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.

learn more… | top users | synonyms

0
votes
1answer
18 views

Need to add blinker module to relay trigger

simulate this circuit – Schematic created using CircuitLab I have a simple light controller box. I have a 2 channel relay that controls a red and green light by magnetic switch. so we can ...
0
votes
0answers
33 views

Voltage regulator circuit - running off a 12V vehicle battery

I am designing a circuit for power regulation [rerquire 5V and 3.3V supplies] from a 12V vehicle battery. The circuit in its current form is attached. Max current drawn by the circuit in normal ...
1
vote
1answer
46 views

12V 345 Amp lawn mower battery to a 12V 10 amp motor?

I have a 12v scissor jack that is meant to plug in to a car cigarette lighter, which I believe is around 10 amps. However, I want to hook this jack directly up to a 12V battery, which is rated at ...
0
votes
3answers
82 views

Is there an affordable Power Supply capable of 12 Volts and 7 Amps? [on hold]

I am trying to power a pump that requires 12 Volts and 7 Amps to run. I have looked around but cannot seem to find a power supply capable of the voltage and the current. Does anyone know where would ...
0
votes
1answer
27 views

What kind of relay do I need for for 12V source with a 5V control voltage

Trying to figure out which relay I need for a project I'm working on. The source is a 12V battery, and I'm looking to turn on a 12v solenoid using a relay. I want the control voltage on the rely to be ...
1
vote
1answer
127 views

Dropping 12V to 7.4V

I'm trying to power up my NXT Mindstorm Brick which needs 7.4V (at least, that's what the battery output is) with a 12V Power Adapter. I'm doing that because I want a constant supply from the socket ...
1
vote
0answers
48 views

Convert a NO push button into an On/Off button

I'm building a boombox, and it needs a couple of switches for main on/off, voltmeter on/off and LED lights on/off. Since I don't have any metalworking tools I am going to buy a premade front panel, ...
0
votes
1answer
36 views

Time delay relay

I am having trouble figuring out what kind of time delayed relay I need for this circuit or if anything will work even. It is used to keep a dome light on for a few seconds in a vehicle after the ...
1
vote
1answer
66 views

Why are some AC/DC adapters light while others are heavy?

I was browsing the thrift store and found a nice pair of JBL 2.0 computer speakers, but they lacked a power adapter. They call for a 12V 1A supply. I have a ton of "bricks" lying around, but no 12V ...
0
votes
2answers
147 views

Generating 12V PWM from 5V PWM

I am generating a 5V PWM signal from my MCU (an Atmel ATMEGA1284P). I need to convert this to a 12V PWM signal. For this I designed the circuit below, something very similar to a Sziklai pair, but ...
0
votes
0answers
61 views

Solar panel - voltage regulator

I am contemplating the possibility to run a trolling motor (to push my canoe) with a 250W solar panel. Electrical Specifications: Peak power: 250 W (minus 0, plus 5W Tolerance!) Optimum operating ...
0
votes
0answers
62 views

Detect a 12V signal with an Arduino [duplicate]

Using a Pro Micro Arduino I want it to look for a 12V signal and turn on a light when it is present. After a quick search I found this, and wired everything accordingly. However after writing code it ...
0
votes
1answer
122 views

Accidentally soldered in 12v 60ma bulbs in a 14v 95ma circuit - dangerous?

I was replacing some lights in my car's HVAC control box, and I used 12v 60ma bulbs (link), and after reinstalling it in the car (bulbs are working), I was doing some Googling and noticed that some ...
0
votes
1answer
53 views

Turn off device when USB power is present

I have a device I'd like to turn off when power is available via a USB socket. The device that needs to be turned on/off is powered by a 12v DC 0.5 amp adapter. USB sockets should have a max 5v 0.5 ...
2
votes
2answers
167 views

+5V and -5V power supply from 12V DC

I'm creating an RGB switcher for a car video system and would like to use the MAX466 chip, which needs -5V, GND and +5V. I have no idea how to change normal 12V DC (car battery) to dual 5V. I found ...
0
votes
1answer
113 views

Designing power supply with 5v and 3.3v from a 12v supply with switching regulators

I have 12V DC coming in from a power brick and I need to supply 5V @ 1A for USB and 3.3V @ 5A max for mSata and PCIe. I basically need to make a small atx power supply that I can integrate on my ...
0
votes
2answers
104 views

Automatic 12V plant watering system?

I'm planning to make a plant watering system . There is a beeper so it will alert us when the soil is dry.I have got a 12V DC motor . So i'll be removing this beeper and i need to add this DC ...
0
votes
1answer
86 views

Transistor shortcut

i would like to fade an led strip using pwm with a n mosfet led that is commanded by a two way switch ( relay and sw1 ) like this: simulate this circuit – Schematic created using ...
2
votes
2answers
356 views

Is this 12 volt LED circuit correct?

I found this "Plant Grow LED light" circuit on the Internet and I wanted to know if: (Please don't feel pressured to answer all my questions. You can just answer a few only if you like.) this is ...
2
votes
2answers
75 views

How to allow only 12v

I am looking to control a 12v LED light off of a zwave appliance module. Here is my issue, the zwave module outputs about a 5v pulse every few seconds while in the off state, which is enough to ...
0
votes
1answer
66 views

Rewiring a 12V charger

I have a Windows tablet with a charger which crapped out. The old charger was 12V / 1.5A - fairly standard but it had a rare tiny pin connector. Rather than buy a new charger, I decided to cannibalise ...
0
votes
3answers
142 views

Potentiometer - How?

I bought a 5m LED strip from Ebay and connected it to 12V 1.5Amps. I am a starter in engineering. What kind of potentiometer do I need to use to lower or increase the brightness? How many Ohms do I ...
1
vote
2answers
380 views

Transistors to switch 12V 2A

I need to switch some power to a device, so I was wondering, if this will work OK, or do I need to add some other stuff to protect it, or make it work correctly. I ran some simulations, on ...
0
votes
2answers
91 views

#2 L7809CV regulators, connected to #2 9vdc motors

I simply want to connect 2 motors as i show in the image, using a 12VDC power source and 2 #L7809CV, right now the circuit is this you can see in the image i made. The GND its the same source for ...
0
votes
2answers
146 views

Circuit Requirements for a 30 min continuous on off cycle

I would like to build a circuit (preferably using components from old common electronics like a VCR or whatever) that continuously cycles on/off in ~ 30 min intervals. Input voltage is from a 12v ...
0
votes
1answer
87 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
59 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
votes
2answers
89 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
91 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
votes
1answer
46 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
101 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
120 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
206 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
votes
0answers
147 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
79 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
vote
1answer
208 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
172 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
85 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
58 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
115 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
839 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
96 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
110 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
vote
1answer
2k 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
51 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
2k 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 ...
-1
votes
3answers
130 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
vote
2answers
224 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
vote
2answers
108 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 ...
-1
votes
2answers
3k 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 ...