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  1. BobK

    LED Driver circuit

    3000 to 4000 Watts of LED power total? This must be some indoor farm. Have you thought about what it will take to cool them as well, that's like running 2 to 3 1500W space heaters constantly. Do expect a visit from the police. Bob
  2. BobK

    LED Driver circuit

    There are many reasonably prices constant current LED drivers out there. Check Ebay. Bob
  3. BobK

    Non isolated mains LED bulb = illegal?

    Why would it be any more illegal than an incandescant bulb that is not isolated? Presumably the PCB is insulated from the heat sink. Bob
  4. BobK

    Mapping voltage from [0 , 1.8] to [0.4 , 1.4]

    You want an opamp circuit with a gain of 1 / 1.8 and an offset of 0.4V. This can be done with a single opamp, though I don't have time to do the design right now. Bob
  5. BobK

    Need advice on adding a USB power port to tablet

    If the current charger plug is just two wires carrying 5V then, using a usb socket, you would just connect the two wires to power and ground. Bob
  6. BobK

    Darlington pair setup for QRD1114 IR phototransistor circuit?

    Use a Schmitt trigger to clean up the signal to a square wave. Bob
  7. BobK

    LM317T Adjustable Voltage Regulator HELP ?

    The extra terminal should be connected to the wiper if anything. Bob
  8. BobK

    Need advice on adding a USB power port to tablet

    Did you find room inside? The tablets I have looked at do not have much in the way of empty space. If you can find space, it is just a matter of hooking up the wires. I presume the old port is a micro USB connector (very thin and about 1/4 in across?) Bob
  9. BobK

    19V 2.6A Monitor Ok To Run 3.16A Power Pack?

    Do 100 W light bulbs pop when you plug them into the same socket that can power a 1000 W toaster? Bob
  10. BobK

    Peltier tiles

    Voltage can be stepped up (at the expense of current.) Current can be stepped up (at the expense of voltage.) Power = Voltage x Current cannot be stepped up. Your Peltier tile will be capable of some amount of power, not energy. Energy = Power x Time, so the energy you can create depends...
  11. BobK

    Newbie LED bookshelf lighting project HELP

    Read this: https://www.electronicspoint.com/got-question-driving-leds-t256849.html Bob
  12. BobK

    LM317T Adjustable Voltage Regulator HELP ?

    If you want to adjust it around 7.5V I would use a 1K fixed resistor and a 500 Ohm pot. This would allow adjustment from about 6 to 9 Volts. With a 10K pot, most of the range would be wasted. Bob
  13. BobK

    LM317T Adjustable Voltage Regulator HELP ?

    The resistors are way too large. Take the K off the end. I.e. use 240 and 1200. Did you see the note in red that R1 must be between 100 and 1000 Ohms? Bob
  14. BobK

    Car Battery Bounce Eliminator

    Isn't there some kind of problem here, if the car is drawing that much current when it is allegedly turned off? Bob
  15. BobK

    Building a simple clock

    Using a PIC to make the 1 Hz clock is overkill, since the PIC could replace all of the rest of your logic as well! Bob
  16. BobK

    powering a LED help

    No, you cannot add a resistor to dim them if you are using a constant current driver, it will just up it's voltage to maintain the constant current! Bob
  17. BobK

    powering a LED help

    Yes, that driver is appropriate. With 3 1W LEDs this is going to very bright! Bob
  18. BobK

    Capacitor Value

    You can always replace a 20% tolerance capactor with a 10% tolerance. Bob
  19. BobK

    Dewalt Charger Circuit

    Tell that to the people who built the charger for my cordless screwdriver. I replaced it with a smart charger after it killed 2 batteries within a year. Bob
  20. BobK

    Locking DC Power Socket

    Like these? http://www.jameco.com/webapp/wcs/stores/servlet/StoreCatalogDrillDownView?langId=-1&storeId=10001&catalogId=10001&freeText=locking%20power%20plug&search_type=jamecoall Bob p.s. Google is your friend.
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