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  1. BobK

    Solar->Battery->Timer->Water pump

    More calculations. Assuming the pump runs on 12V. (at 350mA that would be 4.2 Watts.) You are using 47mAH at 12 V = 0.56 WH per day. So a 1 Watt solar panel would be enough to keep it going even if you get less than 1 Hour of sunlight per day. Bob
  2. BobK

    Solar->Battery->Timer->Water pump

    Don't know how you got that figure. First of all 200mA per day is meaningless, I think you want mAH per day. If the pump draws 350mA and is on 8 minutes per day, this is 8 / 60 * 350 = 47mAH per day. Rechargeable AA NiMH batteries (about 2000mAH) would run it for about 42 days, so you...
  3. BobK

    RF TRANSCEIVER

    bluetooth. Bob
  4. BobK

    Quick question (I hope) about LTspice

    Google is your friend. "LTSPICE DC sweep" pulled up this tutorial: http://denethor.wlu.ca/ltspice/#dsweep Bob
  5. BobK

    Solar Panel with small hobby motor

    Well, the motor does not list a current requirement. It is likely more than the 80mA your solar panel will supply. And by the way, why are you trying to run a motor rated at 1.5-3V off a 6V power supply? If the power supply could supply enough current to run the motor, it would likely...
  6. BobK

    H-BRIDGE schematics

    I cannot open your attachment. Bob
  7. BobK

    Help with electronic terminology

    I believe here, in Massachusetts, USA, all outdoor outlets are required to be GFCI. Edit: And whether or not it is required, it is a good idea. Bob
  8. BobK

    circuit to pulse electromagnet on and off

    The circuit is correct. The MOSFET is acting like a switch for the bulb, when can then draw more than the 200mA that the '555 can output. If it is flashing at 1Hz, you have not used the values show for the timing components. I calculate that that would run at 15KHz. Are you sure you are...
  9. BobK

    Constant Current Power Supply

    Yep, And I did say "a lot less than $450." Bob
  10. BobK

    circuit to pulse electromagnet on and off

    That circuit is seriously flawed. You have the output pin connect to V+, and you have left necessary pins unconnecterd. Here is a correct circuit for a 50% duty cycle astable (figure 4.46): http://www.learnabout-electronics.org/Oscillators/osc44.php Bob
  11. BobK

    Constant Current Power Supply

    Yes, it actually reccommended using batteries because they would be noise free. And at 2ma draw, they will last a while. Bob
  12. BobK

    Constant Current Power Supply

    So page 5 of the second document shows you the circuit you need. You need a 24V regulated supply, a constant current diode and a capacitor. I think you can make this for less than $450! Here are some constant current diodes that should work...
  13. BobK

    Constant Current Power Supply

    You nailed it Steve. After posting something useless (I thought maybe the 2 to 10ma was the output signal), I looked around the website for the device. They sell a "power supply" for $450 for this sensor. Power supply in quotes, because it connects to just 2 wire on the sensor and...
  14. BobK

    Constant Current Power Supply

    Removed. Bob
  15. BobK

    how to use analog sensor+ADC+pic16F877A

    Did you try googling, maybe something like "PIC analog input example C" I got this result: http://extremeelectronics.co.in/microchip-pic-tutorials/using-analog-to-digital-converter-%E2%80%93-pic-microcontroller-tutorial/ Bob
  16. BobK

    Effective use of DC

    Well, a switching power supply can easily get you 80% efficiency, so you are starting with 72 * 40 = 2880 Watts. At 80% you could theoretically get out 2300 W. At 5V this is 460 Amps. Is that really what you want? If so, that is one hell of a power supply to build. Bob
  17. BobK

    iphone charger and synchronize

    In other words, you have made a cable, which most people have 20 of scattered around the house by now, except you left off the data lines. Bob
  18. BobK

    Transistor switch circuit base issue

    Yes, it is good to know why floating inputs can be a problem, but the real lesson is "do not have floating inputs". You will get away with this often with BJTs, but try it with a MOSFET once and you will learn! Bob
  19. BobK

    Wireless trigger for LEDs and buzzers

    You ain't kidding! You can get an equlivant PIC for < 1$ at Microchip Direct. 16F84 is obsolete, which makes it more expensive. Bob
  20. BobK

    Wireless trigger for LEDs and buzzers

    Huh? All PICs support ICSP. Bob
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