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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.

67 questions with no upvoted or accepted answers
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192 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
377 views

UPS battery as auxiliary power supply for car - charging and detecting car on

I'm designing a arduino-based car system that I would like to have running even when the car is off and parked. Though the system is designed to be very energy efficient, I don't want it to run down ...
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96 views

12V voltage regulator

simulate this circuit – Schematic created using CircuitLab I have bought the LM78H12K 12V voltage regulator, for the 12V output. My input voltage is 17 V DC, but unfortunately this component is ...
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64 views

Boost 12v battery cranking amps with supercaps

I have a setup where a 12V AGM battery is powering an inverter. This inverter, for brief periods (1 or 2 seconds - compressor starting) needs more amps than the battery can provide. Is there a ...
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54 views

12VDC Switching to 17VDC high amerage

It's been years since my undergrad work as an EE. I am a physicist and medical researcher now, but, as a startup, we all take on anything we can. Let's face it... 12VDC high current PSU's are cheap. ...
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1answer
37 views

Powering same LED strip from 2 drivers - diode?

So I'm looking at adding some LED mood lighting to our bedroom. End game is to have a single LED strip controlled by 2 different switches Currently, I have 2 switched 240V AC outlets, one either side ...
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64 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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1answer
59 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
152 views

Arduino and car's 12V switch

I'm trying to control my headlights with my Arduino and a LDR. For this I will use the Arduino as a middle man between the lights switch and the actual lights. The switch has three positions OFF / ...
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0answers
300 views

Help needed with over discharge circuit on LifePo4 12V car battery replacement

I'm putting together a LifePo4 battery pack with the intention of replacing the 12V lead acid battery in my 4WD. So far, what I've got is the following. 4 x 10 Ah LifePo4 batteries (38120 Headway) in ...
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1answer
2k views

12v 400 amp cable size for winch or two cables instead of one

I need to run cable to my 12v recovery winch. Run is 15 ft from battery. Winch info says at full load it pulls 400 amps. Instead of running one positive lead due to the size it would need to be i ...
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65 views

Converting a 24v bldc to 12v

So I have been designing a brushless motor and the circuit that drives it is based off of this Texas Instruments one here. The only problem is that this circuit runs off a minimum of 24v. I would like ...
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1answer
116 views

Is this a feasable method for using 12VDC LEDs as power indicators?

I've been looking for the answer, but everything I've found is assuming the LED is of a lesser voltage, or a fixed voltage. More than anything, I'm trying to determine if the concept below is ...
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1answer
35 views

Hi-voltage required for 100% SoC in LA banks?

Talking large banks of expensive true-deep-cycle cells, not the stuff you see in mass retail channels. Maybe the 6v golf cart batts from Sam's, at the "value" low end. I think end-of-life ratings are ...
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0answers
589 views

12v to 5v 10A shielded USB car converter

There seem to be a load of 12v to 5v 3A USB converters around (the vast majority of which seem to be produced by a chinese OEM and then rebranded). However I want to do something a little different......
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74 views

Damaged Switching Regulator

I am working on turning on a board of mine on which I am attempting to use a TI TPS563208 switching regulator. I believe I have followed the typical application in implementing this regulator in my ...
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0answers
1k 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, ...
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0answers
136 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 ...
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33 views

12v ride on toy car tripping breaker under normal load

After sitting idle in the garage for a few weeks, my daughters ride on toy car wouldn't move. Changing the battery with a relatively new one did not help. I tracked the problem down to the shifter (...
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1answer
40 views

Parking Light And Signal light with same LED using MOSFETS

I have a project where I have an existing 12v parking light and I want to also have the turn signal use the same light. I've constructed a circuit using 2x NMOS and 1x PMOS. I think it will work and ...
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1answer
31 views

Wiring 4+ 12v led ring switches from one 12v supply

I am new to electronics and general electronic circuits. I have 4+ led ring switches (from here: follow link) The website says that the rating of the switch contacts is 5A 250VAC with an ...
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41 views

When to monitor battery capacity

While other good answers have stated why discharging a 12V lead acid battery is hurtful to it, I seem to be unable to find how you should monitor it. Assuming I want to stop drawing current from the ...
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1answer
45 views

Controlling 12V 70A Motor(s) with Arduino MEGA (or NANO) and a 4-terminal automotive relay

Components I have: Relay (rated at 12V, 70A, cannot find how much current is needed to saturate its coils) Schematic Arduino MEGA and NANO 12V Powerwheels battery + AA battery packs Motor: 00968-...
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1answer
40 views

Normally Closed Negative Output, Positive Input Relay

I'm attempting to wire up my remote start in my manual transmission vehicle to ONLY start when the vehicle is in neutral. The way that the transmission works is like this: When in neutral, resistance ...
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1answer
96 views

How to check (6 pin) PCI-E power rail on a pc powersupply?

Could anyone tell me if and how i might verify whether or not a PCI-Express 6 pin power lead on a PC is outputting correct voltage(s) ? A while back, I decided to try to refurbish a graphics card ...
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1answer
30 views

24V 3D Printer - power ratings

I have a 3D printer at home and looking to improve some parts. The PSU on the printer has no labels so I'm not certain what it's doing - but the 3D printer's spec. sheet says it's 600W peak and it ...
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3answers
152 views

12VDC to 3 Phase 400V

In order top prevent my seldom used deep well pump (3 Phase, 400V) I plan to daily spin it up for a few seconds. Where the pump is located, the is no power supply (I operate the pump using a ...
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1answer
108 views

Need to determine a mosfet, and wouldn’t mind a little education in the process

I want to start off by saying that I am a complete electronics newb. I know a little but am always looking to learn more. With that said I am asking for a little help and a little learning. Here’s ...
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1answer
63 views

What is the cost of converting 12V (lead acid battery) to 220V and back again to power 12V appliances?

I have a small house measuring ~ 8m x 4.5m. It is in Indonesia and power outages are expected daily. Probably the daily power outage is on average less than half-an-hour, but sometimes the outage can ...
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0answers
30 views

TPS55165Q1 does not work in boost mode

I need a power supply that delivers 12v with an input between 8v and 35v. That's the reason I bought a couple of TPS55165Q1 from Texas instruments. I've made 3 different PCBs with a similar circuit. ...
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1answer
101 views

Solar charge set up damaging battery?

I've installed a 12V 80W solar panel plus controller and attached it to a 12V 105Ah leisure battery. At first it (appeared to?) work. The charge status on the solar charge controller was at max and it ...
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85 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
54 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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49 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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31 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
46 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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42 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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0answers
81 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
70 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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0answers
89 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
74 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
92 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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1answer
113 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 ...
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1answer
48 views

LM2940, 7808 and Multichannel PWM chip

I'm putting together a circuit board to power and dim 5 LED channels. The average voltages on the channels are 12.3V, 11V, 11.4V, 7.8V, 6.6V, and max current is 1A. So my current plan is: 12V ...
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1answer
43 views

12V battery charging inside caravan

Can I use the 12 V power in caravan to drive for example the lights, whilst the battery is being charged by a mains power charger? By the way, The 12 V system is on a separate circuit to mains power. ...
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2answers
268 views

Can I switch two 12v sources with 5 pin relay?

I'm installing a stereo in an RV and would like to maintain default behavior of having the stereo receive power on vehicle accessory power/ignition, but also be controlled by a switch in the RV for ...
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1answer
104 views

Power Supply wiring check

I'm not too confident with electronics and I'm currently working on a project where I need a 12V mains power supply. I got a switch for it and have wired it. I've shown pictures. Is this wiring ...
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1answer
122 views

Which connector type is this?

I'm looking for the bullet type connector that is used with Tracer Power batteries. Here's the link for their version of it: https://www.tracerpower.com/bullet-bare-ends.html I found a connector ...
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1answer
279 views

Can I limit the amps drawn by a charging battery

I want to connect two 12V car batteries. A part of the connection is limited to 15A (cigarette lighter). Is it possible to limit the amps on the wire so I can safely connect the batteries via the 15A ...
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1answer
222 views

Connect 240v PIR motion detector to Raspberry Pi

I want to connect a 240V PIR motion detector directly to my Raspberry Pi 3. Inside its plastic case I found 2 PCBs. One is the power supply board which has a 24VDC relay, a S9013 NPN transistor, ...