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  1. BobK

    The new types of IOT

    Heartbeat as an indicator of emotion? I think its response ro exertion would overwhelm the signal. Bob
  2. BobK

    Capacitor

    As Kelley_eye suggested, there is an infinite number of answers, which means the problem is underspecifed. It is like asking what two numbers do I need to add to make 10. Bob
  3. BobK

    Sample circuit for motion sensor

    That is the IR sensor used in a motion detector. Get a motion detector module, it has all the electronics to output a signal when motion is detected. All you need to do is supply power and wait for a signal. The modules also incorporate a lens that controls the field of view. Something like...
  4. BobK

    The new types of IOT

    It could be anything! :) Bob
  5. BobK

    What trends of Electrical Engineering Market that will make good money in 5 years.

    The fossil fuel industry has a clear interest here, and money involved beyond belief. Who is this unnamed party that is paying people to promote a myth of climate change and winning the fight? It makes absolutely no sense. Bob
  6. BobK

    What trends of Electrical Engineering Market that will make good money in 5 years.

    Only a climate change denier could say this. There is no doubt among scientists that are not paid by the fossil fuel industry that we are changing the climate, and that if not stopped it will cause massive problems with the land mass occupied by millions of people going under water. I'm sorry...
  7. BobK

    Conundrum using resistors? (Raw rookie)

    No, there are all kinds of problems. First, the specs for that LED shows 2.5V to 3.0V. I have never seen a white LED that operates below 3.0V, so that is almost certainly incorrect. And for a 3W LED is is more likely something like 3.5V. And there is not current specification! You need to...
  8. BobK

    Drop voltage on transistor base

    Are you saying when D1 is on the voltage is 1.97 and when it is off it is 1.87? I find that hard to believe. Bob
  9. BobK

    Help with increasing the power of a Philips hue bulb Frankenstein "hack"

    Assuning this bulb screws into a normal lamp socket, just like a mormal incandescent bulb. If that is so, then you can power the bulb by eliminating the old controller board. Wire a nomal lamp socket to the incoming AC lines and just screw it in. If you have no experience with AC line work...
  10. BobK

    Hum and amplifier

    Ground the case. Bob
  11. BobK

    Difference between Brown out and Power on reset

    It would help if you told us what device you are talking about. Bob
  12. BobK

    Diode Da Lima

    A reversed Zener in series with the diode is sometimes used fior this. This increases the voltage across the coil, allowing the current to fall more quickly. Bob
  13. BobK

    Diode Da Lima

    All very nice theory, and all wrong. The reverse voltage the diode sees is only the voltage driving the coil. The diode is there to supress the high voltage spike, and the diode will clamp it at the forward voltage of the diode, typically less tha 1V. A 50V diode wiuld be fine if the coil...
  14. BobK

    Crystal external component selection

    You typically need two capacitors, one from each pin to ground. They should, in series, equal the recommended series capacitance, in this case, 18 pf. Thus, 36 pf caps are called for. Because there will be some stray capacitance, so use 33pf, which is a stadard value. Bob
  15. BobK

    Aux on portable radio

    Yes, you are trying to get an output. You are trying to get a signal out of the radio that that tells you when AUX is selected. But there is no such output from the radio. You would need a schematic of the radio to determine what was needed. Bob
  16. BobK

    Calculating Resistance With Just Voltages? Basic DC Circuit Design

    And you still need to know the current required. Bob
  17. BobK

    A/C Adapter Help Please

    Here is one would work and it looks like it might be the correct plug. I don't suppose you have a vernier caliper so you can measure the inside and outside diameter do you...
  18. BobK

    3.3v Voltage Regulator

    OK, I misread it to think he required 3.3V out. That regulator should work. Bob
  19. BobK

    A/C Adapter Help Please

    You need a 9V adapter capable of at least 500mA, more current capability is OK. Then there is the plug, you will need it to match the original one both in type and polarity. The polarity may be shown on the device it powers. A picture of the old plug and the place it plugged into might help...
  20. BobK

    3.3v Voltage Regulator

    Nope. It still has 220nV typical and 350mV max dropout. To get 3.3V out all the way down to 3.3V, you are going to need a switching regulator. Bob
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