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  1. BobK

    Low cost SMT links

    Okay, I see why those tiny 0Ω resistors might not work! Bob
  2. BobK

    Stepdown voltage

    Theoretically you can get 3X the average current if you step down from 36V to 12V, but the devil is in the details. There is an efficiency issue, which will reduce it by 10 to 20%. And also, it is the average current that is reduced. In the typical buck converter topology, all of the current...
  3. BobK

    Low cost SMT links

    How much current do they have to carry? There are 0 Ohm resistors, which is what I use for jumpers. Bob
  4. BobK

    5V One Channel 1CH IR Infrared Wireless module.

    The remote is obviously made to do a lot more than turning one relay on and off. Are there instructions on how to use the remote? I suspect you just haven't found the secret code yet. Bob
  5. BobK

    +/- 15 volt dc power from battery

    10 alkaline cells for each polarity also works. Bob
  6. BobK

    DAC converter

    Normally from the manufacturer. bob
  7. BobK

    Solar panel.

    You do not supply something with a voltage and a current. You supply it with a voltage, then it draws a current that depends on the voltage. If the voltage source is not capable of supplying the needed current, then the voltage drops. If the motor runs fine on an adequate 9V supply, and it...
  8. BobK

    Solar panel.

    No, it cannot. If the solar panel cannott supply the required current, the voltage has to drop. The motor will always draw the same current at any given voltage and load. Look up Ohm's law. There is no loophole for supplies that cannot provide the needed current. If you have verified that...
  9. BobK

    RC Low pass filter problems

    I suspect it works just fine. The only problem is that the 2.2K resistor and the 8 Ohm speaker form a voltage divider that cuts the signal to the speaker by a factor of more than 300!! If you want to make an RC low pass filter for a speaker, the speaker itself is the R. You calculate the C...
  10. BobK

    Wiring together LED lighting for a display

    Pulling 120 mA from a CR2032 is battery abuse. Or maybe assault on battery. What a stupid design. The batteries appear to be in series, so they are at 6V under no load. More than half the energy is then being wasted heating the batteries. Bob
  11. BobK

    Control for Lamp Circuit Using Low-voltage Push-on/off Button

    Or, you could avoid all of these problems by using X10 components you can install yourself. Bob
  12. BobK

    Lock-in amplifier

    Sound like homework to me. Bob
  13. BobK

    Solar panel.

    If you have a 9V motor and you measure 11.7V across its terminals and it is struggling to run, the motor is defective. Bob
  14. BobK

    Calculate how long a battery will feed a project

    WD2812B is a chip with a single RGB led and PWM to allow 256 levels of brightness for each color. It draws 20 mA per color at the max setting. Count the number of them and multiply by 60mA to get the max current needed. And they do run at 5V, not 12. Bob
  15. BobK

    Help finding the right battery

    Look for an 11.4V Lithium Ion battery. You will need 3000mAH for each hour of operation. Bob
  16. BobK

    Make experiments safer, my workshop and concepts relevant in my opinion

    Then post a link. Bob
  17. BobK

    Optical Pickup

    Or, for the best accuracy. Two video cams at right angles to the string. bob
  18. BobK

    Optical Pickup

    Doppler lidar anyone? bob
  19. BobK

    Make experiments safer, my workshop and concepts relevant in my opinion

    No one is going to read you 5 pages or so of text and pictures. If you have a question you want answered, please post it in a concise form. bob
  20. BobK

    multiplexing a 3A per channel led grid

    Sure. You can run more than one of them by dividing the time. Of course they will not be as bright. The total light output will be the same as running just one. Tell us in. more detail what you are trying to do. Bob
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