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  1. BobK

    Simple Motor Controller Circuit

    The diodes can be mounted directly on the motor terminals instead of on the PCB. Bob
  2. BobK

    Partially shaded solar panels

    Okay, so it does make sense that partial shade of a panel reduces the output beyond the shade percentage. The system he was proposing does have a micro inverter per panel, but I guess most of the panels would be in partial shade from the bare trees during much of the day in the winter, severely...
  3. BobK

    LED's and constant current

    No, you have an an issue right now. It led you to believe that a 6.8Ω resistor dropping 0.6V was enough to control the current to your LED chains. It clearly was not. The effectiveness of a resistor as a current limiter depends on what percentage of the source voltage it is dropping...
  4. BobK

    LED's and constant current

    I hate those LED calculators. I have seen at least one that will recommend 0Ω for the resistor if the forward voltages add up to the power supply voltage. And BTW 2.16V x 100mA is not 0.5W. Bob
  5. BobK

    Problem with new microphone preamp.

    I simulated it with LTSPICE and it works, and has a gain of 230. Input is 2mV p-p output 560mV peak to peak. It should work fine as a microphone preamp. It should not work at all with a line input since it will be clipping like crazy with that gain.
  6. BobK

    Mobility scooter

    The problem is stall current can by 5X the running current. Your controller says 60A max and 40A continuous. I might go a bit higher, like 100A max if the cost is not prohibitive. Do you have an Ohmmeter so that we can determine the stall current? Bob
  7. BobK

    Partially shaded solar panels

    The lovely wife Morticia and I just spent a couple of hours with a solar energy salesperson. One thing he said strikes me as not being true. He claims that if your roof panels are shaded by trees (all deciduous in our case), you get the same loss of power in the winter, when the trees are bare...
  8. BobK

    Creating a variable wien bridge oscillator

    No, I did not say that. The LM386 has a minimum gain of 10. You would probably need to reduce the output, or use a different audio amp where the gain is settable to a lower level. Bob
  9. BobK

    LED Signal Dummy load

    So it sounds like the lights are powered from 110V mains in series with the relay coil, and the relay pulls in whenever the lights are drawing at least 300mA. So, to test this you need a dummy load that pulls more than 300mA. A 40 Watt incandescent light bulb would seem to fill the bill. Bob
  10. BobK

    Creating a variable wien bridge oscillator

    Use an audio amplifier. You "emitter follower" circuit is loading the output of the oscillator unduly due to the biasing resistors, which are unnessary in that configuration. But I would still recommend using an audio amp over trying to fix your circuit. Bob
  11. BobK

    LED Signal Dummy load

    I cannot make any sense of your post. Please try to explain what you are trying to do. Bob
  12. BobK

    Mobility scooter

    To be entirely safe, you could just measure the resistance of the coils. This, with Ohm's law, would give you the stall current. A controller rated for the stall current would handle any load. Bob
  13. BobK

    Voltage Divider to control Current in a Circuit

    Putting 2 cells in series and using a buck converter allows you to get a constant output voltage until the batteries reach their fully discharged state, which means they will last longer than twice what you would get out of 1 battery with no step-down. Bob
  14. BobK

    LED's and constant current

    If the LEDs are properly connected with resistors, I cannot see the current slowly rising from 0.9A to 1.5A. How about a schematic? Also, are they heat sinked? High power LEDs need heat sinking, and the star board they might be on is not a heat sink, it is used to mount them to a heat sink. Bob
  15. BobK

    Mobility scooter

    It should be labelled on the motor, or, you can measure it with a multimeter. The current draw will vary with load, so you would need to test it under load. Have you disassembled the mobility chair yet? Bob
  16. BobK

    LED's and constant current

    Yes, they are supposed to have a constant current flow, but they do not do that themselves, you need a circuit that does that. It sounds like you supplied the LEDs with a constant voltage. As they heat up they will draw more and more current at the same voltage. This is called thermal runaway...
  17. BobK

    help with power consumption.

    True. The product will give the max power used. Bob
  18. BobK

    Mobility scooter

    You need to know the current draw in order to choose a controller. Bob
  19. BobK

    Mobility scooter

    PWM controllers are so cheap on Ebay, it hardly makes sense to build one, especially for the power level needed here. Bob
  20. BobK

    Electric motor to turn a fishing reel

    The stepper motor does allow for accurate speed control as well as positioning. A brushed DC motor would be cheaper, but actual speed control would require feedback. Bob
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