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  1. KrisBlueNZ

    load cell circuit

    Maybe. Check the +5V rail voltage. If it's significantly less than 5V then you should power the circuit separately from a regulated power supply. You said the highest raw value you get from your ADC is 864, not the expected full-scale value of 1023. 864/1023 * 5.0V = 4.22V. If you're talking...
  2. KrisBlueNZ

    speed control problem for helicopter

    As you say, the servo system is failing to keep the motor speed constant. Do you have any information on the servo system?
  3. KrisBlueNZ

    Effects of feedback

    I guess they mean negative feedback? Your course should have taught you enough to answer that question, but if they didn't, Google negative feedback to learn about its effects.
  4. KrisBlueNZ

    Light sensor Interface

    Hi there and welcome to Electronics Point :-) That's an interesting idea and I think you may be able to make it work. I would be concerned about nuisance activations though. You would need to be able to detect a fairly specific sequence of events - a rapid and significant drop in light on one...
  5. KrisBlueNZ

    Hello from the UP of Michigan!

    Hi there and welcome to Electronics Point :-) You've come to the right place! There are lots of people here who are ready to help and explain stuff to you.
  6. KrisBlueNZ

    seeking explanation on basic led flashing circuit

    In that simple version of the oscillator, both transistors are so heavily saturated at the start of the condition time that the duration of the conduction period is actually mostly determined by the charge storage time in both transistors, as you can see from this graph: The green trace shows...
  7. KrisBlueNZ

    DC current draw question

    Hi there and welcome to Electronics Point :-) For 12V DC, almost certainly, yes. The only difference is that the power supply inputs of the devices would all be connected together, rather than all individually isolated from each other, as they would be if they were powered from separate wall...
  8. KrisBlueNZ

    Atmel SamD20 External Interrupt

    Hi there and welcome to Electronics Point :-) Your code was tl;dr but in general, if you can't figure out how to do something "while" you're doing something else, you have to move to some kind of multi-tasking model. There are many approaches. If you only need two independent tasks, a simple...
  9. KrisBlueNZ

    SMD Capacitor identification

    Those are tantalum capacitors, not diodes. They shouldn't measure short; lift one end and measure again.
  10. KrisBlueNZ

    Question about grounding

    Right. But before you connected the common to earth, it was floating, and that's what the author is getting at. The output needs to be floating before you connect either side of it to earth, otherwise you may have a problem. In what way is the "performance different" from a battery? Power...
  11. KrisBlueNZ

    Sony Receiver STR - DA555ES Displays "protection fan" when turned on.

    OK, well, there doesn't appear to be a direct short. There are three points marked above. They are the places where the 5V and 3.3V rails go when they've left the regulator. I would like you to disconnect all three connection points, refit the bridge rectifier, install a new fuse, reinstall...
  12. KrisBlueNZ

    seeking explanation on basic led flashing circuit

    OK, I'll try to explain the two-transistor relaxation oscillator. I ran an LTSpice simulation with the following schematic: The simulation generated the following waveform at Q1B: As you can see, I had to set the initial conditions so Q1B was at 0V, otherwise LTSpice starts the simulation...
  13. KrisBlueNZ

    Sony Receiver STR - DA555ES Displays "protection fan" when turned on.

    OK that's good. So they're OK. When you measure across C960 do you measure a short circuit, or something else? Also, can you measure for shorts on the 3.3V rail (probe points marked A) and 5V rail (probe points marked B). I've labelled the bridge rectifier holes so you can match the photo up...
  14. KrisBlueNZ

    Sony Receiver STR - DA555ES Displays "protection fan" when turned on.

    OK, those indications are right. When the probes are open circuit, it shows "1 ." and when they're short circuited, it shows 1.6Ω. This is OK. What do you mean you "don't get any reading"? Does the multimeter show "1 ."? That's an open circuit indication and it means the capacitors are OK...
  15. KrisBlueNZ

    Sony Receiver STR - DA555ES Displays "protection fan" when turned on.

    Use the meter on the 200Ω range when you're testing for a short circuit (which is what we're doing here). With the probes not touching, it will show an overflow indication, something like "1 ." or "0L". That means open circuit. With the probes touching each other, it will show a low number of...
  16. KrisBlueNZ

    Sony Receiver STR - DA555ES Displays "protection fan" when turned on.

    When you short the multimeter leads together, does it also show a reading and slowly go back to 0Ω? If so, then that's how your multimeter behaves when you measure a short circuit. In that case:
  17. KrisBlueNZ

    seeking explanation on basic led flashing circuit

    It's a two-transistor relaxation oscillator. It's described in various places on the web. I ran a search: https://www.google.com/search?q=two transistor relaxation oscillator -unijunction -multivibrator -ujt&tbm=isch and found the following relevant pages...
  18. KrisBlueNZ

    Sony Receiver STR - DA555ES Displays "protection fan" when turned on.

    Hmm. I see what you mean. Well, it's clear from your photos of the tracks that the regulators on the tall heatsinks are supplied from C960 (the rail marked 9.7V on the schematic) so they must match those regulators on the schematic. The 7805 matches; it's IC955 on the schematic and on the board...
  19. KrisBlueNZ

    Sony Receiver STR - DA555ES Displays "protection fan" when turned on.

    I hope this isn't too late! Radio Shack will have the 7805 (IC955) but they won't have the BA033T (IC902). You could buy a 7805 because they're cheap. They may have a 4700 µF 16V capacitor (C960) and you could buy one of those, but don't replace it until we know that the original is faulty...
  20. KrisBlueNZ

    Christmas Gift for my 15 year old electronics enthusiast

    Great advice Hop... except that the OP is Mum, not Dad :-)
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