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  1. Kiwi Bruv

    newb transistor question

    Guru, The linking of the 0v power supplies did the trick. Many thanks for your patience. I've learned something. Thanks for everyone's interest.
  2. Kiwi Bruv

    newb transistor question

    Guru, many apologies I am sorry if I have confused anyone. I appreciate your time. "You say that it lights with 5V on the base, but I think you mean on its 1.8K base resistor, and a 5V supply for its collector's LED. But when you use a 12V supply for the collector's LED, it doesn't light...
  3. Kiwi Bruv

    newb transistor question

    Thanks Guru. I can see how that will solve the flashing problem. I can only get the LED to light when the supply is all 5v or all 12 v with 12v on the collector and 5v on the base the led doesn't light. I intend to replace the 549 with a darlington for the motor application.
  4. Kiwi Bruv

    newb transistor question

    Thanks. that's exactly what my circuit is like except there's an LEd in the collector line and the transistor input is 5 v. The transistor is saturated. I know this should work. I must have something badly wrong. I can make the LED light if all the + voltages are the same. But even then the...
  5. Kiwi Bruv

    newb transistor question

    I can only do a sketch in bmp format so I can't upload it. Is there another way? I have a BC 549 npn transistor with an led and series resistor connected between the 12 v rail and the collector. The emitter is connected directly to 0 v, no resistor. the base is connected to 5v through a 1.8K...
  6. Kiwi Bruv

    newb transistor question

    I have an npn transistor set up as a switch driving an LED. If everything is connected to the 5v dc supply it works fine. But I want it to switch a 12v supply using a 5v microcontroller output. If I connect everything to the 12 v supply it works great to. But when the base is controlled by the...
  7. Kiwi Bruv

    Buried wire detector

    :)Many thanks everyone.
  8. Kiwi Bruv

    Buried wire detector

    Thanks Siddarth, I picked up the same circuit today. I'll start experimenting after xmas.
  9. Kiwi Bruv

    Buried wire detector

    Thankyou. I've tried the google search but can't find any circuit details just retail invisible fences. Will keep trying though.
  10. Kiwi Bruv

    Buried wire detector

    Hi have basic electronics knowledge. I am building a robot that I want to stay confined in an area outside on the lawn. I want to bury a wire in the ground and use a detector on the robot to keep it within the boundary. I know induction is probably how the thing will work but I have no...
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