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  1. kellys_eye

    Stepping up the voltage for a Geiger Counter

    No, it's unlikely to be a scam. AliExpress operate an 'escrow' payment system such that if you find the product to be defective you WILL be refunded. All you have to do is report the fact the item is dud. The board looks to me to have a simple oscillator and multi-stage rectifier arrangement...
  2. kellys_eye

    555 timer one shot question

    The 'repeat delay' can't be disabled (AFAIK) so keeping your foot on the switch would eventually result in the page turning at some inconvenient time. As you surmise you need a monostable - non-retriggerable (or one-shot) - that requires the footswitch to be lifted and pressed AGAIN for the...
  3. kellys_eye

    Upgrading the plates on hairstraightners

    You can change the 'plates' but all you'd be doing is spreading the same amount of heat (from the element) over a larger area and thus exposing it to greater cooling - nett result being a COOLER plate OR the element would burn out as it doesn't have sufficient output to reach the...
  4. kellys_eye

    What would be the best soldering iron for $200 and under?

    Funny..... I managed to solder properly using an Antex 25W iron for over 30 years. None of the 'temperature control' stuff. It's all down to technique. The propensity for soldering 'stations' is marketing hype for the most part - none of them make you a better solder-er. The only time I've...
  5. kellys_eye

    Simple solution to send a short pulse to Solenoid for n milliseconds?

    Monostable, non-retriggerable. Can be programmed into an Arduino but there are a multitude of discrete circuit - and simple IC circuits like the 555 - that can do it.
  6. kellys_eye

    4 Channel Car Amp not outputting

    32V across the capacitors seems about right to me. Given that there are four identical amplifiers and the odds on all four going mammaries skywards is relatively low, you should be able to identify ONE complete amplifier section and do comparison readings on the others. That said, with ZERO...
  7. kellys_eye

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

    ...they come from the HARDWIRED R6 and R7 connected to +5V and ground..... sheesh...:rolleyes: Try Googling 90004-8076 and see what others have to say about it..... same as us, basically.
  8. kellys_eye

    Twilight zone predictions

    "Bitcoin - the solution to all the worlds financial ailments..."
  9. kellys_eye

    Troubleshoot an amplifier

    Yes, we know. You already started a thread about it.......
  10. kellys_eye

    Inverter in vintage mashine(exchanging original part with equivalent)

    The (eBay) rectangular LEDs look perfectly suitable and could be hot-melt glued onto the edge of the pcb. One at either end (or two - depends on how bright you think the display backlight should be) and a simple series resistor..... job done.
  11. kellys_eye

    Faulty Charging Circuit

    First picture lacks focus. The other two have someone's hand in the way.......
  12. kellys_eye

    Inverter in vintage mashine(exchanging original part with equivalent)

    hmmmm. electroluminescent backlighting eh... 'obsolete' technology, replaced by LED backlighting these days. Judging by the video it seems eminently possible to fit a couple of rectangular LEDs at each end of the display panel and 'edge light' it rather than 'back light' it. Couple of LEDs...
  13. kellys_eye

    Morphy Richards electric blanket controller pcb fault BEPCB020

    'Any' fault in electric blankets has the potential for disastrous consequences and should really be addressed by replacement. Clearly the controller isn't faulty so the blanket itself is - this is something a competent electrical shop should have been able to diagnose. Don't take risks...
  14. kellys_eye

    Rubber glue for holding wires on ICs/PCBs?

    'Evo Stik' was commonly used by the old British Post Office for securing telephone cables along flat surfaces (honestly!) before common sense prevailed and they started using proper clips. But Evo Stik - the stuff that sets reasonably 'hard' and looks like sticky brown toffee - is still found...
  15. kellys_eye

    Inverter in vintage mashine(exchanging original part with equivalent)

    What are the input/output voltages, currents and/or frequency of the inverter? Generally you can get 'inverters' for most applications so a replacement 'should' be available although the pin outs may well differ (show the bottom of the board). Please also show us more about the LCD - what type...
  16. kellys_eye

    Help Identifying MOSFET ?

    Don't test them on a resistance range. You should have a 'diode check' range on your meter, use that. One of the most useful purchases I made recently was this...
  17. kellys_eye

    Need Help Identify a Capacitor and a Resistor

    I see 2.2MΩ and 12pF. More to the point, can you show us more of the circuit board or at least tell us where/how the parts are being used and why you think they are defective (apart from the broken lead, obviously).
  18. kellys_eye

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

    U12 pin 8.....
  19. kellys_eye

    What vibration sensor for bearing monitoring

    AFAIK they use piezo transducers and monitor the frequency of the signal to detect vibrations.
  20. kellys_eye

    Signal mixer, voltage mixer.

    I presume you're referring to the DC level at the output? If so, that's why capacitors are fitted in audio circuit inputs - it blocks the DC part and only allows the 'AC' part of the signal to pass. Since signal generators have to cover a multitude of functions then the better models actually...
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