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  1. BobK

    Understanding LED brightness (mcd and viewing angle)?

    mcd is a measure of light intensity. You can have two LEDs, one with a viewing angle of 120 degrees and another with a viewing angle of 20 degrees, both of which put out the same amount of light, and the second one will have a much higher mcd rating. Which means it will make a small spot of...
  2. BobK

    Trumps solar wall, forget politics we should just build the thing

    Of course the wall does nothing about the half of illegal immigrants who enter the country legally with tourist visas. A wall would simply decrease the number of people crossing the border illegally an increase the number crossing legally but staying illegally. Couple this with the fact that...
  3. BobK

    Homemade capacitors, that hold a charge?

    But you are not going to get up to supercapacitor this way. Bob
  4. BobK

    Fly back driver help

    I believe your assumptions are all correct. Bob
  5. BobK

    Pcb reconfig help needed

    A motor for a garage door opener is probably not rated for continuous operation. It is most likely overheating and the controller is shutting it down. Bob
  6. BobK

    General question regarding fuses

    If you short the battery terminals, there is no current going through the fuse. Bob
  7. BobK

    Induction

    Self induction refers to the affect of the magnetic feild created by a coil on itself. Mutual induction refers to the affect of the magnetic field created by a coil on a different coil. If you have only one coil, you have self induction but no mutual induction. If you have two coils coupled...
  8. BobK

    Regarding Differential Signal...

    I answered that question already. They are routed in parallel to reduce the impact of any interference they might pick up. If you do not route them in parallel, what happens depends on how sensitive the circuit is to interference and how much interference (RFI) exists in the environment. In...
  9. BobK

    PCB Design

    You can be sure that you will see copper, solder mask and holes where they show on the viewer, with the caveat that lines and spaces will vary within the resolution stated by your manufacturer. The variation is typically ±3mil or 0.003 in. Typically all lines and space should be at least twice...
  10. BobK

    Regarding Differential Signal...

    Yes, because interference will be picked up equally by both lines and will not change the difference between them. Bob
  11. BobK

    Shake Flashlights power

    Hybrid cars also use this method for braking, using the generarted power to charge the batteries. Bob
  12. BobK

    Lithium Ion 18650 cell capacity

    No, that is not what the conversion rate would mean. The 85% is for the conversion from the battery voltage to the regulated output. Bob
  13. BobK

    Shake Flashlights power

    Converting motion into electrical power than back to mechanical motion loses power in both directions. You will not create a human powered vehicle that way that is as efficient as a bicycle. Bob
  14. BobK

    PCB Design

    Does this help: I use gerbv, a free Gerber file viewer. Bob
  15. BobK

    Converting an electronic cooling fan to battery operated

    I understand that. I am just saying that he could get a similar fan that already runs on DC. Bob
  16. BobK

    Trumps solar wall, forget politics we should just build the thing

    The lovely wife Morticia has weighed in on this. Solar is not exactly Trump's favorite, coal is. So build the wall out of coal. Win-win: we create jobs for coal miners without putting more C02 in the atmosphere. Brilliant! Bob
  17. BobK

    Lithium Ion 18650 cell capacity

    I think your question has been answered. You discharged to 3V, they discharged to 2.5V when rating the capacity. This would account for the difference. To answer your question though, you need a constant current sink to draw 620mA. Here is a simple circuit: The supply labeled 2V must be a...
  18. BobK

    Trumps solar wall, forget politics we should just build the thing

    You have to know where that is coming from. A "research fellow in energy and environmental policy at The Heritage Foundation" most likely has a degree in Bible Studies. Bob
  19. BobK

    Coil Question

    That is for sure! sets of what? In what way are they functioning incorrectly? It is hard to imagine a coil that is functioning incorrectly. Perhaps the inductance is wrong, or the resistance is too high, but what do you mean by functioning incorrectly? ???? Bob
  20. BobK

    Coil Question

    I am having a lot of trouble understanding what you are asking about. You say you have "made some testers." I assume this means you have wound some coils using the machine. You say they are functional, but not efficient. What does "efficient" mean here? What is it you are trying to...
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