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  1. C

    12VDC Switch Controller - Adjust Timer

    The first thing you do is find each electrolytic and put the same value across it on the underside of the board and let me know when you have increased the timing.
  2. C

    Controlling 2 servos at the same time?

    I have a simple program to operate a servo at the required speed or follow a joystick .You can parallel as many servos as you like.
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    Power Supply Questions

    Also note that the 5V cannot differ much from 5V (tolerance is not very high) How come the 5v cannot vary and yet the tolerance is not required to be very high.
  4. C

    Best AC to DC Converters

    This one is $45 http://www.ebay.com/itm/48V-DC-7-3A-350W-Regulated-Switching-Power-Supply-New-/320814543494?pt=LH_DefaultDomain_0&hash=item4ab2097286
  5. C

    Best AC to DC Converters

    What wattage?
  6. C

    Current Measurement Rating

    "The misunderstanding comes from a wrong interpretation of the meter's ratings. If can measure either up to 10A or up to 1000V. But not both simultaneously." NO. Basically the meter has insulated leads and you can measure either AC or DC up to 10 amp on a 1,000 volt line. "At 1000V there will...
  7. C

    Current Measurement Rating

    1. Because the wire inside the meter will get too hot if more than 10 amps flows. 2. Because the program inside the meter may only be designed to read up to 10 amp. But you can try 12 amps and see if the reading is 12
  8. C

    what AWG cable to use for cordless drill + car battery

    A cordless drill can easily take 20 to 30 amps under load. Depending on the run, you cannot even afford to have a resistance of 1 ohm when you have such high currents.
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    4 Circuits, 20 amps each

    10k at 110v is 90 amp 10k at 240v is 40 amp
  10. C

    what AWG cable to use for cordless drill + car battery

    Use the thickest wire possible as you cannot afford to have any voltage drop. Keep the run as short as possible.
  11. C

    Question about current sources - Not getting the correct current through load

    I agree, the text-book uses far-too-complex language to explain this complex concept and it is no wonder you don't understand it. I will explain in slow-motion how the circuit works. The transistor is basically an emitter-follower and this means the voltage delivered to the base must have the...
  12. C

    Question about current sources - Not getting the correct current through load

    The problem is this: The text book states a RESISTOR LOAD. You have used a LED. And secondly the voltages you have used, create a conflict, due to the characteristic voltage across a LED. You need what we call a BUFFER and this consists of a resistor in series with the LED. Next you need to...
  13. C

    Need help with design issues - resistor questions

    There is going to be an enormous difference in current taken by the panels when supplying 12v as opposed to 14v. This is the FIRST thing you have to consider.
  14. C

    Board needed!

    and let me know where you get "100mah LEDs" because they may sell striped paint too.
  15. C

    Question about current sources - Not getting the correct current through load

    You have all missed the obvious. The LED could be red, yellow, blue,green indio or violet. They all have different characteristic voltage drops and the voltage across each varies slightly due to the different manufacturer and brightness and if it is cheap, junk, good quality, high brightness...
  16. C

    Vbe of 2n3904 in led driver circuit

    Nobody answered the question or even got close. "Figure out which end of the range is the more conservative for your design," ???????? The fact is the transistor will draw almost no base current because the collector current will be less than 0.5mA and the base voltage only rises above about...
  17. C

    Tank Sender Unit Reading ohms one way

    You can do it with a micro that takes 2 readings. Firstly it measures the output voltage and gives you a determination. If the reading is zero it applies a voltage to the output via a voltage divider and takes a second reading. This will be the true reading. If it is zero. The tank is empty.
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    Vbe of 2n3904 in led driver circuit

    Don't frighten him with all that gobbleldy-gook. All you have to do is put a 10R resistor for R3 and drive it with PWM. Now reduce the resistance until you get the brightness you want by adding resistors across the 10R. Do not below one ohm. The transistor is taking so little current that...
  19. C

    Vbe of 2n3904 in led driver circuit

    How many LEDs in each string?
  20. C

    Protection diode melted and burnt

    The problem is C2. It causes a high current flow when the circuit is turned on. It is not needed.
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