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Questions tagged [12v]

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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24 views

12v power supply not putting out right voltage

Built a 12v power supply for music project. The "music from outer space" bipolar design, and my modules connected aint been working right. Tested the power output with multimeter and got 10v with a 1 ...
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1answer
47 views

Make ground signal last longer?

I'm trying to figure out a way to make a ground signal last longer on my car. I'll explain what is happening and what needs to be done. I'm hooking up an factory alarm on my car. It uses a negative ...
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35 views

Bypassing 110v power-supply on LED light-strip?

I am wanting to use 2 16.4ft rolls of multicolor LED strips in my enclosed trailer for lighting. They come with 110v power supply that plugs into another coverter that the LED lights plug into. Is ...
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29 views

Switching between two connections - adding LEDs to car reversing light circuit

I am doing a DIY project on my car and need some help. I have 2 LED COB on the back of the car, which is to be used for 2 different things: If I put the car into reverse gear, then the LED comes on ...
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1answer
42 views

How to measure available amps? Do i need more load?

My new 200W 18v 11a(max) solar panel reads about 24v 4a 50% efficiency at midday on my MTTP Rich solar controller. I presume this is not great. I was wondering... I have a 48v to 12v stepdown ...
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1answer
39 views

Increase voltage drop required to saturate PNP BJT to avoid noise

I have this circuit which must signal +3.3V or 0V depending on the switch status. The the switch is about 20 meters away and is getting EMI from mains. I realized that it only takes -0.7V of ...
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28 views

How to control single 12V LED with 3,3v GPIO? [duplicate]

Heyo! I need to control single 12V LED using Raspberry's GPIO To be more exact, I need to connect 12V LED & push button to 3.3v GPIO in order to control LED (on/off) and read button push events. ...
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1answer
24 views

Directly Using a Smart Charger with An Old Vector Hunting Spotlight? [closed]

I have an old hunting spotlight (http://documents.dewalt.com/documents/English/Instruction%20Manual/Vector/VEC184POB.pdf) which has a small 12V sealed lead-acid battery. The chargers that come with ...
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1answer
73 views

built in charge controllers take amps they need?

Many devices have built in charge controllers that stop charging when battery is at 100%. I read several places that you can charge devices with the manufacturers recommended voltage and that higher ...
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2answers
52 views

Van with Solar power but no auxillary battery and only on sunny days. Do I need switches and isolators?

I have a 2018 Ram Promaster city cargo van with OEM 12v 70AH 120RC Sealed Led acid battery and a 160a alternator. Sitting on top of the battery I have a 1200 Watt pure sine 110v inverter connected ...
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2answers
42 views

Connecting two wires to a DC 12v port on a controller board with 4 pads for a monitor

Sorry, the question was difficult to word. Basically I recently bought a controller board for a monitor and the DC cable I got wasn't correct. So until I get the right part, I just want to test the ...
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60 views

Charge a 12V marine/boat battery with AC

need to build a diode bridge to recharge a battery (car/boat type) from a boat engine that gives 12V AC. I thought of doing something like this: simulate this circuit – Schematic created using ...
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3answers
52 views

How is the fuse amp rating determined for a 12V AGM battery bank?

I would like to put 3 x 130Ah AGM batteries in parallel and attach a fuse to the positive terminal of each battery. What size fuse should I use? How is the amp rating of the fuse determined? The ...
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2answers
43 views

Is it appropriate to use the TB6621 or DRV8871 motor driver for powering 12V 1 amp motors?

I'm looking to make an Arduino powered rock crawler with 4 motors (want independent control of each wheel, also need to reverse). I'm looking into buying 12V DC motors that seem to have about a 1A ...
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1answer
72 views

Powering a radiator fan with 12V DC power supply

I want to run an old VW Fox's radiator fan on a 12V DC power supply. I have managed to burn out two of the PSUs so far. They work for a while but after a while they start overheating and die. I am ...
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2answers
95 views

Measuring the resistance of USB car chargers

I have a few USB chargers that are powered through a 12 V car receptacle. I measured their resistance with a multimeter, applying the probes to the contacts of the 12 V input. One of the chargers had ...
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0answers
38 views

Do I need a cut off circuit for my battery

Do I really need an auto cut off circuit for my battery when my charger only outputs 13V and 1A at max. The battery I want to charge is a 12V 7Ah Sealed Lead Acid. I heard that the cut off for lead ...
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2answers
38 views

Isolated DC/DC converter application circuit / usage

I'm trying to find a basic application circuit schematic for an isolated DC/DC converter – this one specifically: DCWN03E-12 – but I'm having no luck so far. The thing that led me to this particular ...
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3answers
60 views

would like to verify a filter design I need to make for a backup camera in my truck

I am installing a backup camera in my truck. I am getting some source of electrical "noise" in the electrical system in my truck and its not allowing the backup camera to operate. Let me explain a ...
2
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1answer
93 views

UL 840 clearances

The table 8.1 in UL840 doesn't consider clearances for voltages less than 50V (for example). I have to use a clearance of 0.2 mm on the PCB for the case of overvoltage category 1 and pollution degree ...
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1answer
26 views

Mini 360 DC Buck Converter [closed]

I have bought several DC Buck converters for my home-made 3D printer. I'm running a 24V PSU, but my fans are Noctua (12V) ones. So i want to convert 24V down to 12V. And the Voltage output works fine. ...
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1answer
95 views

Regulating 12v source to 12v

I wish to use a 12v deep cycle battery (I used to use this for my CPAP, when camping) put it on a constant charge, preferably a cheap trickle/float charge circuit, like found at Harbor Freight. I ...
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1answer
49 views

Particle Argon controlling 12V, using 3.7V LiPo

I am trying to control a 12V DC motor using a Particle Argon, powered by a 3.7V LiPo. To get 12V I am using this step up regulator, and to control the motor I am using this DC motor controller. I am ...
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0answers
24 views

Variable voltage relay (Open 10v and below, Closed 12v and above)

I need to trigger (close) a relay when my circuit voltage goes from 9v to 12v. Trying to keep this simple but fear that the voltage difference is too small for relay to open when voltage drops to 9v. ...
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0answers
34 views

Raspberry Pi + L293D to switch 12V solenoid valves

I am porting an Arduino project to Raspberry Pi. On the Arduino I switched two 12V solenoid Valves with the help of a L293D IC. It worked perfectly. Now I am porting this system to a Raspberry Pi. ...
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1answer
64 views

LED Lightbar as a turn signal [closed]

I changed my turn signals to LED light bars the other day. They are completely legal, but the issue I'm having is I can't use my parking lights and turn signals. The bulb that I took out and replaced ...
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3answers
913 views

Discharge time of 12 V 8.4 Ah at 5 mA

I have a motorcycle battery rated as 8.4 Ah (20 HR). It also says 8 Ah (10 HR) and I am not sure what the difference is. Anyway, I have a GPS tracker fitted with a rated ...
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1answer
53 views

Polarity. What do “C” & “P” signify?

G4 bi pin LED bulb. Silicone coated Hello all. Thanks for the forum. I have some of these: G4 bi pin LED bulbs. Silicone coated dimmable 12 volt DC. They are 1.5watt. Although not visible on this ...
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1answer
47 views

How to control a lightbar with 20 individual modules? [closed]

The TL;DR version of my question is, how do you control 20 pieces of 12V/1A outputs in the most reliable, compact and cost efficient way, with something programmable? The long version: I got a ...
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1answer
130 views

12v relay latching until no power [duplicate]

So I'm awaiting to wire in one or two relays so that a circuit is not powered until a push button is pressed. Then the circuit remains powered until total power is turned off. I've been trying to ...
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0answers
77 views

Boat wiring mystery puzzle

First post, please forgive any errors. Our dear father passed away leaving us his boat. The owner before had made some changes to the wiring (not for the better) leaving a tangle of loose ends and ...
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1answer
70 views

12 V 3.8 A water pump to 12 V 625CCA battery

Wanting to use car battery to power pump. Pump says it's 12 V 3.8 A, uses a 8 A fuse. Trying to sort out possible solar input needed to run pump but the numbers don't make sense. What size solar panel ...
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1answer
18 views

Dimming LED with speed controller

I'm trying to controll 4 parallel 12V DC LED strips with an speedcontroller. I am able to dim the lights from 100% lit to about 5% lit, but it never turns them off completely. My multimeter can't ...
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8answers
2k views

Using a 12 V 3 A bilge pump on a 12 V 8.5 A LED power supply

I recently bought the following for a grey water system project I'm working on: 3 x 12 V, 3 A bilge pumps 1 x 12 V 12.5 A power supply I'm not an electronics expert, so my assumption was that the ...
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1answer
62 views

Diodes needed (parts) for OR gate automotive relay circuit

I need to power up a make-or-break simple automotive relay (4pin, 40A 12V) via an OR gate. OR gate as follows: Source 1 is the cable that provides +12V to activate car dome light which I will tap ...
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1answer
52 views

Check for 12V with Arduino (Two resistors and a diode)

I need to read the presence of 12V on one of the lines of the board. I want to read using Arduino UNO. I found the following scheme: Is this scheme correct?
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5answers
359 views

Soft start for fridge compresser

I live in an off grid property running on 6 12v batteries. We have a 2000w inverter and are trying to get a fridge to run on our system. We have enough power to run it however the issue I am having is ...
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3answers
54 views

Does a plugged in 12v usb-charger use energy when no device is connected?

I hard-wired a 12v cigarette-plug into my a-pillar. The whole point is to have an additional phone charger on the leftside where my phone mostly sits. I connected it directly to the battery ( with a ...
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4answers
112 views

Do I need a relay for my LED bars?

I installed two 4" 18 watt LED light bars on my ATV. It is currently wired to the factory switch on the ATV handlebars and there is no relay being used. I have had to replace the right LED bar twice ...
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1answer
41 views

Need some assistance with making a battery box

I recently bought a 12v deep cycle battery 75 AH and I made a battery box following these tutorials: https://www.youtube.com/watch?v=cAErwLnsSIY and https://www.youtube.com/watch?v=torSEtjPZ2I (no ...
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1answer
100 views

Should I Use a diode for this application? [closed]

I am trying to run a small 12v motor from the same battery. One source is a timer the other a remote. The timer does not function when both are hooked up to the motor. I’m assuming it is from feedback....
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1answer
44 views

DC Battery Stability

I have a 12 V load that works by connecting an adapter from the AC socket and this adapter output 12v to the load. I decided to make a 12 v battery that can charged and the feed this load , all the ...
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1answer
40 views

How to protect against a short circuit fail in 12VDC X capacitor?

When adding an X capacitor for simple line filtering in a 12V DC electronics project, how would you add protection against an unlikely short circuit failure in that capacitor? Is it as simple as a ...
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1answer
54 views

How to deal with an inconsistent / noisy power signal?

I'm using a 12v power supply to operate a system of sensors that is very sensitive to fluctuations in the voltage input. Unfortunately, I can't control what goes on upstream of my components and this ...
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2answers
50 views

Decrease voltage in circuit

If I have 90 VDC 3.5 A, and I want to reduce to 12 volt, in excellent efficient the amps will be around 25 A. Can I use a 12 V L7812 regulator?
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2answers
114 views

Is there such a switch?

I am looking for a single 12V DC switch which has an on-off-on actuator that will do the following: two 12 volt+ input pins completely separate from each other, each with its own two loads. In other ...
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2answers
105 views

Tachometer Signal Voltage Reduction

I am working on a formula style car and creating a digital dash based on an Arduino. I currently have a signal from the ECU running at 12v DC and a varied frequency depending on the RPM of the engine. ...
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2answers
94 views

Is my 12v lead acid battery 100% dead?

so I got a ups with a 12v lead acid battery that was constantly on so the water inside the cells has disappeared, initially the reading voltage was 0.3v, and when I added distilled water it generally ...
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2answers
154 views

make LED 12v light fixtures

I would like to remove the n27 sockets from household light fixtures and replace them with LED lights used in the automotive industry. I would like to put a reasonable amount of LEDs in the fixture to ...
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1answer
26 views

Charging rate for deep cycle 12v battery

I have a 75 AH deep cycle battery(AGM) and I have a battery charger with 2 modes, 5.5A for car, 2A for motorcycle, as far as I remember, lower charging rate is usually better for longer battery life ...