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  1. 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...
  2. 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...
  3. 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...
  4. 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...
  5. 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...
  6. 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...
  7. J

    Identifying Positive, Negative of LED unit

    :o NOTHING AT ALL (LOL) It's one of those indicator LED units that have lots of LED's inside.
  8. 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...
  9. 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...
  10. 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...
  11. 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...
  12. 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...
  13. 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...
  14. J

    LED flickering with CC driver

    but most of the regulators out there seem to have a temperature rating of 0°C ≤ TJ ≤ 125°C but once you turn them on they do kind of warm up. If the temperature was to drop below the 0°C will it not just be a matter of minutes before it powers up as the vreg will start warming up?
  15. J

    LED flickering with CC driver

    thanks for your replies. duek37, i havent tried more capacitance yet. What would you recommend? I currently have a 22uF Low ESR Electrolytic Capacitor on the output of the LM2940CT. Would you recommend changing this with a higher uF rating Low ESR Electrolytic Capacitor? i would prefer to...
  16. J

    LED flickering with CC driver

    thanks for your reply. I have a IN4007 rectifier diode on the input, i had issues with the IN4007 dying out before and caused the input current to be limited and dim. just wondering can a dying IN4007 on the input of a CC driver cause the flickering?
  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

    1N4007 question

    I've just got a few 1N5822 SCHOTTKY BARRIER DIODES. The specs are: Vfmax = 0.525 @ 3.0 A PIV = 40VDC (28VAC RMS) If = 3.0A Continuous (80A PEAK) Just wondering what the 0.525 forward voltage is about? Is that the amount of voltage that the actual diodes uses? or is that the maximum...
  19. J

    Time delay and polarity switching

    Once the relay is activated and 3 seconds of power has been provided, the output needs to turn off (even if the trigger 12V is still live) The second 3 second output is when the 12V trigger is no longer active and before the relay completely shuts-off the power, i would like it to provide...
  20. 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...
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