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  1. BobK

    Capacitor charging itself?

    Harald's method does not solve the problem as stated. After changing d and increasing V, is it no longer a 3300uF capacitor, it is a 1235.7uF capacitor. Bob
  2. BobK

    Fulham Led driver issue

    Given your contraint that it must work with no power, a relay is probably the best solution. Bob
  3. BobK

    Help with strobes!

    If you are so inclined. Bob
  4. BobK

    BUCK switching waveform ... problem

    Some switchers do not work well with no load. Bob
  5. BobK

    Small print

    A jeweler’s loupe will let you read anything. I got one with an LED light for about $10. Bob
  6. BobK

    Help with strobes!

    +1 on a microcontroller. If you are not experienced with them, Arduino is probably your best bet. Bob
  7. BobK

    Fulham Led driver issue

    The pullup would be on the side of the driver, not the controller. It is not certain that the pullup would be able to override the controller output, but it is easy enough to test. Bob
  8. BobK

    BUCK switching waveform ... problem

    Is a load connected? Bob
  9. BobK

    What's the working principle of this inverter circuit ?

    @WHONOES Read @kellys_eye post again. The circuit is an inverter to produce 230V at 50Hz. Running it at a higher frequency would not do that. Bob
  10. BobK

    Transistor and multimeter current

    No, you are using it wrong. You are placing the probes across the load. That shorts it out and shorts the power supply. You must break the connection to the load and reconnect the load THROUGH the ammeter. I.e. break the connection of the load,say at ground. Then connect the + load from...
  11. BobK

    Advice on LiFePO4-based SLA battery replacement

    Given the difficult electrical and climatic environment seen by a car battery, plus the propensity of Li batteries to catch fire, I would opt for a commercial unit. Bob
  12. BobK

    What's the working principle of this inverter circuit ?

    The 555 produces a square wave. Q7 is an inverter, producing an inverted square wave. Q1 and Q2 are a gate driver for Q3 and Q10 which are in parallel, and ground the upper side of the transformer primary when on. Q4 and Q5 are a gate driver for Q6 and Q9, which ground the lower side of the...
  13. BobK

    Transistor and multimeter current

    How did you check the current? It sounds like you replaced the load with the ammeter. This creates a dead short. The ammeter must be placed in series with the load. Bob
  14. BobK

    Changing AC plug to battery operated

    You could use a small "power bank" used for charging cell phones. If they are too big, you could make one with a smaller battery, but that is more complicated. Power Bank Bob
  15. BobK

    Digital multimeter with room temperature detection.

    Multimeters often come with a temperature probe. Plug it in keep the end from touching anything, and you have the room temperature. Bob
  16. BobK

    Start up I/O lines of PIC micro

    LATA = 0xFF; // set port A outputs to high TRISA = 0; // set port A to output Bob
  17. BobK

    Touchscreen Digital Multimeter Product.

    And what problem is it Which would be done by a camera, not by the scalpel. Bob
  18. BobK

    Connect 12V LEDs to 2 12V car deep cycle batteries

    And make sure the strips are the same kind and the same length. Otherwise they will not split the voltage equally. Bob
  19. BobK

    Touchscreen Digital Multimeter Product.

    No, I would prefer to watch “Saturday Night Fever”, rather than a recording of the measurements taken on my multimeter. Bob
  20. BobK

    Touchscreen Digital Multimeter Product.

    Of course it is possible. The question would be, why would that be better than existing designs? Touch screens are used on phones, tablets etc. to maximize the area available for display of content, instead of taking up room for physical buttons. In a multimeter, this is not a problem, it...
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