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  1. kellys_eye

    Solar charged battery with AC outlet

    Start with a block diagram that shows the individual elements of the overall system that you want. Solar panels - rectifier - power converter/controller - inverter etc Then add the parameters that feel are necessary to do what you want it to do - starting at the 'end' and determining the...
  2. kellys_eye

    Issue in running BLDC motor with microcontroller

    Can your motor power supply deliver sufficient start-up current? This can be many times larger than the steady-state value.
  3. kellys_eye

    Pool shooting robot needs help with rail-gun pool-cue thruster

    By having a mechanical (electrically controlled of course) system of spring compression - but with the position of spring also adjustable - you can get different stroke length and power. I'm envisioning a fixed length spring (compressible) with a variable back-stop for pre-load. You could even...
  4. kellys_eye

    Is a 3000 watt 12v to 120 inverter really just 2 1500 watt inverters ?

    Kiwi is in the right area - the manufacturers may have a DC-equivalent system that you can swap the motor with however this would require substantial rewiring and control systems. I can see why the OP is asking the questions. Gensets for marine use are no different (really) than any other but...
  5. kellys_eye

    Limiting the movement of a motor.

    Indeed they do. Those servos are self-contained but, whilst they might work on a PID basis, as far as the user is concerned it's just a 'pulse position' system. The feedback signal isn't passed 'back' to the user.
  6. kellys_eye

    Hantek scope keeps ticking and wont turn on.

    If it happens intermittently then the bloated capacitor issue is highly likely to be the cause. It's a fairly simple (assuming dismantling is easy...) to swap out all the relevant capacitors for identical (but better quality) replacements. This is not explicitly THE answer but taking it apart...
  7. kellys_eye

    Android tablet pcb

    I've come across similar problems at startup on low-end models that relate to the USB charger socket and daughter board it's all constructed on. Faults like this are quite common - enough so that after-market suppliers offer replacement boards (modules) for a straight swap-out repair.
  8. kellys_eye

    Hantek scope keeps ticking and wont turn on.

    Generally indicative of a fault in the SMPS - common faults being the usual 'bloated capacitor syndrome' although any short circuit or over-voltage situation can cause the same symptoms so opening it up and making a few tests is the next step. The capacitor issue is fairly easy to recognise on...
  9. kellys_eye

    Limiting the movement of a motor.

    The servo I reference to is the type as used in radio controlled models where the position is purely a function of the pulse width applied.
  10. kellys_eye

    Multi meter question?

    Yeah - that's the quote. Being as old as I am my hearing doesn't encompass high frequencies very well these days so I tend to miss the exact nuances of Dave's utterings.....
  11. kellys_eye

    Multi meter question?

    Bouncing mV is quite common - what does it read with the leads shorted? Have you checked the Hylec against any other reliable power supply, just to be sure the Tenma is ok? If the PSU is outputting what it's meant to be then the error is rather high on the Extech so as someone once said -...
  12. kellys_eye

    Android tablet pcb

    What make/model Android tablet? Have you Googled for common startup faults associated with your particular device?
  13. kellys_eye

    Serial communication problem.

    The 74LS series won't do true serial due to supply line limitations (no ability to go 'negative') but is ok for 'fake' serial lines (i.e. TTL levels) but there are many dedicated devices that do. The MAX323, MAX324 and MAX325 are all suitable according to your 'polarity' requirement. See the...
  14. kellys_eye

    Limiting the movement of a motor.

    Two ways. Servo motor or stepper motor. The servo motor requires a pulse width signal - the width of the pulse determines the absolute position of the motor shaft. The stepper motor requires individual pulses (and a circuit to count them) sent in a specific pattern to enable rotation in one...
  15. kellys_eye

    How do I replace this pot with 2 knob pots, coarse fine.

    Don't. Just fit a 10-turn potentiometer in its place.
  16. kellys_eye

    Serial communication problem.

    The net effect you're looking for is to replace SW3 and SW4 (or add in series) with the bi-directional (tri-state) buffers, the enable line(s) of which are connected to the supply feed to the MAX device such that when the power is off the buffers are in their tri-state mode and thus 'isolating'...
  17. kellys_eye

    Serial communication problem.

    The MAX device will only operate in a known state whilst powered up. When powered down you don't know what condition the various pins attain (the datasheet may well reveal all) but it's obvious that the device, in it's powered down state, is affecting the data lines (loading them). The use of...
  18. kellys_eye

    Serial communication problem.

    You should use bi-directional data buffers for each serial data path and enable them as required via the power line (and an inverter gate between both enable lines). Paralleling serial data lines is a 'no-no' (technical term)
  19. kellys_eye

    sleep mode for PIC

    The datasheet should specify the various requirements and/or configurations for sleep mode. What does the manufacturer say?
  20. kellys_eye

    Pool shooting robot needs help with rail-gun pool-cue thruster

    I'd consider using some form of control for the discharge rather than the 'brute force' method as you will have much more control over the cue ball. If you consider a simple loudspeaker and how it operates, you can easily see the cone movement on larger speakers so consider the possibility of a...
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