Search results

Search Forums New Posts
  1. BobK

    2:1 ratio step down transformer question from newbie

    Could you explain further how this would work? Are you talking about using the two secondaries as an autotransformer? Bob
  2. BobK

    How much Hydrogen and Oxygen released..

    But using the electricity you already produced to do the heating would be more efficient. Bob
  3. BobK

    Help circuit for project idea.

    WTF? Is this some kind of drug paraphenalia? Bob
  4. BobK

    Voltage regulating.

    Check this out. A buck converter is much more efficient than a linear regulator and you can't beat the price. http://www.ebay.com/itm/4-40V-to-1-5-35V-DC-DC-Buck-Converter-Step-Down-Voltage-LM2596-Regulator-/140746291933?pt=LH_DefaultDomain_0&hash=item20c521fadd Bob
  5. BobK

    Eectronic watch/clock - HELP

    I meant to say WWVB, which continually broadcasts the time in a binary format. Starting point is here: http://en.wikipedia.org/wiki/WWVB First of all, if you are not in North America, this is useless to you, Secondly, you need a microcontroller to decode the signal and display it as...
  6. BobK

    How much Hydrogen and Oxygen released..

    So, to summarize what Timothy said, You want to use X KWH of energy to split H2O into say 0.8 X KWH worth of Hydrogen. Then transport the engery in the form of Hydrogen to where it used at a cost higher than transporting the electricity. So where is the gain? Once you have the...
  7. BobK

    LED Light Box Troubleshoot

    What is the source of the sound? Perhaps the voltage is not high enough. It needs to be about 1V. Bob
  8. BobK

    How much Hydrogen and Oxygen released..

    It requires 2 electrons to perform the electrolysis of water. The charge of an electron is 1.6 e-19 Coulombs. 1 Amp is 1 Coulomb / second. So that is 6.25 e 18 electrons / second and it will create 3.125 e 18 molecules of Hydrogen per second per amp. Divdiing by Avagadros number (6.02 e 23)...
  9. BobK

    Auto off switch underload?

    What you are describing is a circuit breaker, which has already been suggested. Tell us why neither that nor limit switches is good enough for you. Bob
  10. BobK

    How long will this LED last with this battery?

    LR41 and LR44 are 1.5V batteries. They will not light a 3V to 3.2V LED at all. CR2032 is 3V and could theoretically light it for about 9 hours, but the maximum continuous current it is specified to supply is 3ma, so it is really not an approriate battery for driving this LED except for short...
  11. BobK

    Eectronic watch/clock - HELP

    The way to build a digital clock now is with a microcontroller. It can do everything needed with only a handful of other components necessary, i.e. the display itself, 4 transistors or a darlingon array for digit drivers, a crystal for timing, a few resistors, and some switches for setting the...
  12. BobK

    solenoid power boost

    Wind more turns or up the current. bob
  13. BobK

    need help on small solar panel project.

    Depends on the battery type. http://batteryuniversity.com/ However, my reply was meant to be tongue-in-cheek. It you want to run the fan for about 1 hour a week this would work, otherwise you need a bigger solar panel to run it whenever the sun out. Why don't you tell us more about...
  14. BobK

    Review my circuit

    This may work, but you are running the buzzer off about 2.6V the way it is wired. This is because the base has to be about .7V above the emitter for a transistor to turn on. If the sensor is putting out 3.3V on the base, emitter can only go up to 2.6V. If you switch to buzzer so that it is...
  15. BobK

    Back EMF of an electric motor.

    Back EMF is not a good thing or a bad thing. It is what happens. Bob
  16. BobK

    arduino is it all its cracked up to be?

    I am a PIC guy, so I can't talk about AVR or Arduino. But I concur with CocaCola that it is a waste of money to buy any development board for each of your uController projects. I started with a PICKit 2 and low pin-count demo board ($50). I feel that this was good for me as a start...
  17. BobK

    where to get started on first (sort of) electronics project

    Yes, pot is short for potentiometer. What I described could be built using 1 IC, a handful of resistors, the two pots and two transistors, so it is not really all that complicated. It would also need a dual + and - power supply, whch could be as simple as two batteries. Using a salvaged...
  18. BobK

    Impedance relation between 2 Bjts

    The coupling capacitor is chosen to pass the AC signal of interest, so effectively it has no resistance for the signal. Bob
  19. BobK

    where to get started on first (sort of) electronics project

    I actually built a home made servo that skipped all the pulse width modulation to control position via a pot. It was quite easy. You connect a pot to the shaft of the motor then use an op-amp to compare it's output to another pot used to control the position. The op-amp controls a half bridge...
  20. BobK

    Impedance relation between 2 Bjts

    Zout and Zin form a voltage divider. The actual input voltage seen by the second amplifer is is calcluated from that, i.e. V = Vin * Zin / (Zin + Zout) Bob
Top