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  1. BobK

    PWM to 0-10v

    I simulated the same circuit and it works fine. In your simulation, it looks like the + input is just connected to a label called .8V. This will not put a voltage on the input, you need to connect it to a voltage source. Edit: Also, the LT1055 is not a good opamp to use. You need a single...
  2. BobK

    PWM to 0-10v

    Oh, you wanted an explanation too. You want to convert a range of 2-4V to a range of 0-10V. So, you need to come up with an equation for that. You look at the range of input voltages (2) and the range of output voltages (10) and you know that you need a gain of 5. (10 / 2). Next you look...
  3. BobK

    PWM to 0-10v

  4. BobK

    Load on Power Relay Causing Microcontroller Reset

    The decoupling caps are essential on PICs. I am surprised you could even program them without one. You a 100nF as close as possible to each pair of Vss Vdd pins. Bob
  5. BobK

    Running incandescent or halogen bulb with 2/3 or lower voltage possible?

    Do you really think a halogen lamp glowing red would damage your eyes? Why don't we have millions of people with damaged eyes from halogen lamps that are glowing white and producing 1000s of times more IR than you glowing red one? I mean, it is good to be cautious, but you are being silly. Bob
  6. BobK

    mosfet diode

    BJTs with similar current carrying capacity will typically have a much larger voltage drop and hence power dissipation then an appropriately sized MOSFET when used is switching applications. When use in the linear region, the two will have the same power dissipation, and here BJTs are actually...
  7. BobK

    Running incandescent or halogen bulb with 2/3 or lower voltage possible?

    Lowering the temperature of a filament will not produce more infrared at any frequency than the same filament as at a higher temperature. Have a look at this chart of the black body spectrum: You can see that lowering the temperature decreases the intensity of radiation at all frequencies...
  8. BobK

    When should you buffer a signal?

    An op amp buffer as in the circuit you showed is a good idea here. The impedance of your divider network varies quite a bit depending on which key is pressed. The buffer would lower the impedance and make it the same for all keys. Bob
  9. BobK

    Beginner question: Can I convert speed fan switch to three?

    Sometimes, the fan speed is controlled by switching capacitors in series with a single winding. I believe this is the case on most ceiling fans. Bob
  10. BobK

    How to get 80 mV?

    ???? Bob
  11. BobK

    Driving a led from high-voltage source

    A standard LED takes 20mA. If you were to run it from a 5KV source, that is 100W. It is unlikely that your 5KV source has an extra 100W available. Most likely, it cannot product 100W total. Not to mention the heat you would have to get rid of. Bob
  12. BobK

    Does any one know an inverter chip that uses 12V DC to make a signal with variable freq and Voltage?

    A signal generator chip combined with an audio amp (one that can go to 80KHz) would probably be the simplest way to get what you want.
  13. BobK

    How to get 80 mV?

    Did you bother to read my post? What is the load that the 80mV will drive? This will determine how you can do this. Bob
  14. BobK

    How to get 80 mV?

    Electro. Could you please explain what you are trying to do in an unambiguous way? Saying you want to get 80mV or 80mA does not mean anything. If it is 80mV, the question is across what? If it is 80mA, the question is through what? If it is both, the answer to both of these questions better...
  15. BobK

    2n3055 saturation

    I don't understand why you are trying to use a voltage regulator to supply base current. If you are trying to make a regulated supply, you would need to supply the current through a error amplifier. bob
  16. BobK

    100W RGB LED Driver Questions

    What you need is 3 dimmable 3A LED constant current drivers. The dimming inputs are typically either PWM or 0-10V analog. It sounds like your existing one is controlled by a 5V PWM signal. Bob
  17. BobK

    2n3055 saturation

    What are you actually trying to do? Are you trying to make a regulated 30A supply? If so, saturation is not a question you should be asking about. The transistors cannot regulate when they are saturated, they must be operated in the linear region to regulate a voltage. This is why you...
  18. BobK

    12v LED resistors

    The range does not matter, the fuse will probably blow somewhere above 2A. That was the reason for doing the test on the 10A range first. BTW: I blow that fuse on my multimeter regularly, usually be forgetting it is on current range and trying to measure a voltage. Bob
  19. BobK

    D-Type Flip-Flop (74HC74)

    However, the opposite could occur. You might reset the FF while the reed switch is still closed, and it will be set again immediately. Bob
  20. BobK

    D-Type Flip-Flop (74HC74)

    Too bad you are not using a PIC. Some of the newer ones have an SR latch built in. Bob
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