Search results

Search Forums New Posts
  1. BobK

    Modification of anti-bark control circuit - help please!

    Clap your hands near the mic. Bob
  2. BobK

    Potential divider circuit

    Okay, good. Now, can you figure out the collector resistor based on information given? Bob
  3. BobK

    Mosfets

    If the MOSFET is fully on (or nearly so) at 5V and you charge the gate at 10V it may take it twice as long to fully charge the gate, but the MOSFET will still be turned on in the same time as it would at 5V, since the gate will have reached 5V in that shorter time. Bob
  4. BobK

    Potential divider circuit

    Perhaps we should see what you drew first. Bob
  5. BobK

    Solar Charging for Android Phone

    The cells look to be about 1 x 2 in? Is that correct? If so, they will, combined, be able to put out at most 0.5W or about 1/10 of what is needed for a fast charge. Bob
  6. BobK

    Solar Charging for Android Phone

    What are the specs of the solar cell? I doubt that even 2 of them provide enough power to charge a phone in less than a few days. Also, you can't just connect the solar cells to the phone, you need a voltage regulator in between. A typical plug-in phone charger provides 1A at 5V, which is 5...
  7. BobK

    Mosfets

    Yes, that is a much better MOSFET for you application. Lower Rdson, lower gate charge and lower rise / fall times -- all of these parameters move in the right direction. Bob
  8. BobK

    led heats up,while using mobile battery(3.7V,1000mA)

    Hi and welcome to the forum. There are several problems with your circuit. Your LEDs are not in series as you state, they are in parallel. This is not a good way to connect multiple LEDs. No two are identical and the current will not be equally distributed. Worse yet, the one getting...
  9. BobK

    Mosfets

    No, you really want to get as much current as is reasonable to make it switch fast. Usually just something like 10 Ohms will do. With gate drivers, you typically do not use any resistance. Bob
  10. BobK

    power supply for a printed resistive flexible heater

    dV/dt = I / C But that won't help you much. A circuit to make pulses is a little more complicated than just a capacitor. Bob
  11. BobK

    Mosfets

    Q = I * T So it is the other way around, divide the charge by the time to get the current. In this case 74/440 = .16A. I think you can find MOSFETS that switch a lot faster than that. This would help a lot. Bob
  12. BobK

    if there possible for pic to faulty?

    Yes, like I said in post #23. Bob
  13. BobK

    Common mode input range..opamp

    You are out of spec. Who knows? Bob
  14. BobK

    if there possible for pic to faulty?

    So, I doubt that your PIC is running. What makes you think it is? Change the oscillator setting to INTOSC. Edited: Uh Oh, that is an ancient chip and has no internal oscillator. You must use either a crystal with the osc set to XT or HT, or use an external resistor and capacitor with...
  15. BobK

    DC Offset

    Yes, using a summing amplifier with gain 1 and put 5V into one input and your signal into the other. Bob
  16. BobK

    Using SPI communication with 16f628a PIC

    Let me google that for you Bob
  17. BobK

    Magnetic flux - is directional? How?

    Flux lines are not a real thing, they are a mathematical simplification of the interactions between photons and charges that are fully explained by quantum electrodynamics. Now, to answer your questions: How do they know that? By observation. Do the flux lines grow instantaneously...
  18. BobK

    if there possible for pic to faulty?

    If it works with the XT option, then you have not showed us the correct schematic. There is no crystal in your schematic. If you have no crystal, the oscillator should be set to the internal oscillator. Bob
  19. BobK

    Understanding NPN

    That statement is just plain false. The load resistor and the transistor are in parallel to R2 and R3. And the base emiiter junction is parallel to R3. So they are not a simple voltage divider, and his asseriton that each drops 3V will not be true (he also seems to be assuming that R1, R2 and...
  20. BobK

    if there possible for pic to faulty?

    The other problem could be your configuration word. Please change this from your hex constant to using the __CONFIG() macro with symbolic names for the settings. Then we can see if you have set something wrongly. Bob
Top