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  1. kellys_eye

    Operational Amplifier Internal Resistance

    "Using circuit laws and properties of op-amps....." The basic property of an ideal op-amp input resistance is that its value is 'infinite' and its output resistance is zero (gain, of course, is infinite too) - hence the input terminal theoretically draws no current and is often referred to as a...
  2. kellys_eye

    Which programmer is needed to write in Broadcom chip

    It's more to do with the protocol than the programmer. It could be RS232, it could be SPI it could be ICSP, it could even require chip removal and the appropriate EPROM reader/programmer? What device is it? Are there any in-circuit programming port pins on the PCB?
  3. kellys_eye

    Relay Assistance

    Connect your LED to the 24V supply via a 1kΩ resistor. As soon as the 24V supply is on (i.e. relay activated) the LED will light. No extra relay, no problem with the LED.
  4. kellys_eye

    Wiring buttons or switches to turn certain things on

    Not quit that simple I'm afraid. The XBox is unlikely to simply boot at switch on, requiring the 'on' button to be pressed. I don't have the latest XBox so can't confirm this but if it IS the case then you'll have some additional work to do..... A 'posh' way to do it would be to get two...
  5. kellys_eye

    Geriatric and forgetful

    Sorry to hear of your husbands condition. Any 'device locator' will necessarily require to transmit a signal you can 'locate' and this limits the range if the locator is to be small enough to be acceptable - it's easy to bolt an old CB Radio to a set of keys.... the battery and antenna...
  6. kellys_eye

    Westinghouse 4k TV cycling through different colored screens.

    If you touch the internals you'll void any warranty that you're legally entitled to. I don't think any modern country would allow manufacturers to ignore their legal status of upholding the warranty terms. Check the small print and Google your legal status re warranty issues - here in the UK...
  7. kellys_eye

    Relay Assistance

    No extra relay required. Just fit the appropriate resistor for the LED to operate at 24V and connect it across the relay coil. If it is a 'true' 12V LED then it will already have a series resistor fitted (soldered to one pin?) that allows it to operate at 12V. You could find that resistors...
  8. kellys_eye

    XTW-SY-8 POT

    Note to all - the XTW-SY-8 is a DC-DC converter module using the XL6009 chip. If turning the pot down doesn't stop it getting hot then you've destroyed the device.
  9. kellys_eye

    Illuminated DPDT Switch

    Connect the battery negative(s) to the spare 'middle' contact on both switches.
  10. kellys_eye

    Westinghouse 4k TV cycling through different colored screens.

    Barely a year old. Isn't there a warranty on it? If you're anything like the UK then the warranty has to be upheld by the supplier - not the manufacturer.
  11. kellys_eye

    No power

    This inability to post sufficient information and/or form a structured sentence describing the problem(s) appears to be a growing trend...... milleniums perhaps? :D
  12. kellys_eye

    Current flow in or out?

    Depends on the frequency. What you're suggesting is called 'skin effect'.
  13. kellys_eye

    Help on my mini project

    Ever heard of 'tolerance' - like maybe 10%......
  14. kellys_eye

    Project Qns! HELP needed!

    What qualification do we get for doing your project?
  15. kellys_eye

    Satellite and Radio signal

    LOCAL weather conditions - we frequently lose our satellite reception in heavy down pours or thick snow conditions. But, then again, we're located quite far North so the satellite is 'low' in the sky and the atmospheric transmission path that much longer than for 'equatorial' situated receivers.
  16. kellys_eye

    scroll saw blowing fuses

    Three year warranty on Aldi stuff - you could take it back....
  17. kellys_eye

    No power

    Is the polarity of the (new) plug the same as the old? Many battery/mains powered equipment have a power plug that is CENTRE-PIN-NEGATIVE whilst most modern power packs have a CENTRE-PIN-POSITIVE connection.
  18. kellys_eye

    resistor decade pack

    As above. They come in many forms, from home made versions to precision, calibrated versions and prices will range from $10 to $200 accordingly. They are quite sought after (if they are the 'right' device) and putting it up on eBay will get you its true worth. Do a search on eBay for similar...
  19. kellys_eye

    Yorkville 100watt Mixer/Amp - Replaced Transistors

    The TO92 packaged devices are notorious (in my experience) for not having the pinouts you expect - often the base wire is at one side, collector in the middle etc. Best solution would be to purchase anew BC550 and test its pin out before fitting it. If the 'replaced' BC550 has been inserted...
  20. kellys_eye

    Driving a high power semiconductor laser

    The only possible use for a laser based on a question like that is one of offensive capability. Suggest the Mods make the final decision on this one....
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