Search results

  1. Herschel Peeler

    What battery do I need for these LED bulbs?

    It sounds like the 9 V battery could not supply enough current to drive the LED/ Tell us more about the LEDs. The chart may not apply to your LEDs. 9 to 12 V? How much current?
  2. Herschel Peeler

    Analog Circuit Outputs

    The input of the ADC is usually a very high resistance so very little current should flow. Mostly it just "feels the voltage". I think Kapp is only an engineer and doesn't understand simple questions. :-) He only sees complicated solutions. Not wrong. Just not simple.
  3. Herschel Peeler

    Can anybody explain about how bjt works??

    Super! Thank you for the education. What convinced me was the current mirror argument. I couldn't explain it any other way. Ebers Moll? Not in my books.
  4. Herschel Peeler

    Can anybody explain about how bjt works??

    Oh no! You are starting to make sense. :) Knowing -E-B voltage we cannot predict collector current. Collector current depends on load resistance. What can we predict knowing base voltage? "The gm of bipolar small-signal transistors varies widely, being proportional to the collector current...
  5. Herschel Peeler

    Can anybody explain about how bjt works??

    Good example. CURRENT mirror. Not voltage mirror. Yes the voltage dictates the collector current but the voltage is incidental. Can we calculate the collector current knowing the base voltage? The voltage is the result of current through the base, not the cause. When we pull current through a...
  6. Herschel Peeler

    Can anybody explain about how bjt works??

    An excellent example. A current in is mirrored to a current out. They call it a current mirror not a voltage mirror. But yes, the voltage across one side does cause an equal voltage on the other side which does, in deed, cause a specific current out the collector. The voltage is incidental. The...
  7. Herschel Peeler

    Can anybody explain about how bjt works??

    Hmmm. Does that work for the base resistor also. The emitter resistor configuration isn't used very often. I just don't see that having a very profound effect. I'll have to play with the idea some.
  8. Herschel Peeler

    Connection knowledge

    Does this make sense?
  9. Herschel Peeler

    Color Sensor

    A LED can also be used as a light sensor. Light falling on an LED generates a voltage. The color of the lens (poorly) filters in that color. So an orange LED selects predominately the orange light. I don't know if they will be sensitive enough for you though. A CdS cell (photo resistor) or...
  10. Herschel Peeler

    Headphones - only hear from one side, volume wheel changes which

    What you are describing is the balance pot, not volume control.
  11. Herschel Peeler

    Can anybody explain about how bjt works??

    :-) I use a constant current source and let the voltage fall where it may.
  12. Herschel Peeler

    Can anybody explain about how bjt works??

    ??? Elaborate on this, please. At what point does the nonlinearity change? Yes, it is nonlinear. The linearity changes based on current. The voltage is incidental. The voltage is the result of the current. The causal force at work is the current. Nowhere in the data sheet does it relate base...
  13. Herschel Peeler

    Can anybody explain about how bjt works??

    Yes, we can look at the transistor from the standpoint of a base voltage controlling the collector current or we can view it as base current controlling collector current. Most data sheets refer to base current. It takes an engineer's view to understand it is base voltage. For me, I can't...
  14. Herschel Peeler

    Can anybody explain about how bjt works??

    You speak as though it must be one or the other. Both approaches are acceptable.
  15. Herschel Peeler

    Can anybody explain about how bjt works??

    Your description of the transistor is correct. What formula for gain do you use that uses base voltage? when I read a datasheet for transistors it references collector current and base current to describe gain. We can't use base voltage to indicate gain because the same base voltage gives...
  16. Herschel Peeler

    Charging Circuit

    Not a good enough Image to de-engineer but it looks like a nice circuit. Maybe something like this?
  17. Herschel Peeler

    Can anybody explain about how bjt works??

    And there is nothing incorrect about that explanation at all. I find the current story easier to demonstrate, changing current to show gain. You can't explain gain by discussing base voltage.
  18. Herschel Peeler

    Charging Circuit

    Here is a start. It was a battery charger. You will need to adjust thongs for voltages you want. U1 and Q1 makes a power source to charge the capacitor. R1 and R2 set the voltage to charge it. U2 monitors the voltage on the cap. When it reaches a certain voltage (set by R3 and R4) it triggers...
  19. Herschel Peeler

    Zener Diode

    Do you think the micro will put out more than 4.7 V?
  20. Herschel Peeler

    40 Hz LED

    For others who might follow this thread later,,,,
Top