletely documented logic signal where resistor affects output voltage level

So I've got this marginally documented 12V logic signal from something I have to regard as a black box that I'd like to interface to a pi or arduino (i.e. c 3V). I have 3 lines - 0V, +12V and signal ...
0
votes
1answer
86 views

electrical fridge running on car battery [closed]

I'll be out of grid for some days and I'm planning to have a small electrical fridge with me. It's a 12V 4A small fridge with a cigar lighter plug, but I won't have a car with me, so I think I could ...
1
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1answer
894 views

12V LED strips in series with a 24V power supply?

I am purchasing 50x - 1Meter / 12V / 72 LED /Rigid SMD 5730 strips directly from china. I don't know the LED manufacturer, nor the resistor being used. (yes, this is a gamble) The strip is one that ...
-3
votes
1answer
49 views

12 v xbox connection [duplicate]

Hi again if I just want to connect my tv and x box360 to the mains I've got it connected to the van at no so the neg is to the body and pos is by the fuse box. Can I just wire the transformer neg to ...
0
votes
1answer
780 views

How to build a blinking 12V indicator LED light

I attempt to build a blinking circuit using 12V truck light ( like this one: http://www.princessauto.com/pal/en/Tail-Lights/4-in-LED-Stop-Turn-Tail-Light/8126047.p). I have try to build a single LED ...
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votes
3answers
100 views

Need to cap voltage at 12V, and need to vary voltage down

I tried to find something like this in the knowledge base, but didn't see a perfect match. I have a small submersible pump. 12VDC, 4.8W. Model DC30a-1230. I assume that is 0.4amps. There seem to ...
1
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2answers
133 views

UPS 12V power switching

I was trying to make a sort of UPS circuit with a 12V DC 5Ah power supply and a 12V 5Ah seal-lead battery. My question is that I don't know how to switch quickly from line supply to battery. I've ...
1
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2answers
87 views

Messing with rgb leds and have a question

I have some LEDs that I'm wanting to use in a project. I would like to know what's the best resistor I would need to get the most light out of the 3 different colors using a 12v source. I've measured ...
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2answers
1k views

Charging battery using computer power supply?

I have new 600W ATX computer power supply unit. I have wired green and black together to make power supply turn on when plugged in. I wanted to charge my 12VDC empty battery, without dealing damage to ...
1
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1answer
163 views

Best method to eliminate alternator whine from a 12V line?

I've purchased a Miccus Mini-Jack Rx BlueTooth audio receiver. This device will accept a bluetooth signal from my phone and output it to a headphone jack that I plug into the AUX-In on my car stereo. ...
1
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3answers
222 views

Best way to drop 12V fan to 7-9V? [closed]

So my Xbox one PSU died and microsoft doesn't sell official ones yet, so I bought a third party one and the fan that is in it is a 12V blower fan with 2 wires running right to the board (it says 12V ...
0
votes
1answer
141 views

Can I damage a device using opposite polarity? [closed]

I have a device that requires input of 12V DC with positive polarity and a power supply that outputs 12V DC negative polarity (see figures below). Can I plug it in to try to see if it's working or ...
0
votes
4answers
1k views

Why does my DIY “solar panel circuit” show battery voltage and not solar panel voltage?

I've got two solar panels set up in series as shown on the below schema. I connect positive on panel A to positive on battery, and negative on panel B to negative on battery. The two panels produce 9V ...
-1
votes
1answer
141 views

Why does one LED slightly influence the other parallel LED although controled by differenct MOSFET-N?

I created a simple circuit that turns on and off two 12VDC LED with signals from my Arduino Leonardo R3, which is powered by a 5V USB cable from my PC. The LEDs are attached to a dedicated 12V power ...
2
votes
3answers
334 views

Triple output power supply

I need to power my device with three different voltages: 3.3V, 5V and 12V. I already have a 12V 1A power supply. So my questions are: Can I use the circuit below to get these three voltages? Is it ...
1
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1answer
55 views

Would this be ok to control the speed of a PC fan? [closed]

I have a 240mm PC fan connected to a 12v adapter. The fan is quite noisy and i would like to have the option to turn the speed up/down or off completely. The Fan is: Current (A): 0.18 The 12v Mains ...
2
votes
2answers
126 views

Can I use this high-side driver with arduino?

I have salvaged a PCB with quite few single and multi-channel high side drivers. One of the is VN5E010AH. If I understood datasheet, this chip can drive high voltage using low voltage cmos compatible ...
1
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0answers
61 views

Switching cold cathode fluorescent lights on and off without relay?

I have a few sets of 2-in-1 CCFLs that are designed to be powered off the 12V rail of a computer PSU. I'm planning to build a large 7-seg display using them so I'd like to be able to switch them on ...
6
votes
2answers
2k views

How to make -12V from a +12V supply?

The equipment I have needs +5V +12V and -12V supplied to it. The old PSU which provided all the voltages blew to bits. I have sourced a PSU1 +5V (30A), and PSU2 &PSU3 (two identical +12V (2A) ...
0
votes
2answers
272 views

How to supply power to a 12V solenoid from China, getting hot

I bought this solenoid from ebay and was wondering how to power it. It says 12 volts as you can also see from the picture, but I tested it with putting a 9V battery straight to its terminals for a ...
1
vote
1answer
714 views

Which diodes for 12v indicator light circuit?

Which diodes for 12v indicator light circuit? I have a car whose signal light audio indicator is too soft to hear. I would like to set-up an visual indicator on the dash for when the signal lights ...
6
votes
1answer
2k 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 ...
0
votes
1answer
100 views

NAND gate from BJTs: interfacing +/- 12v op-amp and 5v logic: destroy BJT with excessive Vebo?

I want to switch on a relay when both a 5v logic input is high and a (LM741 used as a) comparator is around +10v, and the circuit I planned to use is below. The problem I see with the circuit is when ...
0
votes
1answer
164 views

Reduce voltage on PSU from 52V to 12V

I'm building a mining rig and is planning on using a ESP120 HP 3kW 52V power supply. I've seen someone get it down to 48V with this mod, but I wonder some one got it down to 12V? Or is it not ...
2
votes
1answer
792 views

Control of 4 pin cpu fan with 3 pin socket and …?

I have a problem with controlling my cpu fan speed since it has a 4 pin connector and the socket on my motherboard is broken (transistor connected to it has burnt). I have it connect at the moment ...
0
votes
0answers
90 views

Discharge limit on a 12V 9800mAh Lithium-ion Battery

I am running a 12V solar system that powers a 5050 LED light bar of 7.4W. Powered by a 25W mono PV and has a total 12V storage of: 1x 6800mAh 1x 9800mAh (Lithium-ion batteries in series) The ...
0
votes
2answers
171 views

12v capacitor / UPS system [duplicate]

I am looking to make a capacitor/UPS system for a few different electrical components in my car. I want to power the rear view camera, headrest monitors, and possibly the head unit for about 30 ...
0
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2answers
170 views

LED lights and heatsink

I want to make a light for my boat roof. If I were to buy these (or similar), would I need to mount them to a heatsink, or would they be fine just as is? The largest size one has a power output of ...
0
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3answers
2k views

How to connect a Inductive Proximity Sensor Switch NPN DC6-36V to PIC18F4550 5V

I have got a LJ12A3-4-Z/BX Inductive Proximity Sensor Switch NPN DC6-36V with this Specifications: Model: LJ12A3-4-Z/BX Theory: Inductive Type Sensor Wire Type: Cylindrical DC 3 Wire Type ...
0
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1answer
497 views

Charge at 24v and discharge at 12v for battery system

Is my thinking correct. Below is a simple diagram of the concept I want to check. Is this: 1: Possible 2: Feasible? I.E are there any concerns or foreseen issues with this design? Edit:
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2answers
185 views

How to use ordinary voltage regulator from a 40amp source?

My power source is 12v 40amp(car battery). My project needs 12v but only 500 or 1000ma max. My 12v voltage regulator (NTE960) explodes with 40amps, so I must reduce the current (too much current for ...
3
votes
2answers
433 views

12V Battery Backup Supply for GPRS Tracker

I have little knowledge on electronics apart from following a few guides. I have made a few 7 segment displays, nothing complicated. Recently my girlfriends car was stolen and she has an insurance ...
1
vote
1answer
98 views

12v socket not providing enough current for mobile phone? [closed]

I've just installed a 12v socket to my motorcycle. The socket has a sticker saying "12V - 1A", and the user manual says that "use is possible up to a power input rating of 12W". Taking that into ...
1
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1answer
209 views

How to use Battery Charge controller (BQ2002N)

I am working with an Arduino which I have a 12v power supply for, but also needs to be able to run off a NiMH/NiCAD battery pack when not connected, and recharge the battery pack when it is connected. ...