Search results

Search Forums New Posts
  1. KrisBlueNZ

    Current bypass

    Did you read what I wrote?
  2. KrisBlueNZ

    Activate a relay when resistance is within a certain range

    Hi there and welcome to Electronics Point :-) I don't know if you can buy something like that, but it's not hard to design. You need a circuit called a window comparator. You connect your resistance and a known resistor in series across the supply voltage to form a voltage divider. This...
  3. KrisBlueNZ

    Current bypass

    Just connect a resistor between your TVS and the IC's input pin. I suggest 180Ω. This will not clamp the voltage but it will limit the current that can flow into the IC to a level that will not damage it.
  4. KrisBlueNZ

    Current bypass

    It's not ideal to pull any input pin of any IC beyond the supply rails, but the IC will have internal clamping diodes, and provided you don't feed too much current into the pin, it is normally acceptable. There's a bit of a clue to this in note 4 below the absolute maximum ratings table. It...
  5. KrisBlueNZ

    Current bypass

    If I asked you how to get to your house, would you post a drawing of your front door? No? Then perhaps you can understand why I need to see the whole schematic!
  6. KrisBlueNZ

    Current bypass

    Show us a schematic. Can you connect the diode in series with the power source, instead of reverse parallel?
  7. KrisBlueNZ

    Need help finding specific lcd size for project

    Hi there and welcome to Electronics Point :-) I had a look on Digi-Key and Mouser and the closest I could find is 240x160, square pixels, but about 3.3" diagonal...
  8. KrisBlueNZ

    Current bypass

    Yes, Schottky diodes can have forward voltages that low, at lowish currents. Germanium diodes have low forward voltages as well. Both Schottky and germanium diodes have quite high leakage currents, and the "knee" in their VF vs. IF graphs may not be as sharp as the knee in the graph for a...
  9. KrisBlueNZ

    4~20 mA current generator

    This sounds like a homework project so I have moved the thread to the Electronics Homework Help section. I have also renamed it. 4~20 mA current loops are used in control systems to transfer analogue quantities such a temperature, pressure, current, voltage, etc from transducers to controllers...
  10. KrisBlueNZ

    Current bypass

    Because of those corrections, the proper value for R1 is about 0.54Ω. I suggest you use four 2.2Ω 0.5W 1% metal film resistors in parallel, which will give you 0.55Ω, and connect another resistance in parallel to drop that down to 0.54Ω. The calculated value is 29.7Ω and 30Ω would be close...
  11. KrisBlueNZ

    Current bypass

    Sorry, I meant nineteen 10Ω resistors in parallel, not 100Ω resistors. Did you read and understand this section of post #13? If you're using a simple diode clamp, your resistor doesn't need to be rated for 50W. At 10A diode current, that diode's typical VF is about 0.88V (not 0.84V as I...
  12. KrisBlueNZ

    Current bypass

    I don't think you'll find a single resistor that meets those requirements. You should connect several resistors in parallel - say, nineteen 100Ω 3W 1% resistors in parallel and an 82Ω resistor and 50Ω trimpot in series, in parallel with the resistors. Then you can adjust the resistance to get...
  13. KrisBlueNZ

    code repeat??

    Post the code you tried, and describe clearly what doesn't work.
  14. KrisBlueNZ

    code repeat??

    What did you try? Do you know about for loops?
  15. KrisBlueNZ

    help me to design 60w portable power supply

    We have a forum for that. It's called Electronics Homework Help. I have moved this thread there.
  16. KrisBlueNZ

    How to make an "auto-on" ?

    You could remove the button if you don't want to use it. I would keep it in case you want to replace it some time in future though.
  17. KrisBlueNZ

    How to make an "auto-on" ?

    Well, this is a relatively simple project to start learning with then! Either. If you can make electrical connections to both sides of the button, you can connect a relay contact in parallel with it. It doesn't matter whether you connect your wires to the actual leads of the button, or to the...
  18. KrisBlueNZ

    How to make an "auto-on" ?

    If you can connect two thin wires to the contacts of the pushbutton, you can make a small circuit that will pulse a reed relay a short time after power is applied, to turn the device ON when power is applied to the circuit. I replied to a similar request recently. See...
  19. KrisBlueNZ

    RS232 & Crossing RX/TX Lines

    That looks right to me
  20. KrisBlueNZ

    making a big magnetic field

    We would be thankful if you would ask your question specifically. What are you trying to achieve?
Top