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  1. flippineck

    choosing a resistor value

    Another possible sensor arrangement based on refraction http://sciencelearn.org.nz/Contexts/Light-and-Sight/Sci-Media/Images/Refraction-of-light-in-water Fit some sort of light beam at an appropriate height just above the 'full' mark, with the beam angled down slightly. The beam should then...
  2. flippineck

    choosing a resistor value

    Could you place the dog bowl on some kind of plinth containing the sensor out of a set of kitchen scales, and use the arduino to look at the weight in grammes?
  3. flippineck

    One shot one day segment timer

    Not sure if anybody makes a timer like this.. You know those plug-in mains timers that work mechanically, like a 24hr clock face & have a ring of tiny 15-minute segments you can click out for 'on' and in toward the centre for off? I'm looking for one that only stores 'on' settings for a day on...
  4. flippineck

    reflowing a board

    I have a board which was built around 2000. It's a control board for a boiler. It has some kind of microprocessor (size and format of a Z80), and a bunch of assorted discrete passive components and semiconductors - some surface mount, some with thru hole wire leads. I'm suspecting the fault I...
  5. flippineck

    Female barrel connector

    One I fixed not too long ago was a PA-something, not sure if it was PA-12 2 things to note - ISTR there were two different options, one was a circular plug and the other was either hexagonal or octagonal. depends on your particular psu / laptop. & the other thing was, the jack actually had...
  6. flippineck

    Combining two ac sources rectifier

    How would one reconcile any random phase and frequency difference between the supplies?
  7. flippineck

    Combining two ac sources rectifier

    I think you are trying to do what I was trying to do with grid power and inverter-based solar power as the sources. Somehow tie them in together in a seamless way such that the load would not 'notice' if one source ceased to provide supply whilst the other 'took up the slack' whilst, taking...
  8. flippineck

    LC Resonance Signal Origin Detector

    I feared as much :-( reciprocal of (6.2831 * root LC) with L in henries and C in farads would give me the resonant frequency in hertz if I wanted to play around with values? Is there an easy way to calculate the inductance value of a simple air cored inductor (e.g. copper wire wound round a...
  9. flippineck

    LC Resonance Signal Origin Detector

    Would I be able to conveniently use a small coil of wire (with or without a ferrite etc. core) in parrallel with a capacitor to detect the strength of a radio transmission at a particular frequency, from a particular direction, if I had some kind of shielding behind it? I was thinking of...
  10. flippineck

    Coax Collinear Antenna

    Slightly off-topic relative to the current thread, but I had something of an epiphany in my understanding of the workings of antennas and radio waves last night, whilst watching a 1940's Canadian Air Force training video. I could never quite 'get' how a radio wave could travel through anything...
  11. flippineck

    Coax Collinear Antenna

    Thanks chaps. Dave, see the copper tube balun bit, for matching the feedline - how do you calculate the dimensions for that bit? Nice yagis on your page btw.. I tried some yagis here on my application (mobile network voice / data) but found them unsuitable because the transmitters I'm trying to...
  12. flippineck

    Coax Collinear Antenna

    it's a case of going from push - pull - push - pull in a plain wire, to swapping round every half cycle so the continuous length presented to the aether goes push - push - push - push? is this the main part of the mechanics of the antenna? I can't help wondering what the ends do. sites often...
  13. flippineck

    Coax Collinear Antenna

    For example http://www.balarad.net/ There seem to be many variations of designs, many plans on the net for this type of vertical omnidirectional radio antenna. They all seem to share the common features, most notably a chain of elements each one half wavelength long. Loads of plans on the net...
  14. flippineck

    How to have a single switch to open/close several lines at the same time

    I don't know if any of these would be useable and cost effective; http://uk.farnell.com/jsp/search/browse.jsp?N=202783...
  15. flippineck

    pcb board coatings

    http://www.paryleneengineering.com/pdf/conformal_coating_removal_techiques.pdf
  16. flippineck

    pcb board coatings

    are you able to read the chip with it still connected in-circuit? could you make a jig that employed sharp points like needles precisely placed? do away with the actual need to remove conformal coating, just punch through it? admittedly this'd be somewhat of a feat of precision engineering but...
  17. flippineck

    LED control chip?

    Image attached, it's the 8-legged chip I'm trying to identify. The board is a power supply taken out of the base of an E27 screw-in domestic lightbulb. The closest I can get to ID'ing it by sight is: 1st line Character 1: "C" or "E" Character 2: "P" of "F" Characters 3 thru 6: Definitely...
  18. flippineck

    Dimmable mains LEDs

    Trip to the supermarket, bought a bog standard inline dimmer (leading edge chop / triac type? a guess - no info in pack. Cost a fiver i.e. next to nothing) Fitted it expecting a bang when I threw the breaker back on. Works! Well, works good enough for my needs There's noticeable mains...
  19. flippineck

    Dimmable mains LEDs

    sorry about double post.. couldn't edit. I've tried what I believe to be a trailing-edge dimmer with a push on-off and rotary dim action on the same knob. http://www.answers.com/Q/Trailing_edge_dimmer_how_does_it_work...
  20. flippineck

    Dimmable mains LEDs

    I had an idea. Could I drive a small transformer, say a 6:1 turns ratio, off the dimmer then drive the LEDs off the transformer secondary? Or, have the transformer in front of the dimmer? I thought that might bring the AC input voltage range down to a suitable level whilst preserving efficiency?
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