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  1. BobK

    Loud music from over-the-fence is causing offence...

    <sarcasm> Here in the U.S. we have the 2'nd amendment to deal with this kind of situation. </sarcasm> Bob
  2. BobK

    understanding discrete circuits

    C2 is there to pass the AC signal from the input to the base of Q3, while blocking the DC level of the input. R2 is negative feedback from the output to the input to set the DC bias level of Q3, consequently of Q1 and Q2. The result should be to set the emitters of Q2 and Q3 to anout half the...
  3. BobK

    understanding discrete circuits

    This is a push pull driver, which you can find lengthy descriptions of many places. Not sure what you want us to do here. I could give you a description of it including what every part does, but I don't think that is what you are looking for, and you would find a better one in many textbooks...
  4. BobK

    Faraday cage?

    A metal case for the power supply is a good idea, most that would be appropriate for a CNC machine tend to come that way. And using shielded cables is a good idea. Bob
  5. BobK

    Automatic object tracing system

    The normal way to do this is GPS and GSM (cell phone) modules. There are commercial products that do it all for a reasonable price. Building one is unlikely to save you much money. Bob
  6. BobK

    Spurious voltage readings for open transistor

    Turn the transistor around, place a 10K resistor from base to emitter. This will eliminate the floating base. And don't use a transistor rated for 45V with a 60V supply, you are just asking for trouble, get one rated for 80V or more. Bob
  7. BobK

    Help with capacitance for a particular load

    Why get a modified sine wave inverter and then try to fix it instead of getting a true sine wave inverter? Bob
  8. BobK

    Faraday cage?

    Tell us more. One does not normally need a Faraday cage for that purpose. Bob
  9. BobK

    which 1Nm motor should I choose for my solar panel cleaner ?

    Due to the inductance of the coils, you need more voltage as the RPMs increase. The 3.2V number is likely the stall or holding current, i.e. when it is not moving. Bob
  10. BobK

    Why is so expensive to fabricate custom IC

    In addition to the high cost of setting up for production, IC manufacturing has another attribute. ICs are fabricated on 12 inch wafers. That is 113 square inches. A high end microprocessor chip is about a 1/2 inch square, or 1/4 of a of square inch. So, the minimum number you can make is...
  11. BobK

    Programming Languages

    By far the most common languages used for microcontrollers are C (not C++) and assembly language. Neither is instantly transportable from one type of micro to another because so much of the program involves tweaking hardware based modules like PWM, UARTS, SPI, and even GPIO. If you keep all...
  12. BobK

    Best ULN2003 Battery Pack(s)

    They can share it even if there is only 1 USB output, as long as the combined current is less than the port is rated for. Bob
  13. BobK

    Best ULN2003 Battery Pack(s)

    Use a 5V power bank. It already had the USB port an provision for charging, and you can buy it for less than the batteries alone. Bob
  14. BobK

    DC-DC Isolator

    Why the resistor between the buffer and the ADC? I have a feeling the drops you are seeing are due to the voltage drop across that resistor when the ADC is sampling. Bob
  15. BobK

    DC-DC Isolator

    And where is the required buffer ampl after the IL300? Bob
  16. BobK

    DC-DC Isolator

    If those are millivolts on the diode test range then they are quite reasonable. 1.8V for the LED and .77V for the photodiodes. Bob
  17. BobK

    Sick of my breadboard! quality breadboard recommendations please.

    The big problem with breadboards and RF is that, even if you do get the circuit working, you cannot transfer it as is to a permanent build using stripboard or pcboard because the capacitance will not be the same. Bob
  18. BobK

    Increasing amperage in a 12 volt DC circuit without transistors or additional power supplies

    A MOSFET is a transistor. Metal Oxide Silicon Field Effect Transistor. Connect the 555 output to the gate, optionally through a 10Ω resistor. Connect the motor - to the drain. Connect the source to ground. Make sure you use a MOSFET that is fully turned on at the output voltage of the 555...
  19. BobK

    Button to button circuit

    The schematic that I accidentally deleted from my earlier post.
  20. BobK

    Button to button circuit

    Whoops, I posted it three times and deleted the embedded image, but it guess that did not remove them entirely.
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