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  1. BobK

    Need a little help on circuit for 120VAC to 12VDC

    I disagree with this. When I was first starting out, building power supplies was a good exercise for me and produced something actually useful. I still have a 5V 7805 power supply and a ±12V power supply made from zeners as pass transistors that still work 40 years later. Bob
  2. BobK

    Solar Cell Prove monitoring project

    This sounds like a good idea, but the capacitor has to be charged to 2/3 of the supply voltage to the '555. I think a garden light solar cell will not produce much more than 2V, so it might not be doable without using multiple cells in series. Bob
  3. BobK

    How can I build a sine wave generator with variable phase?

    It might have nothing to do with the sub-station, we can get hum like that without being close to one. Are you taking a signal from a device plugged into a different electrical outlet than the sub-woofer is? This could be a ground loop problem. Bob
  4. BobK

    How can I build a sine wave generator with variable phase?

    Hmmmmm. Let me think about that :) Bop
  5. BobK

    Is there a way to send a program from my arduino to my computer?

    I am not sure what you are trying to do. Did you lose the source code on the host computer and you are trying to recover it from a programmed device? If so, you will not get back the source program, you will get back the compiled program, in machine language. Bob
  6. BobK

    Audio/Video to RF. Help!!

    Shades of "Back to the Future" where a 1985 IC was replaced with a tube circuit in 1955. Bob
  7. BobK

    Need a little help on circuit for 120VAC to 12VDC

    Only with no current drawn. I simulated it with a 9V AC source. With a 1000uF cap it peaks at 11.4V and goes all the way down to 0. You are not going to get 12V 5A from a 9V transformer. The peak voltage is 12.76 and the 2 diodes in the bridge will drop about 2V at 5A. Bob
  8. BobK

    Need a little help on circuit for 120VAC to 12VDC

    Only if you can handle 12V peak with 12V ripple! 1000uF is way too small for 5A output. Try 22000uF to get about 1V ripple. And use a 12V transformer and a regulator. Bob
  9. BobK

    Continuity testing wire capacitance

    Gee, I would have said a ruler. :) Bob
  10. BobK

    Can voltage be applied to Arduino Uno output(Low)pin?

    No. If you were to connect an output low pin to Vcc, it would likely kill the chip. There has to be a load between Vcc and the pin that will draw no more than the current limit Yes. No, connecting an SSR to an input makes no sense, and if it is connected to an input it will be off. Bob
  11. BobK

    Please help me to run 4 LED's in series from 12v.

    The 4 white LEDs would probably also run just fine with no resistor, because you are not supplying them with enough voltage. If you want the LEDs to be operating at full power, you need to control the current as several people here have stated. Bob
  12. BobK

    Trying to get LED strip to flash simultaneously.

    Which words in "Just add a flashing LED in series" indicates that a buffer transistor would be used? Bob
  13. BobK

    Audio/Video to RF. Help!!

    Hi Miguel. Hopefully, things will be changing for you and your country in the near future. At least we no longer consider you terrorists! Edit to add: I am hoping to visit Cuba soon to really learn how to do the Rumba. Bob
  14. BobK

    Trying to get LED strip to flash simultaneously.

    This has to be a new low in bad advice. Bob
  15. BobK

    Please help me to run 4 LED's in series from 12v.

    Here is how the calculation works: R = (Vs - N * Vf)) / I Where Vs is the supply voltage and Vf is the forward voltage, N is the number of LEDs in series and I is the current. With Vs = 12, N = 4, and Vf = 3, you get 0 for the resistor. If, indeed, the Vf was exactly 3, it should work...
  16. BobK

    Please help me to run 4 LED's in series from 12v.

    If you have 3.3V across each of 4 LEDs that is not 12V. What does your power supply read? Is in an auto? When running they are typically over 14V. Anyway, 4 3V LEDs is too many to run off 12V with a resistor. The voltage across the resistor would be 0. Try again with 2 strings of 2 LEDs...
  17. BobK

    ADC circuit automation design help

    You could make the lower leg of the divider by using 3 resistors connected to different pins on the micro, one for each voltage range. The micro could then select the range by setting just 1 of these pins as output and outputting low. The other two would be set to analog inputs. Bob
  18. BobK

    Can voltage be applied to Arduino Uno output(Low)pin?

    You misunderstand the meaning of input and output. These names do not indicate the direction of current flow as you seem to think. An output port sets a voltage level to either High or Low. Current can flow out if it is set to High and can flow in if it is set to Low. Input ports do not...
  19. BobK

    Frequency to Voltage without ICs

    Yes, it has an analog to digital converter. Bob
  20. BobK

    Reverse bleeper booster

    I wish I had that problem. The one in my Prius is too loud and quite annoying. Bob
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