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  1. BobK

    convert 110v dc to 24v dc

    I'm with Duke. Line voltage switchers have a rectifier as the first stage. DC input should work just fine. Bob
  2. BobK

    Zeroing out a LM317 reference voltage with a zener - PSU build

    The Zener is upside down. Bob
  3. BobK

    fm transmitter using colpit oscilator

    I doubt that either of those circuits will get to 90MHz. Bob
  4. BobK

    Battery over discharge cut-out circuit help

    From the description of the battery: "Over-charge/discharge protection." Bob
  5. BobK

    Oscillator or Not?

    I would also like to warn you about another problem with this type of experiment. It is called the "Texas Sharpshooter Fallacy." It applies to any experiment where one is looking for differences between two groups (experimental and control) without specifying beforehand what the difference is...
  6. BobK

    Oscillator or Not?

    Getting off the electronics and onto experimental design: I hope you plan to blind the evaluation of the seeds under the microscope. If the person doing that evaluation knows whether the seeds have been exposed not not, I guarantee they will see differences, whether they exist or not. Edit...
  7. BobK

    Battery life on full load help?

    I suspect it is 0.2A not mA. Bob
  8. BobK

    Electric Bike

    Match the voltage to the rating of the motor. Bob
  9. BobK

    Broke Cathode Ray TV

    That would be the phosphors. Don't know how toxic they are, but, like I said before, if one exposure was a danger, we would have strict rules about disposing of these. On the other hand, you might glow under a UV light now (just kidding :)) Bob
  10. BobK

    12V, 200Ah Battery with Inverter

    12V battery -> inverter -> 12VDC adapator? That is sort of like burning gasoline to run a generator so you can run an electric heater. Bob
  11. BobK

    I need some help! Amplifier

    I found it instantly by typing in the number TOP261YN. But then, I guess my experience told me that that was the relevant number. Bob
  12. BobK

    Broke Cathode Ray TV

    I wouldn't worry too much. If one incident could cause any damage we would have people in toxic chemical suits picking up and disposing of old TVs. Not sure what it would be that you inhaled though. When you say you broke it, do you mean the CRT itself was shattered? Bob
  13. BobK

    AM transmitter

    And a new proverb is born: "Never use Gorilla glue when Ferret glue will do." Bob
  14. BobK

    Replace fried range hood transformer with cheaper alternative?

    If I read it correctly (it is a bit fuzzy) I see the original is 12V 60W which is 5A and the replacement you want to use is 4A. So, no you need a slightly higher power one. Bob
  15. BobK

    Electric Bike

    You will need a motor speed controller board rated for the voltage and current used by the motor. Take into account that the stall current is much higher than the running current, and the speed controller must handle the higher stall current. You can find these at very reasonable prices (read...
  16. BobK

    Ultrasonic receiver

    Look up op amp bandpass filter. Bob
  17. BobK

    Changing LED colour in old hifi equipment

    The problem is, red and green LEDs have a forward voltage of about 2V whereas blue and white have about 3.3V, so you probably cannot simply replace the LED. LEDs are not voltage driven, they are current driven. For indicator LEDs like these, you typically use a higher voltage and a resistor...
  18. BobK

    Keeps blowing circuit module!! :(

    Looks like my crystal ball is fully functional. The volume control might be a place to look for the input signal to the amp. Bob
  19. BobK

    Keeps blowing circuit module!! :(

    You could also isolate the two using an audio isolation transformer. Then they could run from the same supply. But, I am still not 100% certain that I have diagnosed it correctly. Have you done the continuity check that I suggested? Bob
  20. BobK

    Keeps blowing circuit module!! :(

    You can make it not share a ground by using 2 power supplies and not connecting their grounds together. Which is what you have already tried and it worked. Bob
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