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  1. J

    USB 5V power from 12V car supply

    I have a 12v to 5v(3A Max) converter. I'm planning to hook this to charge my Nexus Android tablet as part of a car in-dash install. My question is: The converter seems to be regulated in terms of voltage but the current says 3A max. Therefore there doesn't seem to be any form of current...
  2. J

    12V Car Camera

    I have a Reverse Camera taken from a Lexus which was being dismantled for parts. It has 4 pins and i'd like to use it on a project I am working on. I am assuming 2 out of the 4 pins will be related to power (ground and +12v) and the other 2 will be maybe the video cable. Is there a way using a...
  3. J

    Multiple 12V batteries in Parallel

    If i have four 12V 100AH batteries wired in parallel, am I correct in believing that the result will be 12V 400AH? whereas if i was to wire in series, then the result will be 48V 100AH. Is this correct? Thanks
  4. J

    Solar Panel and Battery Array Project.

    Hi Guys, I'm in the process of doing up my garden and need some help with the electronics aspect of the design. I will mainly be powering 12V LED lights in the garden along with a 1A pond pump. The plan is to run this of an array of 12V batteries. I'm thinking to start with maybe 3 batteries...
  5. J

    Breadboard help

    Hi Guys, I have the following breadboard diagram that i wish to implement directly without the breadboard: I am trying to understand the flow and which wires connect up to where so that i can directly wire the board to the display. I've started sketching what i think links to what...
  6. J

    Buzzer on Raspberry Pi

    I've managed to work out how to use python and activate either the 3.3v or the 5v GPIO ports on the raspberry pi. For my testing i hooked up a single LED with a resistor to the port. But for my project one of the ports will need a buzzer connected to it. I've never worked with buzzers and...
  7. J

    2pin 12v switch

    I have a 2pin switch, i have a +12v and ground wire going to an LED unit, i want to be able to switch the supply off, can I simply add the switch inline on the +12v wire. So basically, cut the +12v wire and connect one end of each cut to the switch pins? I'm assuming the switch doesnt require...
  8. J

    Halogen Filament Bulb - Polarity

    Just wondering if standard automotive halogen filament bulbs have a certain polarity or can ground and +12v be connected anyway round? reason I ask is because i am in the process of cutting a 9006 Bulb connector and soldering on a H11 connector, but just wondering if i should connect it in a...
  9. J

    Building a LED driver

    Hi Guys, Up until now i've been using a 12v buck type led driver to drive and led unit with 3 led's wired in parallel. It gives my LED unit 3.2v fixed voltage and a constant current of 300mA. I cannot find any buck type drivers that give lower than 300mA and is a 12V DC input. So i'm wondering...
  10. J

    Two 12v inputs switching

    i have an LED light that's powered by two +12v inputs, one for full brightness and another for dim mode. The two power sources are not on at the same time because i've got an auto relay switching kit that switches off the main one if the secondary power source activates. However, just wondering...
  11. J

    Identifying Positive, Negative of LED unit

    I have a car LED unit that goes on the side mirror. The unit has a 2 pin connector. Is there any way to determine which connector is positive and which is negative without randomly trying it and risking getting it wrong way round? Also, is there any way to determine if the unit has it's own...
  12. J

    headlamp levelling solenoid

    I have a old headlamp that I am experimenting with which has a solenoid to adjust the beam height, the solenoid is connected to a 3 pin connector and it basically allows the solenoid to rotate in two different directions. as there is 3 pins, i am guessing its not a simple reverse polarity thing...
  13. J

    12V camera cold weather

    I have a 12V reverse camera installed on my car. but when weather turns cold the camera stops working until it warms up either later during the day or from driving around and the heat generated by the exhaust fume seems to warm it up after a while. The body of the camera is conductive, so...
  14. J

    Voltage Regulator - L7812CV

    I have a L7812CV voltage regulator that I would like to use for automotive application. Need help selecting the correct capacitors for the input and output for ripple rejection. The datasheet uses an example of putting a 330nF capacitor on the input and a 100nF capacitor on the output. The...
  15. J

    LED Driver with 3 wire input

    I purchased a car LED driver second-hand. The output of the driver has two wires to go to the LED black and white. White is positive and black is ground. However, the input has 3 wires, two of which match the output, black and white. I am assuming these are positive and ground. However, there is...
  16. J

    Lowering voltage

    I have a power boosted external tv antenna which comes with a power supply that delivers 6V DC but my receiver box also delivers voltage so i am not using the 6V DC power supply supplied with the antenna. This is working fine, however, when measuring the voltage that my receiver is supplying...
  17. J

    LED flickering with CC driver

    I have a constant current LED driver that delivers 300mA to my LED lights. It's used on a car and uses the cars 12V supply. It's been working fine until now when the weather has turned cold the LED's are flickering and it seems to stop once it has warmed up. I dont think it is the drivers...
  18. J

    Time delay and polarity switching

    Was hoping someone can point me in the right direction and help me out. I want to build some kind of circuit that would allow the following: I have a 12V trigger power source which I want to use as a trigger for a relay. When the 12V trigger source is active, I want the relay to activate...
  19. J

    1N4007 question

    I have 2 LED drivers that I want to drive my LED unit with. One driver is of higher constant current than the other. Both drivers will never be on at the same time. The output of driver 1 and the output of driver 2 will be joined together in parallel and then connected to the input of the LED...
  20. J

    Question about wire

    Just a quick question, can I use household 1 mm2 wire that is rated for 240V lighting use on a 12V lighting application to power a halogen bulb via a 12V car battery?
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