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

1
vote
1answer
40 views

Solenoid Valve blowing power LED - how can i protect the LED?

I have this simple circuit setup and working well to turn a solenoid valve on (close it) and off (open it again) for a watering system I use. missing is an on/off switch before the VCC. However, I ...
0
votes
0answers
58 views

What tool can monitor voltage on a bundle of wires?

I'm working on a vehicle and trying to determine which wires control which circuits - power windows, power locks, starter, trunk release, etc. I've searched but have not been able to find the wiring ...
-1
votes
1answer
24 views

Controlling 12v motors with cheap rc car parts [closed]

I want to use a cheap rc car to control 2 12v motors, I want the motors to go both directions hence the rc car, I 1st bought a motor controller from eBay and hooked up the rc parts, a 12v supply and ...
-6
votes
1answer
53 views

running motors from ownely coupled generator [closed]

i want to do the experiment on motor generator my design is iamgoing to connect a 2 dc motors and 2 dc generators in that 1st dc motor and 1st dc generator is coupled 1st dc motor and 2nd dc motor are ...
1
vote
5answers
143 views

how to provide light for multiple 12 v led lights for 2 weeks

I'm participating in an art show soon in which I am making "sculptural light paintings" of which require a few 12v LED strips. They're the kind that work in aquariums and car's taillights and whatnot, ...
-5
votes
1answer
60 views

Using a power bank to power a router for a few seconds [closed]

Where I live, the electricity often goes out for about 15 seconds, until the backup generator kicks in. I need a cheap way to protect my wireless router and keep the connection uninterrupted for ...
0
votes
2answers
31 views

Use a li-ion battery at two different voltages

I scavenged a li-ion battery from a broken laptop. It is made of 6 Samsung ICR18650 cells (3.75V 2800mAh), parallels two by two so that the total pack is in fact the sum of 3 cells at 3.75V, so 11.25V ...
2
votes
2answers
65 views

Basic 12V Step-Start Circuit For Automotive Fans: Troubleshooting

To keep this short and sweet, I wanted to make a circuit/controller to decrease the inrush current on a large powerful fan for my race car. I ideally just wanted something that wouldn't let the amps ...
0
votes
0answers
66 views

12V / 3.3V soft power switch circuit

Based on the following circuit I would like to build an MCU-controlled latching power switch that switches 12V instead of 5V while still being controlled by 3.3V (tolerant up to 3.6V) GPIO pins of an ...
1
vote
1answer
44 views

Using 12v to supply a Raspberry Pi with a switching regulator

firstly please forgive any confused terminology, I'm not an electrical engineer by trade! I have a Raspberry Pi which is operating a series of relays via its GPIO pins. On the other side of the ...
0
votes
0answers
25 views

Help with solar panel/battery & load calculations

First solar project and I've been researching for a couple of days but still struggling with some basics. Trying to set up a simple 12v system, maintained by a solar panel. Solar Panel> Charge ...
1
vote
4answers
125 views

12V solenoid drawing more current than it needs

I'm fairly new to practical electronics so I apologize if any of this is obvious. I am currently trying to use a microcontroller to control the energizing of several 12V solenoid valves using a PC ...
0
votes
4answers
181 views

Heating a 1km long wire to 110 C using a 12v supply from a car cigarette lighter

I am a complete newbie to anything electrical/electronics. I am doing a project where I need to heat a 1 km long (Nichrome/Kanthal) wire to up to 110 degree Celcius. The only power supply available is ...
0
votes
1answer
31 views

Dual output/dual input canceling 12v trigger

I have a video projector with two 12V trigger outputs (output impedance: 4.7 kilohms). It is attached to two separate motorized screens. Unfortunately the projector software makes the second trigger ...
0
votes
1answer
31 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
63 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
63 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
93 views

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

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
66 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
388 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
98 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
62 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
104 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
253 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
77 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
154 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
61 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
257 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
153 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
131 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
97 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
440 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
88 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
71 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
147 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
621 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
162 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
221 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
157 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
80 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
137 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
169 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
50 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
175 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
176 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
305 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
170 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
91 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
273 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 ...