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
88 views

Why 12v batteries but not 110/240 corresponding with the mains?

I have a basic curiosity question while I trying to learn/figure electrical "things" while I trying to size my UPS. I know that an UPS will convert power from mains (240v in my case) into 12v battery ...
-1
votes
1answer
38 views

Convert 220V AC to give out TWO 12V DC 3 amps [closed]

I need an output of two 12 v dc 3amps , how can do it with a single transformer ? Well i am sorry for i framed the question badly! I have an appliance that need needs 12v 2amp for one component (...
0
votes
3answers
98 views

What switch do I need to enable/disable fan with wind speed measurement by a DIY anemometer?

I'm going to be making a device for burning man that will effectively evaporate grey water from our camp. This will be mostly wind powered, however when there isn't any wind, I plan on using a high ...
0
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1answer
35 views

Low Voltage Disconnect and 2 negatives?

I am looking at something like this LVD 12V and am confused as to the purpose of the two negative terminals. On the BATT side I will have the + coming from the + side of the battery and the - going to ...
0
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1answer
18 views

Power a laptop from 12V Battery using DC-DC Step Up Circuit

I have following items 1) DC - DC Step Up Boost (150W) http://www.ebay.in/itm/131625051992 2) 12V 12Ah Battery (Sealed Lead Acid Battery) 3) LCD Lead-acid Battery Capacity Tester I charge my ...
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0answers
12 views

Why do I connect the positive and the negative to the battery on a boat? [migrated]

My trolling motor for my boat has a black and a red connection. The red goes to the positive on the 12 volt battery. The black goes to the negative on the 12 volt battery. Could I connect the black ...
2
votes
3answers
117 views

Electronic device that is open for 6V and passes current once it reaches 12v? [closed]

Please excuse the way I am this question as I do not have much of an electronics background... I am trying to upgrade the headlights in my car to HID projectors. One of the issues I'm running into is ...
0
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0answers
51 views

Switch circuit design

I tried to ask this question before let's see if can clarify. So I'm building a grape harvester. The equipment has a standard 12 volt system. I have been playing around the past few years with a "row ...
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0answers
53 views

How can I under-drive bright LED strip lights *and* still dim them upstream?

So I'm using 7020 LED strip lights for under-cabinet lighting, and they will be connected (via a compatible power supply) to TRIAC wall switch dimmers (Insteon). There are other light fixtures on this ...
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2answers
76 views

Is it safe to build a floatable speaker?

I'm thinking of building a floatable speaker to float along beside me in a lake or a small river while tubing. I've got some speakers and the following 12V amp: DROK Amplify Module Audio Component ...
0
votes
1answer
102 views

Best way to get 5v or 12v or 0v from arduino pin [closed]

Concerning the answer to this question explained in the link "Best way to get +5V or +12V or 0V from arduino pin" I am at very basic level of electronics because I am in first semester of Electronics ...
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3answers
87 views

Power a 12 volt water pump from a 110 watt solar PV panel

I have a 12 volt DC 9 amp water pump that I would like to power from a 110 watt 12 volt (17.2 volt at peak) 6.4 amp solar PV panel. I only want to run the pump when the sun is out, it's circulating ...
0
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1answer
51 views

Reading the closing of 12 volt circuit over RS232

Car trouble. I suspect the fuel injector circuit. I am trying to construct a com port reader that will place a timestamp into a log on the closing the 12v fuel injector circuit. The fuel injector ...
-1
votes
1answer
55 views

DIY car phone charger

I am converting a wheelchair access vehicle into a campervan. Having removed the old wheelchair ramp lift mechanism, I'm left with a couple of 12V cables in the back. I'd like to turn one of these ...
-2
votes
1answer
53 views

does 12v negative wire amp rating need to match positive

A basic question I am sure but does the amp rating of the negative wire need to match the amp rating of the positive wire used? I am guessing yes but part of me is thinking no I don't need to match ...
0
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1answer
75 views

Single power supply for multiple 12V devices over long run; LED and swimming pool application

Hi I am new to this site and have no electrical training, but I am braving the job of installing 4 5M strips of waterproof(IP68) 5050 RBG LED strips on the interior coping of our above ground pool (...
0
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0answers
17 views

What's the best way of using LiFePO4s in a UPS?

I have built a server using a Raspberry Pi and a couple of USB HDDs. The HDDs are 3.5". The server system also includes a network hub and a router, so I need 5 V @ 2A for the Pi, and 12 V @ 4A for ...
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0answers
135 views

DIY Powerpack 18650 4s3p 14.8V charging

I plan to make a portable audio system with 4 speakers and a subwoofer which are driven by a 12v TDA2030A 2.1 Amplifier. Everything is already packed in a small enclosure (approx. 30x15x30cm) and ...
2
votes
3answers
95 views

+12V and -12V for supplying Op-Amps in my circuit

What is the easiest and cheapest method for acquiring +12V and -12V for supplying LM358 Op-Amps? In my school's laboratory we are using Agilent voltage supply but that kind of supplies are really ...
0
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0answers
45 views

Solar Powered Lantern - Year 9 Project Idea

I am a Year 9 engineering teacher and I want to revise one of my current projects to be better but I need some help. The project idea is using a 1.5v Solar Panel (from a solar garden light) to charge ...
0
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1answer
60 views

Relay circuit with off switch

I've been searching for a similar circuit and only found latching relays with two momentary switches for on and off. I don't know if this circuit has a specific name or not, and since I am a complete ...
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2answers
49 views

12 volt switched by 5 volt

I have an issue with 12 volt DC LEDs installed on a 5 volt DC circuit. Switching must be performed as close to instantaneous as possible. So I searched around but nothing would do what I need. I ...
0
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1answer
60 views

Regulator to feed Arduino VIN with 12V?

I am quite new to electronic and I'd like to build a setup plugged with a 12V PS (because there is a water pump in my setup). But at the same time, I'd like to feed the Arduino VIN with the same ...
0
votes
1answer
72 views

Relay driver from microcontroller

I have put together the following circuit to drive some 12V pumps from a micro-controller using a ULN2003, but it has a few issues. First issue is that the relays click in immediately. I want the ...
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2answers
91 views

First Time Using Integrated Circuits

I am building a circuit for a custom application. I have an old Toyota truck, and I keep leaving the headlights on, because there is no warning buzzer! I have designed a circuit that takes 3 inputs: *...
2
votes
1answer
333 views

Xbox one power adapter wiring - converting it to a 12 volt power supply

Thanks for having a look at my question. I know this may seem like an odd question but here is the history of it. I have a Solidoodle 4 3D printer, Its powered by a knock off xbox 360 brick adapter ...
0
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3answers
66 views

12V motor controller + 20V sensor

What I am projecting is to substitute the manual throttle for a little electric motor with an Arduino computerized one based on two sensors that yields 0-20V. But Arduino works with 5V, so I need a ...
-2
votes
1answer
58 views

Which better charge method for 12v 10w solar panel to 2x 6v 4.5ah battery?

i have 12v 10w solar panel and 2 x 6v/4.5ah battery. Im planning to build control that charge 12v battery (in this i series 2x6v battery) and after i read this Do batteries in series equalize charge ...
0
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2answers
67 views

Changing battery from 12v SLA to 12v Lithium, how can i accomplish this setup?

I am thinking of more speed for a kick scooter project. I have a 800w hub motor for this scooter but at only 40Km/h i am thinking of making it go faster. Now I know that increasing the voltage from 48 ...
0
votes
1answer
43 views

Run CB Radio from AUX power [closed]

Sorry if this isn't the right place for this. I have a Uniden UH015SX (https://www.uniden.com.au/resources_main/pdfs/uh015sx_OM_2yrWarranty-Updated.pdf) which requires 13.8v of DC power, but I'd ...
0
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0answers
63 views

High side switch always closed, because driver BJT is always closed

I'm a hobbyist when it comes to electronics. I'm trying to run a 12vdc fan with a high side switch switched from a 3.3v microcontroller. I've got it on a breadboard and the switch is always closed ...
0
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1answer
56 views

Wiring a car radio with two power sources

This is on a land rover I'm helping sort out for an off-road expedition I'm trying to wire up the radio with two different power sources, but what I've got at the moment is having some undesired ...
0
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1answer
65 views

Optocoupler delay off MOSFET solenoid

This is to trigger a 12v solenoid (acting as a laser shutter) with 5v (JP2) thru an optocoupler. The problem is 5v line have bit fast interruptions on a laser show, so I'd like to add a bit of delay ...
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1answer
316 views

5 Led 12v battery level indicator

I've seen some simple 10 led level indicators such as this Due to space I cannot use 10 leds, how can I reuse this circuit or another for a 5 led indicator?
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1answer
83 views

How long can I run a 1200w car amp on a 12v 50ah battery?

I'm looking to build a portable amplified speaker and want to know how long a 1200W car audio amplifier will run on a 12v 50ah battery supply?
0
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1answer
57 views

using 8 AA or Ni-MH batteries instead of one 12V 23A type battery to power a remote receiver

Sorry for the novice question, but I am thinking there should be a simple solution. I work as a magician and purchased an effect where a snake puppet in a basket goes up and down on a battery powered ...
0
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1answer
64 views

Use 5w/3w 12vdc LED on 60w 12vac cdi ignition

I'm building a vintage two stroke race bike out of a 78' puch maxi. The original points setup is junk and I'm switching to a CDI. I have an LED headlight that I'd love to use for aesthetic purposes. ...
-1
votes
1answer
72 views

Help with son's 18 V car [closed]

I need help with the wiring on my son's car. I'm trying to run 2 x front and 2 x rear #QG550 12 V 45rmp motors using independent 18 V power supplies, 18 V front and 18 V rear. I wish to keep the ...
-4
votes
1answer
91 views

How long will my battery last and how to calculate it? [duplicate]

I have a 12V 18Ah battery I wish to run through a boost converter at 40v and 2.5A to power a 100w led. Could someone figure out how long my battery would power my led and show the calculatins/...
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1answer
45 views

for 12V 4 leds are not glowing

FOR 12v 4 LEDS ARE NOT GLOWING. LAST ONE IS GOING PROBLEM. AFTER USING VOLTAGE DIVIDING NETWORK ALSO leds droping voltage is 6V,3V,3V,1V simultennisly. so last one not glowing. please tell me the ...
4
votes
2answers
269 views

Relay for Intermittent Wiper Function

I want to add an intermittent function to the wipers on my 40-year-old car without any additional switches. The details of the wipers can be found here [http://www.globalsoftware-inc.com/coolerman/...
0
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1answer
99 views

Need help choosing options for 12V supply from a Lithium-Ion battery

There are lots of Class D audio amplifier modules for 12V use that are both readily available and inexpensive, intended for automotive use (hence the 12V rating). I would like to use one of these, ...
0
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3answers
433 views

How do I turn on a magnetic lock with an Arduino?

I have a 12v magnetic lock, which is just an electromagnet. I want to turn it on with my Arduino. I've been able to turn on/off a 5v motor with the Arduino. So I'm guessing the wiring is similar. The ...
0
votes
1answer
88 views

LM2940CT-12 output measuring 9.6V when relay used

So I've got a 12V pump, and a car battery, and I'm trying to regulate the 12-14V from the car battery to 12V output. When using just the LM2940CT-12, it outputs 12V on the dot. But when I use an ...
0
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1answer
174 views

Running a 24V motor on a 12V boat system

I'm trying to design a jigging machine for a fishing boat, using a RaspPi as the controller. (A jigging machine jerks a 1kg lure up and down near the sea bed, and pulls in a fish when it's hooked.) ...
1
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1answer
89 views

Really faint hissing sound from my new 12v AC to DC Power Supply

Just bought this Power supply today and once plugged in to AC, I hear a really faint hissing sound coming from the unit. Is this normal? Or should I have this replaced? Click here to see the video
0
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1answer
86 views

Wiring a lamp in [closed]

Hi guys I'm very new to electronic wiring so take it easy on me. I have a drone that I'm trying to connect a little 12v floodlight too so that it can see at night when it flys; the problem I'm having ...
0
votes
1answer
55 views

Operating multiple low power devices from 1 adapter [duplicate]

I have 3 WRT54G routers (12V), 1 voip gw (9V), 1 cable modem (9v) and a gbit ethernet switch (12v) which are all operating from their own adapters. I planning to build a low power (probably 12V UPS) ...
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1answer
54 views

What is my capacitance? [closed]

I have a current measurement of 300mA on an MCU evaluation board. If my power supply is 19V or 12V what capacitance do I need to use in order to limit the voltage fall to 5V?
0
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1answer
111 views

12v LED Turn on and Dimming based on either MAP signal, or RPM of Car

I've got a simple 12v Red Led strip installed in my car, and i currently have it hooked upto a relay which turns it on when you unlock it from the key fob (the same as the interior / courtesy lighting)...