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  1. kellys_eye

    Faulty Charging Circuit

    I don't trust your schematic. This is why the pcb layout is necessary.
  2. kellys_eye

    Progress

    Preaching to the converted here....!!! I also wander (read- get dragged) around the likes of Ikea and always look at the goods with an eye for using it for 'other purposes'....
  3. kellys_eye

    Why we talk about Quasi TEM instead of TEM in patch antennas?

    http://www.rfwireless-world.com/Terminology/difference-between-TEM-wave-and-quasi-TEM-wave.html ...explains it very well. Basically the differences in dielectric medium 'surrounding' the radiative conductor. In coaxial cable the dielectric is 'constant' but for strip lines (patch antennas)...
  4. kellys_eye

    9v Battery mystery

    Measure the battery voltage (disconnected) and also when it is connected IN circuit. Some battery chemistries don't deliver a true 9V - many are 8.7V or something equally silly and the circuitry in the controller may be set for a certain type of battery. Whilst they may all be labelled as...
  5. kellys_eye

    voltage regulator at 4.3V and 0.7V from 5V input that can handle inputs up to +-12V

    Please do. How is it a power supply? As I see it the circuitry around U10 shows a voltage reference used to compare the relevant logic levels and U10 pin 13 is even connected to a logic gate output (U12) - when has a logic gate output ever been driven by a 'supply'? U12 output can be 1 (5V -...
  6. kellys_eye

    9v Battery mystery

    Do you have a test meter?
  7. kellys_eye

    FM Power

    Just ask the driver to change to the station you all like. Or take a boom box and 'wind the volume up'. We won't assist anyone to break laws where we think they may apply.
  8. kellys_eye

    Help Identifying MOSFET ?

    No, you can't use triacs in place of MOSFETs. I have dozens of recycled MOSFETS that would work in that situation. Many can be found in old computer UPS devices but MOSFETS aren't expensive and ARE easily available. Go to a site like Farnell (UK) and use their parametric search facility where...
  9. kellys_eye

    LED buck drivers and reducing current

    Purely resistive elements will not affect slew rate - unless there's a high reactive element of the resistance itself (wire-wound) but, even then, it would be well outside any operating (switching) frequency range that could make a difference - for normal PWM systems anyway. The difference in...
  10. kellys_eye

    Help Identifying MOSFET ?

    You can use a device with higher ratings for voltage AND/OR current - more is better! What you should take care of doing is ensuring that the Rds(on) value is in the milli-ohm region (the MOSFETS 'on resistance') as this determines the power dissipated in it. The fact that they are currently...
  11. kellys_eye

    FM Power

    Suggest you re-read the local laws as I suspect it also has very strict limitations on you interfering with other peoples reception of legally transmitted signals i.e. deliberately over-riding the bus radio. You may be allowed to transmit on the FM band but NOT to interfere with other signals.
  12. kellys_eye

    LED buck drivers and reducing current

    Reducing the current is a good idea and dropping it 10% is unlikely to make a noticeable difference to light output. You 'could' use a resistor but since Men Well do many other current ranges and 1400mA seems a nice round number, why not just use the correct device without a resistor?
  13. kellys_eye

    Signal mixer, voltage mixer.

    Not DC 'noise' but any DC 'component' that may take the peaks of the actual signal beyond the clipping level of the input.
  14. kellys_eye

    Dvd disc froze, need help

    There are FOUR instances of that movie currently listed on a not-to-be-mentioned 'bay' (and I don't mean 'e') if you need a source....:cool: As mentioned, if you already own it I don't see an issue with downloading a 'repair' of it regardless of how/where you get it. I've had some success...
  15. kellys_eye

    D-sub crimping+connecting practice & choice of tools

    You can also get D-sub connectors with IDC (ribbon cable) termination. These are far faster and easier to make up and with less chance of error. This might also prove useful at the 'other end' of the cable where you don't specify the connected item/devices but could be connected to board via...
  16. kellys_eye

    Signal mixer, voltage mixer.

    Capacitors block the flow of DC.
  17. kellys_eye

    Progress

    I like your approach. Too often I spent time trying to make my home-made equipment look 'professional' rather than concentrating on it actually working properly! I've lost count of the number of iterations of power supply that I've 'packaged' when it works perfectly well regardless of whether...
  18. kellys_eye

    Nostalgia

    I trust you mean your BBC Model (whatever) computer....... the BBC themselves are pariah purveyors of fake news.... I remember seeing a BBC Model A installed in our (lecturers) day room sometime in 1986(?) as a test bed for us to play with. IIRC our college computer labs were fitted out with...
  19. kellys_eye

    Nostalgia

    show us your internet history.......:D:p
  20. kellys_eye

    voltage regulator at 4.3V and 0.7V from 5V input that can handle inputs up to +-12V

    The power monitoring device U10 is being used to check the logic level signal inputs and ensure that they are within the +/-10% tolerance allowed for logic 1 and 0 in a 5V logic system. Pin 23 of A3, A4 and A5 (et al) is tied to ground via R6 (200Ω) - this gives the 'logic 0' level of 0.7V that...
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