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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2answers
69 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
0answers
30 views

Building a 12V UPS [on hold]

I want to build a 12V (2.5-4A output) UPS (or something like that). I have a power supply of 12V and want to get a constant 12V out of it, but for 1-2 seconds (typically every minute or so) to an ...
0
votes
1answer
97 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 ...
0
votes
3answers
68 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 ...
-4
votes
2answers
74 views

filtering 12vdc power [closed]

I have a power supply that outputs 12 V DC when it is connected to 119 V 60 Hz AC supply. However I am getting high ripple of 1.5 volts peak to peak. I think the power supply circuit already has a ...
0
votes
1answer
48 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
51 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
50 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
votes
1answer
61 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
votes
0answers
16 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 ...
0
votes
0answers
99 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
90 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
votes
0answers
44 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
votes
1answer
50 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 ...
0
votes
2answers
43 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
votes
1answer
54 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
70 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 ...
1
vote
2answers
89 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
226 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
votes
3answers
60 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
52 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
votes
2answers
63 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
34 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
votes
0answers
56 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
votes
1answer
53 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
votes
1answer
62 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 ...
-5
votes
1answer
247 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?
0
votes
1answer
75 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
votes
1answer
53 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
votes
1answer
59 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
71 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
86 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/...
-2
votes
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
226 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
votes
1answer
92 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
votes
3answers
367 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
78 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
votes
1answer
152 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
vote
1answer
87 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
votes
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
54 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) ...
-1
votes
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
votes
1answer
94 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)...
0
votes
1answer
198 views

Need circuit for 12 volt 2 Amp step down power supply from 18 volt 1.5 Amp Input

I have a power supply which outputs 18v 1.5 amp. For the purpose of my project, I need a 12v 2 amp power supply. I was wondering, if I can make a simple buck converter to convert 18v 1.5amp DC to 12v ...
-1
votes
1answer
46 views

Replace a 6v synch. motor with a 12v synch. motor in holiday decoration

I have a Santa fibre optic decoration that has a TYC-30 AC6V 5RPM (.8-1W) synch. motor that's very noisy so I want to replace it. I can't seem to source a 6V version of this motor from the inter-webs....
0
votes
1answer
94 views

12V active-low on/off switch

I have a microcontroller that I want to install in my car. One wire coming from the car supplies +12V from the battery independent of whether the car is on or off. This works fine to power the ...
0
votes
5answers
463 views

Using more than one voltage regulator in series

Is there any problem (in addition to a likely loss of current) in using more than one voltage regulator (L7812CV) in series? And is there a real gain in stability? I ask this because I 'm going to ...
0
votes
2answers
113 views

Inverter Design - What DC input voltage for most efficient DC to 120VAC inverter

I have seen several online circuit diagrams for a DC to AC inverter. Commonly many inverters use a transformer to step up 12V to 120V. I understand that inverting from DC to AC requires additional ...
0
votes
1answer
29 views

~12VDC+ Automatic Dimmer Switches

Most automotive vehicles typically have their interior lights fade out 30 seconds or so after the doors are closed. The way I understand it, closing the door will usually depress a momentary on/off ...