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  1. BobK

    Woo-Woo Beginner help to design a 60v 100w load.

    A thousand Watts is a lot of power, it will produce nearly as much heat as a typical space heater. So the big problem is getting rid of that heat. 1000 Watts at 60 V is 16.67 Amps and would be 3.6 Ohms if a resistor. To DIY it, I think your best bet would be to get an old toaster, with a...
  2. BobK

    question: car amplifier at home (diy)

    I just built a new pair of speakers. They are powered by a 16V AC adapter and a 16 Watt amplifier. They can produce sound way louder than I would ever want to listen to. Really, painful level of sound from 16 Watts. And you need 3000? Bob
  3. BobK

    Battery Insulation resistance Caluculation [Software code ]

    So after skimming the PDF you linked, I take it you have been saying "Insulation" when you mean "Isolation". No wonder no one knew what you were talking about. For the rest of the forum: Apparently EV high voltage systems are isolated from the chassis. He is trying to measure the resistance...
  4. BobK

    Battery Insulation resistance Caluculation [Software code ]

    Are you trying to measure the self discharge rate of the battery? What you are saying makes no sense. You cannot put a megger across the battery terminals and get any meaningful results. Bob
  5. BobK

    Capacitor as backup to 12v train camera system power

    Not to mention the fact that the cap is rated at 2.7V. Bob
  6. BobK

    Capacitor as backup to 12v train camera system power

    I give up. Bob
  7. BobK

    Capacitor as backup to 12v train camera system power

    You do not need the Schottky diode after the bridge, the bridge is diodes. Presumably, your bridge is feeding a step down switching regulator to supply the 5V. The capacitor could go either of two places, before or after the step down. If before, it would required higher voltage rating. If...
  8. BobK

    Capacitor as backup to 12v train camera system power

    The capacitor should be powering the camera only during the outages, when track power is available, it should be running off the track power. A properly sized capacitor will charge in less time it needs to provide power, possibly even way less, so a matter of seconds. A 500F capacotor is not...
  9. BobK

    DIY bluetooth speaker

    Link brings you to a login screen. Link the ad, not your order status. Charging off a power bank does not make much sense unless it has more power than your speaker supply, which most do not. If you really want to do that, you could use a step up converter run off the powerbank, but it would...
  10. BobK

    DIY bluetooth speaker

    Why does it "got to have micro usb?" Using a USB connector for 25V is ill advised. Also, you will need more than 25V to charge a 6S Li Ion battery. What does the battery management board call for? Can you provide us a link? Bob
  11. BobK

    “Simple” volt/amp question

    Both Ring and SkyBell also work that way. The Difference is they warn you about it in the intructions and give you alternatives. Bob
  12. BobK

    Capacitor as backup to 12v train camera system power

    I guess his trains take to the air for 3 seconds every now and then. Bob
  13. BobK

    “Simple” volt/amp question

    The simplisafe instructions seem to ignore the problem, yet there are complaints on forums about it not working without a traditional doorbell installed. I have the SkyBell, here is what they say: If would do just that. Indeed, we had an electronic bell and it did not work with it (I...
  14. BobK

    “Simple” volt/amp question

    Be very careful. If it is like other doorbell cams, you cannot simply connect the power supply to it. This is because the standard wiring in the house has the doorbell short two wires which lead through the doorbell chime. If you simply install a power supply, pushing the button, you will...
  15. BobK

    6v LED brighter with 3v battery

    Because they are not new, perhaps? Bob
  16. BobK

    Capacitor as backup to 12v train camera system power

    No, because supercapacitors do not come in voltage high enough. You would need several in series with with additional circuitry to keep the voltages on them balanced as they charge. Maybe that is because that is not what I said. I said across the DC to DC converter, meaning across the input...
  17. BobK

    Capacitor as backup to 12v train camera system power

    A capacitor can simply be placed across the input to your DC to DC converter. None of the listed capacitors will work, The 1F has enough capacitance to help, but it is only good for 5V, which is typical for supercaps. The others are orders of nagnitude too small. Bob
  18. BobK

    Capacitor as backup to 12v train camera system power

    If the current is 1 Amp and he needs it for 3 seconds, and the input can drop to 6V before the 5V is in trouble, here is the math: dV / dt = I / C 6 / 3 = 1 / C 2 = 1 / C 2C = 1 C = 1/2 F It's only a small supercapcitor! Bob
  19. BobK

    Adjustable current souce 12Vin 400mA o/p 32W

    I think it is time you told us what you are trying to do. Bob
  20. BobK

    Charging AA Li-ion batteries

    Lithium Ion batteries are not 1.5V, and, as far as I know do not come in AA size.Most likely you are talking about NiMH batteries. Bob
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