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
0answers
17 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 ...
6
votes
2answers
2k views

How to make -12V from a +12V supply?

The equipment I have needs +5V +12V and -12V supplied to it. The old PSU which provided all the voltages blew to bits. I have sourced a PSU1 +5V (30A), and PSU2 &PSU3 (two identical +12V (2A) ...
0
votes
2answers
94 views

How to supply power to a 12V solenoid from China, getting hot

I bought this solenoid from ebay and was wondering how to power it. It says 12 volts as you can also see from the picture, but I tested it with putting a 9V battery straight to its terminals for a ...
1
vote
1answer
79 views

Which diodes for 12v indicator light circuit?

Which diodes for 12v indicator light circuit? I have a car whose signal light audio indicator is too soft to hear. I would like to set-up an visual indicator on the dash for when the signal lights ...
6
votes
1answer
1k views

Replacing incandescent bulbs with LEDs, unexpected behavior

I have an over-the-stove microwave/ hood vent combo with 2 adjustable-brightness lights. The lights appear to be 12V lamps with a G4-style connector, and they burn out all the time... like every 4 or ...
0
votes
1answer
31 views

NAND gate from BJTs: interfacing +/- 12v op-amp and 5v logic: destroy BJT with excessive Vebo?

I want to switch on a relay when both a 5v logic input is high and a (LM741 used as a) comparator is around +10v, and the circuit I planned to use is below. The problem I see with the circuit is when ...
0
votes
1answer
83 views

Reduce voltage on PSU from 52V to 12V

I'm building a mining rig and is planning on using a ESP120 HP 3kW 52V power supply. I've seen someone get it down to 48V with this mod, but I wonder some one got it down to 12V? Or is it not ...
2
votes
1answer
86 views

Control of 4 pin cpu fan with 3 pin socket and …?

I have a problem with controlling my cpu fan speed since it has a 4 pin connector and the socket on my motherboard is broken (transistor connected to it has burnt). I have it connect at the moment ...
0
votes
0answers
36 views

Discharge limit on a 12V 9800mAh Lithium-ion Battery

I am running a 12V solar system that powers a 5050 LED light bar of 7.4W. Powered by a 25W mono PV and has a total 12V storage of: 1x 6800mAh 1x 9800mAh (Lithium-ion batteries in series) The ...
0
votes
2answers
51 views

12v capacitor / UPS system [duplicate]

I am looking to make a capacitor/UPS system for a few different electrical components in my car. I want to power the rear view camera, headrest monitors, and possibly the head unit for about 30 ...
0
votes
2answers
85 views

LED lights and heatsink

I want to make a light for my boat roof. If I were to buy these (or similar), would I need to mount them to a heatsink, or would they be fine just as is? The largest size one has a power output of ...
0
votes
2answers
139 views

How to connect a Inductive Proximity Sensor Switch NPN DC6-36V to PIC18F4550 5V

I have got a LJ12A3-4-Z/BX Inductive Proximity Sensor Switch NPN DC6-36V with this Specifications: Model: LJ12A3-4-Z/BX Theory: Inductive Type Sensor Wire Type: Cylindrical DC 3 Wire Type ...
0
votes
1answer
73 views

Charge at 24v and discharge at 12v for battery system

Is my thinking correct. Below is a simple diagram of the concept I want to check. Is this: 1: Possible 2: Feasible? I.E are there any concerns or foreseen issues with this design? Edit:
1
vote
2answers
94 views

How to use ordinary voltage regulator from a 40amp source?

My power source is 12v 40amp(car battery). My project needs 12v but only 500 or 1000ma max. My 12v voltage regulator (NTE960) explodes with 40amps, so I must reduce the current (too much current for ...
3
votes
2answers
143 views

12V Battery Backup Supply for GPRS Tracker

I have little knowledge on electronics apart from following a few guides. I have made a few 7 segment displays, nothing complicated. Recently my girlfriends car was stolen and she has an insurance ...
1
vote
1answer
50 views

12v socket not providing enough current for mobile phone? [closed]

I've just installed a 12v socket to my motorcycle. The socket has a sticker saying "12V - 1A", and the user manual says that "use is possible up to a power input rating of 12W". Taking that into ...
1
vote
1answer
85 views

How to use Battery Charge controller (BQ2002N)

I am working with an Arduino which I have a 12v power supply for, but also needs to be able to run off a NiMH/NiCAD battery pack when not connected, and recharge the battery pack when it is connected. ...
0
votes
1answer
169 views

Arduino 12v LED Downlights

I have managed to control an RGB LED Strip with an Arduino Uno R3 successfully. I would now like to switch and dim 12v LED Down lights. I am unsure of how to do this the Transformers I have are ...
0
votes
1answer
217 views

How to amplify 3.3v to 12v (PIR and led strip light)

First off this is very similar to what I need to do How to amplify 3.3 volts to 8-9v? I have a 12v power source PIR and 12v led strip lights, This is the specs for the PIR. I want to cut the leds ...
2
votes
1answer
170 views

Get 12v power from NiMH battery

I have an Arduino project that is powered from 12v/15A dc power source needs to switch to battery power and still get 12v (dc power may start/stop at any time) recharge the battery when dc power ...
1
vote
2answers
195 views

Cuttable 12V LED strip

I'm building a computer, and I want to add LED lighting to the case. However, here in Finland, LED strips are too expensive, and I found this: ...
0
votes
1answer
130 views

Black box on Arduino unsoldered itself due to overheating

Okay, so I was following this tutorial to control an RGB led strip with Arduino Uno R3: http://learn.adafruit.com/rgb-led-strips/usage And the LED strip wasn't lighting, so I tried plugging the other ...
4
votes
3answers
437 views

How to transform 5v to 12v?

I would like to transform 5v 500ma (from USB power) to 12v for a few $dollars of parts. Is this possible with something I could build with some generic parts (not some expensive transformer, etc...)? ...
-1
votes
1answer
46 views

3 relays with a latching relay

I have looked for a product that has 3 relays, 1 NO and 2NC with one NC being latched. Does anyone know of the existence? How about how to build one? 12V DC as well.
0
votes
2answers
120 views

USB car charger with LED

This is related to Is it okay to keep a USB charger plugged into the cigar lighter? - I have a 12v charger that is connected to a phone dock with an integrated micro USB connector. The difference ...
2
votes
0answers
69 views

Is it possible to charge 3 parallel batteries without sending charge to the UPS?

I have a UPS (uninterruptible power supply) with a 220VAC input designed to be used with 12V batteries. It has a rated capacity of 400 watts and I've placed three 12V car batteries in a parallel ...
0
votes
1answer
111 views

Howto safely go from 230V to 12 Volts

I'm playing around with different kind of 12 LED light sourcing. Normally I have used one of these 12 V power adapters (with EU plug). But I have got this idea of changing a halogen lamp with a home ...
1
vote
1answer
104 views

Statically set the speed of a CPU fan

I have two types of DC 12V CPU fans, type AFC0612DE (Delta Electronics) and TA350DC (Nidec). Both types have PWM pins for speed control. I however do not have a controller. I would like to set the ...
0
votes
1answer
1k views

hard-wire 4-port usb hub to my car's 12v switched cig outlet

I would like to hard-wire a 4-port usb hub to my cig outlet. I currently have the hub connected to my power inverter and have to flip a switch to turn on the power. My goal is to do a complete ...
0
votes
1answer
180 views

2 3.2v LED in series on 12v source

hi i am planning to install two small white light LED on my car as parking lights. so basically i am using the reflector along woth LEDs from a torch that uses 3 AA cells(4.5v), the power of LED in ...
2
votes
2answers
2k views

Using a 12V battery while simultaneously charging via solar panel

I have a couple of 12v batteries that I'd like to use to power a cooling apparatus while camping for several days. I also have a 15W solar panel I'd like to use to top-off the battery. Can I use the ...
0
votes
1answer
363 views

using relay to switch between video outputs

Hey all I have a simple question... would I be able to send a video signal (composite) to each relay per camera? Reason being is that I only have one video input but need to be able to use 2 cameras ...
2
votes
2answers
155 views

What do I need to look out for when converting 9V example schematics to 12V?

What do I need to look out for when converting 9V example schematics to 12V? Most of my ICs work until 18V, and it seems to me all the resistor divider stuff is based on ratios, so it should scale ...
2
votes
2answers
1k views

Making 12V DC from 6V AC

I've got a 1980 Honda XL 185s that has a 6 volt electrical system. The headlight uses a 6V AC, 30 watt bulb powered from the generator. The other lights (tail, blinkers) operate off of the 6 volt ...
1
vote
2answers
542 views

Can I get 24V from ATX PSU using 12V and -12V cables?

ATX PSU's have one -12V cable, and a few 12V yellow ones. Could I power up a 24V device by connecting 12V to + on the device and -12V on -?
0
votes
2answers
356 views

How to run 12V compressor directly off battery?

I have a 12V air pump (runs out of the car cigarette lighter). It had worked ok the first few times then stopped working, with smoke billowing out of the receptacle while it was plugged into the ...
2
votes
3answers
397 views

Low Voltage DC Automatic Transfer Switch

I am new to circuits and have a very basic knowledge, and am currently interested in building a simple circuit that would take 2 DC inputs each of 12V 1.5A and output 1 x 12V 1.5A input even if 1 of ...
2
votes
1answer
749 views

Clean 12v car power

I am looking to get a constant, clean 12V from my cars 12V line. I am wondering if all I am in need of to pull this off would be a simple 12V fixed regulator? The 12V would be hooked up to a pico ...
3
votes
2answers
908 views

Detect car +12V using Arduino

I am looking to detect 12+V from a car wire using an Arduino. I have found the following schematic: I know how crazy automotive voltage can get so I just want to make sure the schematic I found ...
1
vote
2answers
222 views

Which potentiometer to use?

New to electronics...so learning as I go. I have a 12vDC 1.5amp power supply that I will be using to power a 12vDC .30a computer fan. I want to use a potentiometer to adjust the speed of the fan but ...
1
vote
1answer
94 views

Reading signals in a car 9-14.5v and translating to arduino HIGH / LOW

I have a project that requires me to trigger certain events in an Arduino based on certain electronic devices in the car being switched on and off. I essentially need to read a 12v HIGH state in the ...
3
votes
3answers
2k views

Switching 12V with an active low 5V signal

I’m trying to switch 12V (max 30mA) with a signal from a MCU that I’d prefer to be active low (so the output voltage is 12V when the control signal is 0V, and 0V when the control signal is 5V). Since ...
2
votes
1answer
210 views

How will the output of a 12V transformer wall wart differ from that of a 12V SMPS brick?

I have been working on a project to drive an electric door strike from an Arduino shield of my own design. Actually, I'm using a Freetronics Eleven and not an official Arduino, which is relevant ...
2
votes
1answer
162 views

Diode selection for truck wiring light application

I need to know what diode I need for a light set up I am working on. The main current flow through the diode is going to be 9v going to power a 55watt roughly ??? amp bulb. There will be ocassional ...
1
vote
1answer
125 views

How to power a 12v outdoor project with microprocessor?

Forgive me if this is a really basic question, but I'm still at the "consideration" stage of a basic LED project, thinking about lighting up one of those flexible LED strips from a microcontroller ...
0
votes
2answers
923 views

How can I use transistors to work as an SPDT relay using the common pin as input and NC/NO as outputs?

PS: If you're impatient, you may skip to THE_POINT below: Basically, this is for various lights in a car - indicators, park/rear light, brake light. I want to convert the simple output from ...
2
votes
2answers
157 views

Series of illuminating LEDs…sort of

So here's my idea: Two rings of 36 LEDs (so 72 total). Starting at the bottom of the first ring, I want to have the first LED illuminate and stay lit, and so on, until the entire ring is lit. Then, ...
1
vote
1answer
263 views

What NPN transistor should I use?

I need to control a 12v 5A (or 3A if need be) with an Arduino UNO which has 5v and 40mA. I, unfortunately don't know how to read transistor data sheets. What NPN transistor should I get for this ...
0
votes
2answers
235 views

Will my relay operate with a 12V battery and simple switch?

If I have the following components: 12v Car Battery 12v 2amp relay push button switch (normally open) Can I simply just link all three components in series and expect the following: The relay to ...
5
votes
1answer
1k views

Arduino Uno with 12V pump: transistor or optocoupler+12V relay?

I'm not a real expert in electronics but I'm going to start a new project that has completely captured me. I need to drive a 12V pump with my Arduino Uno. The pump is "Dp0102" (12V, 0.7A). To power ...