Search results

Search Forums New Posts
  1. BobK

    12 vdc to 6 vdc input stability

    A 6V battery and charger? Bob
  2. BobK

    I need help with capacitors...

    The answer is no. It would be practically indistinguishable from a 100F 2.7V supercapacitor. Bob
  3. BobK

    Boost converter

    Did you read what I wrote about the IRF520? Bob
  4. BobK

    Boost converter

    Here is a simulation, using all your parameters, a logic level MOSFET and a 12.8Ω load to simulate approximately 1A of charging current. Looks pretty good to me. Bob
  5. BobK

    Boost converter

    Change the battery to a resistor that would drop 12.8V at the desired charging current. Also, the IRF520 required 10V to turn on completely. What is the voltage of your pulse source? For a real circuit, running off a 3.7V battery you will have to use not just a logic level MOSFET but one...
  6. BobK

    Converting a PWM wave into pure DC

    Why would you want to follow the peak voltage? The signal in a PWM signal is not the peak voltage (which typically would remain constant), the signal is in the duty cycle. If you have reproduced the duty cycle at a higher voltage, you have reproduced the PWM signal. Perhaps you are using...
  7. BobK

    Magnetic force on current carrying conductor

    Brushless motors generally have the coils fixed and the magnets moving. bob
  8. BobK

    Formula for Magnetic field at a distance

    Unless you have found a magnetic monopole, it falls off as the cube of the distance (field of a dipole.) Near one pole, or near a long straight piece of wire carrying a current, it would be inverse square. Bob
  9. BobK

    Help with designing a relay with adjustable hysteresis

    All comparators have some hysteresis. You can add more hytetesis by using positive feedback. You would indeed need a votage reference to compare to. This can be as simple as s diode and resistor. A 555 uses a reference of Vcc / 3, which is of no use at all for comparing Vcc. Bob
  10. BobK

    Why are actuators inductive?

    Forget electrostatic force, I want an actuator based on the attraction of gluons.... Bob
  11. BobK

    Why are actuators inductive?

    They are not: https://en.wikipedia.org/wiki/Shape-memory_alloy Bob
  12. BobK

    Battery monitor question

    Zener diodes will not give you sharp results at discriminating voltages. You want to use comparators, which will allow a binary result based on an exact voltage. Bob
  13. BobK

    Help with designing a relay with adjustable hysteresis

    The 555 has a push pull output. It goes high and low, not on and off. The on and off depend on how you wire the relay. A relay wired between the output and ground will go on when the output is high. A relay wired between the output and Vcc will go on when the output is low. That said, I...
  14. BobK

    Charging NiMh battery pack with BQ2004 - new thread

    No, that is fine for a fast charge. Bob
  15. BobK

    Charging NiMh battery pack with BQ2004 - new thread

    I think your charging rate is too slow for delta-V termination. This is normally used at C/2 to C charging rates. Bob
  16. BobK

    Can I make a tablet with an Arduino plus an Ethernet shield and a GSM shield?

    I think you are more in Rasp Pi territory here. You could do it with Arduino, but you would be pushing its capabilities. For a Pi, it is no sweat. Bob
  17. BobK

    MOSFET Circuit Help

    It is answers like this that kept us from helping you, which we eventually did anyway as several posters suggested that the fan was dropping the voltage to the barometer. What you say in this post makes no sense. An amplfier does not reduce the power needed to run a fan, all it does is allows...
  18. BobK

    Charging NiMh battery pack with BQ2004

    I think you might be on to something. If the inductor is far smaller and lighter, it probably has a lower max current. If it is not sufficient for the charging current, it might be saturating, causing a large ripple in the voltage, which might trigger the deltaV condition. Bob
  19. BobK

    Replace variable capacitor with varicap

    100nF is fine. Bob
  20. BobK

    Replace variable capacitor with varicap

    Yes, I missed that on the schematic, which was too small to read easily. Are you using a separate isolated supply for V4? Bob
Top