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  1. KrisBlueNZ

    LED Push Button Dimmer

    How about here: http://www.google.com/search?q=introduction+to+microcontrollers
  2. KrisBlueNZ

    LED Push Button Dimmer

    I'm with Bob on this one. If you're making 100 of them, you'd be crazy to do it with discrete circuitry. Unless you specifically want to make a "retro" product! Any microcontroller that runs at more than a few hundred kHz can do this. It doesn't need a PWM peripheral; it doesn't even really...
  3. KrisBlueNZ

    Triggering a 555 timer on opening of a line

    You're welcome. I hope it works for you!
  4. KrisBlueNZ

    555 voltage controlled oscillator question

    OK, but 78xx regulators have a dropout voltage of around 2~2.5V. If you use a 12V regulator, you need 14~14.5V at the input, otherwise the regulator will "drop out", i.e. lose regulation. That's why I suggested using a 78L08 or 7808. Or is your automotive supply 24V? If so, then no problem...
  5. KrisBlueNZ

    Triggering a 555 timer on opening of a line

    Like what? Here's my suggestion. The connector on the laser is shown on the right. The circuit uses the +24V rail from pin 1 (but it draws less than 10 mA from it, so it's very unlikely to cause any problem). It also needs a connection to the 0V rail, which I assume is available on another...
  6. KrisBlueNZ

    Electronic angle finder repair

    Thanks Dave, I missed that. It could be a 4.00 MHz ceramic resonator but I have my doubts. Tokin do make crystal oscillator modules, but they make other things as well, so the tin module could be something else. We need to see some more close-up photos.
  7. KrisBlueNZ

    Help please!!

    The difference between OFF and ON on a smartphone is not that great. Many parts still run while the phone is OFF - the phone can receive calls and texts, wake up on alarms, and turn ON in response to a touch on the screen.
  8. KrisBlueNZ

    Can you tell me what this is

    It looks like an inductor. You can see the wires from the coil wrapping around the pins. None of those numbers gives me any suggestion of what the value might be. You could measure it with an LCR meter.
  9. KrisBlueNZ

    Help please!!

    Well, a smartphone already has all the hardware and most of the software you need, so it's likely to be a lot better than a Raspberry Pi, as well as being more robust and compact. You need to have a look to see if there are any apps that will do the sort of thing you want to do. If there's no...
  10. KrisBlueNZ

    Help please!!

    Hmm. That sounds tricky. Do you have to use a "trail camera"? What's special about them? Could you use a smartphone with a high-quality camera? You might be able to find an app that could detect when you've taken a photo and automatically send it to a server somewhere through a cellular data...
  11. KrisBlueNZ

    Electronic angle finder repair

    What are the markings on the tall black or green thing between the battery holder and the part marked Tokin? When the board is fitted into the enclosure, does anything make contact with it? Perhaps with the four pads along the top edge? Can you show us a picture of the whole unit with the board...
  12. KrisBlueNZ

    Beginner pull up resistor question

    When the switch is open, it's as if it's not there at all. The resistor pulls up the voltage on pin 0 to 5V. It works like a spring or a rubber band. One end of it is connected to +5V and the other end goes to an input on the Arduino, which just "watches" the voltage without affecting it. So the...
  13. KrisBlueNZ

    Beginner pull up resistor question

    Right, it will be, because it's connected to the 0V rail (represented by the earth symbol). That's also right. I assume that's a battery at the left, and that its negative side is connected to 0V, correct? When the switch is open, the resistor pulls pin 0 up to +5V. When the switch is closed...
  14. KrisBlueNZ

    555 voltage controlled oscillator question

    If the injectors are isolated from the block (two insulated wires going into them) then you should be able to switch either the supply side or the return side. Can you draw up a schematic of what you have? Check that the supply voltage for the 4046 isn't dropping when you connect the...
  15. KrisBlueNZ

    DS1307 initializing

    I don't have code to do that, but I've modified your ds1307_init() function. Try this. #define DS1307_I2C_ADDR 0xD0 // I2C address of DS1307 #define DS1307_ADDR_WRITE 0x00 // Address offset for write command #define DS1307_ADDR_READ 0x01 // Address offset for read command #define...
  16. KrisBlueNZ

    Decreasing voltage to motor

    http://www.robotroom.com/PWM5.html
  17. KrisBlueNZ

    LED Push Button Dimmer

    You can do it using diodes between the 4017 outputs and the resistors. The 4017 outputs that are low will reverse-bias their diodes and will have no effect. Only the output that's high will source current through its diode, into the resistor, and into the 555.
  18. KrisBlueNZ

    LED Push Button Dimmer

    Yes, the 4017/555 idea should work for generating a PWM (pulse width modulation, not pulse wave modulation) signal. But not very well! The LM3404 would not replace the PWM generator; it has a different function. It would connect between the PWM signal and the LED string. But you say your LED...
  19. KrisBlueNZ

    Using a bipolar transistor to turn a load on and off

    That's excellent Steve. I have a few suggestions: Suggest 2N3904 as well as BC548 - Americans seem to not know, or dislike, the BC series. Mention relay coils and solenoids, as well as motors, as types of inductive loads. Suggest removing the + and - markings in the diode picture - they don't...
  20. KrisBlueNZ

    LED Screen

    That's excellent Steve. I have a few suggestions: Suggest 2N3904 as well as BC548 - Americans seem to not know, or dislike, the BC series. Mention relay coils and solenoids, as well as motors, as types of inductive loads. Suggest removing the + and - markings in the diode picture - they don't...
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