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  1. BobK

    Transistor help

    Polarity. Bob
  2. BobK

    Resistance of 1 foot of Romex cable?

    That resistance will not help you. If the wire is 14 gauge it is about 2.5milliOhms / foot if it is 12 gauge it is 1.6mlliOhms / foot. So 250 ft of 14 gauge wire would only be about 0.625 Ohms. So first, let's get it straight what you are measuring. I am guessing you are measuring across...
  3. BobK

    N channel high side switch

    Going back to Steve's original suggestion, the simplest way to do what you want is to use a separate floating power supply that connects to the source of the MOFSET, and an opto-isolator to switch the gate based on that power supply. Bob
  4. BobK

    New Programming Language Anyone?

    Well, that seems to be what Arduino and PICAXE are about. Have you used either of them? If so, what are their strengths and weaknesses? Bob
  5. BobK

    New Programming Language Anyone?

    I myself would like to do the same. C is not really that good a fit for programming small micros. I would like to see a language that supports multitasking, at a very simple level, and supports fixed point numbers directly. But I think we would have a hard time convincing anyone to use a...
  6. BobK

    EGT warning light mV switch into V?

    What you need is a comparator. If you use one that includes ground in its input range, you can simply set the - input at 29mV via a voltage divider and put the output of the thermocouple on the + input. when the temp exceeds 1300V the comparator will then go high. Bob
  7. BobK

    How to increase 555 Timer Frequency

    Another forum I frequent only allows editing a post for a short time after it is posted. That would be a good policy here. Bob
  8. BobK

    How to increase 555 Timer Frequency

    Calm down, Chris, You just have to learn how to not read, like I do. Bob
  9. BobK

    Pulse Train Detection

    A thousand times easier! Bob
  10. BobK

    Stepping up voltage

    A better circuit would use a full H-bridge. DC to AC inverter. Bob
  11. BobK

    Pulse Train Detection

    Either it changed, or I misread it the first time. I mentioned 150nS in my post, which I guess Laplace picked up. Bob
  12. BobK

    Stepping up voltage

    Define "work" Bob
  13. BobK

    CAPACITOR

    Yep. Capacitors have very low resistance, compared to a battery, so a large current will flow when you short them. Bob
  14. BobK

    N channel high side switch

    Here is a high-side low-side driver that can handle 1200V. http://www.irf.com/product-info/datasheets/data/ir2213.pdf Bob
  15. BobK

    Capacitors as timed circuit

    There is no current draw given for either product, so it is impossible to tell. But making a guess, the LED strips alone would a good fraction of an amp, lets say 1/3 and the siren would probably take more, so let's say 1 Amp altoghether. To pull 1 Amp from a capacitor for 2 seconds puts...
  16. BobK

    Electric/Battery Metronome

    Instead of a solenoid, I would use an electromaget with a permanent magnet mounted on the pendulum inside the box. A current that attracts the magnet would stop the metronome and a reverse current would kick-start it again. You would need one on each side in order to stop / start it in both...
  17. BobK

    GPS heading display

    You would need a GPS module + a microcontroller programmed to turn a series of readings into a compass directions + the display. Not a trivial project. Bob
  18. BobK

    How to increase 555 Timer Frequency

    I think he was actually talking about R2, which uOhm resistor being discussed at the time. Bob
  19. BobK

    newbie looking for advice

    I hate to tell you this, but you are unlikely to find things that you, as a beginnger, can use in your old phone. These use very small surface mount components that are difficult to deal with and cannot be used at all without a PC board. You would be much better off to buy older style...
  20. BobK

    CAPACITOR

    No, it will provide (for a short time) whatever current the circuit it is connected to will take. This is why capacitors charged to high voltages are so deadly. If you bring an inductor up to 100mA, then disconnedt the current soruce, it will try to continue that current of 100mA creating as...
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