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  1. kellys_eye

    Basic transistor switch

    You only took the first part of my post - when added to the rest of it, i.e. saturation, there's a distinct difference. My post was on the basis that this seems like a homework question and that 'helpful advice' is preferred over a simple 'answer'.
  2. kellys_eye

    Daikin inverter ac 00 error but ac not working gas level correct

    Yes, it is.
  3. kellys_eye

    Which led wire is positive?

    Experience plus learning - something you've been told about more than once but seem to ignore all advice.
  4. kellys_eye

    Which led wire is positive?

    In your particular example, yes, ground is negative.
  5. kellys_eye

    PCB layout tips?

    Why do the 'plated through holes' differ between top and bottom?
  6. kellys_eye

    Basic transistor switch

    calculate the current flowing in the base resistor and multiply it by the current-gain (beta) of the device. Beta is a figure obtained from the datasheet or can be measured yourself. When used as a switch, the transistor is driven into saturation - another parameter obtained from the datasheet...
  7. kellys_eye

    Which led wire is positive?

    the left-hand pad in each square is 'ground' (cathode of LED)
  8. kellys_eye

    Video interphone mafunction

    Need a closer view.....
  9. kellys_eye

    Repair braun CareStyle 7

    Both items are essential safety devices and need to work together to give the required protection. Replacement of parts should be using the manufacturers recommended parts which may be difficult/impossible to source. I wouldn't countenance their replacement using after-market items due to risk...
  10. kellys_eye

    Video interphone mafunction

    Post close-up images of BOTH sides of the circuit board.
  11. kellys_eye

    Repair braun CareStyle 7

    Part 1 is a thermal sensor (thermistor) which will have a resistance that varies with temperature and these devices are often stated as having x ohms @ 20degC (or somesuch). It might even be a thermoucouple device. It may be something more sophisticated such as a silicon diode or another type...
  12. kellys_eye

    Video interphone mafunction

    How did you get a 4-pin plug into a 2-pin socket? If you put the 2-pin into a 4-pin then putting GND on the CVBSIN pin wouldn't do any harm. Still not quite sure how you did what you did.... Is the power supply to the display still giving out 12VDC?
  13. kellys_eye

    arduino digital pin output power question

    Which version (model) of Arduino are you using?
  14. kellys_eye

    Video interphone mafunction

    What 'wrong connection'? The fault is undoubtedly related to your 'wrong connection' but unless we know that connection is/was we're clueless.
  15. kellys_eye

    arduino digital pin output power question

    No - 20mA is what the digital port can SOURCE. It's not 'continuous'. The 'total' permitted depends on the maximum power dissipation of the package - check the datasheet.
  16. kellys_eye

    The magic of Paris, London and Iceland

    So you made parole then! Iceland seems an unusual choice for someone so far removed from this part of the world. It's been 40+ years since I was last there so can't even make a qualified comment on the place any more! I do recall the cold though. It was a February when I was there and stormy...
  17. kellys_eye

    Dark Emitting Diodes (DEDs) May be a New Tool in the War Against COVID-19

    Didn't take the original jab.... no way am I inserting a DED one........
  18. kellys_eye

    Are There 3 Volt MultiMeters?

    You'd be surprised at the kind of sophisticated test meter you can get for 'yard sale' prices these days - new! A digital, auto-range device might be best for a beginner but 'anything' will serve as long as it works and you can prove its accuracy. Analog meters suffer mechanical issues (don't...
  19. kellys_eye

    Identify a PCB

    It's possible to 'reverse' engineer the board to get an idea of the parts that fit and, maybe, determine its purpose. There are only a limited number of 24 and 28-pin 0.6" DIP devices and you should start by determining which pins are connected to Vcc and GND. Some of these devices seem to...
  20. kellys_eye

    Identify a PCB

    Yes, Elektor used hex-shaped pads since issue no.4 way back in 1975. I don't recall them ever using round pads....
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