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  1. BobK

    Headphones from amp speaker wires

    A diode will not work, audio is AC and a diode cuts off half of it. Show us how you made the connections. There should be a way to make it work. Bob
  2. BobK

    Cant get a voltage reading off an working AC/AC Adaptor with a multi meter ?

    If it is AC / AC there is no positive or negative, it is AC - alternating current. And you you are using the DC setting on the multimeter, it might very well read 0. Try reading it on an AC setting. Bob
  3. BobK

    Why don't I get a Sine wave?

    Well, we got some good discussion among ourselves on methods to generate sine waves! Bob
  4. BobK

    electronic schedule of a 4 bits adder

    Which is the complement of B and a forced carry in to the low bit. (for two's complement arithmetic) Bob
  5. BobK

    Power Supply Question

    Easiest way is to use a center tapped 24-0-24 V transformer, then a single diode for each of the positive and negative supplies, using the center tap as common ground. Bob
  6. BobK

    help me pick out the right type of diode

    Hop, I know he did not say this, but I think he is talking about a diode between the + terminal and the bus bar, so the batteries are paralleled only through the diode, which is a common enough circuit. The diode needs to handle the full current you expect on the load, and, depending on how...
  7. BobK

    buck/boost converter problem..advise appriciated

    von, I think you have some misunderstanding of how power supplies work. First of all, what you need is a power supply that can supply the needed voltage and more than the needed current. You do not have to set the current, the device you are powering takes only as much current as it needs...
  8. BobK

    Will it effect laptop's battery if I use charger connected when fully charged?

    Leaving it plugged in all the time is fine. The laptop will keep the battery topped off and will not overcharge it. However, I seem to remember reading that it is a good idea to take it off the charger and let the battery go down every now and then. Not sure if this is still good advice or...
  9. BobK

    Split one electricity cord over two appliances with different voltage inputs

    How many conductors are in the cord? If it is 4, you are luck. You can get 120V by using either hot wire and the neutral. If it is only 3, you can't do that, it is not kosher to use the ground wire for return. Bob
  10. BobK

    converting 2.4 gig wifi to baseband signal.

    Bandwidth increases with increasing frequency. It is not possible to send the same information at the same rate at 64MHz as it is at 2.4GHz. Bob
  11. BobK

    LED path WS2811

    The WS2811 LED strips will do nothing without a controller. They need a data stream to set the color of each individual LED. If you simply power it up, nothing will be on. They work like a shift register. Data is put in asynchronously by having a short pulse for a 0 and a long pulse for a 1...
  12. BobK

    Ni-MH charging circuit query

    The current is not regulated, but it will reduce as the batteries get closer to charged. It is definitely not a smart charger and I think the batteries probably vented because the trickle current was too high at end of charge. Bob
  13. BobK

    SAY WHAT!?!?!?!?

    If you happen to use outlets on the 2 different phases, that method could work. Bob
  14. BobK

    Seeking Knowledge!!

    If you really want to build it from scratch you would start with sand and copper ore. Bob
  15. BobK

    reasons why frequency shows difference in three devices

    Very nice! Question for AK: I have never quite understood how simply coupling audio to the base of the oscillator produces frequency modulation. Is it because the base emitter (or base collector) diode changes capacitance with voltage like a varactor? Bob
  16. BobK

    OK To Reverse One of Two Batteries To Prevent Leakage?

    Also, what kind of batteries are they? NiMH rechargeable ones lose their charge even when no current is drawn. Bob
  17. BobK

    OK To Reverse One of Two Batteries To Prevent Leakage?

    Interesting question. Theoretically, if the batteries are strictly in series with no connection to the center of the two, then it should be okay. If the batteries happen to be connected in parallel though (unlikely) watch out! Bob
  18. BobK

    Why don't I get a Sine wave?

    AK - And I have to disagree with you. It depends on the requirements. If you want a good sine wave adjustable over several decades you can do that with a uP and DAC but not with your one transistor circuit. I could pull parts out of my cabinet an make a uP based one that handles 20 - 20000...
  19. BobK

    Most efficient 1v boost circuit.

    You are comparing running time, but to compare efficiency you need to compare the output as well. The Joule thief and your original circuit are flashing the LED with unknown current and duty cycle. The boost converter would be running the LED at a contant current. If you really want to...
  20. BobK

    Looking to create a new device

    This is clearly a smartphone app. I can think of no reason to do it any other way. Bob
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