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  1. BobK

    The simplest definition of VOLTAGE you can come up with

    There are many other charged particles, for example, protons, muons, quarks. Also, electromagnetic waves have an electric field and therefore create a voltage, and there are no electrons in the electromagnetic wave. Bob
  2. BobK

    The simplest definition of VOLTAGE you can come up with

    It is wrong in so many ways, I don’t know how to start. First, you can have a voltage without any electrons. Second. If the electrons are simply at different places in a vacuum, the voltage depends not only on the number, but how far apart they are. A correct simple definition would be the...
  3. BobK

    My local hackerspace's electronics lab is taking form

    Make mine look spare. Bob
  4. BobK

    320 V DC 15 amps current limiter circuit

    Current sensing resistor, comparator and relay. Bob
  5. BobK

    Question plastic and rubber

    Um. This is an electronics forum. Many of us could answer questions about cooking or gardening better than we can about properties of materials. Bob
  6. BobK

    Buzzing sound in speakers

    That was the point I was trying to get at. You don't want a high gain amplifier driven by an earphone jack. A related question, if anyone knows this. When you turn down the volume on a phone, is it doing that digitally, i.e. by feeding smaller numbers into the DAC or is there an analog...
  7. BobK

    Buzzing sound in speakers

    Are there multiple inputs to the amplifier, if so, how are they labelled, and which one are you using? Bob
  8. BobK

    Buzzing sound in speakers

    In my experience, line level signals are not that subject to picking up hum. When testing the speakers I built recently, I connected my phone output to line inputs without non-shielded wires about 10 inches long and there was zero hum. Is it possible you are using a low level (microphone)...
  9. BobK

    Cascaded DCDC Converters

    Actually, if you are talking about switch mode converters, I see little reason to ever put them in series. The efficiency is lower since you are going through 2 conversions, and the current capacity of the first converter has to be higher than necessary since it has to handle the power at both...
  10. BobK

    Optical mouse interrupts being ratty?

    Try substituting the mouse? Bob
  11. BobK

    A sensor to identify 3 different shapes

    Do you have prior access to these objects? If they are all different weights there is an easy cheat. Bob
  12. BobK

    LM358 Replacement

    It is a very common part, why do you want a substitute it? Bob
  13. BobK

    Does the TDA2030 need negative potential?

    Really, linear audio amps are pretty much obsolete. For $16 I got a class D amp that can produce an honest 25 W into 8 Ohms at 22V. I use it at 16V and get 16 W. It barely gets warm at that level. And all of this using about 1/2 the power a linear amp would use. Bob
  14. BobK

    MOSFET’s dynamic state current and Arduino I/O pins

    In reality, the I/O pin is self limited by something like 100 Ohms output resistance, so the gate will never get anything like the 200mA you calculate. And it will survive that unless you are switching at at high frequency. Add another 220 Ohms and it will absolutely limit the current below...
  15. BobK

    Converting my guitar amp from power to rechargeable battery power

    First step is to determine feasibility. How many Watts? How long do you need it to run between charges? How much space and weght can you tolerate for the battery? Bob
  16. BobK

    Help select suitable Mosfet for driving relay.

    Um, that means the transistor is fully off. How about readings when it is on? Bob
  17. BobK

    Dishwasher Repair- Can anyone identify this resistor?

    It is more likely yellow violet black silver which is 47 Ohms 10%, a standard value. A 0.05% resistor is extremely unlikely in anything short of lab equipment. It looks like a 1 or 2 Watt resistor Bob
  18. BobK

    Transformer layers direction

    He was using the term "windings" when we would say "turns". Bob
  19. BobK

    Transformer layers direction

    There are no taps, he is just doing a single winding of 21 turns in 3 layers. Bob
  20. BobK

    Transformer layers direction

    It is okay to wind the first layer from left to right, then the next from right to left. That does not change the direction (CW/CCW.). If you do change the direction of the winding, the twio layers would cancel each other out. Bob
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