Search results

Search Forums New Posts
  1. kellys_eye

    transister eqvilant

    Check out this thread for full details: https://www.electronicspoint.com/threads/need-help-with-repair.270516/
  2. kellys_eye

    Transceiver Circuit

    Not sure what your problem is? In transmit, you have to look at the circuit with the 'arrows' connected to the points marked 'T' and for receive you look at the circuit with the 'arrows' connected to the points marked 'R'. It may be a useful exercise for you to print out two copies of the...
  3. kellys_eye

    MAX883C/D (Just because!)

    .... or 'COB' as it is known (chip on board). I'm getting too long in the tooth for some of the modern IC packages. I've hand soldered 48-pin chips with a 0.5mm pin pitch (successfully and rather to my surprise too!) but some of the ball-grid array stuff makes me despair. Fortunately, for...
  4. kellys_eye

    2.4 ghz point detection

    You can measure the EM waves 'anywhere' - your problem is resolution of measurement. The principles used in yagi antennas will give you a 'directed beam' both for detection of and radiation of RF energy. Have you looked at 'cantennas'? These are where the radiative element (dipole) is placed...
  5. kellys_eye

    3D Printer Thread

    I think current technology such as ink deposition or even laser etching will always be preferred over using a 3D printer. PCB printing is only 2D after all.
  6. kellys_eye

    Looking for variable frequency transducers or mini speakers

    Unless you have a specific requirement for audio reproduction - measurement, medical, scientific etc - then 'any' speaker set will probably work. Normally you won't find the detailed specifications of 'cheap' speaker sets other than a statement that indicates (say) 300Hz-18kHz - 'proper'...
  7. kellys_eye

    Looking for variable frequency transducers or mini speakers

    That's called a 'loudspeaker' then. You can use a single wide-range device or a selection (low, mid and high frequency) of speakers and an appropriate cross-over filter.
  8. kellys_eye

    PLC

    Change the power supply.
  9. kellys_eye

    2.4 ghz point detection

    S-band and X-band radars are used in the marine field. Beam widths of <1 degree.
  10. kellys_eye

    For Sale: Electrial Engineer's entire Lab; equipment, instruments & components

    These situations always sadden me. The bereaved relatives are probably unaware of the value but equally can often be disappointed at the relatively low sums the sale of which may return. The only 'satisfactory' method of disposal I've ever come across is by donation to worthy causes - a local...
  11. kellys_eye

    Denon AVR-X500 repair!

    Can you post pictures of the power supply board? I'm not even sure we can help you here as unless you can make the tests and repairs we suggest then you'll have to hand it over to another competent person to do it for you - and if they are truely competent they could/would be able to fix it...
  12. kellys_eye

    Delay timer relay control connection problem

    If the timer control has simple normally-open contacts then you don't need the 12V adapter for the 'trigger' voltage - all you need do is feed the 12V from the 'top' 12V adapter to the trigger input via the n.o contacts in the timer controller. It may be that the timer used in the example shown...
  13. kellys_eye

    12V-5V converter

    Dropping 7V at 3A will dissipate 21 watts in an LM317 circuit so that pretty much rules it out if heatsinking is a particular issue to be avoided. An SMPS is perhaps the only way to go but even then it will be of the order 80-90% efficient so perhaps 2W to dissipate, perhaps less if you are...
  14. kellys_eye

    2.4 ghz point detection

    2.4GHz is 'radar' frequency band stuff therefore slotted waveguides will provide a very narrow beam width. The only other practical way to get such a narrow beam would be to use a microwave dish antenna.
  15. kellys_eye

    Looking for variable frequency transducers or mini speakers

    What is the intended purpose for the transducer?
  16. kellys_eye

    Why I don't like wall warts

    Producing the specc's of such PSU's uses pretty much the techniques but the larger the PSU (in terms of power output) the larger the load needed to test it. You can add simple loads like light bulbs (car bulbs are good) but it limits you to doing it in steps rather than a continuous sweep...
  17. kellys_eye

    Why I don't like wall warts

    Not just power supplies - everything is built to 'standard's that you need to know about if you want to meaure them or incorporate devices into your own designs. In the UK, equipment is usually to BS**** (not a swear word!) British Standard which, if you can get hold of them, tell you what you...
  18. kellys_eye

    Why I don't like wall warts

    The 'ohms' readings.... are these your calculations or are these the actual resistors you used to load the output? Per usual specifications you have to account for a 5% drop in output voltage at the maximum load before specifying the actual rating. In other words, load the output until it...
  19. kellys_eye

    ETI magazine Feb 1979 - power supply (ETI-142)

    Could it be classified as 'vintage' as far as electronics are concerned? The designation seems pretty vague these days but as far as usable power supplies go that model seems to be very well specc'd and worth the effort to fully restore. I have a hankering to knock up the mini oscilloscope...
  20. kellys_eye

    Help with my University Project !!

    The term 'buffer' refers to any device that can increase the drive voltage or current with little/no effect on the source signal. You can get inverting and non-inverting, logic level, open-collector etc etc so as far as 'buffering' is concerned you can drive anything - a few extra LED boards...
Top