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  1. BobK

    [Need help] Stepper motor control

    It is likely you are not sequencing the phases correctly. Swap the leads of one of the two coils and it should work. Bob
  2. BobK

    detect mobile phone

    Get one of the boxes police use to emulate a cell tower and talk to the phone. http://www.nytimes.com/2016/02/12/nyregion/new-york-police-dept-cellphone-tracking-stingrays.html?_r=0 Bob
  3. BobK

    Oscillating pulse to stable

    This makes absolutely no sense. If what you want is a constant DC voltage, use a voltage divider from the power supply. Why would you use a 555 timer to produce a constant DC voltage? What is it you are trying to do? Bob
  4. BobK

    Oscillating pulse to stable

    Why would you want to turn the output of the oscillator to a. stable DC voltage? It sort of defeats the purpose. Do you mean you want a DC voltage that varies with the frequency or duty cycle of the oscillator? Bob
  5. BobK

    SMPS Troubles

    As far as I can see, your circuit is doing exactly what I would expect. Agree with Alec_T that the inductor is far too small. Should be on the order of 10s or 100s of uH. Check the current through the coil, I think you will find it to be 100s of Amps. Bob
  6. BobK

    Stabilising wienbridge sine wave using FET

    A Wien Bridge oscillator is not the optimal circuit to be creating a frequency to drive an LED. It is great for putting out a pure sine wave, but you do not want a pure sine wave, you want a square wave. A crystal oscalliator + divider makes much more sense. Bob
  7. BobK

    Help with 3v relay

    So your voltmeter is across the relay contacts. This should show 0V when they are closed, which is apparently what you are reading. Use the meter on Ohms across the contacts, and it should read 0 (or very small <1) when the relay is closed, and infinite when the are open. Bob
  8. BobK

    Infrared sensors help please

    Well, it could be bouncing IR light off the eyelids and detecting changes with detectors. But let's talk about the power that it might use. Compare it, for instance to the power of sunlight. It would be millions of times smaller. So, unless avoid going outside when the sun is out, I don't...
  9. BobK

    Wireless Remote Control AC Power Outlet US Plug Switch For Small Appliances FSS

    Look at X10. It has everything you need. Bob
  10. BobK

    IR carrier frequency

    Are you taking about an IR remote for a TV or other consumer electronics product? If so, you can find the frequency and protocol used by model number online. Bob
  11. BobK

    Potentiometers not working properly in circuit

    I think your ground rail is missing some connections. Bob
  12. BobK

    Wireless Remote Control AC Power Outlet US Plug Switch For Small Appliances FSS

    I am trying to be very patient here, but it is difficult. Let me describe what I think you want, and let's see if I have it right, mostly though use of my crystal ball. You have two devices in the same room that you want to control with two remote buttons, also in the same room. You want...
  13. BobK

    Measuring Amps, Am I Reading This Right!?

    Tell us exactly how you connected the ammeter probes to read 12A. Bob
  14. BobK

    220v to 110v circuit

    Yes, we do, but only 2 outlets in a typical house, one for the stove and one for the dryer. Bob
  15. BobK

    Wireless Remote Control AC Power Outlet US Plug Switch For Small Appliances FSS

    So the button works only if it is exactly 10 feet from the receiver? It would help if you answered my questions instead of just changing your story each time without clarifying anything. If you are worried about one button setting off two systems, that is handled in a completely different way...
  16. BobK

    5000W high power mosfet

    Let's see. The MOSFET Rdson is 0.005Ω, so a resistor of 0.1Ω would dissipate 20 times the power of the MOSFET. MOSFETs do not need resistors to balance the load. They have a negative thermal coefficient, which means if one starts getting hotter, it automatically will carry less of the load...
  17. BobK

    Wireless Remote Control AC Power Outlet US Plug Switch For Small Appliances FSS

    Okay. First the distance was 8 feet. Now it is 8 to 10 feet. Does the button work at 4 feet? Is it a problem if it works at 12 feet? Bob
  18. BobK

    Wireless Remote Control AC Power Outlet US Plug Switch For Small Appliances FSS

    It occurred to me that you did say it has to be wireless. So button on an 8 foot cord would meet your specification! Bob
  19. BobK

    Wireless Remote Control AC Power Outlet US Plug Switch For Small Appliances FSS

    Hi, and welcome to the forum! "8 feet'' is a distance, not an area. Do you mean it should work inside circle of 8 foot radius, and should not work if the distance is 8.1 feet? Should it work through obstacles and walls, or only if the receiver is visible? This is not a simple problem. Bob
  20. BobK

    Help! Transistor radio converted into amp

    Really? try touching the terminals of a 12V car battery. They can supply 400A. Why no whack? Or, if you prefer, charge up a 10000uF cap from the car battery and see if that will give you a whack. As long as there are no capacitors charged to more than about 30V there is not danger of shock...
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