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  1. BobK

    3W LED dimmer

    Ah, a UV LED, that explains the high Vf. Your nomimal 3.7V battery, which will be under 3V when run down, will not power that without a boost converter. And, with the battery voltage varying and with such small resistors, the current through all of your LEDs will not be easily manageable. If...
  2. BobK

    3W LED dimmer

    And how do you control the current then? Assuming a Lithium battery, it will be 4.2V when fully charged, which, if you happen to get and LED on the low end of the forward voltage range (it is always a range, never a specified value,) then you might blow it up. That said, can you show me a link...
  3. BobK

    3W LED dimmer

    Where did you get the negative resistors needed to power the 4.2V LED from 3.7V? I need some of these for my free energy project. Bob
  4. BobK

    Tools to check current [uA]

    An Ammeter with a μA range perhaps? Both of my modest level multimeters will read down to 1/10 th of a μA. Just tried it with a 1Meg resistor and 0.3V source, which was as low as my variable power supply would go. Both read 0.3 on the μA range. Bob
  5. BobK

    Connecting electrical devices into DC grid - polarity

    I have reported your post to the ACSPCA (Alpha Centauri Society for Prevention of Cruelty to Animals.) Bob
  6. BobK

    Remote shotgun blast sound

    Come to think of it, that might have been the purpose of the article or thread. I have done some searches but I can't seem to find it. Bob
  7. BobK

    Remote shotgun blast sound

    These might be a far easier way. I saw an article a while back about a device that charged a capacitor to 100s of volts, and then simply discharged it into a high powered speaker. This was claimed to make a realistic gubshot sound, which makes sense because it would basically act like an...
  8. BobK

    Current used for "each" instruction cycle

    1. The datasheet will tell you how much current is drawn based on the supply voltage and operating frequency. 2. There is probably some delay in getting in and out of sleep mode where some intermediate current is used. Unless the wake time is very short this can probably be ignored. 3. The...
  9. BobK

    Configuring GPIO pins in Sleep-Mode

    GPIO pins will maintain their state in sleep mode. The current they will source or sink depends on what they are connected to. Bob
  10. BobK

    Wind powered phone charger

    With my luck, a rain powered charger would be more suitable. Bob
  11. BobK

    Variable current circuit for High Power LED

    You cannot just hook up 32 of these LEDs in parallel and have them share the current equally. You need current control for each of them, or each string of them in series, which would be preferred in this case. 24V is not enough headroom to allow you to control the current at ~23.5V. And now...
  12. BobK

    Variable current circuit for High Power LED

    Your supply is 24V at 67A. Your load is 64 x 2.1A at 23.5V. Calculate the wattage of each and see if you see a problem there. Bob
  13. BobK

    BMP085 - ADC converter type ?

    Duh, I shouldn’t have posted without looking at the datasheet. :oops:
  14. BobK

    System

    If you are talking about controlling appliances in your home remotely: X10 was the classic, but there are now many new systems under the category of "home automation". Bob
  15. BobK

    BMP085 - ADC converter type ?

    And because they would need 8 more pins to output all 16 bits at once. Bob
  16. BobK

    A/D source impedance

    I am looking a the datasheet for the PIC12F1840. What the datasheet says is that the "recommended impedance of analog voltage source" is 10K. This means that the voltage source driving the pin that you are trying to read with the ADC should have an impedance of no more than 10K. (less is...
  17. BobK

    Positively charged "holes"?

    Think of a block of silicon as having a structure that has a specific number of locations for free electrons. Undoped silicon has all of these locations filled. N-doped silicon has extra free electrons, more than there are locations. P-doped silicon has fewer free electrons, not all of the...
  18. BobK

    Looking for Templates for an Analog Circuit to Control LEDs from a Photo Diode

    800 Watts in a 4x6 cm square? No problem, All you need is water cooling and a car radiator (with fan.) Bob
  19. BobK

    Solar Powered Display Cabinet

    Grid tied is a term used for rooftop solar arrays, where you sell the power to the electric utility. I don’t think that is what you are talking about here. Rather than telling us what you think yoiu need(and being way off base,) tell us what you are trying to do. Bob
  20. BobK

    Very Bad EMI

    How are the ground and power signals layed out? If the relay and the micro share a common track, that could be the problem. They should have completely separate tracks to to the incoming power on the PCB. If this is not the case, try cutting the tracks to the relay and replacing them with...
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